Do not process commands coming from ourselves (help text)

Quite a few changes involved. Mostly variable renames and a few changes to `await`s.

Not ready yet because bot cannot login due to some arcane error of `expected value at line 1 column 1`.

Co-authored-by: projectmoon <projectmoon@noreply.git.agnos.is>
Reviewed-on: #98

.drone.yml

@@ -0,0 +1,27 @@
+kind: pipeline
+name: build-and-test
+
+steps:
+- name: test
+  image: rust:1.80
+  commands:
+  - apt-get update
+  - apt-get install -y cmake
+  - rustup component add rustfmt
+  - cargo build --verbose --all
+  - cargo test --verbose --all
+
+- name: docker
+  image: plugins/docker
+  when:
+    ref:
+    - refs/tags/v*
+    - refs/heads/master
+  settings:
+    auto_tag: true
+    username:
+      from_secret: docker_username
+    password:
+      from_secret: docker_password
+    repo: ghcr.io/projectmoon/chronicle-dicebot
+    registry: ghcr.io

.env

@@ -0,0 +1,2 @@
+DATABASE_URL="sqlite://test-db/dicebot.sqlite"
+SQLX_OFFLINE="true"

.github/workflows/dicebot-ci.yml

@@ -0,0 +1,68 @@
+name: Dicebot CI
+
+on:
+  push:
+    branches:
+      - master
+
+    # Publish `v1.2.3` tags as releases.
+    tags:
+      - v*
+
+  # Run tests for any PRs.
+  pull_request:
+
+env:
+  IMAGE_NAME: chronicle-dicebot
+  CARGO_TERM_COLOR: always
+
+jobs:
+  build_and_test:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Build
+      run: cargo build --verbose
+    - name: Run tests
+      run: cargo test --verbose
+
+  # # Push image to GitHub Packages.
+  # # See also https://docs.docker.com/docker-hub/builds/
+  # push:
+  #   # Ensure test job passes before pushing image.
+  #   needs: build_and_test
+
+  #   runs-on: ubuntu-latest
+  #   if: github.event_name == 'push'
+
+  #   steps:
+  #     - uses: actions/checkout@v2
+
+  #     - name: Build image
+  #       run: docker build . --file Dockerfile --tag $IMAGE_NAME
+
+  #     - name: Log into GitHub Container Registry
+  #     # TODO: Create a PAT with `read:packages` and `write:packages` scopes and save it as an Actions secret `CR_PAT`
+  #       run: echo "${{ secrets.CR_PAT }}" | docker login https://ghcr.io -u ${{ github.actor }} --password-stdin
+
+  #     - name: Push image to GitHub Container Registry
+  #       run: |
+  #         IMAGE_ID=ghcr.io/${{ github.repository_owner }}/$IMAGE_NAME
+
+  #         # Change all uppercase to lowercase
+  #         IMAGE_ID=$(echo $IMAGE_ID | tr '[A-Z]' '[a-z]')
+
+  #         # Strip git ref prefix from version
+  #         VERSION=$(echo "${{ github.ref }}" | sed -e 's,.*/\(.*\),\1,')
+
+  #         # Strip "v" prefix from tag name
+  #         [[ "${{ github.ref }}" == "refs/tags/"* ]] && VERSION=$(echo $VERSION | sed -e 's/^v//')
+
+  #         # Use Docker `latest` tag convention
+  #         [ "$VERSION" == "master" ] && VERSION=latest
+
+  #         echo IMAGE_ID=$IMAGE_ID
+  #         echo VERSION=$VERSION
+
+  #         docker tag $IMAGE_NAME $IMAGE_ID:$VERSION
+  #         docker push $IMAGE_ID:$VERSION

.gitignore

@@ -1,6 +1,14 @@
 target/
 dicebot-config
 todo
+todo.org
 cache
 *.tar
 *.tar.gz
+test-db/
+bot-db*
+# We store a disabled async test in this file
+bigboy
+.#*
+*.sqlite
+.tmp*

Cargo.toml

@@ -1,38 +1,6 @@
-[package]
-name = "chronicle-dicebot"
-version = "0.4.0"
-authors = ["Taylor C. Richberger <taywee@gmx.com>", "projectmoon <projectmoon@agnos.is>"]
-edition = "2018"
-license = 'MIT'
-description = 'A simple async Matrix dicebot'
-readme = 'README.md'
-repository = 'https://github.com/ProjectMoon/matrix-dicebot'
-keywords = ["games", "dice", "matrix", "bot"]
-categories = ["games"]
+[workspace]
 
-[dependencies]
-log = "0.4"
-env_logger = "0.7"
-toml = "0.5"
-nom = "5"
-rand = "0.7"
-thiserror = "1.0"
-itertools = "0.9"
-async-trait = "0.1"
-url = "2.1"
-dirs = "3.0"
-
-# The versioning of the matrix SDK follows its Cargo.toml. The SDK and
-# macros are on master, but it imports the common and base from 0.1.0.
-matrix-sdk = { git = "https://github.com/matrix-org/matrix-rust-sdk", rev = "master" }
-matrix-sdk-common-macros = { git = "https://github.com/matrix-org/matrix-rust-sdk", rev = "master" }
-matrix-sdk-common = { git = "https://github.com/matrix-org/matrix-rust-sdk", rev = "0.1.0" }
-matrix-sdk-base = { git = "https://github.com/matrix-org/matrix-rust-sdk", rev = "0.1.0", default_features = false }
-
-[dependencies.serde]
-version = "1"
-features = ['derive']
-
-[dependencies.tokio]
-version = "0.2"
-features = ["rt-core", "macros", "time", "signal"]
+members = [
+    "dicebot",
+    "rpc"
+]

Dockerfile

@@ -1,21 +1,16 @@
-# Builder image
-FROM bougyman/voidlinux:glibc as builder
-RUN xbps-install -Sy base-devel libressl-devel wget gnupg rustup
+# Builder image with development dependencies.
+FROM ghcr.io/void-linux/void-linux:latest-mini-x86_64 as builder
+RUN xbps-install -S
+RUN xbps-install -yu xbps
+RUN xbps-install -Syu
+RUN xbps-install -Sy base-devel rustup cmake wget gnupg
+RUN xbps-install -Sy openssl-devel libstdc++-devel
 RUN rustup-init -qy
 
 # Install tini for signal processing and zombie killing
-ENV TINI_VERSION v0.18.0
-ENV TINI_SIGN_KEY 595E85A6B1B4779EA4DAAEC70B588DFF0527A9B7
-RUN set -eux; \
-  wget -O /usr/local/bin/tini "https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini"; \
-  wget -O /usr/local/bin/tini.asc "https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini.asc"; \
-  export GNUPGHOME="$(mktemp -d)"; \
-  gpg --batch --keyserver ha.pool.sks-keyservers.net --recv-keys "$TINI_SIGN_KEY"; \
-  gpg --batch --verify /usr/local/bin/tini.asc /usr/local/bin/tini; \
-  command -v gpgconf && gpgconf --kill all || :; \
-  rm -r "$GNUPGHOME" /usr/local/bin/tini.asc; \
-  chmod +x /usr/local/bin/tini; \
-	tini --version
+ENV TINI_VERSION v0.19.0
+ADD https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini /usr/local/bin/tini
+RUN chmod +x /usr/local/bin/tini
 
 # Build dicebot
 RUN mkdir -p /root/src
@@ -24,7 +19,10 @@ ADD . ./
 RUN . /root/.cargo/env && cargo build --release
 
 # Final image
-FROM bougyman/voidlinux:latest
+FROM ghcr.io/void-linux/void-linux:latest-mini-x86_64
+RUN xbps-install -S
+RUN xbps-install -yu xbps
+RUN xbps-install -Syu
 RUN xbps-install -Sy ca-certificates libstdc++
 COPY --from=builder \
     /root/src/target/release/dicebot \
@@ -34,4 +32,5 @@ COPY --from=builder \
     /usr/local/bin/
 
 ENV XDG_CACHE_HOME "/cache"
+ENV DATABASE_PATH "/cache/bot-db"
 ENTRYPOINT [ "/usr/local/bin/tini", "-v", "--", "/usr/local/bin/dicebot", "/config/dicebot-config.toml" ]

LICENSE

@@ -1,3 +1,16 @@
+This software is governed by the terms of the Affero GNU General
+Public License. Portions of the code come from the original
+MIT-licensed project, and the terms of the MIT license also apply to
+those portions. In files that are partially or wholly subject to the
+MIT license in addition to the Affero GNU General Public License, this
+is noted with a header at the top of the file.
+
+Original upstream project: https://gitlab.com/Taywee/axfive-matrix-dicebot
+
+For code from the original project that is governed by the MIT license
+in addition to the Affero GNU General Public License, the following
+terms apply:
+
 MIT License
 
 Copyright (c) 2020 Taylor C. Richberger
@@ -19,3 +32,668 @@ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
+
+The project as a whole is governed by the terms of the Affero GNU
+General Public License:
+
+                    GNU AFFERO GENERAL PUBLIC LICENSE
+                       Version 3, 19 November 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
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+<https://www.gnu.org/licenses/>.

README.md

@@ -1,12 +1,103 @@
-# axfive-matrix-dicebot
+# Tenebrous Dicebot
 
-This is a fork of the
-[axfive-matrix-dicebot](https://gitlab.com/Taywee/axfive-matrix-dicebot)
-with basic support for the Chronicles of Darkness 2E Storytelling
-System, with future plans to extend the codebase further to support
-variables and perhaps character sheet management. It also contains
-various fixes, uses the Matrix SDK for connectivity, and has a Docker
-image.
+[![Build Status](https://drone.agnos.is/api/badges/projectmoon/tenebrous-dicebot/status.svg)](https://drone.agnos.is/projectmoon/tenebrous-dicebot)
+[![Matrix Chat](https://img.shields.io/matrix/tenebrous:agnos.is?label=matrix&server_fqdn=matrix.org)][matrix-room]
+
+_This repository is hosted on [Agnos.is Git][main-repo] and mirrored
+to [GitHub][github-repo]._
+
+This is a dice rolling bot for facilitating roleplaying games on the
+Matrix messaging platform. It currently has basic support for the
+Chronicles of Darkness 2E Storytelling System and Call of Cthulhu,
+with plans to extend the codebase further to support other systems and
+character sheet management.
+
+## Features
+
+`tenebrous-dicebot` is a dice rolling bot for facilitating
+role-playing games over Matrix (and anything that Matrix can bridge
+to, like Discord). It currently has the following features:
+
+* Rolling arbitrary dice expressions (e.g. 1d4, 1d20+5, 1d8+1d6, etc).
+* Rolling dice pools for the Chronicles of Darkness 2E Storytelling
+System.
+* Rolling dice for the Call of Cthulhu system.
+* Works in encrypted or unencrypted Matrix rooms.
+* Storing variables created by the user.
+
+## Support and Community
+
+The project has a Matrix room at [#tenebrous:agnos.is][matrix-room].
+It is also possible to make a post in [GitHub
+Discussions][github-discussions].
+
+For reporting bugs, we prefer that you open an issue on
+[git.agnos.is][agnosis-git-issues]. However, you may also open an
+issue on [GitHub][github-issues].
+
+### Development and Contributions
+
+All development occurs on [git.agnos.is][main-repo]. If you wish to
+contribute, please open a pull request there. In some cases, pull
+requests from GitHub may be accepted. All contributions must be
+licensed under [AGPL 3.0 or later][agpl] to be accepted.
+
+## Building and Installation
+
+### Docker Image
+
+The easiest way to run the dice bot is to use the [official Docker
+image][docker-image]. It is distributed on GitHub Container Registry
+by a CI pipeline.
+
+The `latest` tag always points to the most recent successfully built
+master commit and is considered unstable, while individual tags are
+considered stable.
+
+* Unstable: `docker pull ghcr.io/projectmoon/chronicle-dicebot:latest`
+* Stable: `docker pull ghcr.io/projectmoon/chronicle-dicebot:X.Y.Z`
+
+This image is based on [Void Linux](https://voidlinux.org/). To build
+the image yourself, run `docker build -t chronicle-dicebot .` in the
+root of the repository.
+
+After pulling or building the image, see [instructions on how to use
+the Docker image](#running-the-bot).
+
+### Install from crates.io
+
+The project can be from [crates.io][crates-io]. To install it, execute
+`cargo install tenebrous-dicebot`. This will make the following
+executables available on your system:
+
+* `dicebot`: Main dicebot executable.
+* `dicebot-cmd`: Run dicebot commands from the command line.
+* `dicebot_migrate`: Standalone database migrator (not required).
+* `tonic_client`: Test client for the gRPC connection (not required).
+
+### Build from Source
+
+Precompiled executables are not yet available. Clone this repository
+and run `cargo install`.
+
+Building the project requires:
+
+* Basic build environment (`build-essential` on Ubuntu, `base-devel`
+  on Void and Arch, etc).
+* Rust 1.45.0 or higher.
+* OpenSSL/LibreSSL development headers installed.
+* `olm-sys` crate dependencies: cmake, libstdc++.
+* glibc.
+
+#### Why doesn't it build on musl libc?
+
+As far as I can tell, the project doesn't build on musl libc. It
+certainly doesn't build a static binary out of the box using the
+rust-musl-builder. This appears to be due to a transitive dependency
+of the Rust Matrix SDK.
+
+Any PRs to get the project or Matrix SDK to properly be built into a
+static binary using musl would be very useful.
 
 ## Usage
 
@@ -14,7 +105,12 @@ To use it, you can invite the bot to any room you want, and it will
 automatically jump in. Then you can simply give a dice expressions for
 either the Storytelling System or more traditional RPG dice rolls.
 
-The commands `!roll` and `!r` can handle arbitrary dice roll expressions.
+The bot supports a `!help` command for basic help information about
+its capabilities.
+
+### Basic Dice Rolling
+The commands `!roll` and `!r` can handle arbitrary dice roll
+expressions.
 
 ```
 !roll 4d6
@@ -22,76 +118,183 @@ The commands `!roll` and `!r` can handle arbitrary dice roll expressions.
 !r 3d12 - 5d2 + 3 - 7d3 + 20d20
 ```
 
+#### Keep/Drop Dice
+The bot supports either keeping the highest dice in a roll, or
+dropping the highest dice in a roll.  This allows the bot to handle 
+things like D&D 5e advantage or disadvantage.
+
+```
+!roll 2d20k1
+!r 2d20dh1 + 5
+!r 10d10k5 + 10d10dh5 - 2
+```
+
+### Storytelling System
+
 The commands `!pool` (or `!rp`) and `!chance` are for the Storytelling
 System, and they use a specific syntax to support the dice system. The
 simplest version of the command is `!pool <num>` to roll a pool of the
 given size using the most common type of roll.
 
-The type of roll can be controlled by adding `n`, `e`, or `r` after
+The type of roll can be controlled by adding `n`, `e`, or `r` before
 the number, for 9-again, 8-again, and rote quality rolls. The number
 of successes required for an exceptional success can be controlled by
 `s<num>`, e.g. `s3` to only need 3 successes for an exceptional
-success.
+success. All modifiers should come before the number, with a `:`
+colon.
 
 Examples:
 
 ```
-!pool 8     //regular pool of 8 dice
-!pool 8n    //roll 8 dice, 9-again
-!pool 8ns3  //roll 8 dice, 9-again with only 3 successes for exceptional
-!pool 5rs2  //5 dice, rote quality, 2 successes for exceptional
+!pool 8      //regular pool of 8 dice
+!pool n:8    //roll 8 dice, 9-again
+!pool ns3:8  //roll 8 dice, 9-again with only 3 successes for exceptional
+!pool rs2:5  //5 dice, rote quality, 2 successes for exceptional
+```
+
+### Call of Cthulhu System
+
+The commands `!cthRoll`, `!cthroll`, `!cthARoll` and `!cthadv` are for
+the Call of Cthulhu system. `!cthRoll` and `!cthroll` are for rolling
+percentile dice against a target number. A `b:` or `bb:` can be
+prepended to get one or two bonus dice.
+
+`!cthARoll` and `!cthadv` are for skill advancement.
+
+Examples:
 
 ```
+!cthRoll 50     //roll against a target of 50
+!cthRoll bb:60  //roll against a target of 60 with 2 bonus dice
+!cthARoll 30    //advancement roll against a target of 30
+```
+
+### User Variables
+
+Users can store variables for use with the Storytelling dice pool
+system. Variables are stored on a per-room, per-user basis in the
+database (currently located in the cache directory if using the Docker
+image).
+
+Examples:
+
+```
+!set myvar 5 //stores 5 for this room under the name "myvar"
+!get myvar //will print 5
+```
+
+Variables can be referenced in dice pool and Call of Cthulhu rolling
+expressions, for example `!pool myvar` or `!pool myvar+3` or `!cthroll
+myvar`. The Call of Cthulhu advancement roll also accepts variables,
+and if a variable is used, and the roll is successful, it will update
+the variable with the new skill.
 
 ## Running the Bot
-You can run the bot by creating a bot account, building the dicebot
-program (either from this repo, and creating a config file that looks
-like this:
 
-```ini
-[matrix]
-home_server = https://'matrix.org'
-username = 'thisismyusername'
-password = 'thisismypassword'
+The easiest way to run the bot is to use the [official Docker
+image][docker-image], although you can also [run the binary
+directly](#running-binary-directly).
+
+A typical docker run command using the official Docker image should
+look something like this:
+
 ```
-
-Of course replacing all the necessary fields. Then you can run the
-"dicebot" binary pointing at that, and it will log in and hum along
-and do its thing.
-
-You can also just run it on the command line with the `dicebot-cmd`
-command, which expects you to feed it one of the command expressions
-as shown above, and will give you the plaintext response.
-
-## Docker Image
-
-The dice bot can run in a minimal Docker image based on [Void
-Linux](https://voidlinux.org/). To create the Docker image, run
-`docker build -t chronicle-dicebot .` in the root of the repository.
-
-A typical docker run command should look something like this:
-```
-VERSION="0.3.0"
+# Run unstable version of the bot
+VERSION="latest"
 docker run --rm -d --name dicebot \
 -v /path/to/dicebot-config.toml:/config/dicebot-config.toml:ro \
--v /path/to/cache//:/cache \
-chronicle-dicebot:$VERSION
+-v /path/to/cache/:/cache \
+ghcr.io/projectmoon/chronicle-dicebot:$VERSION
 ```
 
 The Docker image requires two volume mounts: the location of the
-config file, which should be mounted at `/config/dicebot-config.toml`,
-and a cache directory to store client state after initial sync. That
-should be mounted at `/cache/`in the container.
+[config file][config-file], which should be mounted at
+`/config/dicebot-config.toml`, and a cache directory to store the
+database and client state after initial sync. That should be mounted
+at `/cache/`in the container.
 
-Properly automated docker builds are forthcoming.
+### Configuration File
+
+The configuration file is a TOML file with three sections.
+
+```toml
+[matrix]
+home_server = 'https://example.com'
+username = 'thisismyusername'
+password = 'thisismypassword'
+
+[database]
+path = '/path/to/database/directory/'
+
+[bot]
+oldest_message_age = 300
+```
+
+The `[matrix]` section contains the information for logging in to the
+bot's matrix account.
+
+ - `home_server`: The URL for the Matrix homeserver the bot should log
+   in to. This should be the proper hostname of the homeserver that
+   you would enter into the login box, which might be different than
+   the server name that is displayed to other users.
+ - `username`: Bot account username.
+ - `password`: Bot account password.
+
+The `[database]` section contains information for connecting to the
+embedded database. Note: **you do not need this** if you are using the
+Docker image.
+ - `path`: Path on the filesystem to use as the database storage
+   directory.
+
+The `[bot]` section has settings for controlling how the bot operates.
+This section is optional and the settings will fall back to their
+default values if the section or setting is not present.
+
+ - `oldest_message_age`: the oldest time (in seconds) in the past that
+   a message can be before being ignored. This prevents the bot from
+   processing out-of-context old commands received while offline. The
+   default value is 900 seconds (15 minutes).
+
+### Running Binary Directly
+
+If you have [built the application from source](#build-from-source),
+you can invoke the dice bot directly instead of using Docker by
+running `dicebot /path/to/config.toml`. By default, the user account
+cache is stored in a [platform-dependent location][dirs]. If you want
+to change the cache location on Linux, for example, you can run
+`export XDG_CACHE_HOME=/path/to/cache` before invoking the bot.
+
+Installing the application directly also installs `dicebot-cmd`, which
+allows you to run arbitrary bot commands on the command line. This
+does not connect to a running instance of the bot; it just processes
+commands locally.
 
