package main

import (
	"fmt"
	"git.gammaspectra.live/S.O.N.G/Kirika/audio"
	"git.gammaspectra.live/S.O.N.G/Kirika/audio/format/flac"
	"git.gammaspectra.live/S.O.N.G/Kirika/audio/format/mp3"
	"git.gammaspectra.live/S.O.N.G/Kirika/audio/format/opus"
	"git.gammaspectra.live/S.O.N.G/Kirika/audio/format/tta"
	"git.gammaspectra.live/S.O.N.G/Kirika/audio/packetizer"
	"io"
	"log"
	"net/http"
	"os"
	"path"
	"strings"
	"sync"
	"time"
)

const maxBufferSize = 10

type QueueTrackEntry struct {
	QueueIdentifier audio.QueueIdentifier
	Path            string
	Metadata        struct {
		Title  string `json:"title"`
		Album  string `json:"album"`
		Artist string `json:"artist"`
		Art    string `json:"art"`
	}

	original map[string]interface{}
}

type Queue struct {
	NowPlaying chan *QueueTrackEntry
	QueueEmpty chan *QueueTrackEntry
	audioQueue *audio.Queue
	mounts     []*StreamMount
	queue      []*QueueTrackEntry
	mutex      sync.RWMutex
	config     *Config
	wg         sync.WaitGroup
}

func NewQueue(config *Config) *Queue {
	q := &Queue{
		NowPlaying: make(chan *QueueTrackEntry, 1),
		QueueEmpty: make(chan *QueueTrackEntry),
		config:     config,
		audioQueue: audio.NewQueue(44100, 2),
	}
	blocksPerSecond := 20

	sources := SplitAudioSource(audio.NewFilterChain(q.audioQueue.GetSource(), audio.NewBufferFilter(16), audio.NewRealTimeFilter(blocksPerSecond), audio.NewBufferFilter(maxBufferSize*blocksPerSecond)), len(config.Streams))
	for i, s := range q.config.Streams {
		mount := NewStreamMount(sources[i], s.MountPath, s.Codec, s.Container, s.Bitrate)
		if mount == nil {
			log.Panicf("could not initialize %s\n", s.MountPath)
		}
		q.mounts = append(q.mounts, mount)
		q.wg.Add(1)
		go mount.Process(&q.wg)
	}

	return q
}

func (q *Queue) Wait() {
	q.wg.Wait()
	close(q.NowPlaying)
}

var flacFormat = flac.NewFormat()
var ttaFormat = tta.NewFormat()
var mp3Format = mp3.NewFormat()
var opusFormat = opus.NewFormat()

func (q *Queue) AddTrack(entry *QueueTrackEntry, tail bool) error {

	f, err := os.Open(entry.Path)
	if err != nil {
		return err
	}
	var source audio.Source
	switch strings.ToLower(path.Ext(entry.Path)) {
	case ".flac":
		source, err = flacFormat.Open(f)
	case ".tta":
		source, err = ttaFormat.Open(f)
	case ".mp3":
		source, err = mp3Format.Open(f)
	case ".ogg", ".opus":
		source, err = opusFormat.Open(f)
	}

	if err != nil {
		f.Close()
		return err
	}

	if source.Blocks == nil {
		f.Close()
		return fmt.Errorf("could not find decoder for %s", entry.Path)
	}

	startCallback := func(queue *audio.Queue, entry *audio.QueueEntry) {
		log.Printf("now playing %s\n", f.Name())
		if e := q.Get(entry.Identifier); e != nil {
			q.NowPlaying <- e
		}
	}

	endCallback := func(queue *audio.Queue, entry *audio.QueueEntry) {

	}

	removeCallback := func(queue *audio.Queue, entry *audio.QueueEntry) {
		defer f.Close()
		q.Remove(entry.Identifier)
		q.HandleQueue()
	}

	q.mutex.Lock()
	defer q.mutex.Unlock()

