// Copyright 2015-2018 Parity Technologies (UK) Ltd.
// This file is part of Parity.

// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Parity.  If not, see <http://www.gnu.org/licenses/>.

// Copyright 2019 Conflux Foundation. All rights reserved.
// Conflux is free software and distributed under GNU General Public License.
// See http://www.gnu.org/licenses/

//! General IO module.

//TODO: use Poll from mio
#![allow(deprecated)]

mod service_mio;
mod worker;

use mio::{deprecated::NotifyError, Poll, Token};
use std::{cell::Cell, error, fmt};

thread_local! {
    /// Stack size
    /// Should be modified if it is changed in Rust since it is no way
    /// to know or get it
    pub static LOCAL_STACK_SIZE: Cell<usize> = Cell::new(::std::env::var("RUST_MIN_STACK").ok().and_then(|s| s.parse().ok()).unwrap_or(2 * 1024 * 1024));
}

#[derive(Debug)]
/// IO Error
pub enum IoError {
    Mio(::std::io::Error),
    /// Error concerning the Rust standard library's IO subsystem.
    StdIo(::std::io::Error),
}

impl fmt::Display for IoError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        // just defer to the std implementation for now.
        // we can refine the formatting when more variants are added.
        match *self {
            IoError::Mio(ref std_err) => std_err.fmt(f),
            IoError::StdIo(ref std_err) => std_err.fmt(f),
        }
    }
}

impl error::Error for IoError {
    fn description(&self) -> &str { "IO error" }
}

impl From<::std::io::Error> for IoError {
    fn from(err: ::std::io::Error) -> IoError { IoError::StdIo(err) }
}

impl<Message> From<NotifyError<service_mio::IoMessage<Message>>> for IoError
where Message: Send
{
    fn from(_err: NotifyError<service_mio::IoMessage<Message>>) -> IoError {
        IoError::Mio(::std::io::Error::new(
            ::std::io::ErrorKind::ConnectionAborted,
            "Network IO notification error",
        ))
    }
}

/// Generic IO handler.
/// All the handler function are called from within IO event loop.
/// `Message` type is used as notification data
pub trait IoHandler<Message>: Send + Sync
where Message: Send + Sync + 'static
{
    /// Initialize the handler
    fn initialize(&self, _io: &IoContext<Message>) {}
    /// Timer function called after a timeout created with `HandlerIo::timeout`.
    fn timeout(&self, _io: &IoContext<Message>, _timer: TimerToken) {}
    /// Called when a broadcasted message is received. The message can only be
    /// sent from a different IO handler.
    fn message(&self, _io: &IoContext<Message>, _message: &Message) {}
    /// Called when an IO stream gets closed
    fn stream_hup(&self, _io: &IoContext<Message>, _stream: StreamToken) {}
    /// Called when an IO stream can be read from
    fn stream_readable(&self, _io: &IoContext<Message>, _stream: StreamToken) {}
    /// Called when an IO stream can be written to
    fn stream_writable(&self, _io: &IoContext<Message>, _stream: StreamToken) {}
    /// Register a new stream with the event loop
    fn register_stream(
        &self, _stream: StreamToken, _reg: Token, _event_loop: &Poll,
    ) {
    }
    /// Re-register a stream with the event loop
    fn update_stream(
        &self, _stream: StreamToken, _reg: Token, _event_loop: &Poll,
    ) {
    }
    /// Deregister a stream. Called when stream is removed from event loop
    fn deregister_stream(&self, _stream: StreamToken, _event_loop: &Poll) {}
}

pub use crate::service_mio::{
    IoChannel, IoContext, IoManager, IoService, StreamToken, TimerToken,
    TOKENS_PER_HANDLER,
};

#[cfg(test)]
mod tests {
    use super::*;
    use std::{
        sync::{atomic, Arc},
        thread,
        time::Duration,
    };

    // Mio's behaviour is too unstable for this test. Sometimes we have to wait
    // a few milliseconds, sometimes more than 5 seconds for the message to
    // arrive. Therefore we ignore this test in order to not have spurious
    // failure when running continuous integration.
    #[test]
    #[ignore]
    fn send_message_to_handler() {
        struct MyHandler(atomic::AtomicBool);

        #[derive(Clone)]
        struct MyMessage {
            data: u32,
        }

        impl IoHandler<MyMessage> for MyHandler {
            fn message(&self, _io: &IoContext<MyMessage>, message: &MyMessage) {
                assert_eq!(message.data, 5);
                self.0.store(true, atomic::Ordering::SeqCst);
            }
        }

        let handler = Arc::new(MyHandler(atomic::AtomicBool::new(false)));
        let poll = Arc::new(Poll::new().unwrap());

        let service = IoService::<MyMessage>::start(poll)
            .expect("Error creating network service");
        service.register_handler(handler.clone()).unwrap();

        service.send_message(MyMessage { data: 5 }).unwrap();

        thread::sleep(Duration::from_secs(1));
        assert!(handler.0.load(atomic::Ordering::SeqCst));
    }

    #[test]
    fn timeout_working() {
        struct MyHandler(atomic::AtomicBool);

        #[derive(Clone)]
        #[allow(dead_code)]
        struct MyMessage {
            data: u32,
        }

        impl IoHandler<MyMessage> for MyHandler {
            fn initialize(&self, io: &IoContext<MyMessage>) {
                io.register_timer_once(1234, Duration::from_millis(500))
                    .unwrap();
            }

            fn timeout(&self, _io: &IoContext<MyMessage>, timer: TimerToken) {
                assert_eq!(timer, 1234);
                assert!(!self.0.swap(true, atomic::Ordering::SeqCst));
            }
        }

        let handler = Arc::new(MyHandler(atomic::AtomicBool::new(false)));
        let poll = Arc::new(Poll::new().unwrap());

        let service = IoService::<MyMessage>::start(poll)
            .expect("Error creating network service");
        service.register_handler(handler.clone()).unwrap();

        thread::sleep(Duration::from_secs(2));
        assert!(handler.0.load(atomic::Ordering::SeqCst));
    }

    #[test]
    fn multi_timeout_working() {
        struct MyHandler(atomic::AtomicUsize);

        #[derive(Clone)]
        #[allow(dead_code)]
        struct MyMessage {
            data: u32,
        }

        impl IoHandler<MyMessage> for MyHandler {
            fn initialize(&self, io: &IoContext<MyMessage>) {
                io.register_timer(1234, Duration::from_millis(500)).unwrap();
            }

            fn timeout(&self, _io: &IoContext<MyMessage>, timer: TimerToken) {
                assert_eq!(timer, 1234);
                self.0.fetch_add(1, atomic::Ordering::SeqCst);
            }
        }

        let handler = Arc::new(MyHandler(atomic::AtomicUsize::new(0)));
        let poll = Arc::new(Poll::new().unwrap());

        let service = IoService::<MyMessage>::start(poll)
            .expect("Error creating network service");
        service.register_handler(handler.clone()).unwrap();

        thread::sleep(Duration::from_secs(2));
        assert!(handler.0.load(atomic::Ordering::SeqCst) >= 2);
    }
}