use crate::av::xcoder::XCoder;
use crate::av::Rational;
use crate::transcoder::{Transcoder, SECONDS_PER_SEGMENT};
use async_std::channel::{bounded, Receiver, RecvError, SendError, Sender, TryRecvError};
use async_std::sync::{Arc, RwLock, RwLockReadGuard};
use async_std::task;
use futures::channel::oneshot::{
    channel as one_shot, Receiver as OneShotReceiver, Sender as OneShotSender,
};
use serde::Serialize;
use std::cmp::min;
use std::collections::{HashMap, HashSet};
use std::option::Option::Some;
use std::thread::Builder;
use std::thread::JoinHandle;
use uuid::Uuid;

#[derive(Debug, Default)]
struct OneShotSet(Vec<OneShotSender<()>>);

impl OneShotSet {
    fn add(&mut self) -> OneShotReceiver<()> {
        let (s, r) = one_shot::<()>();
        self.0.push(s);

        r
    }

    fn trigger(&mut self) {
        while let Some(sender) = self.0.pop() {
            sender.send(()).unwrap()
        }
    }

    fn new() -> OneShotSet {
        OneShotSet(vec![])
    }
}

#[derive(Debug, Default)]
pub struct TranscoderEvents {
    init_queue: OneShotSet,
    segment_queue: HashMap<u32, OneShotSet>,
}

impl TranscoderEvents {
    pub fn new() -> TranscoderEvents {
        Default::default()
    }
}

#[derive(Debug)]
pub struct TranscoderInstance {
    id: Uuid,
    channel: Channel<Message>,
    state: RwLock<TranscoderInstanceState>,
    command: TranscoderCommand,
    events: RwLock<TranscoderEvents>,
    status: RwLock<TranscoderStatus>,
}

impl TranscoderInstance {
    pub async fn state<T>(&self, block: fn(RwLockReadGuard<TranscoderInstanceState>) -> T) -> T {
        block(self.state.read().await)
    }

    pub fn id(&self) -> Uuid {
        self.id
    }

    pub async fn seek(&self, segment: u32) {
        self.channel.send(Message::Seek(segment)).await.unwrap()
    }

    pub async fn wait_for_segment(&self, segment: u32) -> bool {
        {
            let state = self.state.read().await;
            if state.info.segments() < segment {
                return false;
            }

            if state.segments.contains(&segment) {
                return true;
            }

            if state.state == TranscoderState::Finished {
                return false;
            }
        }

        println!("Waiting in segment queue for segment {}", segment);
        let r = {
            self.events
                .write()
                .await
                .segment_queue
                .entry(segment)
                .or_insert_with(|| OneShotSet::new())
                .add()
        };

        r.await.is_ok()
    }

    pub async fn wait_for_init(&self) -> bool {
        if self.state.read().await.init_written {
            return true;
        }

        let r = { self.events.write().await.init_queue.add() };

        r.await.is_ok()
    }

    pub async fn status(&self) -> TranscoderStatus {
        self.status.read().await.clone()
    }
}

#[derive(Serialize, Debug, Clone, Copy, Ord, PartialOrd, Eq, PartialEq)]
pub enum TranscoderState {
    None,
    Seeking,
    Transcoding,
    Failed,
    Stopped,
    Finished,
}

impl Default for TranscoderState {
    fn default() -> Self {
        TranscoderState::None
    }
}

#[derive(Serialize, Debug, Clone, Default)]
pub struct VideoInput {
    pub codec: String,
    pub encoder: String,
    pub decoder: String,
    pub frame_rate_rat: Option<[u32; 2]>,
    pub frame_rate: Option<f64>,
    pub width: u32,
    pub height: u32,
    pub time_scale: i32,
}

#[derive(Serialize, Debug, Clone, Default)]
pub struct AudioInput {
    pub codec: String,
    pub encoder: String,
    pub decoder: String,
    pub channels: i32,
    pub channel_layout: String,
    pub sample_rate: i32,
    pub time_scale: i32,
}

#[derive(Serialize, Debug, Clone, Default)]
pub struct TranscoderStatus {
    pub state: TranscoderState,
    pub failure_reason: Option<String>,
    pub segments: Vec<u32>,
    pub init_written: bool,
    pub duration_secs: f64,
    pub current_segment: u32,
    pub segment_count: u32,
    pub video: VideoInput,
    pub audio: Option<AudioInput>,
}

#[derive(Debug, Default)]
pub struct TranscoderInstanceState {
    thread: Option<JoinHandle<()>>,
    info: TranscoderInfo,
    segments: HashSet<u32>,
    init_written: bool,
    state: TranscoderState,
    failure_reason: Option<String>,
}

impl TranscoderInstanceState {
    #[inline]
    pub fn info(&self) -> &TranscoderInfo {
        &self.info
    }

    #[inline]
    pub fn segments(&self) -> &HashSet<u32> {
        &self.segments
    }

    #[inline]
    pub fn init_written(&self) -> bool {
        self.init_written
    }
}

