use crate::errors::Error;
use rocket::data::{Data, FromData, Outcome, ToByteUnit};
use rocket::request::Request;
use std::default::Default;
use std::ops::Deref;

pub mod cofd;

/// A struct wrapping a protobuf that allows it to be used as binary
/// data submitted via POST using fetch API. Can automatically be
/// dereferenced into its wrapped type.
#[derive(Debug)]
pub(crate) struct Proto<T>(T)
where
    T: prost::Message + Default;

/// Converts the body of a POST request containing encoded protobuf
/// data into the wrapped type.
#[rocket::async_trait]
impl<T> FromData for Proto<T>
where
    T: prost::Message + Default,
{
    type Error = crate::errors::Error;

    async fn from_data(_req: &Request<'_>, data: Data) -> Outcome<Self, Error> {
        use rocket::http::Status;

        let bytes: Vec<u8> = match data.open(2.mebibytes()).stream_to_vec().await {
            Ok(read_bytes) => read_bytes,
            Err(e) => return Outcome::Failure((Status::new(422, "invalid protobuf"), e.into())),
        };

        match T::decode(bytes.as_ref()) {
            Ok(decoded) => Outcome::Success(Proto(decoded)),
            Err(e) => Outcome::Failure((Status::new(422, "invalid protobuf"), e.into())),
        }
    }
}

/// Enable automatically calling methods on a decoded Proto instance.
impl<T> Deref for Proto<T>
where
    T: prost::Message + Default,
{
    type Target = T;

    fn deref(&self) -> &T {
        &self.0
    }
}