 ## Future plans
 
 The most basic plans are:
 
-* To add support for simple per-user variable management, e.g. setting
-  a name to a value (`gnosis = 3`) and then using those in dice rolls.
+* Resource counting: creation of custom counters that can go up and
+  down.
 * Perhaps some sort of character sheet integration. But for that, we
   would need a sheet service.
-* Automation of Docker builds.
 * Use environment variables instead of config file in Docker image.
+* Per-system game rules.
+
+## Credits
+
+This was orignally a fork of the [axfive-matrix-dicebot][axfive], with
+support added for Chronicles of Darkness and Call of Cthulhu.
+
+[axfive]: https://gitlab.com/Taywee/axfive-matrix-dicebot
+[config-file]: #Configuration-File
+[docker-image]: https://github.com/users/ProjectMoon/packages/container/package/chronicle-dicebot
+[dirs]: https://docs.rs/dirs/2.0.2/dirs/
+[main-repo]: https://git.agnos.is/projectmoon/tenebrous-dicebot
+[github-repo]: https://github.com/ProjectMoon/matrix-dicebot
+[roadmap]: https://git.agnos.is/projectmoon/tenebrous-dicebot/wiki/Roadmap
+[crates-io]: https://crates.io/crates/tenebrous-dicebot
+[matrix-room]: https://matrix.to/#/#tenebrous:agnos.is
+[agnosis-git-issues]: https://git.agnos.is/projectmoon/tenebrous-dicebot/issues
+[github-discussions]: https://github.com/ProjectMoon/matrix-dicebot/discussions
+[github-issues]: https://github.com/ProjectMoon/matrix-dicebot/issues
+[agpl]: https://www.gnu.org/licenses/agpl-3.0.en.html

axfive-matrix-dicebot.code-workspace

@@ -1,8 +0,0 @@
-{
-	"folders": [
-		{
-			"path": "."
-		}
-	],
-	"settings": {}
-}

dicebot/Cargo.toml

@@ -0,0 +1,57 @@
+[package]
+name = "tenebrous-dicebot"
+version = "0.13.2"
+rust-version = "1.68"
+authors = ["projectmoon <projectmoon@agnos.is>", "Taylor C. Richberger <taywee@gmx.com>"]
+edition = "2018"
+license = 'AGPL-3.0-or-later'
+description = 'An async Matrix dice bot for role-playing games'
+readme = '../README.md'
+repository = 'https://git.agnos.is/projectmoon/matrix-dicebot'
+keywords = ["games", "dice", "matrix", "bot"]
+categories = ["games"]
+
+[build-dependencies]
+tonic-build = "0.4"
+
+[dependencies]
+# indexmap version locked fixes a dependency cycle.
+# indexmap = "=1.6.2"
+log = "0.4"
+tracing-subscriber = "0.2"
+toml = "0.5"
+nom = "5"
+rand = "0.8"
+rust-argon2 = "0.8"
+thiserror = "1.0"
+itertools = "0.10"
+async-trait = "0.1"
+url = "2.1"
+dirs = "3.0"
+indoc = "1.0"
+combine = "4.5"
+futures = "0.3"
+html2text = "0.2"
+phf = { version = "0.8", features = ["macros"] }
+matrix-sdk = { version = "0.6" }
+refinery = { version = "0.8", features = ["rusqlite"]}
+barrel = { version = "0.7", features = ["sqlite3"] }
+strum = { version = "0.22", features = ["derive"] }
+tempfile = "3"
+substring = "1.4"
+fuse-rust = "0.2"
+tonic = "0.4"
+prost = "0.7"
+tenebrous-rpc = { path = "../rpc", version = "0.1.0" }
+
+[dependencies.sqlx]
+version = "0.6"
+features = [ "offline", "sqlite", "runtime-tokio-native-tls" ]
+
+[dependencies.serde]
+version = "1"
+features = ['derive']
+
+[dependencies.tokio]
+version = "1"
+features = [ "full" ]

dicebot/sqlx-data.json

@@ -0,0 +1,139 @@
+{
+  "db": "SQLite",
+  "19d89370cac05c1bc4de0eb3508712da9ca133b1cf9445b5407d238f89c3ab0c": {
+    "query": "SELECT device_id FROM bot_state limit 1",
+    "describe": {
+      "columns": [
+        {
+          "name": "device_id",
+          "ordinal": 0,
+          "type_info": "Text"
+        }
+      ],
+      "parameters": {
+        "Right": 0
+      },
+      "nullable": [
+        false
+      ]
+    }
+  },
+  "26903a92a7de34df3e227fe599e41ae1bb61612eb80befad398383af36df0ce4": {
+    "query": "DELETE FROM accounts WHERE user_id = ?",
+    "describe": {
+      "columns": [],
+      "parameters": {
+        "Right": 1
+      },
+      "nullable": []
+    }
+  },
+  "2d4a32735da04509c2e3c4f99bef79ef699964f58ae332b0611f3de088596e1e": {
+    "query": "INSERT INTO accounts (user_id, password, account_status)\n               VALUES (?, ?, ?)\n               ON CONFLICT(user_id) DO\n               UPDATE SET password = ?, account_status = ?",
+    "describe": {
+      "columns": [],
+      "parameters": {
+        "Right": 5
+      },
+      "nullable": []
+    }
+  },
+  "59313c67900a1a9399389720b522e572f181ae503559cd2b49d6305acb9e2207": {
+    "query": "SELECT key, value as \"value: i32\" FROM user_variables\n               WHERE room_id = ? AND user_id = ?",
+    "describe": {
+      "columns": [
+        {
+          "name": "key",
+          "ordinal": 0,
+          "type_info": "Text"
+        },
+        {
+          "name": "value: i32",
+          "ordinal": 1,
+          "type_info": "Int64"
+        }
+      ],
+      "parameters": {
+        "Right": 2
+      },
+      "nullable": [
+        false,
+        false
+      ]
+    }
+  },
+  "636b1b868eaf04cd234fbf17747d94a66e81f7bc1b060ba14151dbfaf40eeefc": {
+    "query": "SELECT value as \"value: i32\" FROM user_variables\n               WHERE user_id = ? AND room_id = ? AND key = ?",
+    "describe": {
+      "columns": [
+        {
+          "name": "value: i32",
+          "ordinal": 0,
+          "type_info": "Int64"
+        }
+      ],
+      "parameters": {
+        "Right": 3
+      },
+      "nullable": [
+        false
+      ]
+    }
+  },
+  "667b26343ce44e1c48ac689ce887ef6a0558a2ce199f7372a5dce58672499c5a": {
+    "query": "INSERT INTO user_state (user_id, active_room)\n               VALUES (?, ?)\n               ON CONFLICT(user_id) DO\n               UPDATE SET active_room = ?",
+    "describe": {
+      "columns": [],
+      "parameters": {
+        "Right": 3
+      },
+      "nullable": []
+    }
+  },
+  "711d222911c1258365a6a0de1fe00eeec4686fd3589e976e225ad599e7cfc75d": {
+    "query": "SELECT count(*) as \"count: i32\" FROM user_variables\n               WHERE room_id = ? and user_id = ?",
+    "describe": {
+      "columns": [
+        {
+          "name": "count: i32",
+          "ordinal": 0,
+          "type_info": "Int"
+        }
+      ],
+      "parameters": {
+        "Right": 2
+      },
+      "nullable": [
+        false
+      ]
+    }
+  },
+  "bba0fc255e7c30d1d2d9468c68ba38db6e8a13be035aa1152933ba9247b14f8c": {
+    "query": "SELECT event_id FROM room_events\n               WHERE room_id = ? AND event_id = ?",
+    "describe": {
+      "columns": [
+        {
+          "name": "event_id",
+          "ordinal": 0,
+          "type_info": "Text"
+        }
+      ],
+      "parameters": {
+        "Right": 2
+      },
+      "nullable": [
+        false
+      ]
+    }
+  },
+  "dce9bb45cf954054a920ee8b53852c6d562e3588d76bbfaa1433d8309d4e4921": {
+    "query": "DELETE FROM user_state WHERE user_id = ?",
+    "describe": {
+      "columns": [],
+      "parameters": {
+        "Right": 1
+      },
+      "nullable": []
+    }
+  }
+}

dicebot/src/basic/dice.rs

@@ -1,23 +1,57 @@
-pub mod parser;
-
+/**
+ * In addition to the terms of the AGPL, this file is governed by the
+ * terms of the MIT license, from the original axfive-matrix-dicebot
+ * project.
+ */
 use std::fmt;
 use std::ops::{Deref, DerefMut};
 
+/// A basic dice roll, in XdY notation, like "1d4" or "3d6".
+/// Optionally supports D&D advantage/disadvantge keep-or-drop
+/// functionality.
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
 pub struct Dice {
     pub(crate) count: u32,
     pub(crate) sides: u32,
+    pub(crate) keep_drop: KeepOrDrop,
+}
+
+/// Enum indicating how to handle bonuses or penalties using extra
+/// dice. If set to Keep, the roll will keep the highest X number of
+/// dice in the roll, and add those together. If set to Drop, the
+/// opposite is performed, and the lowest X number of dice are added
+/// instead. If set to None, then all dice in the roll are added up as
+/// normal.
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub enum KeepOrDrop {
+    /// Keep only the X highest dice for adding up to the total.
+    Keep(u32),
+
+    /// Keep only the X lowest dice (i.e. drop the highest) for adding
+    /// up to the total.
+    Drop(u32),
+
+    /// Add up all dice in the roll for the total.
+    None,
 }
 
 impl fmt::Display for Dice {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{}d{}", self.count, self.sides)
+        match self.keep_drop {
+            KeepOrDrop::Keep(keep) => write!(f, "{}d{}k{}", self.count, self.sides, keep),
+            KeepOrDrop::Drop(drop) => write!(f, "{}d{}dh{}", self.count, self.sides, drop),
+            KeepOrDrop::None => write!(f, "{}d{}", self.count, self.sides),
+        }
     }
 }
 
 impl Dice {
-    fn new(count: u32, sides: u32) -> Dice {
-        Dice { count, sides }
+    pub fn new(count: u32, sides: u32, keep_drop: KeepOrDrop) -> Dice {
+        Dice {
+            count,
+            sides,
+            keep_drop,
+        }
     }
 }
 
@@ -52,7 +86,7 @@ impl fmt::Display for SignedElement {
 }
 
 #[derive(Debug, PartialEq, Eq, Clone)]
-pub struct ElementExpression(Vec<SignedElement>);
+pub struct ElementExpression(pub Vec<SignedElement>);
 
 impl Deref for ElementExpression {
     type Target = Vec<SignedElement>;

dicebot/src/basic/mod.rs

@@ -0,0 +1,3 @@
+pub mod dice;
+pub mod parser;
+pub mod roll;

dicebot/src/basic/parser.rs

@@ -0,0 +1,360 @@
+/**
+ * In addition to the terms of the AGPL, this file is governed by the
+ * terms of the MIT license, from the original axfive-matrix-dicebot
+ * project.
+ */
+use nom::bytes::complete::take_while;
+use nom::error::ErrorKind as NomErrorKind;
+use nom::Err as NomErr;
+use nom::{
+    alt, bytes::complete::tag, character::complete::digit1, complete, many0, named,
+    sequence::tuple, tag, IResult,
+};
+
+use super::dice::*;
+
+//******************************
+//Legacy Code
+//******************************
+
+fn is_whitespace(input: char) -> bool {
+    input == ' ' || input == '\n' || input == '\t' || input == '\r'
+}
+
+/// Eat whitespace, returning it
+pub fn eat_whitespace(input: &str) -> IResult<&str, &str> {
+    let (input, whitespace) = take_while(is_whitespace)(input)?;
+    Ok((input, whitespace))
+}
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+enum Sign {
+    Plus,
+    Minus,
+}
+
+/// Intermediate parsed value for a keep-drop expression to indicate
+/// which one it is.
+enum ParsedKeepOrDrop<'a> {
+    Keep(&'a str),
+    Drop(&'a str),
+    NotPresent,
+}
+
+macro_rules! too_big {
+    ($input: expr) => {
+        NomErr::Error(($input, NomErrorKind::TooLarge))
+    };
+}
+
+/// Parse a dice expression.  Does not eat whitespace
+fn parse_dice(input: &str) -> IResult<&str, Dice> {
+    let (input, (count, _, sides)) = tuple((digit1, tag("d"), digit1))(input)?;
+    let count: u32 = count.parse().map_err(|_| too_big!(count))?;
+    let sides = sides.parse().map_err(|_| too_big!(sides))?;
+    let (input, keep_drop) = parse_keep_or_drop(input, count)?;
+    Ok((input, Dice::new(count, sides, keep_drop)))
+}
+
+/// Extract keep/drop number as a string. Fails if the value is not a
+/// string.
+fn parse_keep_or_drop_text<'a>(
+    symbol: &'a str,
+    input: &'a str,
+) -> IResult<&'a str, ParsedKeepOrDrop<'a>> {
+    let (parsed_kd, input) = match tuple::<&str, _, (_, _), _>((tag(symbol), digit1))(input) {
+        // if ok, one of the expressions is present
+        Ok((rest, (_, kd_expr))) => match symbol {
+            "k" => (ParsedKeepOrDrop::Keep(kd_expr), rest),
+            "dh" => (ParsedKeepOrDrop::Drop(kd_expr), rest),
+            _ => panic!("Unrecogized keep-drop symbol: {}", symbol),
+        },
+        // otherwise absent (attempt to keep all dice)
+        Err(_) => (ParsedKeepOrDrop::NotPresent, input),
+    };
+
+    Ok((input, parsed_kd))
+}
+
+/// Parse keep/drop expression, which consits of "k" or "dh" following
+/// a dice expression. For example, "1d4h3" or "1d4dh2".
+fn parse_keep_or_drop<'a>(input: &'a str, count: u32) -> IResult<&'a str, KeepOrDrop> {
+    let (input, keep) = parse_keep_or_drop_text("k", input)?;
+    let (input, drop) = parse_keep_or_drop_text("dh", input)?;
+
+    use ParsedKeepOrDrop::*;
+    let keep_drop: KeepOrDrop = match (keep, drop) {
+        //Potential valid Keep expression.
+        (Keep(keep), NotPresent) => match keep.parse().map_err(|_| too_big!(input))? {
+            _i if _i > count || _i == 0 => Ok(KeepOrDrop::None),
+            i => Ok(KeepOrDrop::Keep(i)),
+        },
+        //Potential valid Drop expression.
+        (NotPresent, Drop(drop)) => match drop.parse().map_err(|_| too_big!(input))? {
+            _i if _i >= count => Ok(KeepOrDrop::None),
+            i => Ok(KeepOrDrop::Drop(i)),
+        },
+        //No Keep or Drop specified; regular behavior.
+        (NotPresent, NotPresent) => Ok(KeepOrDrop::None),
+        //Anything else is an error.
+        _ => Err(NomErr::Error((input, NomErrorKind::Many1))),
+    }?;
+
+    Ok((input, keep_drop))
+}
+
+// Parse a single digit expression.  Does not eat whitespace
+fn parse_bonus(input: &str) -> IResult<&str, u32> {
+    let (input, bonus) = digit1(input)?;
+    Ok((input, bonus.parse().unwrap()))
+}
+
+// Parse a sign expression.  Eats whitespace.
+fn parse_sign(input: &str) -> IResult<&str, Sign> {
+    let (input, _) = eat_whitespace(input)?;
+    named!(sign(&str) -> Sign, alt!(
+            complete!(tag!("+")) => { |_| Sign::Plus } |
+            complete!(tag!("-")) => { |_| Sign::Minus }
+    ));
+
+    let (input, sign) = sign(input)?;
+    Ok((input, sign))
+}
+
+// Parse an element expression.  Eats whitespace.
+fn parse_element(input: &str) -> IResult<&str, Element> {
+    let (input, _) = eat_whitespace(input)?;
+    named!(element(&str) -> Element, alt!(
+            parse_dice => { |d| Element::Dice(d) } |
+            parse_bonus => { |b| Element::Bonus(b) }
+    ));
+
+    let (input, element) = element(input)?;
+    Ok((input, element))
+}
+
+// Parse a signed element expression.  Eats whitespace.
+fn parse_signed_element(input: &str) -> IResult<&str, SignedElement> {
+    let (input, _) = eat_whitespace(input)?;
+    let (input, sign) = parse_sign(input)?;
+    let (input, _) = eat_whitespace(input)?;
+
+    let (input, element) = parse_element(input)?;
+    let element = match sign {
+        Sign::Plus => SignedElement::Positive(element),
+        Sign::Minus => SignedElement::Negative(element),
+    };
+    Ok((input, element))
+}
+
+// Parse a full element expression.  Eats whitespace.
+pub fn parse_element_expression(input: &str) -> IResult<&str, ElementExpression> {
+    named!(first_element(&str) -> SignedElement, alt!(
+            parse_signed_element => { |e| e } |
+            parse_element => { |e| SignedElement::Positive(e) }
+    ));
+    let (input, first) = first_element(input)?;
+    let (input, rest) = if input.trim().is_empty() {
+        (input, vec![first])
+    } else {
+        named!(rest_elements(&str) -> Vec<SignedElement>, many0!(parse_signed_element));
+        let (input, mut rest) = rest_elements(input)?;
+        rest.insert(0, first);
+        (input, rest)
+    };
+
+    Ok((input, ElementExpression(rest)))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn dice_test() {
+        assert_eq!(
+            parse_dice("2d4"),
+            Ok(("", Dice::new(2, 4, KeepOrDrop::None)))
+        );
+        assert_eq!(
+            parse_dice("20d40"),
+            Ok(("", Dice::new(20, 40, KeepOrDrop::None)))
+        );
+        assert_eq!(
+            parse_dice("8d7"),
+            Ok(("", Dice::new(8, 7, KeepOrDrop::None)))
+        );
+        assert_eq!(
+            parse_dice("2d20k1"),
+            Ok(("", Dice::new(2, 20, KeepOrDrop::Keep(1))))
+        );
+        assert_eq!(
+            parse_dice("100d10k90"),
+            Ok(("", Dice::new(100, 10, KeepOrDrop::Keep(90))))
+        );
+        assert_eq!(
+            parse_dice("11d10k10"),
+            Ok(("", Dice::new(11, 10, KeepOrDrop::Keep(10))))
+        );
+        assert_eq!(
+            parse_dice("12d10k11"),
+            Ok(("", Dice::new(12, 10, KeepOrDrop::Keep(11))))
+        );
+        assert_eq!(
+            parse_dice("12d10k13"),
+            Ok(("", Dice::new(12, 10, KeepOrDrop::None)))
+        );
+        assert_eq!(
+            parse_dice("12d10k0"),
+            Ok(("", Dice::new(12, 10, KeepOrDrop::None)))
+        );
+        assert_eq!(
+            parse_dice("20d40dh5"),
+            Ok(("", Dice::new(20, 40, KeepOrDrop::Drop(5))))
+        );
+        assert_eq!(
+            parse_dice("8d7dh9"),
+            Ok(("", Dice::new(8, 7, KeepOrDrop::None)))
+        );
+        assert_eq!(
+            parse_dice("8d7dh8"),
+            Ok(("", Dice::new(8, 7, KeepOrDrop::None)))
+        );
+    }
+
+    #[test]
+    fn cant_have_both_keep_and_drop_test() {
+        let res = parse_dice("1d4k3dh2");
+        assert!(res.is_err());
+        match res {
+            Err(NomErr::Error((_, kind))) => {
+                assert_eq!(kind, NomErrorKind::Many1);
+            }
+            _ => panic!("Got success, expected error"),
+        }
+    }
+
+    #[test]
+    fn big_number_of_dice_doesnt_crash_test() {
+        let res = parse_dice("64378631476346123874527551481376547657868536d4");
+        assert!(res.is_err());
+        match res {
+            Err(NomErr::Error((input, kind))) => {
+                assert_eq!(kind, NomErrorKind::TooLarge);
+                assert_eq!(input, "64378631476346123874527551481376547657868536");
+            }
+            _ => panic!("Got success, expected error"),
+        }
+    }
+
+    #[test]
+    fn big_number_of_sides_doesnt_crash_test() {
+        let res = parse_dice("1d423562312587425472658956278456298376234876");
+        assert!(res.is_err());
+        match res {
+            Err(NomErr::Error((input, kind))) => {
+                assert_eq!(kind, NomErrorKind::TooLarge);
+                assert_eq!(input, "423562312587425472658956278456298376234876");
+            }
+            _ => panic!("Got success, expected error"),
+        }
+    }
+
+    #[test]
+    fn element_test() {
+        assert_eq!(
+            parse_element("  \t\n\r\n 8d7 \n"),
+            Ok((" \n", Element::Dice(Dice::new(8, 7, KeepOrDrop::None))))
+        );
+        assert_eq!(
+            parse_element("  \t\n\r\n 3d20k2 \n"),
+            Ok((" \n", Element::Dice(Dice::new(3, 20, KeepOrDrop::Keep(2)))))
+        );
+        assert_eq!(
+            parse_element("  \t\n\r\n 8 \n"),
+            Ok((" \n", Element::Bonus(8)))
+        );
+    }
+
+    #[test]
+    fn signed_element_test() {
+        assert_eq!(
+            parse_signed_element("+ 7"),
+            Ok(("", SignedElement::Positive(Element::Bonus(7))))
+        );
+        assert_eq!(
+            parse_signed_element("  \t\n\r\n- 8 \n"),
+            Ok((" \n", SignedElement::Negative(Element::Bonus(8))))
+        );
+        assert_eq!(
+            parse_signed_element("  \t\n\r\n- 8d4 \n"),
+            Ok((
+                " \n",
+                SignedElement::Negative(Element::Dice(Dice::new(8, 4, KeepOrDrop::None)))
+            ))
+        );
+        assert_eq!(
+            parse_signed_element("  \t\n\r\n- 8d4k4 \n"),
+            Ok((
+                " \n",
+                SignedElement::Negative(Element::Dice(Dice::new(8, 4, KeepOrDrop::Keep(4))))
+            ))
+        );
+        assert_eq!(
+            parse_signed_element("  \t\n\r\n+ 8d4 \n"),
+            Ok((
+                " \n",
+                SignedElement::Positive(Element::Dice(Dice::new(8, 4, KeepOrDrop::None)))
+            ))
+        );
+    }
+
+    #[test]
+    fn element_expression_test() {
+        assert_eq!(
+            parse_element_expression("8d4"),
+            Ok((
+                "",
+                ElementExpression(vec![SignedElement::Positive(Element::Dice(Dice::new(
+                    8,
+                    4,
+                    KeepOrDrop::None
+                )))])
+            ))
+        );
+        assert_eq!(
+            parse_element_expression("\t2d20k1 + 5"),
+            Ok((
+                "",
+                ElementExpression(vec![
+                    SignedElement::Positive(Element::Dice(Dice::new(2, 20, KeepOrDrop::Keep(1)))),
+                    SignedElement::Positive(Element::Bonus(5)),
+                ])
+            ))
+        );
+        assert_eq!(
+            parse_element_expression(" -  8d4 \n "),
+            Ok((
+                " \n ",
+                ElementExpression(vec![SignedElement::Negative(Element::Dice(Dice::new(
+                    8,
+                    4,
+                    KeepOrDrop::None
+                )))])
+            ))
+        );
+        assert_eq!(
+            parse_element_expression("\t3d4k2 + 7 - 5 - 6d12dh3 + 1d1 + 53 1d5 "),
+            Ok((
+                " 1d5 ",
+                ElementExpression(vec![
+                    SignedElement::Positive(Element::Dice(Dice::new(3, 4, KeepOrDrop::Keep(2)))),
+                    SignedElement::Positive(Element::Bonus(7)),
+                    SignedElement::Negative(Element::Bonus(5)),
+                    SignedElement::Negative(Element::Dice(Dice::new(6, 12, KeepOrDrop::Drop(3)))),
+                    SignedElement::Positive(Element::Dice(Dice::new(1, 1, KeepOrDrop::None))),
+                    SignedElement::Positive(Element::Bonus(53)),
+                ])
+            ))
+        );
+    }
+}

dicebot/src/basic/roll.rs

@@ -1,4 +1,10 @@
-use crate::dice;
+/**
+ * In addition to the terms of the AGPL, this file is governed by the
+ * terms of the MIT license, from the original axfive-matrix-dicebot
+ * project.
+ */
+use crate::basic::dice;
+use crate::basic::dice::KeepOrDrop;
 use rand::prelude::*;
 use std::fmt;
 use std::ops::{Deref, DerefMut};
@@ -14,15 +20,27 @@ pub trait Rolled {
 }
 
 #[derive(Debug, PartialEq, Eq, Clone)]
-pub struct DiceRoll(pub Vec<u32>);
+/// array of rolls in order, how many dice to keep, and how many to drop
+///   keep indicates how many of the highest dice to keep
+///   drop indicates how many of the highest dice to drop
+pub struct DiceRoll (pub Vec<u32>, usize, usize);
 
 impl DiceRoll {
     pub fn rolls(&self) -> &[u32] {
         &self.0
     }
 
+    pub fn keep(&self) -> usize {
+        self.1
+    }
+
+    pub fn drop(&self) -> usize {
+        self.2
+    }
+
+    // only count kept dice in total
     pub fn total(&self) -> u32 {
-        self.0.iter().sum()
+        self.0[self.2..self.1].iter().sum()
     }
 }
 