	if tail {
		entry.QueueIdentifier = q.audioQueue.AddTail(source, startCallback, endCallback, removeCallback)
	} else {
		entry.QueueIdentifier = q.audioQueue.AddHead(source, startCallback, endCallback, removeCallback)
	}

	entry.original["queue_id"] = entry.QueueIdentifier

	if tail || len(q.queue) == 0 {
		q.queue = append(q.queue, entry)
	} else {
		q.queue = append(q.queue[:1], append([]*QueueTrackEntry{entry}, q.queue[1:]...)...)
	}

	return nil
}

func (q *Queue) HandleQueue() {
	if q.audioQueue.GetQueueSize() == 0 {
		q.AddTrack(<-q.QueueEmpty, true)
	}
}

func (q *Queue) GetQueue() (result []*QueueTrackEntry) {
	q.mutex.RLock()
	defer q.mutex.RUnlock()

	if len(q.queue) > 1 {
		result = make([]*QueueTrackEntry, len(q.queue)-1)
		copy(result, q.queue[1:])
	}

	return
}

func (q *Queue) Get(identifier audio.QueueIdentifier) *QueueTrackEntry {
	q.mutex.RLock()
	defer q.mutex.RUnlock()
	for _, e := range q.queue {
		if e.QueueIdentifier == identifier {
			return e
		}
	}

	return nil
}

func (q *Queue) GetNowPlaying() *QueueTrackEntry {
	if e := q.audioQueue.GetQueueHead(); e != nil {
		return q.Get(e.Identifier)
	}

	return nil
}

func (q *Queue) SkipNowPlaying() bool {
	if e := q.audioQueue.GetQueueHead(); e != nil {
		return q.Remove(e.Identifier)
	}

	return false
}

func (q *Queue) GetIndex(index int) *QueueTrackEntry {
	if e := q.audioQueue.GetQueueIndex(index + 1); e != nil {
		return q.Get(e.Identifier)
	}

	return nil
}

func (q *Queue) GetHead() *QueueTrackEntry {
	if e := q.audioQueue.GetQueueIndex(1); e != nil {
		return q.Get(e.Identifier)
	}

	return nil
}

func (q *Queue) GetTail() *QueueTrackEntry {
	if i, e := q.audioQueue.GetQueueTail(); i != 0 && e != nil {
		return q.Get(e.Identifier)
	}

	return nil
}

func (q *Queue) Remove(identifier audio.QueueIdentifier) bool {
	q.mutex.Lock()
	for i, e := range q.queue {
		if e.QueueIdentifier == identifier {
			q.queue = append(q.queue[:i], q.queue[i+1:]...)
			q.mutex.Unlock()
			q.audioQueue.Remove(identifier)
			return true
		}
	}
	q.mutex.Unlock()
	q.audioQueue.Remove(identifier)
	return false
}

type httpWriter struct {
	timeout time.Duration
	writer  http.ResponseWriter
}

func (h *httpWriter) Write(p []byte) (n int, err error) {
	if h.writer != nil {
		n, err = h.writer.Write(p)
		if err != nil {
			h.writer = nil
		}
		return
	}
	return 0, io.EOF
}

func (h *httpWriter) Close() (err error) {
	h.writer = nil
	return nil
}

func (h *httpWriter) Flush() {
	if h.writer != nil {
		//TODO: not deadline aware?
		/*if flusher, ok := h.writer.(http.Flusher); ok {
			flusher.Flush()
		}*/
	}
}

func (q *Queue) GetListeners() (listeners []*ListenerInformation) {
	q.mutex.RLock()
	defer q.mutex.RUnlock()

	listeners = make([]*ListenerInformation, 0, 1)

	for _, mount := range q.mounts {
		listeners = append(listeners, mount.GetListeners()...)
	}
	return
}

