use serde::{self, Deserialize, Serialize};
use reqwest::{Client, Url};
use crate::matrix::SyncCommand;
use std::path::PathBuf;
use std::fs;

const USER_AGENT: &str = "AxFive Matrix DiceBot/0.1.0 (+https://gitlab.com/Taywee/axfive-matrix-dicebot)";

/// The "matrix" section of the config, which gives home server, login information, and etc.
#[derive(Serialize, Deserialize, Debug)]
pub struct MatrixConfig {
    /// Your homeserver of choice, as an FQDN without scheme or path
    pub home_server: String,

    /// The next batch to grab.  This should be set automatically
    pub next_batch: Option<String>,
    pub login: toml::Value,
}

#[derive(Serialize, Deserialize, Debug)]
pub struct Config {
    pub matrix: MatrixConfig,
}

pub struct DiceBot {
    config_path: Option<PathBuf>,
    config: Config,
    access_token: String,
    next_batch: Option<String>,
    client: Client,
    home_server: Url,
}

#[derive(Deserialize, Debug)]
struct LoginResponse {
    access_token: String,
}

impl DiceBot {
    pub async fn new(config_path: Option<PathBuf>, config: Config) -> Result<Self, Box<dyn std::error::Error>> {
        let home_server: Url = format!("https://{}", config.matrix.home_server).parse()?;
        let client = Client::new();
        let request = serde_json::to_string(&config.matrix.login)?;
        let mut login_url = home_server.clone();
        login_url.set_path("/_matrix/client/r0/login");
        let response = client.post(login_url)
            .header("user-agent", USER_AGENT)
            .body(request)
            .send()
            .await?;
        let body: LoginResponse = serde_json::from_str(&response.text().await?)?;
        let next_batch = config.matrix.next_batch.clone();
        Ok(DiceBot{
            home_server,
            config_path,
            client,
            config,
            access_token: body.access_token,
            next_batch,
        })
    }

    pub async fn from_path<P: Into<PathBuf>>(config_path: P) -> Result<Self, Box<dyn std::error::Error>> {
        let config_path = config_path.into();
        let config = {
            let contents = fs::read_to_string(&config_path)?;
            toml::from_str(&contents)?
        };
        DiceBot::new(Some(config_path), config).await
    }

    /// Build a url using the current home server and the given path, as well as appending the
    /// access token
    fn url(&self, path: &str, query: &[(&str, &str)]) -> Url {
        let mut url = self.home_server.clone();
        url.set_path(path);
        {
            let mut query_pairs = url.query_pairs_mut();
            query_pairs.append_pair("access_token", &self.access_token);

            for pair in query.iter() {
                query_pairs.append_pair(pair.0, pair.1);
            }
        }

        url
    }

    pub async fn sync(&mut self) -> Result<(), Box<dyn std::error::Error>> {
        let mut sync_url = self.url("/_matrix/client/r0/sync", &[("timeout", "30000")]);

        // TODO: handle http 429
        if let Some(since) = &self.next_batch {
            sync_url.query_pairs_mut()
                .append_pair("since", since);
        }
        let body = self.client.get(sync_url)
            .header("user-agent", USER_AGENT)
            .send()
            .await?
            .text()
            .await?;
        let sync: SyncCommand = serde_json::from_str(&body).unwrap();
        println!("{:#?}", sync);
        self.next_batch = Some(sync.next_batch);
        Ok(())
    }

    pub async fn logout(mut self) -> Result<(), Box<dyn std::error::Error>> {
        let logout_url = self.url("/_matrix/client/r0/logout", &[]);
        self.client.post(logout_url)
            .header("user-agent", USER_AGENT)
            .body("{}")
            .send()
            .await?;

        self.config.matrix.next_batch = self.next_batch;

        if let Some(config_path) = self.config_path {
            let config = toml::to_string_pretty(&self.config)?;
            fs::write(config_path, config)?;
        }

        Ok(())
    }
}