@@ -36,11 +54,21 @@ impl fmt::Display for DiceRoll {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "{}", self.rolled_value())?;
         let rolls = self.rolls();
-        let mut iter = rolls.iter();
+        let keep  = self.keep();
+        let drop  = self.drop();
+        let mut iter = rolls.iter().enumerate();
         if let Some(first) = iter.next() {
-            write!(f, " ({}", first)?;
+            if drop != 0 {
+                write!(f, " ([{}]", first.1)?;
+            } else {
+                write!(f, " ({}", first.1)?;
+            }
             for roll in iter {
-                write!(f, " + {}", roll)?;
+                if roll.0 >= keep || roll.0 < drop {
+                    write!(f, " + [{}]", roll.1)?;
+                } else {
+                    write!(f, " + {}", roll.1)?;
+                }
             }
             write!(f, ")")?;
         }
@@ -53,11 +81,17 @@ impl Roll for dice::Dice {
 
     fn roll(&self) -> DiceRoll {
         let mut rng = rand::thread_rng();
-        let rolls: Vec<_> = (0..self.count)
-            .map(|_| rng.gen_range(1, self.sides + 1))
+        let mut rolls: Vec<_> = (0..self.count)
+            .map(|_| rng.gen_range(1..=self.sides))
             .collect();
+        // sort rolls in descending order
+        rolls.sort_by(|a, b| b.cmp(a));
 
-        DiceRoll(rolls)
+        match self.keep_drop {
+            KeepOrDrop::Keep(k)  => DiceRoll(rolls,k as usize, 0),
+            KeepOrDrop::Drop(dh) => DiceRoll(rolls,self.count as usize, dh as usize),
+            KeepOrDrop::None     => DiceRoll(rolls,self.count as usize, 0),
+        }
     }
 }
 
@@ -193,18 +227,26 @@ mod tests {
     use super::*;
     #[test]
     fn dice_roll_display_test() {
-        assert_eq!(DiceRoll(vec![1, 3, 4]).to_string(), "8 (1 + 3 + 4)");
-        assert_eq!(DiceRoll(vec![]).to_string(), "0");
+        assert_eq!(DiceRoll(vec![1, 3, 4], 3, 0).to_string(), "8 (1 + 3 + 4)");
+        assert_eq!(DiceRoll(vec![], 0, 0).to_string(), "0");
         assert_eq!(
-            DiceRoll(vec![4, 7, 2, 10]).to_string(),
+            DiceRoll(vec![4, 7, 2, 10], 4, 0).to_string(),
             "23 (4 + 7 + 2 + 10)"
         );
+        assert_eq!(
+            DiceRoll(vec![20, 13, 11, 10], 3, 0).to_string(),
+            "44 (20 + 13 + 11 + [10])"
+        );
+        assert_eq!(
+            DiceRoll(vec![20, 13, 11, 10], 4, 1).to_string(),
+            "34 ([20] + 13 + 11 + 10)"
+        );
     }
 
     #[test]
     fn element_roll_display_test() {
         assert_eq!(
-            ElementRoll::Dice(DiceRoll(vec![1, 3, 4])).to_string(),
+            ElementRoll::Dice(DiceRoll(vec![1, 3, 4], 3, 0)).to_string(),
             "8 (1 + 3 + 4)"
         );
         assert_eq!(ElementRoll::Bonus(7).to_string(), "7");
@@ -213,11 +255,11 @@ mod tests {
     #[test]
     fn signed_element_roll_display_test() {
         assert_eq!(
-            SignedElementRoll::Positive(ElementRoll::Dice(DiceRoll(vec![1, 3, 4]))).to_string(),
+            SignedElementRoll::Positive(ElementRoll::Dice(DiceRoll(vec![1, 3, 4], 3, 0))).to_string(),
             "8 (1 + 3 + 4)"
         );
         assert_eq!(
-            SignedElementRoll::Negative(ElementRoll::Dice(DiceRoll(vec![1, 3, 4]))).to_string(),
+            SignedElementRoll::Negative(ElementRoll::Dice(DiceRoll(vec![1, 3, 4], 3, 0))).to_string(),
             "-8 (1 + 3 + 4)"
         );
         assert_eq!(
@@ -234,14 +276,14 @@ mod tests {
     fn element_expression_roll_display_test() {
         assert_eq!(
             ElementExpressionRoll(vec![SignedElementRoll::Positive(ElementRoll::Dice(
-                DiceRoll(vec![1, 3, 4])
+                DiceRoll(vec![1, 3, 4], 3, 0)
             )),])
             .to_string(),
             "8 (1 + 3 + 4)"
         );
         assert_eq!(
             ElementExpressionRoll(vec![SignedElementRoll::Negative(ElementRoll::Dice(
-                DiceRoll(vec![1, 3, 4])
+                DiceRoll(vec![1, 3, 4], 3, 0)
             )),])
             .to_string(),
             "-8 (1 + 3 + 4)"
@@ -258,8 +300,8 @@ mod tests {
         );
         assert_eq!(
             ElementExpressionRoll(vec![
-                SignedElementRoll::Positive(ElementRoll::Dice(DiceRoll(vec![1, 3, 4]))),
-                SignedElementRoll::Negative(ElementRoll::Dice(DiceRoll(vec![1, 2]))),
+                SignedElementRoll::Positive(ElementRoll::Dice(DiceRoll(vec![1, 3, 4], 3, 0))),
+                SignedElementRoll::Negative(ElementRoll::Dice(DiceRoll(vec![1, 2], 2, 0))),
                 SignedElementRoll::Positive(ElementRoll::Bonus(4)),
                 SignedElementRoll::Negative(ElementRoll::Bonus(7)),
             ])
@@ -268,13 +310,33 @@ mod tests {
         );
         assert_eq!(
             ElementExpressionRoll(vec![
-                SignedElementRoll::Negative(ElementRoll::Dice(DiceRoll(vec![1, 3, 4]))),
-                SignedElementRoll::Positive(ElementRoll::Dice(DiceRoll(vec![1, 2]))),
+                SignedElementRoll::Negative(ElementRoll::Dice(DiceRoll(vec![1, 3, 4], 3, 0))),
+                SignedElementRoll::Positive(ElementRoll::Dice(DiceRoll(vec![1, 2], 2, 0))),
                 SignedElementRoll::Negative(ElementRoll::Bonus(4)),
                 SignedElementRoll::Positive(ElementRoll::Bonus(7)),
             ])
             .to_string(),
             "-2 (-8 (1 + 3 + 4) + 3 (1 + 2) - 4 + 7)"
         );
+        assert_eq!(
+            ElementExpressionRoll(vec![
+                SignedElementRoll::Negative(ElementRoll::Dice(DiceRoll(vec![4, 3, 1], 3, 0))),
+                SignedElementRoll::Positive(ElementRoll::Dice(DiceRoll(vec![12, 2], 1, 0))),
+                SignedElementRoll::Negative(ElementRoll::Bonus(4)),
+                SignedElementRoll::Positive(ElementRoll::Bonus(7)),
+            ])
+            .to_string(),
+            "7 (-8 (4 + 3 + 1) + 12 (12 + [2]) - 4 + 7)"
+        );
+        assert_eq!(
+            ElementExpressionRoll(vec![
+                SignedElementRoll::Negative(ElementRoll::Dice(DiceRoll(vec![4, 3, 1], 3, 1))),
+                SignedElementRoll::Positive(ElementRoll::Dice(DiceRoll(vec![12, 2], 2, 0))),
+                SignedElementRoll::Negative(ElementRoll::Bonus(4)),
+                SignedElementRoll::Positive(ElementRoll::Bonus(7)),
+            ])
+            .to_string(),
+            "13 (-4 ([4] + 3 + 1) + 14 (12 + 2) - 4 + 7)"
+        );
     }
 }

dicebot/src/bin/dicebot-cmd.rs

@@ -0,0 +1,51 @@
+use matrix_sdk::ruma::room_id;
+use matrix_sdk::Client;
+use tenebrous_dicebot::commands;
+use tenebrous_dicebot::commands::ResponseExtractor;
+use tenebrous_dicebot::context::{Context, RoomContext};
+use tenebrous_dicebot::db::sqlite::Database;
+use tenebrous_dicebot::error::BotError;
+use tenebrous_dicebot::models::Account;
+use url::Url;
+
+#[tokio::main]
+async fn main() -> Result<(), BotError> {
+    let input = std::env::args().skip(1).collect::<Vec<String>>().join(" ");
+    let command = match commands::parser::parse_command(&input) {
+        Ok(command) => command,
+        Err(e) => return Err(e),
+    };
+
+    let homeserver = Url::parse("http://example.com")?;
+    let db_path = tempfile::NamedTempFile::new_in(".").unwrap();
+    let db = Database::new(
+        db_path
+            .path()
+            .to_str()
+            .expect("Could not get path to temporary db"),
+    )
+    .await?;
+
+    let context = Context {
+        db,
+        account: Account::default(),
+        matrix_client: Client::new(homeserver).await.expect("Could not create matrix client"),
+        origin_room: RoomContext {
+            id: &room_id!("!fakeroomid:example.com"),
+            display_name: "fake room".to_owned(),
+            secure: false,
+        },
+        active_room: RoomContext {
+            id: &room_id!("!fakeroomid:example.com"),
+            display_name: "fake room".to_owned(),
+            secure: false,
+        },
+        username: "@localuser:example.com",
+        message_body: &input,
+    };
+
+    let message = command.execute(&context).await.message_html("fakeuser");
+    let message = html2text::from_read(message.as_bytes(), 80);
+    println!("{}", message.trim());
+    Ok(())
+}

dicebot/src/bin/dicebot.rs

@@ -0,0 +1,73 @@
+//Needed for nested Result handling from tokio. Probably can go away after 1.47.0.
+#![type_length_limit = "7605144"]
+use futures::try_join;
+use log::error;
+use matrix_sdk::Client;
+use std::env;
+use std::sync::{Arc, RwLock};
+use tenebrous_dicebot::bot::DiceBot;
+use tenebrous_dicebot::config::*;
+use tenebrous_dicebot::db::sqlite::Database;
+use tenebrous_dicebot::error::BotError;
+use tenebrous_dicebot::rpc;
+use tenebrous_dicebot::state::DiceBotState;
+use tracing_subscriber::filter::EnvFilter;
+
+/// Attempt to create config object and ddatabase connection pool from
+/// the given config path. An error is returned if config creation or
+/// database pool creation fails for some reason.
+async fn init(config_path: &str) -> Result<(Arc<Config>, Database, Client), BotError> {
+    let cfg = read_config(config_path)?;
+    let cfg = Arc::new(cfg);
+    let sqlite_path = format!("{}/dicebot.sqlite", cfg.database_path());
+    let db = Database::new(&sqlite_path).await?;
+    let client = tenebrous_dicebot::matrix::create_client(&cfg).await?;
+    Ok((cfg, db, client))
+}
+
+#[tokio::main]
+async fn main() -> Result<(), BotError> {
+    let filter = if env::var("RUST_LOG").is_ok() {
+        EnvFilter::from_default_env()
+    } else {
+        EnvFilter::new("tonic=info,tenebrous_dicebot=info,dicebot=info,refinery=info")
+    };
+
+    tracing_subscriber::fmt().with_env_filter(filter).init();
+
+    match run().await {
+        Ok(_) => (),
+        Err(e) => error!("Error: {}", e),
+    }
+
+    Ok(())
+}
+
+async fn run() -> Result<(), BotError> {
+    let config_path = std::env::args()
+        .skip(1)
+        .next()
+        .expect("Need a config as an argument");
+
+    let (cfg, db, client) = init(&config_path).await?;
+    let grpc = rpc::serve_grpc(&cfg, &db, &client);
+    let bot = run_bot(&cfg, &db, &client);
+
+    match try_join!(bot, grpc) {
+        Ok(_) => (),
+        Err(e) => error!("Error: {:?}", e),
+    };
+
+    Ok(())
+}
+
+async fn run_bot(cfg: &Arc<Config>, db: &Database, client: &Client) -> Result<(), BotError> {
+    let state = Arc::new(RwLock::new(DiceBotState::new(&cfg)));
+
+    match DiceBot::new(cfg, &state, db, client) {
+        Ok(bot) => bot.run().await?,
+        Err(e) => println!("Error connecting: {:?}", e),
+    };
+
+    Ok(())
+}

dicebot/src/bin/dicebot_migrate.rs

@@ -0,0 +1,16 @@
+use std::env;
+use tenebrous_dicebot::db::sqlite::migrator;
+
+#[tokio::main]
+async fn main() -> Result<(), migrator::MigrationError> {
+    let args: Vec<String> = env::args().collect();
+    let db_path: &str = match &args[..] {
+        [_, path] => path.as_ref(),
+        [_, _, ..] => panic!("Expected exactly 0 or 1 argument"),
+        _ => "dicebot.sqlite",
+    };
+
+    println!("Using database: {}", db_path);
+
+    migrator::migrate(db_path).await
+}

dicebot/src/bin/tonic_client.rs

@@ -0,0 +1,33 @@
+use tenebrous_rpc::protos::dicebot::UserIdRequest;
+use tenebrous_rpc::protos::dicebot::{dicebot_client::DicebotClient};
+use tonic::{metadata::MetadataValue, transport::Channel, Request};
+
+async fn create_client(
+    shared_secret: &str,
+) -> Result<DicebotClient<Channel>, Box<dyn std::error::Error>> {
+    let channel = Channel::from_static("http://0.0.0.0:9090")
+        .connect()
+        .await?;
+
+    let bearer = MetadataValue::from_str(&format!("Bearer {}", shared_secret))?;
+
+    let client = DicebotClient::with_interceptor(channel, move |mut req: Request<()>| {
+        req.metadata_mut().insert("authorization", bearer.clone());
+        Ok(req)
+    });
+
+    Ok(client)
+}
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let mut client = create_client("example-key").await?;
+
+    let request = tonic::Request::new(UserIdRequest {
+        user_id: "@projectmoon:agnos.is".into(),
+    });
+
+    let response = client.rooms_for_user(request).await?.into_inner();
+    println!("Rooms: {:?}", response.rooms);
+    Ok(())
+}

dicebot/src/bot/command_execution.rs

@@ -0,0 +1,173 @@
+use crate::context::{Context, RoomContext};
+use crate::db::sqlite::Database;
+use crate::error::BotError;
+use crate::logic;
+use crate::matrix;
+use crate::{
+    commands::{execute_command, ExecutionResult, ResponseExtractor},
+    models::Account,
+};
+use futures::stream::{self, StreamExt};
+use matrix_sdk::ruma::{OwnedEventId, RoomId};
+use matrix_sdk::{self, room::Joined, Client};
+use std::clone::Clone;
+use std::convert::TryFrom;
+
+/// Handle responding to a single command being executed. Wil print
+/// out the full result of that command.
+pub(super) async fn handle_single_result(
+    client: &Client,
+    cmd_result: &ExecutionResult,
+    respond_to: &str,
+    room: &Joined,
+    event_id: OwnedEventId,
+) {
+    let html = cmd_result.message_html(respond_to);
+    let plain = cmd_result.message_plain(respond_to);
+    matrix::send_message(client, room.room_id(), (&html, &plain), Some(event_id)).await;
+}
+
+/// Format failure messages nicely in either HTML or plain text. If
+/// plain is true, plain-text will be returned. Otherwise, formatted
+/// HTML.
+fn format_failures(
+    errors: &[(&str, &BotError)],
+    commands_executed: usize,
+    respond_to: &str,
+    plain: bool,
+) -> String {
+    let respond_to = match plain {
+        true => respond_to.to_owned(),
+        false => format!(
+            "<a href=\"https://matrix.to/#/{}\">{}</a>",
+            respond_to, respond_to
+        ),
+    };
+
+    let failures: Vec<String> = errors
+        .iter()
+        .map(|&(cmd, err)| format!("<strong>{}:</strong> {}", cmd, err))
+        .collect();
+
+    let message = format!(
+        "{}: Executed {} commands ({} failed)\n\nFailures:\n{}",
+        respond_to,
+        commands_executed,
+        errors.len(),
+        failures.join("\n")
+    )
+    .replace("\n", "<br/>");
+
+    match plain {
+        true => html2text::from_read(message.as_bytes(), message.len()),
+        false => message,
+    }
+}
+
+/// Handle responding to multiple commands being executed. Will print
+/// out how many commands succeeded and failed (if any failed).
+pub(super) async fn handle_multiple_results(
+    client: &Client,
+    results: &[(String, ExecutionResult)],
+    respond_to: &str,
+    room: &Joined,
+) {
+    let user_pill = format!(
+        "<a href=\"https://matrix.to/#/{}\">{}</a>",
+        respond_to, respond_to
+    );
+
+    let errors: Vec<(&str, &BotError)> = results
+        .into_iter()
+        .filter_map(|(cmd, result)| match result {
+            Err(e) => Some((cmd.as_ref(), e)),
+            _ => None,
+        })
+        .collect();
+
+    let (message, plain) = if errors.len() == 0 {
+        (
+            format!("{}: Executed {} commands", user_pill, results.len()),
+            format!("{}: Executed {} commands", respond_to, results.len()),
+        )
+    } else {
+        (
+            format_failures(&errors, results.len(), respond_to, false),
+            format_failures(&errors, results.len(), respond_to, true),
+        )
+    };
+
+    matrix::send_message(client, room.room_id(), (&message, &plain), None).await;
+}
+
+/// Map an account's active room value to an actual matrix room, if
+/// the account has an active room. This only retrieves the
+/// user-specified active room, and doesn't perform any further
+/// filtering.
+fn get_account_active_room(client: &Client, account: &Account) -> Result<Option<Joined>, BotError> {
+    let active_room = account
+        .registered_user()
+        .and_then(|u| u.active_room.as_deref())
+        .map(|room_id| <&RoomId>::try_from(room_id))
+        .transpose()?
+        .and_then(|active_room_id| client.get_joined_room(active_room_id));
+
+    Ok(active_room)
+}
+
+/// Execute a single command in the list of commands. Can fail if the
+/// Account value cannot be created/fetched from the database, or if
+/// room display names cannot be calculated. Otherwise, the success or
+/// error of command execution itself is returned.
+async fn execute_single_command(
+    command: &str,
+    db: &Database,
+    client: &Client,
+    origin_room: &Joined,
+    sender: &str,
+) -> ExecutionResult {
+    let origin_ctx = RoomContext::new(origin_room, sender).await?;
+    let account = logic::get_account(db, sender).await?;
+    let active_room = get_account_active_room(client, &account)?;
+
+    // Active room is used in secure command-issuing rooms. In
+    // "public" rooms, where other users are, treat origin as the
+    // active room.
+    let active_room = active_room
+        .as_ref()
+        .filter(|_| origin_ctx.secure)
+        .unwrap_or(origin_room);
+
+    let active_ctx = RoomContext::new(active_room, sender).await?;
+
+    let ctx = Context {
+        account,
+        db: db.clone(),
+        matrix_client: client.clone(),
+        origin_room: origin_ctx,
+        username: &sender,
+        active_room: active_ctx,
+        message_body: &command,
+    };
+
+    execute_command(&ctx).await
+}
+
+/// Attempt to execute all commands sent to the bot in a message. This
+/// asynchronously executes all commands given to it. A Vec of all
+/// commands and their execution results are returned.
+pub(super) async fn execute(
+    commands: Vec<&str>,
+    db: &Database,
+    client: &Client,
+    room: &Joined,
+    sender: &str,
+) -> Vec<(String, ExecutionResult)> {
+    stream::iter(commands)
+        .then(|command| async move {
+            let result = execute_single_command(command, db, client, room, sender).await;
+            (command.to_owned(), result)
+        })
+        .collect()
+        .await
+}

dicebot/src/bot/event_handlers.rs

@@ -0,0 +1,163 @@
+use super::DiceBot;
+use crate::db::sqlite::Database;
+use crate::db::Rooms;
+use crate::error::BotError;
+use log::{debug, error, info, warn};
+use matrix_sdk::ruma::events::room::member::RoomMemberEventContent;
+use matrix_sdk::ruma::events::{StrippedStateEvent, SyncMessageLikeEvent};
+use matrix_sdk::{self, room::Room, ruma::events::room::message::RoomMessageEventContent};
+use matrix_sdk::{Client, DisplayName};
+use std::ops::Sub;
+use std::time::UNIX_EPOCH;
+use std::time::{Duration, SystemTime};
+
+/// Check if a message is recent enough to actually process. If the
+/// message is within "oldest_message_age" seconds, this function
+/// returns true. If it's older than that, it returns false and logs a
+/// debug message.
+fn check_message_age(
+    event: &SyncMessageLikeEvent<RoomMessageEventContent>,
+    oldest_message_age: u64,
+) -> bool {
+    let sending_time = event
+        .origin_server_ts()
+        .to_system_time()
+        .unwrap_or(UNIX_EPOCH);
+
+    let oldest_timestamp = SystemTime::now().sub(Duration::from_secs(oldest_message_age));
+
+    if sending_time > oldest_timestamp {
+        true
+    } else {
+        let age = match oldest_timestamp.duration_since(sending_time) {
+            Ok(n) => format!("{} seconds too old", n.as_secs()),
+            Err(_) => "before the UNIX epoch".to_owned(),
+        };
+
+        debug!("Ignoring message because it is {}: {:?}", age, event);
+        false
+    }
+}
+
+/// Determine whether or not to process a received message. This check
+/// is necessary in addition to the event processing check because we
+/// may receive message events when entering a room for the first
+/// time, and we don't want to respond to things before the bot was in
+/// the channel, but we do want to respond to things that were sent if
+/// the bot left and rejoined quickly.
+async fn should_process_message<'a>(
+    bot: &DiceBot,
+    event: &SyncMessageLikeEvent<RoomMessageEventContent>,
+) -> Result<(String, String), BotError> {
+    //Ignore messages that are older than configured duration.
+    if !check_message_age(event, bot.config.oldest_message_age()) {
+        let state_check = bot.state.read().unwrap();
+        if !((*state_check).logged_skipped_old_messages()) {
+            drop(state_check);
+            let mut state = bot.state.write().unwrap();
+            (*state).skipped_old_messages();
+        }
+
+        return Err(BotError::ShouldNotProcessError);
+    }
+
+    let msg_body: String = event
+        .as_original()
+        .map(|e| e.content.body())
+        .map(str::to_string)
+        .unwrap_or_else(|| String::new());
+
+    let sender_username: String = format!(
+        "@{}:{}",
+        event.sender().localpart(),
+        event.sender().server_name()
+    );
+
+    // Do not process messages from the bot itself. Otherwise it might
+    // try to execute its own commands.
+    let bot_username = bot
+        .client
+        .user_id()
+        .map(|u| format!("@{}:{}", u.localpart(), u.server_name()))
+        .unwrap_or_default();
+
+    if sender_username == bot_username {
+        return Err(BotError::ShouldNotProcessError);
+    }
+
+    Ok((msg_body, sender_username))
+}
+
+async fn should_process_event(db: &Database, room_id: &str, event_id: &str) -> bool {
+    db.should_process(room_id, event_id)
+        .await
+        .unwrap_or_else(|e| {
+            error!(
+                "Database error when checking if we should process an event: {}",
+                e.to_string()
+            );
+            false
+        })
+}
+
+pub(super) async fn on_stripped_state_member(
+    event: StrippedStateEvent<RoomMemberEventContent>,
+    client: Client,
+    room: Room,
+) {
+    let room = match room {
+        Room::Invited(invited_room) => invited_room,
+        _ => return,
+    };
+
+    if room.own_user_id().as_str() != event.state_key {
+        return;
+    }
+
+    info!(
+        "Autojoining room {}",
+        room.display_name()
+            .await
+            .ok()
+            .unwrap_or_else(|| DisplayName::Named("[error]".to_string()))
+    );
+
+    if let Err(e) = client.join_room_by_id(&room.room_id()).await {
+        warn!("Could not join room: {}", e.to_string())
+    }
+}
+
+pub(super) async fn on_room_message(
+    event: SyncMessageLikeEvent<RoomMessageEventContent>,
+    room: Room,
+    bot: DiceBot,
+) {
+    let room = match room {
+        Room::Joined(joined_room) => joined_room,
+        _ => return,
+    };
+
+    let room_id = room.room_id().as_str();
+    if !should_process_event(&bot.db, room_id, event.event_id().as_str()).await {
+        return;
+    }
+
+    let (msg_body, sender_username) =
+        if let Ok((msg_body, sender_username)) = should_process_message(&bot, &event).await {
+            (msg_body, sender_username)
+        } else {
+            return;
+        };
+
+    let results = bot
+        .execute_commands(&room, &sender_username, &msg_body)
+        .await;
+
+    bot.handle_results(
+        &room,
+        &sender_username,
+        event.event_id().to_owned(),
+        results,
+    )
+    .await;
+}