func (q *Queue) HandleRadioRequest(writer http.ResponseWriter, request *http.Request) {
	for _, mount := range q.mounts {
		if strings.HasSuffix(request.URL.Path, mount.Mount) {
			writer.Header().Set("Server", "MeteorLight/radio")
			writer.Header().Set("Content-Type", mount.MimeType)
			writer.Header().Set("Accept-Ranges", "none")
			writer.Header().Set("Connection", "keep-alive")
			writer.Header().Set("X-Audiocast-Name", q.config.Radio.Name)
			writer.Header().Set("Cache-Control", "no-store, max-age=0, no-transform")
			writer.Header().Set("X-Content-Type-Options", "nosniff")

			byteWriter := &httpWriter{writer: writer, timeout: time.Second * 2}

			var wgClient sync.WaitGroup

			writeCallback := func(packet packetizer.Packet) error {
				//TODO: icy
				/*
					select {
					case <-request.Context().Done():
						// Client gave up
					default:
					}

				*/
				_, err := byteWriter.Write(packet.GetData())
				byteWriter.Flush()
				return err
			}
			wgClient.Add(1)

			var headers []HeaderEntry
			for k, v := range request.Header {
				for _, s := range v {
					headers = append(headers, HeaderEntry{
						Name:  k,
						Value: s,
					})
				}
			}

			uriPath := request.URL.Path
			if len(request.URL.Query().Encode()) > 0 {
				uriPath += "?" + request.URL.Query().Encode()
			}

			getKnownBufferSize := func() time.Duration {
				userAgent := request.Header.Get("user-agent")
				if strings.Index(userAgent, "libmpv") != -1 || strings.Index(userAgent, "mpv ") != -1 { //mpv
					return time.Millisecond * 2500
				} else if strings.Index(userAgent, "libvlc") != -1 { //VLC
					return time.Millisecond * 2500
				} else if strings.Index(userAgent, "lavf/") != -1 { //ffplay
					return time.Millisecond * 2500
				} else if strings.Index(userAgent, "gvfs/") != -1 { //gvfs
					return time.Millisecond * 2500
				} else if strings.Index(userAgent, "Music Player Daemon ") != -1 { //MPD
					return time.Millisecond * 2500
				} else if strings.Index(userAgent, " Chrome/") != -1 { //Chromium-based
					return time.Millisecond * 5000
				} else if strings.Index(userAgent, " Safari/") != -1 { //Safari-based
					return time.Millisecond * 5000
				} else if strings.Index(userAgent, " Gecko/") != -1 { //Gecko-based (Firefox)
					return time.Millisecond * 5000
				} else if request.Header.Get("icy-metadata") == "1" { //other unknown players
					return time.Millisecond * 5000
				}

				//fallback and provide maximum buffer
				return time.Second * maxBufferSize
			}

			sampleBufferLimit := int64(q.config.Queue.BufferSeconds * mount.SampleRate)
			if q.config.Queue.BufferSeconds == 0 { //auto buffer setup based on user agent and other client headers
				sampleBufferLimit = int64(getKnownBufferSize().Seconds() * float64(mount.SampleRate))
			}

			mount.AddListener(&StreamListener{
				Information: ListenerInformation{
					Mount:   mount.Mount,
					Path:    uriPath,
					Headers: headers,
				},
				Start: func(packets []packetizer.Packet) error {
					if len(packets) > 0 {
						sampleBufferMin := packets[len(packets)-1].GetSampleNumber() - sampleBufferLimit
						for _, p := range packets {
							if p.KeepMode() != packetizer.Discard || p.GetSampleNumber() >= sampleBufferMin {
								if err := writeCallback(p); err != nil {
									return err
								}
							}
						}
					}
					return nil
				},
				Write: writeCallback,
				Close: func() {
					byteWriter.Close()
					wgClient.Done()
				},
			})
			wgClient.Wait()
			return
		}
	}

	writer.WriteHeader(http.StatusNotFound)
	return
}