#[macro_use]
extern crate failure;
#[macro_use]
extern crate serde_derive;
extern crate serde;
extern crate serde_json;
extern crate languageserver_types;
extern crate drop_bomb;
#[macro_use]
extern crate crossbeam_channel;
extern crate threadpool;
#[macro_use]
extern crate log;
extern crate flexi_logger;
extern crate libeditor;
extern crate libanalysis;

mod io;
mod caps;
mod req;
mod dispatch;

use threadpool::ThreadPool;
use crossbeam_channel::{bounded, Sender, Receiver};
use flexi_logger::Logger;
use libanalysis::WorldState;

use ::{
    io::{Io, RawMsg},
};

pub type Result<T> = ::std::result::Result<T, ::failure::Error>;

fn main() -> Result<()> {
    Logger::with_env_or_str("m=trace")
        .log_to_file()
        .directory("log")
        .start()?;
    info!("starting server");
    match ::std::panic::catch_unwind(|| main_inner()) {
        Ok(res) => {
            info!("shutting down: {:?}", res);
            res
        }
        Err(_) => {
            error!("server panicked");
            bail!("server panicked")
        }
    }
}

fn main_inner() -> Result<()> {
    let mut io = Io::from_stdio();
    let res = initialize(&mut io);
    info!("shutting down IO...");
    let io_res = io.stop();
    info!("... IO is down");
    match (res, io_res) {
        (Ok(()), Ok(())) => Ok(()),
        (res, Ok(())) => res,
        (Ok(()), io_res) => io_res,
        (res, Err(io_err)) => {
            error!("shutdown error: {:?}", io_err);
            res
        }
    }
}

fn initialize(io: &mut Io) -> Result<()> {
    loop {
        match io.recv()? {
            RawMsg::Request(req) => {
                if let Some((_params, resp)) = dispatch::expect::<req::Initialize>(io, req)? {
                    resp.result(io, req::InitializeResult {
                        capabilities: caps::SERVER_CAPABILITIES
                    })?;
                    match io.recv()? {
                        RawMsg::Notification(n) => {
                            if n.method != "initialized" {
                                bail!("expected initialized notification");
                            }
                        }
                        _ => {
                            bail!("expected initialized notification");
                        }
                    }
                    return initialized(io);
                }
            }
            RawMsg::Notification(n) => {
                bail!("expected initialize request, got {:?}", n)
            }
            RawMsg::Response(res) => {
                bail!("expected initialize request, got {:?}", res)
            }
        }
    }
}

type Thunk = Box<for<'a> FnBox<&'a mut Io, Result<()>>>;

fn initialized(io: &mut Io) -> Result<()> {
    let mut world = WorldState::new();
    let mut pool = ThreadPool::new(4);
    let (sender, receiver) = bounded::<Thunk>(16);
    let res = main_loop(io, &mut world, &mut pool, sender, receiver.clone());
    info!("waiting for background jobs to finish...");
    receiver.for_each(drop);
    pool.join();
    info!("...background jobs have finished");
    res
}

fn main_loop(
    io: &mut Io,
    world: &mut WorldState,
    pool: &mut ThreadPool,
    sender: Sender<Thunk>,
    receiver: Receiver<Thunk>,
) -> Result<()> {
    info!("server initialized, serving requests");
    loop {
        enum Event {
            Msg(RawMsg),
            Thunk(Thunk),
            ReceiverDead,
        }

        let event = select! {
            recv(io.receiver(), msg) => match msg {
                Some(msg) => Event::Msg(msg),
                None => Event::ReceiverDead,
            },
            recv(receiver, thunk) => Event::Thunk(thunk.unwrap()),
        };

        let msg = match event {
            Event::ReceiverDead => {
                io.cleanup_receiver()?;
                unreachable!();
            }
            Event::Thunk(thunk) => {
                thunk.call_box(io)?;
                continue;
            }
            Event::Msg(msg) => msg,
        };

        match msg {
            RawMsg::Request(req) => {
                let req = match dispatch::parse_as::<req::SyntaxTree>(req)? {
                    Ok((params, resp)) => {
                        let world = world.snapshot();
                        let sender = sender.clone();
                        pool.execute(move || {
                            let res: Result<String> = (|| {
                                let path = params.text_document.uri.to_file_path()
                                    .map_err(|()| format_err!("invalid path"))?;
                                let file = world.file_syntax(&path)?;
                                Ok(libeditor::syntax_tree(&file))
                            })();

                            sender.send(Box::new(|io: &mut Io| resp.response(io, res)))
                        });
                        continue;
                    }
                    Err(req) => req,
                };

                if let Some(((), resp)) = dispatch::expect::<req::Shutdown>(io, req)? {
                    info!("shutdown request");
                    resp.result(io, ())?;
                    return Ok(());
                }
            }
            msg => {
                eprintln!("msg = {:?}", msg);
            }
        }
    }
}


trait FnBox<A, R>: Send {
    fn call_box(self: Box<Self>, a: A) -> R;
}

impl<A, R, F: FnOnce(A) -> R + Send> FnBox<A, R> for F {
    fn call_box(self: Box<F>, a: A) -> R {
        (*self)(a)
    }
}