dicebot/src/bot/mod.rs

@@ -0,0 +1,172 @@
+use crate::commands::ExecutionResult;
+use crate::config::*;
+use crate::db::sqlite::Database;
+use crate::db::DbState;
+use crate::error::BotError;
+use crate::state::DiceBotState;
+use log::info;
+use matrix_sdk::room::Room;
+use matrix_sdk::ruma::events::room::message::RoomMessageEventContent;
+use matrix_sdk::ruma::events::SyncMessageLikeEvent;
+use matrix_sdk::ruma::OwnedEventId;
+use matrix_sdk::{self, room::Joined, Client};
+use matrix_sdk::config::SyncSettings;
+use std::clone::Clone;
+use std::sync::{Arc, RwLock};
+
+mod command_execution;
+pub mod event_handlers;
+
+/// How many commands can be in one message. If the amount is higher
+/// than this, we reject execution.
+const MAX_COMMANDS_PER_MESSAGE: usize = 50;
+
+/// The DiceBot struct represents an active dice bot. The bot is not
+/// connected to Matrix until its run() function is called.
+#[derive(Clone)]
+pub struct DiceBot {
+    /// A reference to the configuration read in on application start.
+    config: Arc<Config>,
+
+    /// The matrix client.
+    client: Client,
+
+    /// State of the dicebot
+    state: Arc<RwLock<DiceBotState>>,
+
+    /// Active database layer
+    db: Database,
+}
+
+impl DiceBot {
+    /// Create a new dicebot with the given configuration and state
+    /// actor. This function returns a Result because it is possible
+    /// for client creation to fail for some reason (e.g. invalid
+    /// homeserver URL).
+    pub fn new(
+        config: &Arc<Config>,
+        state: &Arc<RwLock<DiceBotState>>,
+        db: &Database,
+        client: &Client,
+    ) -> Result<Self, BotError> {
+        Ok(DiceBot {
+            client: client.clone(),
+            config: config.clone(),
+            state: state.clone(),
+            db: db.clone(),
+        })
+    }
+
+    /// Logs in to matrix and potentially records a new device ID. If
+    /// no device ID is found in the database, a new one will be
+    /// generated by the matrix SDK, and we will store it.
+    async fn login(&self, client: &Client) -> Result<(), BotError> {
+        let username = self.config.matrix_username();
+        let password = self.config.matrix_password();
+
+        // Pull device ID from database, if it exists. Then write it
+        // to DB if the library generated one for us.
+        let device_id: Option<String> = self.db.get_device_id().await?;
+        let device_id: Option<&str> = device_id.as_deref();
+
+        let no_device_ld_login = || client.login_username(username, password);
+        let device_id_login = |id| client.login_username(username, password).device_id(id);
+        let login = device_id.map_or_else(no_device_ld_login, device_id_login);
+
+        login.send().await?;
+
+        if device_id.is_none() {
+            let device_id = client.device_id().ok_or(BotError::NoDeviceIdFound)?;
+            self.db.set_device_id(device_id.as_str()).await?;
+            info!("Recorded new device ID: {}", device_id.as_str());
+        } else {
+            info!("Using existing device ID: {}", device_id.unwrap());
+        }
+
+        info!("Logged in as {}", username);
+        Ok(())
+    }
+
+    async fn bind_events(&self) {
+        //on room message: need closure to pass bot ref in.
+        self.client
+            .add_event_handler({
+                let bot: DiceBot = self.clone();
+                move |event: SyncMessageLikeEvent<RoomMessageEventContent>, room: Room| {
+                    let bot = bot.clone();
+                    async move { event_handlers::on_room_message(event, room, bot).await }
+                }
+            });
+
+        //auto-join handler
+        self.client
+            .add_event_handler(event_handlers::on_stripped_state_member);
+    }
+
+    /// Logs the bot in to Matrix and listens for events until program
+    /// terminated, or a panic occurs. Originally adapted from the
+    /// matrix-rust-sdk command bot example.
+    pub async fn run(self) -> Result<(), BotError> {
+        let client = self.client.clone();
+        self.login(&client).await?;
+        self.bind_events().await;
+
+        info!("Listening for commands");
+
+        // TODO replace with sync_with_callback for cleaner shutdown
+        // process.
+        client.sync(SyncSettings::default()).await?;
+        Ok(())
+    }
+
+    async fn execute_commands(
+        &self,
+        room: &Joined,
+        sender: &str,
+        msg_body: &str,
+    ) -> Vec<(String, ExecutionResult)> {
+        let commands: Vec<&str> = msg_body
+            .lines()
+            .filter(|line| line.starts_with("!"))
+            .take(MAX_COMMANDS_PER_MESSAGE + 1)
+            .collect();
+
+        //Up to 50 commands allowed, otherwise we send back an error.
+        let results: Vec<(String, ExecutionResult)> = if commands.len() < MAX_COMMANDS_PER_MESSAGE {
+            command_execution::execute(commands, &self.db, &self.client, room, sender).await
+        } else {
+            vec![("".to_owned(), Err(BotError::MessageTooLarge))]
+        };
+
+        results
+    }
+
+    pub async fn handle_results(
+        &self,
+        room: &Joined,
+        sender_username: &str,
+        event_id: OwnedEventId,
+        results: Vec<(String, ExecutionResult)>,
+    ) {
+        if results.len() >= 1 {
+            if results.len() == 1 {
+                command_execution::handle_single_result(
+                    &self.client,
+                    &results[0].1,
+                    sender_username,
+                    &room,
+                    event_id,
+                )
+                .await;
+            } else if results.len() > 1 {
+                command_execution::handle_multiple_results(
+                    &self.client,
+                    &results,
+                    sender_username,
+                    &room,
+                )
+                .await;
+            }
+        }
+    }
+}

dicebot/src/cofd/dice.rs

@@ -0,0 +1,779 @@
+use crate::context::Context;
+use crate::error::{BotError, DiceRollingError};
+use crate::parser::dice::{Amount, Element, Operator};
+use itertools::Itertools;
+use std::convert::TryFrom;
+use std::fmt;
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub enum DicePoolQuality {
+    TenAgain,
+    NineAgain,
+    EightAgain,
+    Rote,
+    ChanceDie,
+    NoExplode,
+}
+
+impl fmt::Display for DicePoolQuality {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            DicePoolQuality::TenAgain => write!(f, "ten-again"),
+            DicePoolQuality::NineAgain => write!(f, "nine-again"),
+            DicePoolQuality::EightAgain => write!(f, "eight-again"),
+            DicePoolQuality::Rote => write!(f, "rote quality"),
+            DicePoolQuality::ChanceDie => write!(f, "chance die"),
+            DicePoolQuality::NoExplode => write!(f, "no roll-agains"),
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub struct DicePoolModifiers {
+    pub(crate) success_on: i32,
+    pub(crate) exceptional_on: i32,
+    pub(crate) quality: DicePoolQuality,
+}
+
+impl DicePoolModifiers {
+    pub fn default() -> DicePoolModifiers {
+        DicePoolModifiers {
+            success_on: 8,
+            exceptional_on: 5,
+            quality: DicePoolQuality::TenAgain,
+        }
+    }
+
+    pub fn custom_quality(quality: DicePoolQuality) -> DicePoolModifiers {
+        let success_on = if quality != DicePoolQuality::ChanceDie {
+            8
+        } else {
+            10
+        };
+        DicePoolModifiers {
+            success_on: success_on,
+            exceptional_on: 5,
+            quality: quality,
+        }
+    }
+
+    pub fn custom_exceptional_on(exceptional_on: i32) -> DicePoolModifiers {
+        DicePoolModifiers {
+            success_on: 8,
+            exceptional_on: exceptional_on,
+            quality: DicePoolQuality::TenAgain,
+        }
+    }
+
+    pub fn custom(quality: DicePoolQuality, exceptional_on: i32) -> DicePoolModifiers {
+        DicePoolModifiers {
+            success_on: 8,
+            exceptional_on: exceptional_on,
+            quality: quality,
+        }
+    }
+}
+
+#[derive(Debug, PartialEq)]
+pub struct DicePool {
+    pub(crate) amounts: Vec<Amount>,
+    pub(crate) sides: i32,
+    pub(crate) modifiers: DicePoolModifiers,
+}
+
+impl DicePool {
+    pub fn easy_pool(dice_amount: i32, quality: DicePoolQuality) -> DicePool {
+        DicePool {
+            amounts: vec![Amount {
+                operator: Operator::Plus,
+                element: Element::Number(dice_amount),
+            }],
+            sides: 10,
+            modifiers: DicePoolModifiers::custom_quality(quality),
+        }
+    }
+
+    pub fn easy_with_modifiers(dice_amount: i32, modifiers: DicePoolModifiers) -> DicePool {
+        DicePool {
+            amounts: vec![Amount {
+                operator: Operator::Plus,
+                element: Element::Number(dice_amount),
+            }],
+            sides: 10,
+            modifiers: modifiers,
+        }
+    }
+
+    pub fn new(amounts: Vec<Amount>, modifiers: DicePoolModifiers) -> DicePool {
+        DicePool {
+            amounts: amounts,
+            sides: 10, //TODO make configurable
+            //TODO make configurable
+            modifiers: modifiers,
+        }
+    }
+
+    pub fn chance_die() -> DicePool {
+        DicePool::easy_pool(1, DicePoolQuality::ChanceDie)
+    }
+}
+
+///The result of a successfully executed roll of a dice pool. Does not
+///contain the heavy information of the DicePool instance.
+pub struct RolledDicePool {
+    pub(crate) num_dice: i32,
+    pub(crate) roll: DicePoolRoll,
+    pub(crate) modifiers: DicePoolModifiers,
+}
+
+impl RolledDicePool {
+    fn from(pool: &DicePool, num_dice: i32, rolls: Vec<i32>) -> RolledDicePool {
+        RolledDicePool {
+            modifiers: pool.modifiers,
+            num_dice: num_dice,
+            roll: DicePoolRoll {
+                rolls: rolls,
+                modifiers: pool.modifiers,
+            },
+        }
+    }
+}
+
+impl fmt::Display for RolledDicePool {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let dice_plural = if self.num_dice == 1 { "die" } else { "dice" };
+        write!(
+            f,
+            "{} {} ({}, exceptional on {} successes)",
+            self.num_dice, dice_plural, self.modifiers.quality, self.modifiers.exceptional_on
+        )
+    }
+}
+
+///Store all rolls of the dice pool dice into one struct.
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub struct DicePoolRoll {
+    modifiers: DicePoolModifiers,
+    rolls: Vec<i32>,
+}
+
+/// Amount of dice to display before cutting off and showing "and X
+/// more", so we don't spam the room with huge messages.
+const MAX_DISPLAYED_ROLLS: usize = 15;
+
+fn fmt_rolls(pool: &DicePoolRoll) -> String {
+    let rolls = pool.rolls();
+    if rolls.len() > MAX_DISPLAYED_ROLLS {
+        let shown_amount = rolls.into_iter().take(MAX_DISPLAYED_ROLLS).join(", ");
+        format!(
+            "{}, and {} more",
+            shown_amount,
+            rolls.len() - MAX_DISPLAYED_ROLLS
+        )
+    } else {
+        rolls.into_iter().join(", ")
+    }
+}
+
+fn fmt_for_failure(pool: &DicePoolRoll) -> String {
+    match pool.modifiers.quality {
+        //There should only be 1 die in a chance die roll.
+        DicePoolQuality::ChanceDie if pool.rolls().first() == Some(&1) => {
+            String::from("dramatic failure!")
+        }
+        _ => String::from("failure!"),
+    }
+}
+
+impl DicePoolRoll {
+    pub fn rolls(&self) -> &[i32] {
+        &self.rolls
+    }
+
+    pub fn successes(&self) -> i32 {
+        let successes: usize = self
+            .rolls
+            .iter()
+            .filter(|&roll| *roll >= self.modifiers.success_on)
+            .count();
+
+        i32::try_from(successes).unwrap_or(0)
+    }
+
+    pub fn is_exceptional(&self) -> bool {
+        self.successes() >= self.modifiers.exceptional_on
+    }
+}
+
+/// Attach a Context to a dice pool. Needed for database access.
+pub struct DicePoolWithContext<'a>(pub &'a DicePool, pub &'a Context<'a>);
+
+impl fmt::Display for DicePoolRoll {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let successes = self.successes();
+        if successes > 0 {
+            let success_msg = if self.is_exceptional() {
+                format!("{} successes (exceptional!)", successes)
+            } else {
+                format!("{} successes", successes)
+            };
+
+            write!(f, "{} ({})", success_msg, fmt_rolls(&self))?;
+        } else {
+            write!(f, "{} ({})", fmt_for_failure(&self), fmt_rolls(&self))?;
+        }
+
+        Ok(())
+    }
+}
+
+trait DieRoller {
+    fn roll_number(&mut self, sides: i32) -> i32;
+}
+
+///A version of DieRoller that uses a rand::Rng to roll numbers.
+struct RngDieRoller<R: rand::Rng>(R);
+
+impl<R: rand::Rng> DieRoller for RngDieRoller<R> {
+    fn roll_number(&mut self, sides: i32) -> i32 {
+        self.0.gen_range(1..=sides)
+    }
+}
+
+///Roll a die in the pool, that "explodes" on a given number or higher. Dice will keep
+///being rolled until the result is lower than the explode number, which is normally 10.
+///Statistically speaking, usually one result will be returned from this function.
+fn roll_exploding_die<R: DieRoller>(
+    roller: &mut R,
+    sides: i32,
+    explode_on_or_higher: i32,
+) -> Vec<i32> {
+    let mut results = vec![];
+    loop {
+        let roll = roller.roll_number(sides);
+        results.push(roll);
+        if roll < explode_on_or_higher {
+            break;
+        }
+    }
+    results
+}
+
+///A die with the rote quality is re-rolled once if the roll fails. Otherwise, it obeys
+///all normal rules (re-roll 10s). Re-rolled dice are appended to the result set, so we
+///can keep track of the actual dice that were rolled.
+fn roll_rote_die<R: DieRoller>(roller: &mut R, sides: i32, success_on: i32) -> Vec<i32> {
+    let mut rolls = roll_exploding_die(roller, sides, 10);
+
+    if rolls.len() == 1 && rolls[0] < success_on {
+        rolls.append(&mut roll_exploding_die(roller, sides, 10));
+    }
+
+    rolls
+}
+
+///Roll a single die in the pool, potentially rolling additional dice depending on  pool
+///behavior. The default ten-again will "explode" the die if the result is 10 (repeatedly, if
+///there are multiple 10s). Nine- and eight-again will explode similarly if the result is
+///at least that number. Rote quality will re-roll a failure once, while also exploding
+///on 10. The function returns a Vec of all rolled dice (usually 1).
+fn roll_die<R: DieRoller>(roller: &mut R, pool: &DicePool) -> Vec<i32> {
+    let mut results = vec![];
+    let sides = pool.sides;
+    let success_on = pool.modifiers.success_on;
+
+    match pool.modifiers.quality {
+        DicePoolQuality::TenAgain => results.append(&mut roll_exploding_die(roller, sides, 10)),
+        DicePoolQuality::NineAgain => results.append(&mut roll_exploding_die(roller, sides, 9)),
+        DicePoolQuality::EightAgain => results.append(&mut roll_exploding_die(roller, sides, 8)),
+        DicePoolQuality::Rote => results.append(&mut roll_rote_die(roller, sides, success_on)),
+        DicePoolQuality::ChanceDie | DicePoolQuality::NoExplode => {
+            results.push(roller.roll_number(sides))
+        }
+    }
+
+    results
+}
+
+fn roll_dice<'a, R: DieRoller>(pool: &DicePool, num_dice: i32, roller: &mut R) -> Vec<i32> {
+    (0..num_dice)
+        .flat_map(|_| roll_die(roller, &pool))
+        .collect()
+}
+
+///Roll the dice in a dice pool, according to behavior documented in the various rolling
+///methods.
+pub async fn roll_pool(pool: &DicePoolWithContext<'_>) -> Result<RolledDicePool, BotError> {
+    if pool.0.amounts.len() > 100 {
+        return Err(DiceRollingError::ExpressionTooLarge.into());
+    }
+
+    let num_dice = crate::logic::calculate_dice_amount(&pool.0.amounts, &pool.1).await?;
+    let mut roller = RngDieRoller(rand::thread_rng());
+
+    if num_dice > 0 {
+        let rolls = roll_dice(&pool.0, num_dice, &mut roller);
+        Ok(RolledDicePool::from(&pool.0, num_dice, rolls))
+    } else {
+        let chance_die = DicePool::chance_die();
+        let pool = DicePoolWithContext(&chance_die, &pool.1);
+        let rolls = roll_dice(&pool.0, 1, &mut roller);
+        Ok(RolledDicePool::from(&pool.0, 1, rolls))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::db::sqlite::Database;
+    use crate::db::Variables;
+    use url::Url;
+
+    macro_rules! dummy_room {
+        () => {
+            crate::context::RoomContext {
+                id: &matrix_sdk::ruma::room_id!("!fakeroomid:example.com"),
+                display_name: "displayname".to_owned(),
+                secure: false,
+            }
+        };
+    }
+
+    ///Instead of being random, generate a series of numbers we have complete
+    ///control over.
+    struct SequentialDieRoller {
+        results: Vec<i32>,
+        position: usize,
+    }
+
+    impl SequentialDieRoller {
+        fn new(results: Vec<i32>) -> SequentialDieRoller {
+            SequentialDieRoller {
+                results: results,
+                position: 0,
+            }
+        }
+    }
+
+    impl DieRoller for SequentialDieRoller {
+        fn roll_number(&mut self, _sides: i32) -> i32 {
+            let roll = self.results[self.position];
+            self.position += 1;
+            roll
+        }
+    }
+
+    //Sanity checks
+    #[test]
+    pub fn chance_die_has_success_on_10_test() {
+        assert_eq!(10, DicePool::chance_die().modifiers.success_on);
+    }
+
+    #[test]
+    pub fn non_chance_die_has_success_on_8_test() {
+        fn check_success_on(quality: DicePoolQuality) {
+            let modifiers = DicePoolModifiers::custom_quality(quality);
+            let amount = vec![Amount {
+                operator: Operator::Plus,
+                element: Element::Number(1),
+            }];
+            assert_eq!(8, DicePool::new(amount, modifiers).modifiers.success_on);
+        }
+
+        check_success_on(DicePoolQuality::TenAgain);
+        check_success_on(DicePoolQuality::NineAgain);
+        check_success_on(DicePoolQuality::EightAgain);
+        check_success_on(DicePoolQuality::Rote);
+        check_success_on(DicePoolQuality::NoExplode);
+    }
+
+    //Dice rolling tests.
+    #[test]
+    pub fn ten_again_test() {
+        let mut roller = SequentialDieRoller::new(vec![10, 8, 1]);
+        let rolls = roll_exploding_die(&mut roller, 10, 10);
+        assert_eq!(vec![10, 8], rolls);
+    }
+
+    #[test]
+    pub fn nine_again_test() {
+        let mut roller = SequentialDieRoller::new(vec![10, 9, 8, 1]);
+        let rolls = roll_exploding_die(&mut roller, 10, 9);
+        assert_eq!(vec![10, 9, 8], rolls);
+    }
+
+    #[test]
+    pub fn eight_again_test() {
+        let mut roller = SequentialDieRoller::new(vec![10, 9, 8, 8, 1]);
+        let rolls = roll_exploding_die(&mut roller, 10, 8);
+        assert_eq!(vec![10, 9, 8, 8, 1], rolls);
+    }
+
+    #[test]
+    pub fn rote_quality_fail_then_succeed_test() {
+        let mut roller = SequentialDieRoller::new(vec![5, 8, 1]);
+        let rolls = roll_rote_die(&mut roller, 10, 8);
+        assert_eq!(vec![5, 8], rolls);
+    }
+
+    #[test]
+    pub fn rote_quality_fail_twice_test() {
+        let mut roller = SequentialDieRoller::new(vec![5, 6, 10]);
+        let rolls = roll_rote_die(&mut roller, 10, 8);
+        assert_eq!(vec![5, 6], rolls);
+    }
+
+    #[test]
+    pub fn rote_quality_fail_then_explode_test() {
+        let mut roller = SequentialDieRoller::new(vec![5, 10, 8, 1]);
+        let rolls = roll_rote_die(&mut roller, 10, 8);
+        assert_eq!(vec![5, 10, 8], rolls);
+    }
+
+    #[test]
+    pub fn rote_quality_obeys_success_on_test() {
+        //With success_on = 8, should only roll once.
+        let mut roller = SequentialDieRoller::new(vec![8, 7]);
+        let rolls = roll_rote_die(&mut roller, 10, 8);
+        assert_eq!(vec![8], rolls);
+
+        //With success_on = 9, we should re-roll if it's an 8.
+        roller = SequentialDieRoller::new(vec![8, 7]);
+        let rolls = roll_rote_die(&mut roller, 10, 9);
+        assert_eq!(vec![8, 7], rolls);
+    }
+
+    #[test]
+    fn dice_pool_modifiers_chance_die_test() {
+        let modifiers = DicePoolModifiers::custom_quality(DicePoolQuality::ChanceDie);
+        assert_eq!(10, modifiers.success_on);
+    }
+
+    #[test]
+    fn dice_pool_modifiers_default_sanity_check() {
+        let modifiers = DicePoolModifiers::default();
+        assert_eq!(8, modifiers.success_on);
+        assert_eq!(5, modifiers.exceptional_on);
+        assert_eq!(DicePoolQuality::TenAgain, modifiers.quality);
+    }
+
+    #[test]
+    pub fn no_explode_roll_test() {
+        let pool = DicePool::easy_pool(1, DicePoolQuality::NoExplode);
+        let mut roller = SequentialDieRoller::new(vec![10, 8]);
+        let roll = roll_dice(&pool, 1, &mut roller);
+        assert_eq!(vec![10], roll);
+    }
+
+    #[test]
+    fn number_of_dice_equality_test() {
+        let num_dice = 5;
+        let rolls = vec![1, 2, 3, 4, 5];
+        let pool = DicePool::easy_pool(5, DicePoolQuality::TenAgain);
+        let rolled_pool = RolledDicePool::from(&pool, num_dice, rolls);
+        assert_eq!(5, rolled_pool.num_dice);
+    }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
+    async fn rejects_large_expression_test() {
+        let db_path = tempfile::NamedTempFile::new_in(".").unwrap();
+        let homeserver = Url::parse("http://example.com").unwrap();
+        let db = Database::new(db_path.path().to_str().unwrap())
+            .await
+            .unwrap();
+
+        let ctx = Context {
+            account: crate::models::Account::default(),
+            db: db,
+            matrix_client: matrix_sdk::Client::new(homeserver).await.unwrap(),
+            origin_room: dummy_room!(),
+            active_room: dummy_room!(),
+            username: "username",
+            message_body: "message",
+        };
+
+        let mut amounts = vec![];
+
+        for _ in 0..500 {
+            amounts.push(Amount {
+                operator: Operator::Plus,
+                element: Element::Number(1),
+            });
+        }
+
+        let pool = DicePool::new(amounts, DicePoolModifiers::default());
+        let pool_with_ctx = DicePoolWithContext(&pool, &ctx);
+        let result = roll_pool(&pool_with_ctx).await;
+        assert!(matches!(
+            result,
+            Err(BotError::DiceRollingError(
+                DiceRollingError::ExpressionTooLarge
+            ))
+        ));
+    }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
+    async fn converts_to_chance_die_test() {
+        let db_path = tempfile::NamedTempFile::new_in(".").unwrap();
+        crate::db::sqlite::migrator::migrate(db_path.path().to_str().unwrap())
+            .await
+            .unwrap();
+
+        let db = Database::new(db_path.path().to_str().unwrap())
+            .await
+            .unwrap();
+
+        let homeserver = Url::parse("http://example.com").unwrap();
+        let ctx = Context {
+            account: crate::models::Account::default(),
+            db: db,
+            matrix_client: matrix_sdk::Client::new(homeserver).await.unwrap(),
+            origin_room: dummy_room!(),
+            active_room: dummy_room!(),
+            username: "username",
+            message_body: "message",
+        };
+
+        let mut amounts = vec![];
+
+        amounts.push(Amount {
+            operator: Operator::Plus,
+            element: Element::Number(-1),
+        });
+
+        let pool = DicePool::new(amounts, DicePoolModifiers::default());
+        let pool_with_ctx = DicePoolWithContext(&pool, &ctx);
+        let result = roll_pool(&pool_with_ctx).await;
+        assert!(result.is_ok());
+
+        let roll = result.unwrap();
+        assert_eq!(DicePoolQuality::ChanceDie, roll.modifiers.quality);
+        assert_eq!(1, roll.num_dice);
+    }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
+    async fn can_resolve_variables_test() {
+        let db_path = tempfile::NamedTempFile::new_in(".").unwrap();
+        crate::db::sqlite::migrator::migrate(db_path.path().to_str().unwrap())
+            .await
+            .unwrap();
+
+        let db = Database::new(db_path.path().to_str().unwrap())
+            .await
+            .unwrap();
+
+        let homeserver = Url::parse("http://example.com").unwrap();
+        let ctx = Context {
+            account: crate::models::Account::default(),
+            db: db.clone(),
+            matrix_client: matrix_sdk::Client::new(homeserver).await.unwrap(),
+            origin_room: dummy_room!(),
+            active_room: dummy_room!(),
+            username: "username",
+            message_body: "message",
+        };
+
+        db.set_user_variable(
+            &ctx.username,
+            &ctx.origin_room.id.as_str(),
+            "myvariable",
+            10,
+        )
+        .await
+        .expect("could not set myvariable to 10");
+
+        let amounts = vec![Amount {
+            operator: Operator::Plus,
+            element: Element::Variable("myvariable".to_owned()),
+        }];
+
+        let pool = DicePool::new(amounts, DicePoolModifiers::default());
+
+        assert_eq!(
+            crate::logic::calculate_dice_amount(&pool.amounts, &ctx)
+                .await
+                .unwrap(),
+            10
+        );
+    }
+
+    //DicePool tests
+    #[test]
+    fn easy_pool_chance_die_test() {
+        let pool = DicePool::easy_pool(1, DicePoolQuality::ChanceDie);
+        assert_eq!(10, pool.modifiers.success_on);
+    }
+
+    #[test]
+    fn easy_pool_quality_test() {
+        fn check_quality(quality: DicePoolQuality) {
+            let pool = DicePool::easy_pool(1, quality);
+            assert_eq!(quality, pool.modifiers.quality);
+        }
+
+        check_quality(DicePoolQuality::TenAgain);
+        check_quality(DicePoolQuality::NineAgain);
+        check_quality(DicePoolQuality::EightAgain);
+        check_quality(DicePoolQuality::Rote);
+        check_quality(DicePoolQuality::ChanceDie);
+        check_quality(DicePoolQuality::NoExplode);
+    }
+
+    #[test]
+    fn is_successful_on_equal_test() {
+        let result = DicePoolRoll {
+            rolls: vec![8],
+            modifiers: DicePoolModifiers {
+                exceptional_on: 5,
+                success_on: 8,
+                quality: DicePoolQuality::TenAgain,
+            },
+        };
+
+        assert_eq!(1, result.successes());
+    }
+
+    #[test]
+    fn chance_die_success_test() {
+        let result = DicePoolRoll {
+            rolls: vec![10],
+            modifiers: DicePoolModifiers {
+                exceptional_on: 5,
+                success_on: 10,
+                quality: DicePoolQuality::ChanceDie,
+            },
+        };
+
+        assert_eq!(1, result.successes());
+    }
+
+    #[test]
+    fn chance_die_fail_test() {
+        let result = DicePoolRoll {
+            rolls: vec![9],
+            modifiers: DicePoolModifiers {
+                exceptional_on: 5,
+                success_on: 10,
+                quality: DicePoolQuality::ChanceDie,
+            },
+        };
+
+        assert_eq!(0, result.successes());
+    }
+
+    #[test]
+    fn is_exceptional_test() {
+        let result = DicePoolRoll {
+            rolls: vec![8, 8, 9, 10, 8],
+            modifiers: DicePoolModifiers {
+                exceptional_on: 5,
+                success_on: 8,
+                quality: DicePoolQuality::TenAgain,
+            },
+        };
+
+        assert_eq!(5, result.successes());
+        assert_eq!(true, result.is_exceptional());
+    }
+
+    #[test]
+    fn is_not_exceptional_test() {
+        let result = DicePoolRoll {
+            rolls: vec![8, 8, 9, 10],
+            modifiers: DicePoolModifiers::default(),
+        };
+
+        assert_eq!(4, result.successes());
+        assert_eq!(false, result.is_exceptional());
+    }
+
+    //Format tests
+    #[test]
+    fn formats_rolled_dice_pool_single_die() {
+        let pool = DicePool::easy_pool(5, DicePoolQuality::TenAgain);
+        let rolled_pool = RolledDicePool::from(&pool, 1, vec![1]);
+        let message = format!("{}", rolled_pool);
+        assert!(message.starts_with("1 die"));
+    }
+
+    #[test]
+    fn formats_rolled_dice_pool_multiple_dice() {
+        let pool = DicePool::easy_pool(5, DicePoolQuality::TenAgain);
+        let rolled_pool = RolledDicePool::from(&pool, 2, vec![1, 2]);
+        let message = format!("{}", rolled_pool);
+        assert!(message.starts_with("2 dice"));
+    }
+
+    #[test]
+    fn formats_rolled_dice_pool_zero_dice() {
+        let pool = DicePool::easy_pool(5, DicePoolQuality::TenAgain);
+        let rolled_pool = RolledDicePool::from(&pool, 0, vec![]);
+        let message = format!("{}", rolled_pool);
+        assert!(message.starts_with("0 dice"));
+    }
+
+    #[test]
+    fn formats_dramatic_failure_test() {
+        let result = DicePoolRoll {
+            rolls: vec![1],
+            modifiers: DicePoolModifiers::custom_quality(DicePoolQuality::ChanceDie),
+        };
+
+        assert_eq!("dramatic failure!", fmt_for_failure(&result));
+    }
+
+    #[test]
+    fn formats_regular_failure_when_not_chance_die_test() {
+        let result = DicePoolRoll {
+            rolls: vec![1],
+            modifiers: DicePoolModifiers {
+                quality: DicePoolQuality::TenAgain,
+                exceptional_on: 5,
+                success_on: 10,
+            },
+        };
+
+        assert_eq!("failure!", fmt_for_failure(&result));
+    }
+
+    #[test]
+    fn formats_lots_of_dice_test() {
+        let result = DicePoolRoll {
+            modifiers: DicePoolModifiers::default(),
+            rolls: vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1, 2, 3, 4, 5, 6, 7, 8, 9],
+        };
+
+        assert_eq!(
+            "1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1, 2, 3, 4, 5, and 4 more",
+            fmt_rolls(&result)
+        );
+    }
+
+    #[test]
+    fn shows_more_than_10_dice_test() {
+        //Make sure we display more than 10 dice when below the display limit (15).
+        let result = DicePoolRoll {
+            modifiers: DicePoolModifiers::default(),
+            rolls: vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14],
+        };
+
+        assert_eq!(
+            "1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14",
+            fmt_rolls(&result)
+        );
+    }
+
+    #[test]
+    fn shows_exactly_15_dice_test() {
+        //If we are at format limit (15), make sure all are shown
+        let result = DicePoolRoll {
+            modifiers: DicePoolModifiers::default(),
+            rolls: vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15],
+        };
+
+        assert_eq!(
+            "1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15",
+            fmt_rolls(&result)
+        );
+    }
+}

