use ::mime::Mime;
use axum::{
    http::{StatusCode, header},
    response::{IntoResponse, Response},
};
use rust_embed::EmbeddedFile;

use super::{error::NotFound, mime};
use crate::error::{
    Internal,
    failed::{Failed, ResultExt},
};

#[derive(rust_embed::Embed)]
#[folder = "$OUT_DIR/ui"]
pub struct Assets;

impl Assets {
    pub fn load(path: impl AsRef<str>) -> Result<Asset, Error> {
        let path = path.as_ref();
        let mime = mime::from_path(path).fail("Failed to determine MIME type from asset path")?;

        Self::get(path)
            .map(|file| Asset(mime, file))
            .ok_or(Error::NotFound(path.into()))
    }

    pub fn index() -> Result<Asset, Internal> {
        // "not found" in this case really is an internal error, as it should
        // never happen. `index.html` is a known-valid path with a known-valid
        // file extension.
        Ok(Self::load("index.html")?)
    }
}

pub struct Asset(Mime, EmbeddedFile);

impl IntoResponse for Asset {
    fn into_response(self) -> Response {
        let Self(mime, file) = self;
        (
            StatusCode::OK,
            [(header::CONTENT_TYPE, mime.as_ref())],
            file.data,
        )
            .into_response()
    }
}

#[derive(Debug, thiserror::Error)]
pub enum Error {
    #[error("not found: {0}")]
    NotFound(String),
    #[error(transparent)]
    Failed(#[from] Failed),
}

impl IntoResponse for Error {
    fn into_response(self) -> Response {
        match self {
            Self::NotFound(_) => NotFound(self.to_string()).into_response(),
            Self::Failed(_) => Internal::from(self).into_response(),
        }
    }
}