use axum::{
    extract::{Path, Request, State},
    http::{header, StatusCode},
    middleware::{self, Next},
    response::{IntoResponse, Redirect, Response},
    routing::get,
    Router,
};
use mime_guess::Mime;
use rust_embed::EmbeddedFile;

use crate::{app::App, channel, error::Internal, login::Login};

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

impl Assets {
    fn load(path: impl AsRef<str>) -> Result<Asset, NotFound<String>> {
        let path = path.as_ref();
        let mime = mime_guess::from_path(path).first_or_octet_stream();

        Self::get(path)
            .map(|file| Asset(mime, file))
            .ok_or(NotFound(format!("not found: {path}")))
    }

    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.
        Ok(Self::load("index.html")?)
    }
}

pub fn router(app: &App) -> Router<App> {
    [
        Router::new()
            .route("/*path", get(asset))
            .route("/setup", get(setup)),
        Router::new()
            .route("/", get(root))
            .route("/login", get(login))
            .route("/ch/:channel", get(channel))
            .route_layer(middleware::from_fn_with_state(app.clone(), setup_required)),
    ]
    .into_iter()
    .fold(Router::default(), Router::merge)
}

async fn asset(Path(path): Path<String>) -> Result<Asset, NotFound<String>> {
    Assets::load(path)
}

async fn root(login: Option<Login>) -> Result<impl IntoResponse, Internal> {
    if login.is_none() {
        Ok(Redirect::temporary("/login").into_response())
    } else {
        Ok(Assets::index()?.into_response())
    }
}

async fn login() -> Result<impl IntoResponse, Internal> {
    Assets::index()
}

async fn setup(State(app): State<App>) -> Result<impl IntoResponse, Internal> {
    if app.setup().completed().await? {
        Ok(Redirect::to("/login").into_response())
    } else {
        Ok(Assets::index().into_response())
    }
}

async fn channel(
    State(app): State<App>,
    login: Option<Login>,
    Path(channel): Path<channel::Id>,
) -> Result<impl IntoResponse, Internal> {
    if login.is_none() {
        Ok(Redirect::temporary("/").into_response())
    } else if app.channels().get(&channel).await?.is_none() {
        Ok(NotFound(Assets::index()?).into_response())
    } else {
        Ok(Assets::index()?.into_response())
    }
}

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)]
#[error("{0}")]
struct NotFound<E>(pub E);

impl<E> IntoResponse for NotFound<E>
where
    E: IntoResponse,
{
    fn into_response(self) -> Response {
        let Self(response) = self;
        (StatusCode::NOT_FOUND, response).into_response()
    }
}

pub async fn setup_required(State(app): State<App>, request: Request, next: Next) -> Response {
    match app.setup().completed().await {
        Ok(true) => next.run(request).await,
        Ok(false) => Redirect::to("/setup").into_response(),
        Err(error) => Internal::from(error).into_response(),
    }
}