dicebot/src/cofd/parser.rs

@@ -0,0 +1,233 @@
+use crate::cofd::dice::{DicePool, DicePoolModifiers, DicePoolQuality};
+use crate::error::BotError;
+use crate::parser::dice::{parse_amounts, DiceParsingError};
+use combine::parser::char::{digit, spaces, string};
+use combine::{choice, count, many1, one_of, Parser};
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+enum ParsedInfo {
+    Quality(DicePoolQuality),
+    ExceptionalOn(i32),
+}
+
+pub fn parse_modifiers(input: &str) -> Result<DicePoolModifiers, DiceParsingError> {
+    if input.len() == 0 {
+        return Ok(DicePoolModifiers::default());
+    }
+
+    let input = input.trim();
+
+    let quality = one_of("nerx".chars())
+        .skip(spaces().silent())
+        .map(|quality| match quality {
+            'n' => ParsedInfo::Quality(DicePoolQuality::NineAgain),
+            'e' => ParsedInfo::Quality(DicePoolQuality::EightAgain),
+            'r' => ParsedInfo::Quality(DicePoolQuality::Rote),
+            'x' => ParsedInfo::Quality(DicePoolQuality::NoExplode),
+            _ => ParsedInfo::Quality(DicePoolQuality::TenAgain), //TODO add warning log
+        });
+
+    let exceptional_on = string("s")
+        .and(many1(digit()))
+        .map(|s| s.1) //Discard the s; only need the number
+        .skip(spaces().silent())
+        .map(|num_as_str: String| {
+            ParsedInfo::ExceptionalOn(match num_as_str.parse::<i32>() {
+                Ok(success_on) => success_on,
+                Err(_) => 5, //TODO add warning log
+            })
+        });
+
+    let mut parser = count(2, choice((quality, exceptional_on)))
+        .skip(spaces().silent())
+        .map(|modifiers: Vec<ParsedInfo>| modifiers);
+
+    let (result, rest) = parser.parse(input)?;
+
+    if rest.len() == 0 {
+        convert_to_modifiers(&result)
+    } else {
+        Err(DiceParsingError::UnconsumedInput)
+    }
+}
+
+fn convert_to_modifiers(parsed: &Vec<ParsedInfo>) -> Result<DicePoolModifiers, DiceParsingError> {
+    use ParsedInfo::*;
+    if parsed.len() == 0 {
+        Ok(DicePoolModifiers::default())
+    } else if parsed.len() == 1 {
+        match parsed[0] {
+            ExceptionalOn(exceptional_on) => {
+                Ok(DicePoolModifiers::custom_exceptional_on(exceptional_on))
+            }
+            Quality(quality) => Ok(DicePoolModifiers::custom_quality(quality)),
+        }
+    } else if parsed.len() == 2 {
+        match parsed[..] {
+            [ExceptionalOn(exceptional_on), Quality(quality)] => {
+                Ok(DicePoolModifiers::custom(quality, exceptional_on))
+            }
+            [Quality(quality), ExceptionalOn(exceptional_on)] => {
+                Ok(DicePoolModifiers::custom(quality, exceptional_on))
+            }
+            _ => Err(DiceParsingError::InvalidModifiers.into()),
+        }
+    } else {
+        //We don't expect this clause to be hit, because the parser works 0 to 2 times.
+        Err(DiceParsingError::InvalidModifiers.into())
+    }
+}
+
+pub fn parse_dice_pool(input: &str) -> Result<DicePool, BotError> {
+    let (amounts, modifiers_str) = parse_amounts(input)?;
+    let modifiers = parse_modifiers(modifiers_str)?;
+    Ok(DicePool::new(amounts, modifiers))
+}
+
+pub fn create_chance_die() -> Result<DicePool, BotError> {
+    Ok(DicePool::chance_die())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn quality_test() {
+        let result = parse_modifiers("n");
+        assert!(result.is_ok());
+        assert_eq!(
+            result.unwrap(),
+            DicePoolModifiers::custom_quality(DicePoolQuality::NineAgain)
+        );
+
+        let result = parse_modifiers("e");
+        assert!(result.is_ok());
+        assert_eq!(
+            result.unwrap(),
+            DicePoolModifiers::custom_quality(DicePoolQuality::EightAgain)
+        );
+
+        let result = parse_modifiers("r");
+        assert!(result.is_ok());
+        assert_eq!(
+            result.unwrap(),
+            DicePoolModifiers::custom_quality(DicePoolQuality::Rote)
+        );
+
+        let result = parse_modifiers("x");
+        assert!(result.is_ok());
+        assert_eq!(
+            result.unwrap(),
+            DicePoolModifiers::custom_quality(DicePoolQuality::NoExplode)
+        );
+
+        let result = parse_modifiers("b");
+        assert!(result.is_err());
+        assert!(matches!(result, Err(DiceParsingError::UnconsumedInput)));
+    }
+
+    #[test]
+    fn multiple_quality_failure_test() {
+        let result = parse_modifiers("ne");
+        assert!(result.is_err());
+        assert!(matches!(result, Err(DiceParsingError::InvalidModifiers)));
+    }
+
+    #[test]
+    fn exceptional_success_test() {
+        let result = parse_modifiers("s3");
+        assert!(result.is_ok());
+        assert_eq!(result.unwrap(), DicePoolModifiers::custom_exceptional_on(3));
+
+        let result = parse_modifiers("s33");
+        assert!(result.is_ok());
+        assert_eq!(
+            result.unwrap(),
+            DicePoolModifiers::custom_exceptional_on(33)
+        );
+
+        let result = parse_modifiers("s3q");
+        assert!(result.is_err());
+        assert!(matches!(result, Err(DiceParsingError::UnconsumedInput)));
+    }
+
+    #[test]
+    fn dice_pool_number_only_test() {
+        let result = parse_dice_pool("8");
+        assert!(result.is_ok());
+        assert_eq!(
+            result.unwrap(),
+            DicePool::easy_pool(8, DicePoolQuality::TenAgain)
+        );
+    }
+
+    #[test]
+    fn dice_pool_number_with_quality() {
+        let result = parse_dice_pool("8 n");
+        assert!(result.is_ok());
+        assert_eq!(
+            result.unwrap(),
+            DicePool::easy_pool(8, DicePoolQuality::NineAgain)
+        );
+    }
+
+    #[test]
+    fn dice_pool_number_with_success_change() {
+        let modifiers = DicePoolModifiers::custom_exceptional_on(3);
+        let result = parse_dice_pool("8 s3");
+        assert!(result.is_ok());
+        assert_eq!(result.unwrap(), DicePool::easy_with_modifiers(8, modifiers));
+    }
+
+    #[test]
+    fn dice_pool_with_quality_and_success_change() {
+        let modifiers = DicePoolModifiers::custom(DicePoolQuality::Rote, 3);
+        let result = parse_dice_pool("8 rs3");
+        assert!(result.is_ok());
+        assert_eq!(result.unwrap(), DicePool::easy_with_modifiers(8, modifiers));
+    }
+
+    #[test]
+    fn dice_pool_complex_expression_test() {
+        use crate::parser::dice::*;
+        let modifiers = DicePoolModifiers::custom(DicePoolQuality::Rote, 3);
+        let amounts = vec![
+            Amount {
+                operator: Operator::Plus,
+                element: Element::Number(8),
+            },
+            Amount {
+                operator: Operator::Plus,
+                element: Element::Number(10),
+            },
+            Amount {
+                operator: Operator::Minus,
+                element: Element::Number(2),
+            },
+            Amount {
+                operator: Operator::Plus,
+                element: Element::Variable("varname".to_owned()),
+            },
+        ];
+
+        let expected = DicePool::new(amounts, modifiers);
+
+        let result = parse_dice_pool("8+10-2+varname rs3");
+        assert!(result.is_ok());
+        assert_eq!(result.unwrap(), expected);
+
+        let result = parse_dice_pool("8+10-   2 + varname      rs3");
+        assert!(result.is_ok());
+        assert_eq!(result.unwrap(), expected);
+
+        let result = parse_dice_pool("8+ 10 -2 + varname           rs3");
+        assert!(result.is_ok());
+        assert_eq!(result.unwrap(), expected);
+
+        //This one has tabs in it.
+        let result = parse_dice_pool(" 	8	+ 10 -2 + varname	r	s3");
+        assert!(result.is_ok());
+        assert_eq!(result.unwrap(), expected);
+    }
+}

dicebot/src/commands/basic_rolling.rs

@@ -0,0 +1,48 @@
+use super::{Command, Execution, ExecutionResult};
+use crate::basic::dice::ElementExpression;
+use crate::basic::parser::parse_element_expression;
+use crate::basic::roll::Roll;
+use crate::context::Context;
+use crate::error::BotError;
+use async_trait::async_trait;
+use nom::Err as NomErr;
+use std::convert::TryFrom;
+
+pub struct RollCommand(pub ElementExpression);
+
+impl TryFrom<String> for RollCommand {
+    type Error = BotError;
+
+    fn try_from(input: String) -> Result<Self, Self::Error> {
+        let result = parse_element_expression(&input);
+        match result {
+            Ok((rest, expression)) if rest.len() == 0 => Ok(RollCommand(expression)),
+            //"Legacy code boundary": translates Nom errors into BotErrors.
+            Ok(_) => Err(BotError::NomParserIncomplete),
+            Err(NomErr::Error(e)) => Err(BotError::NomParserError(e.1)),
+            Err(NomErr::Failure(e)) => Err(BotError::NomParserError(e.1)),
+            Err(NomErr::Incomplete(_)) => Err(BotError::NomParserIncomplete),
+        }
+    }
+}
+
+#[async_trait]
+impl Command for RollCommand {
+    fn name(&self) -> &'static str {
+        "roll regular dice"
+    }
+
+    fn is_secure(&self) -> bool {
+        false
+    }
+
+    async fn execute(&self, _ctx: &Context<'_>) -> ExecutionResult {
+        let roll = self.0.roll();
+        let html = format!(
+            "<strong>Dice:</strong> {}</p><p><strong>Result</strong>: {}",
+            self.0, roll
+        );
+
+        Execution::success(html)
+    }
+}

dicebot/src/commands/cofd.rs

@@ -0,0 +1,48 @@
+use super::{Command, Execution, ExecutionResult};
+use crate::cofd::dice::{roll_pool, DicePool, DicePoolWithContext};
+use crate::cofd::parser::{create_chance_die, parse_dice_pool};
+use crate::context::Context;
+use crate::error::BotError;
+use async_trait::async_trait;
+use std::convert::TryFrom;
+
+pub struct PoolRollCommand(pub DicePool);
+
+impl PoolRollCommand {
+    pub fn chance_die() -> Result<PoolRollCommand, BotError> {
+        let pool = create_chance_die()?;
+        Ok(PoolRollCommand(pool))
+    }
+}
+
+impl TryFrom<String> for PoolRollCommand {
+    type Error = BotError;
+
+    fn try_from(input: String) -> Result<Self, Self::Error> {
+        let pool = parse_dice_pool(&input)?;
+        Ok(PoolRollCommand(pool))
+    }
+}
+
+#[async_trait]
+impl Command for PoolRollCommand {
+    fn name(&self) -> &'static str {
+        "roll dice pool"
+    }
+
+    fn is_secure(&self) -> bool {
+        false
+    }
+
+    async fn execute(&self, ctx: &Context<'_>) -> ExecutionResult {
+        let pool_with_ctx = DicePoolWithContext(&self.0, ctx);
+        let rolled_pool = roll_pool(&pool_with_ctx).await?;
+
+        let html = format!(
+            "<strong>Pool:</strong> {}</p><p><strong>Result</strong>: {}",
+            rolled_pool, rolled_pool.roll
+        );
+
+        Execution::success(html)
+    }
+}

dicebot/src/commands/cthulhu.rs

@@ -0,0 +1,77 @@
+use super::{Command, Execution, ExecutionResult};
+use crate::context::Context;
+use crate::cthulhu::dice::{
+    advancement_roll, regular_roll, AdvancementRoll, AdvancementRollWithContext, DiceRoll,
+    DiceRollWithContext,
+};
+use crate::cthulhu::parser::{parse_advancement_roll, parse_regular_roll};
+use crate::error::BotError;
+use async_trait::async_trait;
+use std::convert::TryFrom;
+
+pub struct CthRoll(pub DiceRoll);
+
+impl TryFrom<String> for CthRoll {
+    type Error = BotError;
+
+    fn try_from(input: String) -> Result<Self, Self::Error> {
+        let roll = parse_regular_roll(&input)?;
+        Ok(CthRoll(roll))
+    }
+}
+
+#[async_trait]
+impl Command for CthRoll {
+    fn name(&self) -> &'static str {
+        "roll percentile dice"
+    }
+
+    fn is_secure(&self) -> bool {
+        false
+    }
+
+    async fn execute(&self, ctx: &Context<'_>) -> ExecutionResult {
+        let roll_with_ctx = DiceRollWithContext(&self.0, ctx);
+        let executed_roll = regular_roll(&roll_with_ctx).await?;
+
+        let html = format!(
+            "<strong>Roll:</strong> {}</p><p><strong>Result</strong>: {}",
+            executed_roll, executed_roll.roll
+        );
+
+        Execution::success(html)
+    }
+}
+
+pub struct CthAdvanceRoll(pub AdvancementRoll);
+
+impl TryFrom<String> for CthAdvanceRoll {
+    type Error = BotError;
+
+    fn try_from(input: String) -> Result<Self, Self::Error> {
+        let roll = parse_advancement_roll(&input)?;
+        Ok(CthAdvanceRoll(roll))
+    }
+}
+
+#[async_trait]
+impl Command for CthAdvanceRoll {
+    fn name(&self) -> &'static str {
+        "roll skill advancement dice"
+    }
+
+    fn is_secure(&self) -> bool {
+        false
+    }
+
+    async fn execute(&self, ctx: &Context<'_>) -> ExecutionResult {
+        let roll_with_ctx = AdvancementRollWithContext(&self.0, ctx);
+        let executed_roll = advancement_roll(&roll_with_ctx).await?;
+        let html = format!(
+            "<strong>Roll:</strong> {}</p><p><strong>Result</strong>: {}",
+            executed_roll, executed_roll.roll
+        );
+
+        Execution::success(html)
+    }
+}