#[derive(Debug, Default)]
pub struct TranscoderManager {
    instances: HashMap<Uuid, Arc<TranscoderInstance>>,
}

#[derive(Debug, Clone)]
pub struct Channel<T> {
    receiver: Receiver<T>,
    sender: Sender<T>,
}

impl<T> Channel<T> {
    async fn send(&self, msg: T) -> Result<(), SendError<T>> {
        self.sender.send(msg).await
    }

    fn send_blocking(&self, msg: T) -> Result<(), SendError<T>> {
        task::block_on(self.sender.send(msg))
    }

    async fn recv(&self) -> Result<T, RecvError> {
        self.receiver.recv().await
    }

    fn recv_blocking(&self) -> Result<T, RecvError> {
        task::block_on(self.receiver.recv())
    }

    fn try_recv(&self) -> Result<T, TryRecvError> {
        self.receiver.try_recv()
    }
}

fn new_channel() -> (Channel<Message>, Channel<Message>) {
    let (sender_a, receiver_a) = bounded(25);
    let (sender_b, receiver_b) = bounded(25);

    (
        Channel {
            sender: sender_a,
            receiver: receiver_b,
        },
        Channel {
            sender: sender_b,
            receiver: receiver_a,
        },
    )
}

#[derive(Debug, Clone)]
pub struct TranscoderCommand {
    input: String,
    output: String,
    audio: Option<i32>,
    video: Option<i32>,
}

#[derive(Debug, Clone, Default)]
pub struct TranscoderInfo {
    pub duration_secs: f64,
    pub audio: Option<AudioInput>,
    pub video: VideoInput,
}

impl TranscoderInfo {
    fn segments(&self) -> u32 {
        (self.duration_secs / SECONDS_PER_SEGMENT as f64).ceil() as u32
    }
}

#[derive(Debug)]
pub enum Message {
    Info(TranscoderInfo),
    SegmentReady(u32),
    Seek(u32),
    Seeking,
    Failure(String),
    Stop,
    Stopped,
    Finished(f64, u32),
}

fn transcoder_thread_main(command: TranscoderCommand, channel: Channel<Message>) {
    if let Err(err) = transcoder_thread(command, &channel) {
        channel.send_blocking(Message::Failure(err)).unwrap();
        return;
    }
}

fn transcoder_thread(command: TranscoderCommand, channel: &Channel<Message>) -> Result<(), String> {
    let transcoder = Transcoder::create(
        &command.input,
        &command.output,
        command.video,
        command.audio,
    );

    let mut transcoder = match transcoder {
        Ok(t) => t,
        Err(e) => {
            channel.send_blocking(Message::Failure(e)).unwrap();
            return Ok(());
        }
    };

    let mut segments = HashSet::new();
    let mut video_segments = HashSet::new();
    let mut video_last_segment = None;
    let mut audio_segments = HashSet::new();
    let mut audio_last_segment = None;
    transcoder.open()?;

    channel
        .send_blocking(Message::Info(TranscoderInfo {
            duration_secs: transcoder.duration_secs(),
            audio: transcoder.audio().map(|audio| AudioInput {
                codec: audio.input_stream().codec_name(),
                decoder: audio.decoder().name(),
                encoder: audio.encoder().name(),
                channels: audio.decoder().channels(),
                channel_layout: audio.decoder().channel_layout_name(),
                sample_rate: audio.decoder().sample_rate(),
                time_scale: audio.output_stream().time_base().den(),
            }),
            video: VideoInput {
                codec: transcoder.video_stream().codec_name(),
                encoder: transcoder.video_encoder().name(),
                decoder: transcoder.video_decoder().name(),
                frame_rate_rat: transcoder
                    .avg_frame_rate()
                    .map(|x| [x.den() as u32, x.num() as u32]),
                frame_rate: transcoder.avg_frame_rate().map(|x| x.as_f64()),
                width: transcoder.video_decoder().width() as u32,
                height: transcoder.video_decoder().height() as u32,
                time_scale: transcoder.video_stream_output().time_base().den(),
            },
        }))
        .unwrap();

    let mut completed = false;
    let has_audio = transcoder.has_audio();

    while !completed {
        if transcoder.transcode()? {
            while let Ok(msg) = channel.try_recv() {
                match msg {
                    Message::Seek(segment) => {
                        channel.send_blocking(Message::Seeking).unwrap();
                        let stream = Some(transcoder.video_stream().index());
                        transcoder.seek(segment, stream)?;
                    }
                    Message::Stop => {
                        transcoder.stop();
                        channel.send_blocking(Message::Stopped).unwrap();
                        return Ok(());
                    }

