use std::net::{TcpListener, TcpStream};
use std::pin::Pin;
use std::string;
use std::sync::Arc;
use std::task::{Context, Poll};

use anyhow::Result;
use bytes::Bytes;
use http_body_util::Full;
use hyper::body::Incoming;
use hyper::service::service_fn;
use hyper::{Request, Response};
use macro_rules_attribute::apply;
use minijinja::{context, Environment};
use smol::{fs, io, prelude::*, Async, Executor};
use smol_hyper::rt::{FuturesIo, SmolTimer};
use smol_macros::main;

mod assets;
mod loader;
mod page;

use crate::assets::AssetStore;
use crate::loader::*;
use crate::page::*;

struct AppState<'a> {
    pub pages: Vec<Page>,
    env: Environment<'a>,
}

/// Serves a request and returns a response.
async fn serve(req: Request<Incoming>, state: Arc<AppState<'_>>) -> Result<Response<Full<Bytes>>> {
    println!("Serving {}", req.uri());

    let path = req.uri().path();
    let mreow = state.pages.iter().find(|&x| {
        if let Some(path_x) = &x.header.path {
            println!("{},{}", path_x, path);
            if path_x == path {
                true
            } else {
                false
            }
        } else {
            false
        }
    });
    let reply: Bytes = match mreow {
        Some(x) => state
            .env
            .get_template(&x.header.id)
            .unwrap()
            .render(context! {})
            .unwrap()
            .into(),
        None => match AssetStore::new("./templateServe/_assets/".into())
            .load_asset(path)
            .await
        {
            Ok(asset) => asset,
            Err(_) => "".into(),
        },
    };
    Ok(Response::new(Full::new(reply.into())))
}

async fn handle_client(client: Async<TcpStream>, state: Arc<AppState<'_>>) -> Result<()> {
    let client = SmolStream::Plain(client);

    hyper::server::conn::http1::Builder::new()
        .timer(SmolTimer::new())
        .serve_connection(
            FuturesIo::new(client),
            service_fn(move |req| serve(req, state.clone())),
        )
        .await?;
    Ok(())
}

/// Listens for incoming connections and serves them.
async fn listen(
    ex: &Arc<Executor<'static>>,
    listener: Async<TcpListener>,
    state: Arc<AppState<'static>>,
) -> Result<()> {
    loop {
        // Wait for a new client.
        let (client, _) = listener.accept().await?;
        let cloned_state = state.clone();

        // Spawn a task to handle this connection.
        ex.spawn({
            async move {
                if let Err(e) = handle_client(client, cloned_state).await {
                    println!("Error while handling client: {}", e);
                }
            }
        })
        .detach();
    }
}

async fn init<'a>() -> Result<AppState<'a>> {
    let mut env = Environment::new();
    let mut pages: Vec<Page> = Vec::new();
    env.add_global("globals", context! {version => "0.1.0"});
    let mut state: AppState = AppState { pages, env };
    state.load_from_fs().await?;

    Ok(state)
}

#[apply(main!)]
async fn main(ex: &Arc<Executor<'static>>) -> Result<()> {
    let mut state = init().await?;

    let _ = listen(
        ex,
        Async::<TcpListener>::bind(([127, 0, 0, 1], 8000))?,
        Arc::new(state),
    )
    .await;
    Ok(())
}

/// A TCP or TCP+TLS connection.
enum SmolStream {
    Plain(Async<TcpStream>),
}

impl AsyncRead for SmolStream {
    fn poll_read(
        mut self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        buf: &mut [u8],
    ) -> Poll<io::Result<usize>> {
        match &mut *self {
            Self::Plain(s) => Pin::new(s).poll_read(cx, buf),
        }
    }
}

impl AsyncWrite for SmolStream {
    fn poll_write(
        mut self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        buf: &[u8],
    ) -> Poll<io::Result<usize>> {
        match &mut *self {
            Self::Plain(s) => Pin::new(s).poll_write(cx, buf),
        }
    }

    fn poll_close(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
        match &mut *self {
            Self::Plain(s) => Pin::new(s).poll_close(cx),
        }
    }

    fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
        match &mut *self {
            Self::Plain(s) => Pin::new(s).poll_close(cx),
        }
    }
}