dicebot/src/commands/management.rs

@@ -0,0 +1,200 @@
+use super::{Command, Execution, ExecutionResult};
+use crate::db::Users;
+use crate::error::BotError::{AccountDoesNotExist, PasswordCreationError};
+use crate::logic::hash_password;
+use crate::models::{AccountStatus, User};
+use crate::{context::Context, error::BotError};
+use async_trait::async_trait;
+use std::convert::{Into, TryFrom};
+
+pub struct RegisterCommand;
+
+impl TryFrom<String> for RegisterCommand {
+    type Error = BotError;
+
+    fn try_from(_: String) -> Result<Self, Self::Error> {
+        Ok(RegisterCommand)
+    }
+}
+
+#[async_trait]
+impl Command for RegisterCommand {
+    fn name(&self) -> &'static str {
+        "register user account"
+    }
+
+    fn is_secure(&self) -> bool {
+        true
+    }
+
+    async fn execute(&self, ctx: &Context<'_>) -> ExecutionResult {
+        if ctx.account.is_registered() {
+            return Err(BotError::AccountAlreadyExists);
+        }
+
+        let user = User {
+            username: ctx.username.to_owned(),
+            password: None,
+            account_status: AccountStatus::Registered,
+            ..Default::default()
+        };
+
+        ctx.db.upsert_user(&user).await?;
+
+        Execution::success(format!(
+            "User account {} registered for bot commands.",
+            ctx.username
+        ))
+    }
+}
+
+pub struct UnlinkCommand(pub String);
+
+impl TryFrom<String> for UnlinkCommand {
+    type Error = BotError;
+
+    fn try_from(value: String) -> Result<Self, Self::Error> {
+        Ok(UnlinkCommand(value))
+    }
+}
+
+#[async_trait]
+impl Command for UnlinkCommand {
+    fn name(&self) -> &'static str {
+        "unlink user accountx from external applications"
+    }
+
+    fn is_secure(&self) -> bool {
+        true
+    }
+
+    async fn execute(&self, ctx: &Context<'_>) -> ExecutionResult {
+        let mut user = ctx
+            .db
+            .get_user(&ctx.username)
+            .await?
+            .ok_or(BotError::AccountDoesNotExist)?;
+
+        user.password = None;
+        ctx.db.upsert_user(&user).await?;
+
+        Execution::success(format!(
+            "Accounted {} is now inaccessible to external applications.",
+            ctx.username
+        ))
+    }
+}
+
+pub struct LinkCommand(pub String);
+
+impl TryFrom<String> for LinkCommand {
+    type Error = BotError;
+
+    fn try_from(value: String) -> Result<Self, Self::Error> {
+        Ok(LinkCommand(value))
+    }
+}
+
+#[async_trait]
+impl Command for LinkCommand {
+    fn name(&self) -> &'static str {
+        "link user account to external applications"
+    }
+
+    fn is_secure(&self) -> bool {
+        true
+    }
+
+    async fn execute(&self, ctx: &Context<'_>) -> ExecutionResult {
+        let mut user = ctx
+            .db
+            .get_user(&ctx.username)
+            .await?
+            .ok_or(BotError::AccountDoesNotExist)?;
+
+        let pw_hash = hash_password(&self.0).map_err(|e| PasswordCreationError(e))?;
+        user.password = Some(pw_hash);
+        ctx.db.upsert_user(&user).await?;
+
+        Execution::success(format!(
+            "Accounted now available for external use. Please log in to \
+             external applications with username {} and the password you set.",
+            ctx.username
+        ))
+    }
+}
+
+pub struct CheckCommand;
+
+impl TryFrom<String> for CheckCommand {
+    type Error = BotError;
+
+    fn try_from(_: String) -> Result<Self, Self::Error> {
+        Ok(CheckCommand)
+    }
+}
+
+#[async_trait]
+impl Command for CheckCommand {
+    fn name(&self) -> &'static str {
+        "check user account status"
+    }
+
+    fn is_secure(&self) -> bool {
+        true
+    }
+
+    async fn execute(&self, ctx: &Context<'_>) -> ExecutionResult {
+        let user = ctx.db.get_user(&ctx.username).await?;
+
+        match user {
+            Some(user) => match user.password {
+                Some(_) => Execution::success(
+                    "Account exists, and is available to external applications with a password. \
+                     If you forgot your password, change it with !link."
+                        .to_string(),
+                ),
+                None => Execution::success(
+                    "Account exists, but is not available to external applications.".to_string(),
+                ),
+            },
+            None => Execution::success(
+                "No account registered. Only simple commands in public rooms are available."
+                    .to_string(),
+            ),
+        }
+    }
+}
+
+pub struct UnregisterCommand;
+
+impl TryFrom<String> for UnregisterCommand {
+    type Error = BotError;
+
+    fn try_from(_: String) -> Result<Self, Self::Error> {
+        Ok(UnregisterCommand)
+    }
+}
+
+#[async_trait]
+impl Command for UnregisterCommand {
+    fn name(&self) -> &'static str {
+        "unregister user account"
+    }
+
+    fn is_secure(&self) -> bool {
+        true
+    }
+
+    async fn execute(&self, ctx: &Context<'_>) -> ExecutionResult {
+        let user = ctx.db.get_user(&ctx.username).await?;
+
+        match user {
+            Some(_) => {
+                ctx.db.delete_user(&ctx.username).await?;
+                Execution::success("Your user account has been removed.".to_string())
+            }
+            None => Err(AccountDoesNotExist.into()),
+        }
+    }
+}

dicebot/src/commands/misc.rs

@@ -0,0 +1,38 @@
+use super::{Command, Execution, ExecutionResult};
+use crate::context::Context;
+use crate::error::BotError;
+use crate::help::{parse_help_topic, HelpTopic};
+use async_trait::async_trait;
+use std::convert::TryFrom;
+
+pub struct HelpCommand(pub Option<HelpTopic>);
+
+impl TryFrom<String> for HelpCommand {
+    type Error = BotError;
+
+    fn try_from(input: String) -> Result<Self, Self::Error> {
+        let topic = parse_help_topic(&input);
+        Ok(HelpCommand(topic))
+    }
+}
+
+#[async_trait]
+impl Command for HelpCommand {
+    fn name(&self) -> &'static str {
+        "help information"
+    }
+
+    fn is_secure(&self) -> bool {
+        false
+    }
+
+    async fn execute(&self, _ctx: &Context<'_>) -> ExecutionResult {
+        let help = match &self.0 {
+            Some(topic) => topic.message(),
+            _ => "There is no help for this topic",
+        };
+
+        let html = format!("<strong>Help:</strong> {}", help.replace("\n", "<br/>"));
+        Execution::success(html)
+    }
+}

dicebot/src/commands/mod.rs

@@ -0,0 +1,301 @@
+use crate::context::Context;
+use crate::error::BotError;
+use async_trait::async_trait;
+use log::{error, info};
+use thiserror::Error;
+
+pub mod basic_rolling;
+pub mod cofd;
+pub mod cthulhu;
+pub mod management;
+pub mod misc;
+pub mod parser;
+pub mod rooms;
+pub mod variables;
+
+/// A custom error type specifically related to parsing command text.
+/// Does not wrap an execution failure.
+#[derive(Error, Debug)]
+pub enum CommandError {
+    #[error("invalid command: {0}")]
+    InvalidCommand(String),
+
+    #[error("command can only be executed from encrypted direct message")]
+    InsecureExecution,
+
+    #[error("ignored command")]
+    IgnoredCommand,
+}
+
+/// A successfully executed command returns a message to be sent back
+/// to the user in HTML (plain text used as a fallback by message
+/// formatter).
+#[derive(Debug)]
+pub struct Execution {
+    html: String,
+}
+
+impl Execution {
+    pub fn success(html: String) -> ExecutionResult {
+        Ok(Execution { html })
+    }
+
+    /// Response message in HTML.
+    pub fn html(&self) -> String {
+        self.html.clone()
+    }
+}
+
+/// Wraps either a successful command execution response, or an error
+/// that occurred.
+pub type ExecutionResult = Result<Execution, BotError>;
+
+/// Extract response messages out of a type, whether it is success or
+/// failure.
+pub trait ResponseExtractor {
+    /// HTML representation of the message, directly mentioning the
+    /// username.
+    fn message_html(&self, username: &str) -> String;
+
+    fn message_plain(&self, username: &str) -> String;
+}
+
+impl ResponseExtractor for ExecutionResult {
+    /// Error message in bolded HTML.
+    fn message_html(&self, username: &str) -> String {
+        // TODO use user display name too (element seems to render this
+        // without display name)
+        let username = format!(
+            "<a href=\"https://matrix.to/#/{}\">{}</a>",
+            username, username
+        );
+
+        match self {
+            Ok(resp) => format!("<p>{}</p>", resp.html).replace("\n", "<br/>"),
+            Err(e) => format!("<p>{}: <strong>{}</strong></p>", username, e).replace("\n", "<br/>"),
+        }
+    }
+
+    fn message_plain(&self, username: &str) -> String {
+        let message = match self {
+            Ok(resp) => format!("{}", resp.html),
+            Err(e) => format!("{}", e),
+        };
+
+        format!(
+            "{}:\n{}",
+            username,
+            html2text::from_read(message.as_bytes(), message.len())
+        )
+    }
+}
+
+/// The trait that any command that can be executed must implement.
+#[async_trait]
+pub trait Command: Send + Sync {
+    async fn execute(&self, ctx: &Context<'_>) -> ExecutionResult;
+    fn name(&self) -> &'static str;
+    fn is_secure(&self) -> bool;
+}
+
+/// Determine if we are allowed to execute this command. Currently the
+/// rules are that secure commands must be executed in secure rooms
+/// (encrypted + direct), and anything else can be executed where
+/// ever. Later, we can add stuff like admin/regular user power
+/// separation, etc.
+fn execution_allowed(cmd: &(impl Command + ?Sized), ctx: &Context<'_>) -> Result<(), CommandError> {
+    match cmd {
+        cmd if cmd.is_secure() && ctx.is_secure() => Ok(()),
+        cmd if cmd.is_secure() && !ctx.is_secure() => Err(CommandError::InsecureExecution),
+        _ => Ok(()),
+    }
+}
+
+/// Attempt to execute a command, and return the content that should
+/// go back to Matrix, if the command was executed, whether or not the
+/// command was successful.
+pub async fn execute_command(ctx: &Context<'_>) -> ExecutionResult {
+    let cmd = parser::parse_command(&ctx.message_body)?;
+
+    let result = match execution_allowed(cmd.as_ref(), ctx) {
+        Ok(_) => cmd.execute(ctx).await,
+        Err(e) => Err(e.into()),
+    };
+
+    log_command(cmd.as_ref(), ctx, &result);
+    result
+}
+
+/// Log result of an executed command.
+fn log_command(cmd: &(impl Command + ?Sized), ctx: &Context, result: &ExecutionResult) {
+    use substring::Substring;
+    let command = match cmd.is_secure() {
+        true => cmd.name(),
+        false => ctx.message_body,
+    };
+
+    let dots = match command.len() {
+        _len if _len > 30 => "[...]",
+        _ => "",
+    };
+
+    let command = command.substring(0, 30);
+
+    match result {
+        Ok(_) => {
+            info!(
+                "[{}] {} <{}{}> - success",
+                ctx.origin_room.display_name, ctx.username, command, dots
+            );
+        }
+        Err(e) => {
+            error!(
+                "[{}] {} <{}{}> - {}",
+                ctx.origin_room.display_name, ctx.username, command, dots, e
+            );
+        }
+    };
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use management::RegisterCommand;
+    use url::Url;
+    use matrix_sdk::ruma::room_id;
+
+    macro_rules! dummy_room {
+        () => {
+            crate::context::RoomContext {
+                id: &room_id!("!fakeroomid:example.com"),
+                display_name: "displayname".to_owned(),
+                secure: false,
+            }
+        };
+    }
+
+    macro_rules! secure_room {
+        () => {
+            crate::context::RoomContext {
+                id: &room_id!("!fakeroomid:example.com"),
+                display_name: "displayname".to_owned(),
+                secure: true,
+            }
+        };
+    }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
+    async fn secure_context_secure_command_allows_execution() {
+        let db_path = tempfile::NamedTempFile::new_in(".").unwrap();
+        let db = crate::db::sqlite::Database::new(db_path.path().to_str().unwrap())
+            .await
+            .unwrap();
+
+        let homeserver = Url::parse("http://example.com").unwrap();
+
+        let ctx = Context {
+            account: crate::models::Account::default(),
+            db: db,
+            matrix_client: matrix_sdk::Client::new(homeserver).await.unwrap(),
+            origin_room: secure_room!(),
+            active_room: secure_room!(),
+            username: "myusername",
+            message_body: "!notacommand",
+        };
+
+        let cmd = RegisterCommand;
+        assert_eq!(execution_allowed(&cmd, &ctx).is_ok(), true);
+    }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
+    async fn secure_context_insecure_command_allows_execution() {
+        let db_path = tempfile::NamedTempFile::new_in(".").unwrap();
+        let db = crate::db::sqlite::Database::new(db_path.path().to_str().unwrap())
+            .await
+            .unwrap();
+
+        let homeserver = Url::parse("http://example.com").unwrap();
+
+        let ctx = Context {
+            account: crate::models::Account::default(),
+            db: db,
+            matrix_client: matrix_sdk::Client::new(homeserver).await.unwrap(),
+            origin_room: secure_room!(),
+            active_room: secure_room!(),
+            username: "myusername",
+            message_body: "!notacommand",
+        };
+
+        let cmd = variables::GetVariableCommand("".to_owned());
+        assert_eq!(execution_allowed(&cmd, &ctx).is_ok(), true);
+    }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
+    async fn insecure_context_insecure_command_allows_execution() {
+        let db_path = tempfile::NamedTempFile::new_in(".").unwrap();
+        let db = crate::db::sqlite::Database::new(db_path.path().to_str().unwrap())
+            .await
+            .unwrap();
+
+        let homeserver = Url::parse("http://example.com").unwrap();
+
+        let ctx = Context {
+            account: crate::models::Account::default(),
+            db: db,
+            matrix_client: matrix_sdk::Client::new(homeserver).await.unwrap(),
+            origin_room: dummy_room!(),
+            active_room: dummy_room!(),
+            username: "myusername",
+            message_body: "!notacommand",
+        };
+
+        let cmd = variables::GetVariableCommand("".to_owned());
+        assert_eq!(execution_allowed(&cmd, &ctx).is_ok(), true);
+    }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
+    async fn insecure_context_secure_command_denies_execution() {
+        let db_path = tempfile::NamedTempFile::new_in(".").unwrap();
+        let db = crate::db::sqlite::Database::new(db_path.path().to_str().unwrap())
+            .await
+            .unwrap();
+
+        let homeserver = Url::parse("http://example.com").unwrap();
+
+        let ctx = Context {
+            account: crate::models::Account::default(),
+            db: db,
+            matrix_client: matrix_sdk::Client::new(homeserver).await.unwrap(),
+            origin_room: dummy_room!(),
+            active_room: dummy_room!(),
+            username: "myusername",
+            message_body: "!notacommand",
+        };
+
+        let cmd = RegisterCommand;
+        assert_eq!(execution_allowed(&cmd, &ctx).is_err(), true);
+    }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
+    async fn unrecognized_command() {
+        let db_path = tempfile::NamedTempFile::new_in(".").unwrap();
+        let db = crate::db::sqlite::Database::new(db_path.path().to_str().unwrap())
+            .await
+            .unwrap();
+
+        let homeserver = Url::parse("http://example.com").unwrap();
+
+        let ctx = Context {
+            account: crate::models::Account::default(),
+            db: db,
+            matrix_client: matrix_sdk::Client::new(homeserver).await.unwrap(),
+            origin_room: dummy_room!(),
+            active_room: dummy_room!(),
+            username: "myusername",
+            message_body: "!notacommand",
+        };
+
+        let result = execute_command(&ctx).await;
+        assert!(result.is_err());
+    }
+}

dicebot/src/commands/parser.rs

@@ -0,0 +1,247 @@
+/**
+ * In addition to the terms of the AGPL, portions of this file are
+ * governed by the terms of the MIT license, from the original
+ * axfive-matrix-dicebot project.
+ */
+use crate::commands::{
+    basic_rolling::RollCommand,
+    cofd::PoolRollCommand,
+    cthulhu::{CthAdvanceRoll, CthRoll},
+    management::{CheckCommand, LinkCommand, RegisterCommand, UnlinkCommand, UnregisterCommand},
+    misc::HelpCommand,
+    rooms::{ListRoomsCommand, SetRoomCommand},
+    variables::{
+        DeleteVariableCommand, GetAllVariablesCommand, GetVariableCommand, SetVariableCommand,
+    },
+    Command,
+};
+use crate::error::BotError;
+use combine::parser::char::{char, letter, space};
+use combine::{any, many1, optional, Parser};
+use std::convert::TryFrom;
+use thiserror::Error;
+
+#[derive(Debug, Clone, PartialEq, Error)]
+pub enum CommandParsingError {
+    #[error("unrecognized command: {0}")]
+    UnrecognizedCommand(String),
+
+    #[error("parser error: {0}")]
+    InternalParseError(#[from] combine::error::StringStreamError),
+}
+
+/// Split an input string into its constituent command and "everything
+/// else" parts. Extracts the command separately from its input (i.e.
+/// rest of the line) and returns a tuple of (command_input, command).
+/// Whitespace at the start and end of the command input is removed.
+fn split_command(input: &str) -> Result<(String, String), CommandParsingError> {
+    let input = input.trim();
+
+    let exclamation = char('!');
+    let word = many1(letter()).map(|value: String| value);
+    let at_least_one_space = many1(space().silent()).map(|value: String| value);
+    let cmd_input = optional(at_least_one_space.and(many1(any()).map(|value: String| value)));
+
+    let mut parser = exclamation.and(word).and(cmd_input);
+
+    //TODO make less wacky, possibly by mapping it into a struct and
+    // making use of skip. This super-wacky tuple is:
+    //  (parsed_input, rest)
+    //Where parsed_input is:
+    //  (!command, option<arguments>)
+    //Where !command is:
+    //  ('!', command)
+    //Were option<arguments> is:
+    // Option tuple of (whitespace, arguments)
+    let (command, command_input) = match parser.parse(input)? {
+        (((_, command), Some((_, command_input))), _) => (command, command_input),
+        (((_, command), None), _) => (command, "".to_string()),
+    };
+
+    Ok((command, command_input))
+}
+
+/// Atempt to convert text input to a Boxed command type. Shortens
+/// boilerplate.
+macro_rules! convert_to {
+    ($type:ident, $input: expr) => {
+        $type::try_from($input).map(|cmd| Box::new(cmd) as Box<dyn Command>)
+    };
+}
+
+/// Potentially parse a command expression. If we recognize the
+/// command, an error should be raised if the command is misparsed. If
+/// we don't recognize the command, return an error.
+pub fn parse_command(input: &str) -> Result<Box<dyn Command>, BotError> {
+    match split_command(input) {
+        Ok((cmd, cmd_input)) => match cmd.to_lowercase().as_ref() {
+            "variables" => convert_to!(GetAllVariablesCommand, cmd_input),
+            "get" => convert_to!(GetVariableCommand, cmd_input),
+            "set" => convert_to!(SetVariableCommand, cmd_input),
+            "del" => convert_to!(DeleteVariableCommand, cmd_input),
+            "r" | "roll" => convert_to!(RollCommand, cmd_input),
+            "rp" | "pool" => convert_to!(PoolRollCommand, cmd_input),
+            "chance" => PoolRollCommand::chance_die().map(|cmd| Box::new(cmd) as Box<dyn Command>),
+            "cthroll" => convert_to!(CthRoll, cmd_input),
+            "cthadv" | "ctharoll" => convert_to!(CthAdvanceRoll, cmd_input),
+            "help" => convert_to!(HelpCommand, cmd_input),
+            "register" => convert_to!(RegisterCommand, cmd_input),
+            "link" => convert_to!(LinkCommand, cmd_input),
+            "unlink" => convert_to!(UnlinkCommand, cmd_input),
+            "check" => convert_to!(CheckCommand, cmd_input),
+            "unregister" => convert_to!(UnregisterCommand, cmd_input),
+            "rooms" => convert_to!(ListRoomsCommand, cmd_input),
+            "room" => convert_to!(SetRoomCommand, cmd_input),
+            _ => Err(CommandParsingError::UnrecognizedCommand(cmd).into()),
+        },
+        //All other errors passed up.
+        Err(e) => Err(e.into()),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    //TODO these errors don't seem to implement the right traits to do
+    //eq checks or even unwrap_err!
+
+    #[test]
+    fn non_command_test() {
+        let result = parse_command("not a command");
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn empty_message_test() {
+        let result = parse_command("");
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn just_exclamation_mark_test() {
+        let result = parse_command("!");
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn newline_test() {
+        assert!(parse_command("\n!roll 1d4").is_ok());
+    }
+
+    #[test]
+    fn whitespace_and_newline_test() {
+        assert!(parse_command("    \n!roll 1d4").is_ok());
+    }
+
+    #[test]
+    fn newline_and_whitespace_test() {
+        assert!(parse_command("\n    !cthroll 50").is_ok());
+    }
+
+    #[test]
+    fn word_with_exclamation_mark_test() {
+        let result1 = parse_command("hello !notacommand");
+        assert!(result1.is_err());
+
+        let result2 = parse_command("hello!");
+        assert!(result2.is_err());
+
+        let result3 = parse_command("hello!notacommand");
+        assert!(result3.is_err());
+    }
+
+    #[test]
+    fn basic_command_test() {
+        assert_eq!(
+            ("roll".to_string(), "1d4".to_string()),
+            split_command("!roll 1d4").expect("got parsing error")
+        );
+    }
+
+    #[test]
+    fn whitespace_at_start_test() {
+        assert_eq!(
+            ("roll".to_string(), "1d4".to_string()),
+            split_command("   !roll 1d4").expect("got parsing error")
+        );
+    }
+
+    #[test]
+    fn whitespace_at_end_test() {
+        assert_eq!(
+            ("roll".to_string(), "1d4".to_string()),
+            split_command("!roll 1d4   ").expect("got parsing error")
+        );
+    }
+
+    #[test]
+    fn whitespace_on_both_ends_test() {
+        assert_eq!(
+            ("roll".to_string(), "1d4".to_string()),
+            split_command("   !roll 1d4   ").expect("got parsing error")
+        );
+    }
+
+    #[test]
+    fn single_command_test() {
+        assert_eq!(
+            ("roll".to_string(), "".to_string()),
+            split_command("!roll").expect("got parsing error")
+        );
+
+        assert_eq!(
+            ("thisdoesnotexist".to_string(), "".to_string()),
+            split_command("!thisdoesnotexist").expect("got parsing error")
+        );
+    }
+
+    #[test]
+    fn bad_command_test() {
+        assert!(split_command("roll 1d4").is_err());
+        assert!(split_command("roll").is_err());
+    }
+
+    #[test]
+    fn chance_die_is_not_malformed() {
+        assert!(parse_command("!chance").is_ok());
+    }
+
+    #[test]
+    fn roll_malformed_expression_test() {
+        assert!(parse_command("!roll 1d20asdlfkj").is_err());
+        assert!(parse_command("!roll 1d20asdlfkj   ").is_err());
+    }
+
+    #[test]
+    fn roll_dice_pool_malformed_expression_test() {
+        assert!(parse_command("!pool 8abc").is_err());
+        assert!(parse_command("!pool 8abc    ").is_err());
+    }
+
+    #[test]
+    fn pool_whitespace_test() {
+        parse_command("!pool 8   ns3    ").expect("was error");
+        parse_command("   !pool 8 ns3").expect("was error");
+        parse_command("   !pool 8   ns3    ").expect("was error");
+    }
+
+    #[test]
+    fn help_whitespace_test() {
+        parse_command("!help stuff   ").expect("was error");
+        parse_command("   !help stuff").expect("was error");
+        parse_command("   !help stuff   ").expect("was error");
+    }
+
+    #[test]
+    fn roll_whitespace_test() {
+        parse_command("!roll 1d4 + 5d6 -3   ").expect("was error");
+        parse_command("!roll 1d4 + 5d6 -3   ").expect("was error");
+        parse_command("   !roll 1d4 + 5d6 -3   ").expect("was error");
+    }
+
+    #[test]
+    fn case_insensitive_test() {
+        parse_command("!CTHROLL 40").expect("command parsing is not case sensitive.");
+    }
+}

