#![feature(future_join)]

use std::{env, path::PathBuf};

use actix_files;
use actix_web::{
    dev::ServiceResponse,
    error,
    http::{header::ContentType, StatusCode},
    middleware::{ErrorHandlerResponse, ErrorHandlers, Logger},
    web, App, FromRequest, HttpRequest, HttpResponse, HttpServer, Responder, Result,
};
use actix_web_lab::respond::Html;
use async_channel;
use futures::{pin_mut, select, FutureExt};
use minijinja;
use minijinja_autoreload::AutoReloader;

use crate::util::CustomResult;
use crate::webui::worker::worker_loop;

mod views;
mod worker;

struct MiniJinjaRenderer {
    tmpl_env: web::Data<minijinja_autoreload::AutoReloader>,
}

impl MiniJinjaRenderer {
    fn render(&self, tmpl: &str, ctx: impl Into<minijinja::value::Value>) -> Result<Html> {
        log::info!("Rendering template {:?}", tmpl);
        self.tmpl_env
            .acquire_env()
            .map_err(|_| error::ErrorInternalServerError("could not acquire template env"))?
            .get_template(tmpl)
            .map_err(|e| error::ErrorInternalServerError(format!("{:?}", e)))?
            .render(ctx.into())
            .map(Html)
            .map_err(|err| {
                log::error!("{err}");
                error::ErrorInternalServerError("template error")
            })
    }
}

impl FromRequest for MiniJinjaRenderer {
    type Error = actix_web::Error;
    type Future = actix_utils::future::Ready<Result<Self, Self::Error>>;

    fn from_request(req: &HttpRequest, _pl: &mut actix_web::dev::Payload) -> Self::Future {
        let tmpl_env = <web::Data<minijinja_autoreload::AutoReloader>>::extract(req)
            .into_inner()
            .unwrap();

        actix_utils::future::ready(Ok(Self { tmpl_env }))
    }
}

#[tokio::main]
pub async fn web_ui_main(port: u16, enable_template_autoreload: bool) -> CustomResult<()> {
    // The closure is invoked every time the environment is outdated to recreate it.
    let tmpl_reloader = AutoReloader::new(move |notifier| {
        let mut env: minijinja::Environment<'static> = minijinja::Environment::new();

        let tmpl_path = PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("resources/templates");
        log::info!("Using template dir {:?}", tmpl_path);

        // if watch_path is never called, no fs watcher is created
        if enable_template_autoreload {
            notifier.watch_path(&tmpl_path, true);
        }
        env.set_source(minijinja::Source::from_path(tmpl_path));
        Ok(env)
    });

    let (s, r) = async_channel::unbounded::<i32>();

    let tmpl_reloader = web::Data::new(tmpl_reloader);

    let server = HttpServer::new(move || {
        App::new()
            .app_data(tmpl_reloader.clone())
            .app_data(web::Data::new(s.clone()))
            .service(
                actix_files::Files::new("/static", "./resources/static/").use_last_modified(true),
            )
            .service(views::index)
            .service(views::actions)
            .service(views::overview)
            .service(views::overview_submit_button)
            .service(views::actions_partials)
            .service(views::push_event)
            .wrap(ErrorHandlers::new().handler(StatusCode::NOT_FOUND, not_found))
            .wrap(Logger::default())
    })
    .workers(2)
    .bind(("0.0.0.0", port))
    .unwrap();

    let t1 = server.run().fuse();
    let t2 = worker_loop(r).fuse();
    pin_mut!(t1, t2);

    select! {
        x = t1 => x,
        y = t2 => y,
    };
    Ok(())
}

/// Error handler for a 404 Page not found error.
fn not_found<B>(svc_res: ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> {
    let res = get_error_response(&svc_res, "Page not found");

    Ok(ErrorHandlerResponse::Response(ServiceResponse::new(
        svc_res.into_parts().0,
        res.map_into_right_body(),
    )))
}

/// Generic error handler.
fn get_error_response<B>(res: &ServiceResponse<B>, error: &str) -> HttpResponse {
    let req = res.request();

    let tmpl_env = MiniJinjaRenderer::extract(req).into_inner().unwrap();

    // Provide a fallback to a simple plain text response in case an error occurs during the
    // rendering of the error page.
    let fallback = |err: &str| {
        HttpResponse::build(res.status())
            .content_type(ContentType::plaintext())
            .body(err.to_string())
    };

    let ctx = minijinja::context! {
        error => error,
        status_code => res.status().as_str(),
    };

    match tmpl_env.render("error.html", ctx) {
        Ok(body) => body
            .customize()
            .with_status(res.status())
            .respond_to(req)
            .map_into_boxed_body(),

        Err(_) => fallback(error),
    }
}