use crate::{
    audio::TrackInfo, database::MusicIndex, music_scanner::MusicScanner, Error, FatalError,
};
use flow::{ok, Flow};
use std::{
    sync::{
        mpsc::{channel, Receiver, RecvTimeoutError, Sender},
        Arc,
    },
    thread,
    thread::JoinHandle,
    time::{Duration, Instant},
};

fn scan_frequency() -> Duration {
    Duration::from_secs(60)
}

pub enum ControlMsg {
    Exit,
}

pub enum TrackMsg {
    UpdateInProgress,
    UpdateComplete,
}

pub enum PlaybackMsg {
    PositionUpdate,
    Playing,
    Pausing,
    Stopping,
}

pub struct Core {
    db: Arc<dyn MusicIndex>,
    _track_handle: JoinHandle<()>,
    _track_rx: Receiver<TrackMsg>,
    _playback_handle: JoinHandle<()>,
    _playback_rx: Receiver<PlaybackMsg>,
    control_tx: Sender<ControlMsg>,
}

impl Core {
    pub fn new(
        db: Arc<dyn MusicIndex>,
        scanner: impl MusicScanner + 'static,
    ) -> Flow<Core, FatalError, Error> {
        let (control_tx, control_rx) = channel::<ControlMsg>();
        let db = db;

        let (_track_handle, _track_rx) = {
            let (track_tx, track_rx) = channel();
            let db = db.clone();
            let track_handle = thread::spawn(move || {
                let mut next_scan = Instant::now();
                loop {
                    if Instant::now() >= next_scan {
                        let _ = track_tx.send(TrackMsg::UpdateInProgress);
                        for track in scanner.scan() {
                            match track {
                                Ok(track) => db.add_track(track),
                                Err(_) => ok(()),
                            };
                        }
                        let _ = track_tx.send(TrackMsg::UpdateComplete);
                        next_scan = Instant::now() + scan_frequency();
                    }
                    match control_rx.recv_timeout(Duration::from_millis(1000)) {
                        Ok(ControlMsg::Exit) => return,
                        Err(RecvTimeoutError::Timeout) => (),
                        Err(RecvTimeoutError::Disconnected) => return,
                    }
                }
            });
            (track_handle, track_rx)
        };

        let (_playback_handle, _playback_rx) = {
            let (_playback_tx, playback_rx) = channel();
            let playback_handle = thread::spawn(move || {});
            (playback_handle, playback_rx)
        };

        ok(Core {
            db,
            _track_handle,
            _track_rx,
            _playback_handle,
            _playback_rx,
            control_tx,
        })
    }

    pub fn list_tracks<'a>(&'a self) -> Flow<Vec<TrackInfo>, FatalError, Error> {
        self.db.list_tracks().map_err(Error::DatabaseError)
    }

    pub fn exit(&self) {
        let _ = self.control_tx.send(ControlMsg::Exit);
        /*
        self.track_handle.join();
        self.playback_handle.join();
        */
    }
}

#[cfg(test)]
mod test {
    use super::*;
    use crate::{audio::TrackId, database::MemoryIndex, music_scanner::factories::MockScanner};
    use std::collections::HashSet;

    fn with_example_index<F>(f: F)
    where
        F: Fn(Core),
    {
        let index = MemoryIndex::new();
        let scanner = MockScanner::new();
        match Core::new(Arc::new(index), scanner) {
            Flow::Ok(core) => {
                thread::sleep(Duration::from_millis(10));
                f(core)
            }
            Flow::Err(error) => panic!("{:?}", error),
            Flow::Fatal(error) => panic!("{:?}", error),
        }
    }

    #[test]
    fn it_lists_tracks() {
        with_example_index(|core| match core.list_tracks() {
            Flow::Ok(tracks) => {
                let track_ids = tracks
                    .iter()
                    .map(|t| t.id.clone())
                    .collect::<HashSet<TrackId>>();
                assert_eq!(track_ids.len(), 5);
                assert_eq!(
                    track_ids,
                    HashSet::from([
                        TrackId::from("/home/savanni/Track 1.mp3".to_owned()),
                        TrackId::from("/home/savanni/Track 2.mp3".to_owned()),
                        TrackId::from("/home/savanni/Track 3.mp3".to_owned()),
                        TrackId::from("/home/savanni/Track 4.mp3".to_owned()),
                        TrackId::from("/home/savanni/Track 5.mp3".to_owned()),
                    ])
                );
            }
            Flow::Fatal(err) => panic!("fatal error: {:?}", err),
            Flow::Err(err) => panic!("error: {:?}", err),
        })
    }
}