dicebot/src/commands/rooms.rs

@@ -0,0 +1,187 @@
+use super::{Command, Execution, ExecutionResult};
+use crate::context::Context;
+use crate::db::Users;
+use crate::error::BotError;
+use crate::matrix;
+use async_trait::async_trait;
+use fuse_rust::{Fuse, FuseProperty, Fuseable};
+use futures::stream::{self, StreamExt, TryStreamExt};
+use matrix_sdk::{ruma::OwnedUserId, Client};
+use std::convert::TryFrom;
+
+/// Holds matrix room ID and display name as strings, for use with
+/// searching. See search_for_room.
+#[derive(Clone, Debug, Eq, PartialEq)]
+struct RoomNameAndId {
+    id: String,
+    name: String,
+}
+
+/// Allows searching for a room name and ID struct, instead of just
+/// searching room display names directly.
+impl Fuseable for RoomNameAndId {
+    fn properties(&self) -> Vec<FuseProperty> {
+        vec![FuseProperty {
+            value: String::from("name"),
+            weight: 1.0,
+        }]
+    }
+
+    fn lookup(&self, key: &str) -> Option<&str> {
+        match key {
+            "name" => Some(&self.name),
+            _ => None,
+        }
+    }
+}
+
+/// Attempt to find a room by either name or Matrix Room ID query
+/// string. It prefers the exact room ID first, and then falls back to
+/// fuzzy searching based on room display name. The best match is
+/// returned, or None if no matches were found.
+fn search_for_room<'a>(
+    rooms_for_user: &'a [RoomNameAndId],
+    search_for: &str,
+) -> Option<&'a RoomNameAndId> {
+    //Lowest score is the best match.
+    let best_fuzzy_match = || -> Option<&RoomNameAndId> {
+        Fuse::default()
+            .search_text_in_fuse_list(search_for, &rooms_for_user)
+            .into_iter()
+            .min_by(|r1, r2| r1.score.partial_cmp(&r2.score).unwrap())
+            .and_then(|result| rooms_for_user.get(result.index))
+    };
+
+    rooms_for_user
+        .iter()
+        .find(|room| room.id == search_for)
+        .or_else(best_fuzzy_match)
+}
+
+async fn get_rooms_for_user(
+    client: &Client,
+    user_id: &str,
+) -> Result<Vec<RoomNameAndId>, BotError> {
+    let user_id = OwnedUserId::try_from(user_id)?;
+    let rooms_for_user = matrix::get_rooms_for_user(client, &user_id).await?;
+    let mut rooms_for_user: Vec<RoomNameAndId> = stream::iter(rooms_for_user)
+        .filter_map(|room| async move {
+            Some(room.display_name().await.map(|room_name| RoomNameAndId {
+                id: room.room_id().to_string(),
+                name: room_name.to_string(),
+            }))
+        })
+        .try_collect()
+        .await?;
+
+    //Alphabetically descending, symbols first, ignore case.
+    let sort = |r1: &RoomNameAndId, r2: &RoomNameAndId| {
+        r1.name.to_lowercase().cmp(&r2.name.to_lowercase())
+    };
+
+    rooms_for_user.sort_by(sort);
+    Ok(rooms_for_user)
+}
+
+pub struct ListRoomsCommand;
+
+impl TryFrom<String> for ListRoomsCommand {
+    type Error = BotError;
+
+    fn try_from(_: String) -> Result<Self, Self::Error> {
+        Ok(ListRoomsCommand)
+    }
+}
+
+#[async_trait]
+impl Command for ListRoomsCommand {
+    fn name(&self) -> &'static str {
+        "list rooms"
+    }
+
+    fn is_secure(&self) -> bool {
+        true
+    }
+
+    async fn execute(&self, ctx: &Context<'_>) -> ExecutionResult {
+        let rooms_for_user: Vec<String> = get_rooms_for_user(&ctx.matrix_client, ctx.username)
+            .await
+            .map(|rooms| {
+                rooms
+                    .into_iter()
+                    .map(|room| format!("  {}  |  {}", room.id, room.name))
+                    .collect()
+            })?;
+
+        let html = format!("<pre>{}</pre>", rooms_for_user.join("\n"));
+        Execution::success(html)
+    }
+}
+
+pub struct SetRoomCommand(String);
+
+impl TryFrom<String> for SetRoomCommand {
+    type Error = BotError;
+
+    fn try_from(input: String) -> Result<Self, Self::Error> {
+        Ok(SetRoomCommand(input))
+    }
+}
+
+#[async_trait]
+impl Command for SetRoomCommand {
+    fn name(&self) -> &'static str {
+        "set active room"
+    }
+
+    fn is_secure(&self) -> bool {
+        true
+    }
+
+    async fn execute(&self, ctx: &Context<'_>) -> ExecutionResult {
+        if !ctx.account.is_registered() {
+            return Err(BotError::AccountDoesNotExist);
+        }
+
+        let rooms_for_user = get_rooms_for_user(&ctx.matrix_client, ctx.username).await?;
+        let room = search_for_room(&rooms_for_user, &self.0);
+
+        if let Some(room) = room {
+            let mut new_user = ctx
+                .account
+                .registered_user()
+                .cloned()
+                .ok_or(BotError::AccountDoesNotExist)?;
+
+            new_user.active_room = Some(room.id.clone());
+            ctx.db.upsert_user(&new_user).await?;
+            Execution::success(format!(r#"Active room set to "{}""#, room.name))
+        } else {
+            Err(BotError::RoomDoesNotExist)
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
+    async fn set_room_prefers_room_id_over_name() {
+        let rooms = vec![
+            RoomNameAndId {
+                id: "roomid".to_string(),
+                name: "room_name".to_string(),
+            },
+            RoomNameAndId {
+                id: "anotherone".to_string(),
+                name: "roomid".to_string(),
+            },
+        ];
+
+        let found_room = search_for_room(&rooms, "roomid");
+
+        assert!(found_room.is_some());
+        assert_eq!(found_room.unwrap(), &rooms[0]);
+    }
+}

dicebot/src/commands/variables.rs

@@ -0,0 +1,161 @@
+use super::{Command, Execution, ExecutionResult};
+use crate::context::Context;
+use crate::db::errors::DataError;
+use crate::db::Variables;
+use crate::error::BotError;
+use async_trait::async_trait;
+use std::convert::TryFrom;
+
+pub struct GetAllVariablesCommand;
+
+impl TryFrom<String> for GetAllVariablesCommand {
+    type Error = BotError;
+
+    fn try_from(_: String) -> Result<Self, Self::Error> {
+        Ok(GetAllVariablesCommand)
+    }
+}
+
+#[async_trait]
+impl Command for GetAllVariablesCommand {
+    fn name(&self) -> &'static str {
+        "get all variables"
+    }
+
+    fn is_secure(&self) -> bool {
+        false
+    }
+
+    async fn execute(&self, ctx: &Context<'_>) -> ExecutionResult {
+        let variables = ctx
+            .db
+            .get_user_variables(&ctx.username, ctx.active_room_id().as_str())
+            .await?;
+
+        let mut variable_list: Vec<String> = variables
+            .into_iter()
+            .map(|(name, value)| format!(" - {} = {}", name, value))
+            .collect();
+
+        variable_list.sort();
+
+        let value = variable_list.join("\n");
+        let html = format!(
+            "<strong>Variables:</strong><br/>{}",
+            value.replace("\n", "<br/>")
+        );
+
+        Execution::success(html)
+    }
+}
+
+pub struct GetVariableCommand(pub String);
+
+impl TryFrom<String> for GetVariableCommand {
+    type Error = BotError;
+
+    fn try_from(input: String) -> Result<Self, Self::Error> {
+        Ok(GetVariableCommand(input))
+    }
+}
+
+#[async_trait]
+impl Command for GetVariableCommand {
+    fn name(&self) -> &'static str {
+        "retrieve variable value"
+    }
+
+    fn is_secure(&self) -> bool {
+        false
+    }
+
+    async fn execute(&self, ctx: &Context<'_>) -> ExecutionResult {
+        let name = &self.0;
+        let result = ctx
+            .db
+            .get_user_variable(&ctx.username, ctx.active_room_id().as_str(), name)
+            .await;
+
+        let value = match result {
+            Ok(num) => format!("{} = {}", name, num),
+            Err(DataError::KeyDoesNotExist(_)) => format!("{} is not set", name),
+            Err(e) => return Err(e.into()),
+        };
+
+        let html = format!("<strong>Variable:</strong> {}", value);
+        Execution::success(html)
+    }
+}
+
+pub struct SetVariableCommand(pub String, pub i32);
+
+impl TryFrom<String> for SetVariableCommand {
+    type Error = BotError;
+
+    fn try_from(input: String) -> Result<Self, Self::Error> {
+        let (variable_name, value) = crate::parser::variables::parse_set_variable(&input)?;
+        Ok(SetVariableCommand(variable_name, value))
+    }
+}
+
+#[async_trait]
+impl Command for SetVariableCommand {
+    fn name(&self) -> &'static str {
+        "set variable value"
+    }
+
+    fn is_secure(&self) -> bool {
+        false
+    }
+
+    async fn execute(&self, ctx: &Context<'_>) -> ExecutionResult {
+        let name = &self.0;
+        let value = self.1;
+
+        ctx.db
+            .set_user_variable(&ctx.username, ctx.active_room_id().as_str(), name, value)
+            .await?;
+
+        let content = format!("{} = {}", name, value);
+        let html = format!("<strong>Set Variable:</strong> {}", content);
+        Execution::success(html)
+    }
+}
+
+pub struct DeleteVariableCommand(pub String);
+
+impl TryFrom<String> for DeleteVariableCommand {
+    type Error = BotError;
+
+    fn try_from(input: String) -> Result<Self, Self::Error> {
+        Ok(DeleteVariableCommand(input))
+    }
+}
+
+#[async_trait]
+impl Command for DeleteVariableCommand {
+    fn name(&self) -> &'static str {
+        "delete variable"
+    }
+
+    fn is_secure(&self) -> bool {
+        false
+    }
+
+    async fn execute(&self, ctx: &Context<'_>) -> ExecutionResult {
+        let name = &self.0;
+        let result = ctx
+            .db
+            .delete_user_variable(&ctx.username, ctx.active_room_id().as_str(), name)
+            .await;
+
+        let value = match result {
+            Ok(()) => format!("{} now unset", name),
+            Err(DataError::KeyDoesNotExist(_)) => format!("{} is not currently set", name),
+            Err(e) => return Err(e.into()),
+        };
+
+        let html = format!("<strong>Remove Variable:</strong> {}", value);
+        Execution::success(html)
+    }
+}

dicebot/src/config.rs

@@ -0,0 +1,342 @@
+use serde::{self, Deserialize, Serialize};
+use std::env;
+use std::fs;
+use std::path::PathBuf;
+use thiserror::Error;
+
+#[derive(Error, Debug)]
+pub enum ConfigError {
+    #[error("i/o error: {0}")]
+    IoError(#[from] std::io::Error),
+
+    #[error("toml parsing error: {0}")]
+    TomlParsingError(#[from] toml::de::Error),
+}
+
+pub fn read_config<P: Into<PathBuf>>(config_path: P) -> Result<Config, ConfigError> {
+    let config_path = config_path.into();
+    let config = {
+        let contents = fs::read_to_string(&config_path)?;
+        deserialize_config(&contents)?
+    };
+
+    Ok(config)
+}
+
+fn deserialize_config(contents: &str) -> Result<Config, ConfigError> {
+    let config = toml::from_str(&contents)?;
+    Ok(config)
+}
+
+/// The "matrix" section of the config, which gives home server, login information, and etc.
+#[derive(Serialize, Deserialize, Clone, Debug)]
+struct MatrixConfig {
+    /// Your homeserver of choice, as an FQDN without scheme or path
+    home_server: String,
+
+    /// Username to login as. Only the localpart.
+    username: String,
+
+    /// Bot account password.
+    password: String,
+}
+
+const DEFAULT_OLDEST_MESSAGE_AGE: u64 = 15 * 60;
+
+fn db_path_from_env() -> String {
+    env::var("DATABASE_PATH")
+        .expect("could not find database path in config or environment variable")
+}
+
+/// The "bot" section of the config file, for bot settings.
+#[derive(Serialize, Deserialize, Clone, Debug, Default)]
+struct BotConfig {
+    /// How far back from current time should we process a message?
+    oldest_message_age: Option<u64>,
+
+    /// What address and port to run the RPC service on. If not
+    /// specified, RPC will not be enabled.
+    rpc_addr: Option<String>,
+
+    /// The shared secret key between the bot and any RPC clients that
+    /// want to connect to it. The RPC server will reject any clients
+    /// that don't present the shared key.
+    rpc_key: Option<String>,
+}
+
+/// The "database" section of the config file.
+#[derive(Serialize, Deserialize, Clone, Debug)]
+struct DatabaseConfig {
+    /// Path to the database storage directory. Required.
+    path: Option<String>,
+}
+
+impl DatabaseConfig {
+    #[inline]
+    #[must_use]
+    fn path(&self) -> String {
+        self.path.clone().unwrap_or_else(|| db_path_from_env())
+    }
+}
+
+impl BotConfig {
+    /// Determine the oldest allowable message age, in seconds. If the
+    /// setting is defined, use that value. If it is not defined, fall
+    /// back to DEFAULT_OLDEST_MESSAGE_AGE (15 minutes).
+    #[inline]
+    #[must_use]
+    fn oldest_message_age(&self) -> u64 {
+        self.oldest_message_age
+            .unwrap_or(DEFAULT_OLDEST_MESSAGE_AGE)
+    }
+
+    #[inline]
+    #[must_use]
+    fn rpc_addr(&self) -> Option<String> {
+        self.rpc_addr.clone()
+    }
+
+    #[inline]
+    #[must_use]
+    fn rpc_key(&self) -> Option<String> {
+        self.rpc_key.clone()
+    }
+}
+
+/// Represents the toml config file for the dicebot. The sections of
+/// the config are not directly accessible; instead the config
+/// provides friendly methods that handle default values, etc.
+#[derive(Serialize, Deserialize, Clone, Debug)]
+pub struct Config {
+    matrix: MatrixConfig,
+    database: Option<DatabaseConfig>,
+    bot: Option<BotConfig>,
+}
+
+impl Config {
+    /// The matrix homeserver URL.
+    #[inline]
+    #[must_use]
+    pub fn matrix_homeserver(&self) -> &str {
+        &self.matrix.home_server
+    }
+
+    /// The username used to connect to the matrix server.
+    #[inline]
+    #[must_use]
+    pub fn matrix_username(&self) -> &str {
+        &self.matrix.username
+    }
+
+    /// The password used to connect to the matrix server.
+    #[inline]
+    #[must_use]
+    pub fn matrix_password(&self) -> &str {
+        &self.matrix.password
+    }
+
+    /// The path to the database storage directory.
+    #[inline]
+    #[must_use]
+    pub fn database_path(&self) -> String {
+        self.database
+            .as_ref()
+            .map(|db| db.path())
+            .unwrap_or_else(|| db_path_from_env())
+    }
+
+    /// Figure out the allowed oldest message age, in seconds. This will
+    /// be the defined oldest message age in the bot config, if the bot
+    /// configuration and associated "oldest_message_age" setting are
+    /// defined. If the bot config or the message setting are not defined,
+    /// it will default to 15 minutes.
+    #[inline]
+    #[must_use]
+    pub fn oldest_message_age(&self) -> u64 {
+        self.bot
+            .as_ref()
+            .map(|bc| bc.oldest_message_age())
+            .unwrap_or(DEFAULT_OLDEST_MESSAGE_AGE)
+    }
+
+    #[inline]
+    #[must_use]
+    pub fn rpc_addr(&self) -> Option<String> {
+        self.bot.as_ref().and_then(|bc| bc.rpc_addr())
+    }
+
+    #[inline]
+    #[must_use]
+    pub fn rpc_key(&self) -> Option<String> {
+        self.bot.as_ref().and_then(|bc| bc.rpc_key())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn oldest_message_default_no_setting_test() {
+        let cfg = Config {
+            matrix: MatrixConfig {
+                home_server: "".to_owned(),
+                username: "".to_owned(),
+                password: "".to_owned(),
+            },
+            database: Some(DatabaseConfig {
+                path: Some("".to_owned()),
+            }),
+            bot: Some(BotConfig {
+                oldest_message_age: None,
+                ..Default::default()
+            }),
+        };
+
+        assert_eq!(15 * 60, cfg.oldest_message_age());
+    }
+
+    #[test]
+    fn oldest_message_default_no_bot_config_test() {
+        let cfg = Config {
+            matrix: MatrixConfig {
+                home_server: "".to_owned(),
+                username: "".to_owned(),
+                password: "".to_owned(),
+            },
+            database: Some(DatabaseConfig {
+                path: Some("".to_owned()),
+            }),
+            bot: None,
+        };
+
+        assert_eq!(15 * 60, cfg.oldest_message_age());
+    }
+
+    #[test]
+    fn db_path_uses_setting_first_test() {
+        let cfg = Config {
+            matrix: MatrixConfig {
+                home_server: "".to_owned(),
+                username: "".to_owned(),
+                password: "".to_owned(),
+            },
+            database: Some(DatabaseConfig {
+                path: Some("the-db-path".to_owned()),
+            }),
+            bot: None,
+        };
+
+        assert_eq!("the-db-path".to_owned(), cfg.database_path());
+    }
+
+    #[test]
+    fn db_path_uses_env_if_setting_not_defined_test() {
+        env::set_var("DATABASE_PATH", "the-db-path");
+
+        let cfg = Config {
+            matrix: MatrixConfig {
+                home_server: "".to_owned(),
+                username: "".to_owned(),
+                password: "".to_owned(),
+            },
+            database: Some(DatabaseConfig { path: None }),
+            bot: None,
+        };
+
+        assert_eq!("the-db-path".to_owned(), cfg.database_path());
+
+        env::remove_var("DATABASE_PATH");
+    }
+
+    #[test]
+    fn db_path_uses_env_if_section_not_defined_test() {
+        env::set_var("DATABASE_PATH", "the-db-path");
+
+        let cfg = Config {
+            matrix: MatrixConfig {
+                home_server: "".to_owned(),
+                username: "".to_owned(),
+                password: "".to_owned(),
+            },
+            database: None,
+            bot: None,
+        };
+
+        assert_eq!("the-db-path".to_owned(), cfg.database_path());
+
+        env::remove_var("DATABASE_PATH");
+    }
+
+    use indoc::indoc;
+
+    #[test]
+    fn deserialize_config_without_bot_section_test() {
+        let contents = indoc! {"
+            [matrix]
+            home_server = 'https://matrix.example.com'
+            username = 'username'
+            password = 'password'
+
+            [database]
+            path = ''
+        "};
+
+        let cfg: Result<_, _> = deserialize_config(contents);
+        assert_eq!(true, cfg.is_ok());
+    }
+
+    #[test]
+    fn deserialize_config_without_oldest_message_setting_test() {
+        let contents = indoc! {"
+            [matrix]
+            home_server = 'https://matrix.example.com'
+            username = 'username'
+            password = 'password'
+
+            [database]
+            path = ''
+
+            [bot]
+            not_a_real_setting = 2
+        "};
+
+        let cfg: Result<_, _> = deserialize_config(contents);
+        assert_eq!(true, cfg.is_ok());
+    }
+
+    #[test]
+    fn deserialize_config_without_db_path_setting_test() {
+        let contents = indoc! {"
+            [matrix]
+            home_server = 'https://matrix.example.com'
+            username = 'username'
+            password = 'password'
+
+            [database]
+            not_a_real_setting = 1
+
+            [bot]
+            not_a_real_setting = 2
+        "};
+
+        let cfg: Result<_, _> = deserialize_config(contents);
+        assert_eq!(true, cfg.is_ok());
+    }
+
+    #[test]
+    fn deserialize_config_without_db_section_test() {
+        let contents = indoc! {"
+            [matrix]
+            home_server = 'https://matrix.example.com'
+            username = 'username'
+            password = 'password'
+
+            [bot]
+            not_a_real_setting = 2
+        "};
+
+        let cfg: Result<_, _> = deserialize_config(contents);
+        assert_eq!(true, cfg.is_ok());
+    }
+}

dicebot/src/context.rs

@@ -0,0 +1,76 @@
+use crate::db::sqlite::Database;
+use crate::error::BotError;
+use crate::models::Account;
+use matrix_sdk::room::Joined;
+use matrix_sdk::ruma::{RoomId, UserId};
+use matrix_sdk::Client;
+use std::convert::TryFrom;
+
+/// A context carried through the system providing access to things
+/// like the database.
+#[derive(Clone)]
+pub struct Context<'a> {
+    pub db: Database,
+    pub matrix_client: Client,
+    pub origin_room: RoomContext<'a>,
+    pub active_room: RoomContext<'a>,
+    pub username: &'a str,
+    pub message_body: &'a str,
+    pub account: Account,
+}
+
+impl Context<'_> {
+    pub fn active_room_id(&self) -> &RoomId {
+        self.active_room.id
+    }
+
+    pub fn room_id(&self) -> &RoomId {
+        self.origin_room.id
+    }
+
+    pub fn is_secure(&self) -> bool {
+        self.origin_room.secure
+    }
+}
+
+#[derive(Clone)]
+pub struct RoomContext<'a> {
+    pub id: &'a RoomId,
+    pub display_name: String,
+    pub secure: bool,
+}
+
+impl RoomContext<'_> {
+    pub async fn new_with_name<'a>(
+        room: &'a Joined,
+        sending_user: &str,
+    ) -> Result<RoomContext<'a>, BotError> {
+        // TODO is_direct is a hack; the bot should set eligible rooms
+        // to Direct Message upon joining, if other contact has
+        // requested it. Waiting on SDK support.
+        let display_name =
+            room
+            .display_name()
+            .await
+            .ok()
+            .map(|d| d.to_string())
+            .unwrap_or_default();
+
+        let sending_user = <&UserId>::try_from(sending_user)?;
+        let user_in_room = room.get_member(sending_user).await.ok().is_some();
+        let is_direct = room.active_members().await?.len() == 2;
+
+        Ok(RoomContext {
+            id: room.room_id(),
+            display_name,
+            secure: room.is_encrypted() && is_direct && user_in_room,
+        })
+    }
+
+    pub async fn new<'a>(
+        room: &'a Joined,
+        sending_user: &'a str,
+    ) -> Result<RoomContext<'a>, BotError> {
+        Self::new_with_name(room, sending_user).await
+    }
+}