                    _ => {}
                };
            }

            if video_last_segment != transcoder.last_written_segment() {
                if let Some(segment) = transcoder.last_written_segment() {
                    video_segments.insert(segment);
                    if !has_audio || audio_segments.contains(&segment) {
                        channel
                            .send_blocking(Message::SegmentReady(segment))
                            .unwrap();
                        segments.insert(segment);
                    }
                }

                video_last_segment = transcoder.last_written_segment();
            }

            if audio_last_segment != transcoder.last_written_audio_segment() {
                if let Some(segment) = transcoder.last_written_audio_segment() {
                    audio_segments.insert(segment);
                    if video_segments.contains(&segment) {
                        channel
                            .send_blocking(Message::SegmentReady(segment))
                            .unwrap();
                        segments.insert(segment);
                    }
                }

                audio_last_segment = transcoder.last_written_audio_segment();
            }
        } else {
            println!("EOF, seeking to missed parts");
            let mut si: u32 = 0;
            while si <= transcoder.latest_written_segment().unwrap() as u32 {
                if segments.contains(&si) {
                    si += 1;
                    continue;
                }

                println!("Seeking to segment {}", si);
                transcoder.seek(si, Some(transcoder.video_stream().index()))?;
                break;
            }

            if si > transcoder.latest_written_segment().unwrap() {
                completed = true;
            }
        }
    }

    transcoder.finish()?;
    channel
        .send_blocking(Message::SegmentReady(transcoder.segment()))
        .unwrap();
    let duration = transcoder.latest_frame_secs();
    let segment_count = transcoder.segment();
    transcoder.stop();
    channel
        .send_blocking(Message::Finished(duration, segment_count))
        .unwrap();

    Ok(())
}

impl TranscoderManager {
    pub fn start(
        &mut self,
        input: String,
        audio: Option<i32>,
        video: Option<i32>,
    ) -> Result<Uuid, std::io::Error> {
        let uuid = Uuid::new_v4();
        let command = TranscoderCommand {
            input: input.clone(),
            output: format!("/tmp/transotf/{}/", uuid),
            audio,
            video,
        };
        let (thread_channel, own_channel) = new_channel();
        let thread = {
            let command = command.clone();
            Builder::new()
                .name(format!("t#{}", uuid))
                .spawn(|| transcoder_thread_main(command, thread_channel))?
        };

        let instance = TranscoderInstance {
            id: uuid,
            command,
            state: RwLock::new({
                let mut it = TranscoderInstanceState::default();
                it.thread = Some(thread);
                it
            }),
            channel: own_channel,
            events: RwLock::new(TranscoderEvents::new()),
            status: Default::default(),
        };

        let instance = Arc::new(instance);
        self.instances.insert(uuid, instance.clone());

        task::spawn(async move {
            loop {
                let fut = instance.channel.recv();
                if let Ok(x) = fut.await {
                    println!("[{}] {:?}", uuid, &x);
                    match x {
                        Message::Finished(duration, segment_count) => {
                            {
                                let mut status = instance.status.write().await;
                                status.state = TranscoderState::Finished;
                                status.segment_count = segment_count;
                                status.duration_secs = duration;
                            }

                            {
                                let mut state = instance.state.write().await;
                                if let Some(join_handle) =
                                    std::mem::replace(&mut state.thread, None)
                                {
                                    join_handle.join().unwrap();
                                }
                            }

                            break;
                        }

                        Message::Stopped => {
                            let mut status = instance.status.write().await;
                            status.state = TranscoderState::Stopped
                        }

                        Message::Failure(error) => {
                            let mut status = instance.status.write().await;
                            status.state = TranscoderState::Failed;
                            status.failure_reason = Some(error);
                        }

                        Message::Info(info) => {
                            {
                                let mut state = instance.state.write().await;
                                state.info = info.clone()
                            }

                            {
                                let mut status = instance.status.write().await;
                                status.audio = info.audio;
                                status.video = info.video;
                                status.segment_count =
                                    (info.duration_secs / SECONDS_PER_SEGMENT as f64).ceil() as u32;
                                status.duration_secs = info.duration_secs
                            }
                        }

                        Message::Seeking => {
                            let mut status = instance.status.write().await;
                            status.state = TranscoderState::Seeking
                        }

                        Message::SegmentReady(segment) => {
                            let mut state = instance.state.write().await;
                            if segment == 0 {
                                state.init_written = true;
                                instance.events.write().await.init_queue.trigger()
                            }

                            let current_segment = min(segment + 1, state.info.segments() - 1);

                            {
                                let mut status = instance.status.write().await;
                                status.init_written = true;
                                status.current_segment = current_segment;
                                status.state = TranscoderState::Transcoding;

                                if state.segments.insert(segment) {
                                    status.segments.push(segment);
                                }
                            }

                            instance
                                .events
                                .write()
                                .await
                                .segment_queue
                                .get_mut(&segment)
                                .map(|x| x.trigger());

                            let mut skip_ahead = 1 + segment;
                            while state.info.segments() > skip_ahead
                                && state.segments.contains(&skip_ahead)
                            {
                                skip_ahead += 1;
                            }

                            if skip_ahead > (segment + 5) {
                                instance.seek(skip_ahead).await;
                            }
                        }

                        _ => {}
                    }
                } else {
                    return;
                }
            }
        });

        Ok(uuid)
    }

    pub fn get(&self, id: Uuid) -> Option<Arc<TranscoderInstance>> {
        self.instances.get(&id).cloned()
    }
}