dicebot/src/cthulhu/dice.rs

@@ -0,0 +1,775 @@
+use crate::context::Context;
+use crate::db::Variables;
+use crate::error::{BotError, DiceRollingError};
+use crate::logic::calculate_single_die_amount;
+use crate::parser::dice::{Amount, DiceParsingError, Element};
+use rand::rngs::StdRng;
+use rand::Rng;
+use rand::SeedableRng;
+use std::convert::TryFrom;
+use std::fmt;
+
+/// A planned dice roll.
+#[derive(Clone, Debug, PartialEq)]
+pub struct DiceRoll {
+    pub amount: Amount,
+    pub modifier: DiceRollModifier,
+}
+
+pub struct DiceRollWithContext<'a>(pub &'a DiceRoll, pub &'a Context<'a>);
+
+/// Potential modifier on the die roll to be made.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum DiceRollModifier {
+    /// No bonuses or penalties.
+    Normal,
+
+    /// Roll one extra die and pick the lower of two results.
+    OneBonus,
+
+    /// Roll two extra dice and pick the lower of all results.
+    TwoBonus,
+
+    /// Roll one extra die and pick the higher of two results.
+    OnePenalty,
+
+    /// Roll two extra dice and pick the higher of all results.
+    TwoPenalty,
+}
+
+impl fmt::Display for DiceRollModifier {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let message = match self {
+            Self::Normal => "no modifiers",
+            Self::OneBonus => "one bonus die",
+            Self::TwoBonus => "two bonus dice",
+            Self::OnePenalty => "one penalty die",
+            Self::TwoPenalty => "two penalty dice",
+        };
+
+        write!(f, "{}", message)?;
+        Ok(())
+    }
+}
+
+/// The outcome of a die roll, either some kind of success or failure.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum RollResult {
+    /// Basic success. The rolled number was equal to or less than the target number.
+    Success,
+
+    /// Hard success means the rolled number was equal to or less than
+    /// the target number divided by 2 (rounded down).
+    HardSuccess,
+
+    /// Extreme success means the rolled number was equal to or less
+    /// than the target number divided by 5 (rounded down).
+    ExtremeSuccess,
+
+    /// A critical success occurs on a roll of 1.
+    CriticalSuccess,
+
+    /// A basic failure means that the roll was above the target number.
+    Failure,
+
+    /// A fumble occurs if the target number is below 50 and the roll
+    /// was 96 - 100, OR if the roll result was 100. This means lower
+    /// target numbers are more likely to produce a fumble.
+    Fumble,
+}
+
+impl fmt::Display for RollResult {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let message = match self {
+            Self::Success => "success!",
+            Self::HardSuccess => "hard success!",
+            Self::ExtremeSuccess => "extreme success!",
+            Self::CriticalSuccess => "critical success!",
+            Self::Failure => "failure!",
+            Self::Fumble => "fumble!",
+        };
+
+        write!(f, "{}", message)?;
+        Ok(())
+    }
+}
+
+/// A struct wrapping the target and the actual dice roll result. This
+/// is done for formatting purposes, so we can display the target
+/// number (calculated from resolving variables) separately from the
+/// result.
+pub struct ExecutedDiceRoll {
+    /// The number we must meet for the roll to be considered a
+    /// success.
+    pub target: u32,
+
+    /// Stored for informational purposes in display.
+    pub modifier: DiceRollModifier,
+
+    /// The actual roll result.
+    pub roll: RolledDice,
+}
+
+impl fmt::Display for ExecutedDiceRoll {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let message = format!("target: {}, with {}", self.target, self.modifier);
+        write!(f, "{}", message)?;
+        Ok(())
+    }
+}
+
+/// A struct wrapping the target and the actual advancement roll
+/// result. This is done for formatting purposes, so we can display
+/// the target number (calculated from resolving variables) separately
+/// from the result.
+pub struct ExecutedAdvancementRoll {
+    /// The number we must exceed for the roll to be considered a
+    /// success.
+    pub target: u32,
+
+    /// The actual roll result.
+    pub roll: RolledAdvancement,
+}
+
+impl fmt::Display for ExecutedAdvancementRoll {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let message = format!("target: {}", self.target);
+        write!(f, "{}", message)?;
+        Ok(())
+    }
+}
+
+//TODO need to keep track of all rolled numbers for informational purposes!
+/// The outcome of a roll.
+pub struct RolledDice {
+    /// The d100 result actually rolled.
+    num_rolled: u32,
+
+    /// The number we must meet for the roll to be considered a
+    /// success.
+    target: u32,
+}
+
+impl RolledDice {
+    /// Calculate what type of success or failure this roll is.
+    /// Consult the RollResult enum for descriptions of what each
+    /// result requires.
+    pub fn result(&self) -> RollResult {
+        let hard_target = self.target / 2u32;
+        let extreme_target = self.target / 5u32;
+        if (self.target < 50 && self.num_rolled > 95) || self.num_rolled == 100 {
+            RollResult::Fumble
+        } else if self.num_rolled == 1 {
+            RollResult::CriticalSuccess
+        } else if self.num_rolled <= extreme_target {
+            RollResult::ExtremeSuccess
+        } else if self.num_rolled <= hard_target {
+            RollResult::HardSuccess
+        } else if self.num_rolled <= self.target {
+            RollResult::Success
+        } else {
+            RollResult::Failure
+        }
+    }
+}
+
+impl fmt::Display for RolledDice {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let message = format!(
+            "{} against {}: {}",
+            self.num_rolled,
+            self.target,
+            self.result()
+        );
+        write!(f, "{}", message)?;
+        Ok(())
+    }
+}
+
+/// A planned advancement roll, where the target number is the
+/// existing skill amount.
+#[derive(Clone, Debug, PartialEq)]
+pub struct AdvancementRoll {
+    /// The amount (0 to 100) of the existing skill. We must beat this
+    /// target number to advance the skill, or roll above a 95.
+    pub existing_skill: Amount,
+}
+
+impl fmt::Display for AdvancementRoll {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let message = format!("advancement for skill of {:?}", self.existing_skill);
+        write!(f, "{}", message)?;
+        Ok(())
+    }
+}
+
+/// A struct holding an advancement roll and the context, so we can
+/// translate variables to numbers.
+pub struct AdvancementRollWithContext<'a>(pub &'a AdvancementRoll, pub &'a Context<'a>);
+
+/// A completed advancement roll.
+pub struct RolledAdvancement {
+    existing_skill: u32,
+    num_rolled: u32,
+    advancement: u32,
+    successful: bool,
+}
+
+impl RolledAdvancement {
+    /// The new skill amount, which will be the same if the roll was a
+    /// failure.
+    pub fn new_skill_amount(&self) -> u32 {
+        self.existing_skill + self.advancement
+    }
+
+    /// How much the skill advanced (1 to 10). 0 if the advancement
+    /// roll failed.
+    pub fn advancement(&self) -> u32 {
+        self.advancement
+    }
+
+    /// Whether or not the advancement roll was successful.
+    pub fn successful(&self) -> bool {
+        self.successful
+    }
+}
+
+impl fmt::Display for RolledAdvancement {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let message = if self.successful {
+            format!(
+                "success! new skill is {} (advanced by {}).",
+                self.new_skill_amount(),
+                self.advancement
+            )
+        } else {
+            format!("failure! skill remains at {}", self.existing_skill)
+        };
+
+        write!(
+            f,
+            "rolled {} against {}: {}",
+            self.num_rolled, self.existing_skill, message
+        )?;
+        Ok(())
+    }
+}
+
+/// This is a trait so we can inject controlled dice rolls in unit
+/// tests.
+trait DieRoller {
+    fn roll(&mut self) -> u32;
+}
+
+/// Macro to determine if an Amount is a variable.
+macro_rules! is_variable {
+    ($existing_skill:ident) => {
+        matches!(
+            $existing_skill,
+            Amount {
+                element: Element::Variable(_),
+                ..
+            }
+        )
+    };
+}
+
+/// A die roller than can have an RNG implementation injected, but
+/// must be thread-safe. Required for the async dice rolling code.
+struct RngDieRoller<R: Rng + ?Sized + Send>(R);
+
+impl<R: Rng + ?Sized + Send> DieRoller for RngDieRoller<R> {
+    fn roll(&mut self) -> u32 {
+        self.0.gen_range(0..=9)
+    }
+}
+
+/// Roll a single percentile die according to the rules. We cannot
+/// simply roll a d100 due to the way the game calculates roll results
+/// with bonus/penalty dice. The unit roll (ones place) is added to
+/// the tens roll, unless both results are 0, in which case the result
+/// is 100.
+fn roll_percentile_dice<R: DieRoller>(roller: &mut R, unit_roll: u32) -> u32 {
+    let tens_roll = roller.roll() * 10;
+
+    if tens_roll == 0 && unit_roll == 0 {
+        100
+    } else {
+        tens_roll + unit_roll
+    }
+}
+
+fn roll_regular_dice<R: DieRoller>(
+    modifier: &DiceRollModifier,
+    target: u32,
+    roller: &mut R,
+) -> RolledDice {
+    use DiceRollModifier::*;
+
+    let num_rolls = match modifier {
+        Normal => 1,
+        OneBonus | OnePenalty => 2,
+        TwoBonus | TwoPenalty => 3,
+    };
+
+    let unit_roll = roller.roll();
+
+    let rolls: Vec<u32> = (0..num_rolls)
+        .map(|_| roll_percentile_dice(roller, unit_roll))
+        .collect();
+
+    let num_rolled = match modifier {
+        Normal => rolls.first(),
+        OneBonus | TwoBonus => rolls.iter().min(),
+        OnePenalty | TwoPenalty => rolls.iter().max(),
+    }
+    .unwrap();
+
+    RolledDice {
+        num_rolled: *num_rolled,
+        target: target,
+    }
+}
+
+fn roll_advancement_dice<R: DieRoller>(target: u32, roller: &mut R) -> RolledAdvancement {
+    let unit_roll = roller.roll();
+    let percentile_roll = roll_percentile_dice(roller, unit_roll);
+
+    if percentile_roll > target || percentile_roll > 95 {
+        RolledAdvancement {
+            num_rolled: percentile_roll,
+            existing_skill: target,
+            advancement: roller.roll() + 1,
+            successful: true,
+        }
+    } else {
+        RolledAdvancement {
+            num_rolled: percentile_roll,
+            existing_skill: target,
+            advancement: 0,
+            successful: false,
+        }
+    }
+}
+
+/// Make a roll with a target number and potential modifier. In a
+/// normal roll, only one percentile die is rolled (1d100). With
+/// bonuses or penalties, more dice are rolled, and either the lowest
+/// (in case of bonus) or highest (in case of penalty) result is
+/// picked. Rolls are not simply d100; the unit roll (ones place) is
+/// rolled separately from the tens place, and then the unit number is
+/// added to each potential roll before picking the lowest/highest
+/// result.
+pub async fn regular_roll(
+    roll_with_ctx: &DiceRollWithContext<'_>,
+) -> Result<ExecutedDiceRoll, BotError> {
+    let target = calculate_single_die_amount(&roll_with_ctx.0.amount, roll_with_ctx.1).await?;
+    let target = u32::try_from(target).map_err(|_| DiceRollingError::InvalidAmount)?;
+
+    let mut roller = RngDieRoller::<StdRng>(SeedableRng::from_entropy());
+    let rolled_dice = roll_regular_dice(&roll_with_ctx.0.modifier, target, &mut roller);
+
+    Ok(ExecutedDiceRoll {
+        target,
+        modifier: roll_with_ctx.0.modifier,
+        roll: rolled_dice,
+    })
+}
+
+async fn update_skill(ctx: &Context<'_>, variable: &str, value: u32) -> Result<(), BotError> {
+    use std::convert::TryInto;
+    let value: i32 = value.try_into()?;
+    ctx.db
+        .set_user_variable(
+            &ctx.username,
+            &ctx.active_room_id().as_str(),
+            variable,
+            value,
+        )
+        .await?;
+    Ok(())
+}
+
+fn extract_variable(amount: &Amount) -> Result<&str, DiceParsingError> {
+    match amount.element {
+        Element::Variable(ref varname) => Ok(&varname[..]),
+        _ => Err(DiceParsingError::WrongElementType),
+    }
+}
+pub async fn advancement_roll(
+    roll_with_ctx: &AdvancementRollWithContext<'_>,
+) -> Result<ExecutedAdvancementRoll, BotError> {
+    let existing_skill = &roll_with_ctx.0.existing_skill;
+    let target = calculate_single_die_amount(existing_skill, roll_with_ctx.1).await?;
+
+    let target = u32::try_from(target).map_err(|_| DiceRollingError::InvalidAmount)?;
+
+    if target > 100 {
+        return Err(DiceRollingError::InvalidAmount.into());
+    }
+
+    let mut roller = RngDieRoller::<StdRng>(SeedableRng::from_entropy());
+    let roll = roll_advancement_dice(target, &mut roller);
+
+    drop(roller);
+
+    if roll.successful && is_variable!(existing_skill) {
+        let variable_name: &str = extract_variable(existing_skill)?;
+        update_skill(roll_with_ctx.1, variable_name, roll.new_skill_amount()).await?;
+    }
+
+    Ok(ExecutedAdvancementRoll { target, roll })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::db::sqlite::Database;
+    use crate::parser::dice::{Amount, Element, Operator};
+    use url::Url;
+    use matrix_sdk::ruma::room_id;
+
+    macro_rules! dummy_room {
+        () => {
+            crate::context::RoomContext {
+                id: &room_id!("!fakeroomid:example.com"),
+                display_name: "displayname".to_owned(),
+                secure: false,
+            }
+        };
+    }
+
+    /// Generate a series of numbers manually for testing. For this
+    /// die system, the first roll in the Vec should be the unit roll,
+    /// and any subsequent rolls should be the tens place roll. The
+    /// results rolled must come from a d10 (0 to 9).
+    struct SequentialDieRoller {
+        results: Vec<u32>,
+        position: usize,
+    }
+
+    impl SequentialDieRoller {
+        fn new(results: Vec<u32>) -> SequentialDieRoller {
+            SequentialDieRoller {
+                results,
+                position: 0,
+            }
+        }
+    }
+
+    impl DieRoller for SequentialDieRoller {
+        fn roll(&mut self) -> u32 {
+            let roll = self.results[self.position];
+            self.position += 1;
+            roll
+        }
+    }
+
+    #[test]
+    fn extract_variable_gets_variable_name() {
+        let amount = Amount {
+            operator: Operator::Plus,
+            element: Element::Variable("abc".to_string()),
+        };
+
+        let result = extract_variable(&amount);
+
+        assert!(result.is_ok());
+        assert_eq!(result.unwrap(), "abc");
+    }
+
+    #[test]
+    fn extract_variable_fails_on_number() {
+        let result = extract_variable(&Amount {
+            operator: Operator::Plus,
+            element: Element::Number(1),
+        });
+
+        assert!(result.is_err());
+        assert!(matches!(result, Err(DiceParsingError::WrongElementType)));
+    }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
+    async fn regular_roll_rejects_negative_numbers() {
+        let roll = DiceRoll {
+            amount: Amount {
+                operator: Operator::Plus,
+                element: Element::Number(-10),
+            },
+            modifier: DiceRollModifier::Normal,
+        };
+
+        let db_path = tempfile::NamedTempFile::new_in(".").unwrap();
+        crate::db::sqlite::migrator::migrate(db_path.path().to_str().unwrap())
+            .await
+            .unwrap();
+
+        let db = Database::new(db_path.path().to_str().unwrap())
+            .await
+            .unwrap();
+
+        let homeserver = Url::parse("http://example.com").unwrap();
+        let ctx = Context {
+            account: crate::models::Account::default(),
+            db: db,
+            matrix_client: matrix_sdk::Client::new(homeserver).await.unwrap(),
+            origin_room: dummy_room!(),
+            active_room: dummy_room!(),
+            username: "username",
+            message_body: "message",
+        };
+
+        let roll_with_ctx = DiceRollWithContext(&roll, &ctx);
+        let result = regular_roll(&roll_with_ctx).await;
+        assert!(result.is_err());
+        assert!(matches!(
+            result,
+            Err(BotError::DiceRollingError(DiceRollingError::InvalidAmount))
+        ));
+    }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
+    async fn advancement_roll_rejects_negative_numbers() {
+        let roll = AdvancementRoll {
+            existing_skill: Amount {
+                operator: Operator::Plus,
+                element: Element::Number(-10),
+            },
+        };
+
+        let db_path = tempfile::NamedTempFile::new_in(".").unwrap();
+        crate::db::sqlite::migrator::migrate(db_path.path().to_str().unwrap())
+            .await
+            .unwrap();
+
+        let db = Database::new(db_path.path().to_str().unwrap())
+            .await
+            .unwrap();
+
+        let homeserver = Url::parse("http://example.com").unwrap();
+        let ctx = Context {
+            account: crate::models::Account::default(),
+            db: db,
+            matrix_client: matrix_sdk::Client::new(homeserver).await.unwrap(),
+            origin_room: dummy_room!(),
+            active_room: dummy_room!(),
+            username: "username",
+            message_body: "message",
+        };
+
+        let roll_with_ctx = AdvancementRollWithContext(&roll, &ctx);
+        let result = advancement_roll(&roll_with_ctx).await;
+        assert!(result.is_err());
+        assert!(matches!(
+            result,
+            Err(BotError::DiceRollingError(DiceRollingError::InvalidAmount))
+        ));
+    }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
+    async fn advancement_roll_rejects_big_numbers() {
+        let roll = AdvancementRoll {
+            existing_skill: Amount {
+                operator: Operator::Plus,
+                element: Element::Number(3000),
+            },
+        };
+
+        let db_path = tempfile::NamedTempFile::new_in(".").unwrap();
+        crate::db::sqlite::migrator::migrate(db_path.path().to_str().unwrap())
+            .await
+            .unwrap();
+
+        let db = Database::new(db_path.path().to_str().unwrap())
+            .await
+            .unwrap();
+
+        let homeserver = Url::parse("http://example.com").unwrap();
+        let ctx = Context {
+            account: crate::models::Account::default(),
+            db: db,
+            matrix_client: matrix_sdk::Client::new(homeserver).await.unwrap(),
+            origin_room: dummy_room!(),
+            active_room: dummy_room!(),
+            username: "username",
+            message_body: "message",
+        };
+
+        let roll_with_ctx = AdvancementRollWithContext(&roll, &ctx);
+        let result = advancement_roll(&roll_with_ctx).await;
+        assert!(result.is_err());
+        assert!(matches!(
+            result,
+            Err(BotError::DiceRollingError(DiceRollingError::InvalidAmount))
+        ));
+    }
+
+    #[test]
+    fn is_variable_macro_succeds_on_variable() {
+        let amount = Amount {
+            operator: Operator::Plus,
+            element: Element::Variable("abc".to_string()),
+        };
+
+        assert_eq!(is_variable!(amount), true);
+    }
+
+    #[test]
+    fn is_variable_macro_fails_on_number() {
+        let amount = Amount {
+            operator: Operator::Plus,
+            element: Element::Number(1),
+        };
+
+        assert_eq!(is_variable!(amount), false);
+    }
+
+    #[test]
+    fn regular_roll_succeeds_when_below_target() {
+        //Roll 30, succeeding.
+        let mut roller = SequentialDieRoller::new(vec![0, 3]);
+        let rolled = roll_regular_dice(&DiceRollModifier::Normal, 50, &mut roller);
+        assert_eq!(RollResult::Success, rolled.result());
+    }
+
+    #[test]
+    fn regular_roll_hard_success_when_rolling_half() {
+        //Roll 25, succeeding.
+        let mut roller = SequentialDieRoller::new(vec![5, 2]);
+        let rolled = roll_regular_dice(&DiceRollModifier::Normal, 50, &mut roller);
+        assert_eq!(RollResult::HardSuccess, rolled.result());
+    }
+
+    #[test]
+    fn regular_roll_extreme_success_when_rolling_one_fifth() {
+        //Roll 10, succeeding extremely.
+        let mut roller = SequentialDieRoller::new(vec![0, 1]);
+        let rolled = roll_regular_dice(&DiceRollModifier::Normal, 50, &mut roller);
+        assert_eq!(RollResult::ExtremeSuccess, rolled.result());
+    }
+
+    #[test]
+    fn regular_roll_extreme_success_target_above_100() {
+        //Roll 30, succeeding extremely.
+        let mut roller = SequentialDieRoller::new(vec![0, 3]);
+        let rolled = roll_regular_dice(&DiceRollModifier::Normal, 150, &mut roller);
+        assert_eq!(RollResult::ExtremeSuccess, rolled.result());
+    }
+
+    #[test]
+    fn regular_roll_critical_success_on_one() {
+        //Roll 1.
+        let mut roller = SequentialDieRoller::new(vec![1, 0]);
+        let rolled = roll_regular_dice(&DiceRollModifier::Normal, 50, &mut roller);
+        assert_eq!(RollResult::CriticalSuccess, rolled.result());
+    }
+
+    #[test]
+    fn regular_roll_fail_when_above_target() {
+        //Roll 60.
+        let mut roller = SequentialDieRoller::new(vec![0, 6]);
+        let rolled = roll_regular_dice(&DiceRollModifier::Normal, 50, &mut roller);
+        assert_eq!(RollResult::Failure, rolled.result());
+    }
+
+    #[test]
+    fn regular_roll_is_fumble_when_skill_below_50_and_roll_at_least_96() {
+        //Roll 96.
+        let mut roller = SequentialDieRoller::new(vec![6, 9]);
+        let rolled = roll_regular_dice(&DiceRollModifier::Normal, 49, &mut roller);
+        assert_eq!(RollResult::Fumble, rolled.result());
+    }
+
+    #[test]
+    fn regular_roll_is_failure_when_skill_at_or_above_50_and_roll_at_least_96() {
+        //Roll 96.
+        let mut roller = SequentialDieRoller::new(vec![6, 9]);
+        let rolled = roll_regular_dice(&DiceRollModifier::Normal, 50, &mut roller);
+        assert_eq!(RollResult::Failure, rolled.result());
+
+        //Roll 96.
+        let mut roller = SequentialDieRoller::new(vec![6, 9]);
+        let rolled = roll_regular_dice(&DiceRollModifier::Normal, 68, &mut roller);
+        assert_eq!(RollResult::Failure, rolled.result());