package main

import (
	"errors"
	"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"
	"log"
	"net/http"
	"os"
	"path"
	"strconv"
	"strings"
	"sync"
	"sync/atomic"
	"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 QueueMetadataPacket struct {
	sampleNumber int64
	TrackEntry   *QueueTrackEntry
}

func (p *QueueMetadataPacket) KeepMode() packetizer.KeepMode {
	return packetizer.KeepLast
}

func (p *QueueMetadataPacket) GetStartSampleNumber() int64 {
	return p.sampleNumber
}

func (p *QueueMetadataPacket) GetEndSampleNumber() int64 {
	return p.sampleNumber
}

func (p *QueueMetadataPacket) Category() int64 {
	return -1
}

func (p *QueueMetadataPacket) GetData() []byte {
	return nil
}

type Queue struct {
	NowPlaying    chan *QueueTrackEntry
	QueueEmpty    chan *QueueTrackEntry
	Duration      time.Duration
	durationError int64
	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
			for _, mount := range q.mounts {
				mount.MetadataQueue.Enqueue(&QueueMetadataPacket{
					//TODO: carry error
					sampleNumber: int64(q.Duration * time.Duration(queue.GetSampleRate()) / time.Second),
					TrackEntry:   e,
				})
			}
		}
	}

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

	}

	removeCallback := func(queue *audio.Queue, entry *audio.QueueEntry) {
		defer f.Close()
		atomic.AddInt64((*int64)(&q.Duration), int64((time.Second*time.Duration(entry.ReadSamples))/time.Duration(entry.Source.SampleRate)))

		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
}

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")

			var packetWriteCallback func(packet packetizer.Packet) error

			//buffer a bit, drop channels when buffer grows to not lock others. They will get disconnected elsewhere
			const byteSliceChannelBuffer = 128
			writeChannel := make(chan []byte, byteSliceChannelBuffer)
			var requestDone error
			var wgClient sync.WaitGroup

			if numberValue, err := strconv.Atoi(request.Header.Get("icy-metadata")); err == nil && numberValue >= 1 {
				metadataToSend := make(map[string]string)
				const icyInterval = 8192
				icyCounter := 0
				writer.Header().Set("Icy-MetaInt", fmt.Sprintf("%d", icyInterval))

				writeIcy := func() []byte {
					packetContent := make([]byte, 1, 4096)
					for k, v := range metadataToSend {
						packetContent = append(packetContent, []byte(fmt.Sprintf("%s='%s';", k, v))...)
						delete(metadataToSend, k)

						//shouldn't send multiple properties in same packet if we want working single quotes, wait until next ICY frame
						break
					}

					contentLength := len(packetContent) - 1
					if contentLength > 16*255 {
						//cannot send long titles
						return make([]byte, 1)
					}

					if (contentLength % 16) == 0 { //already padded
						packetContent[0] = byte(contentLength / 16)
					} else {
						packetContent[0] = byte(contentLength/16) + 1
						packetContent = append(packetContent, make([]byte, 16-(contentLength%16))...)
					}

					return packetContent
				}

				packetWriteCallback = func(packet packetizer.Packet) error {
					if requestDone != nil {
						return requestDone
					}
					if metadataPacket, ok := packet.(*QueueMetadataPacket); ok {
						if len(metadataPacket.TrackEntry.Metadata.Artist) > 0 {
							metadataToSend["StreamTitle"] = fmt.Sprintf("%s - %s", metadataPacket.TrackEntry.Metadata.Artist, metadataPacket.TrackEntry.Metadata.Title)
						} else {
							metadataToSend["StreamTitle"] = metadataPacket.TrackEntry.Metadata.Title
						}
						if len(metadataPacket.TrackEntry.Metadata.Art) > 0 {
							metadataToSend["StreamURL"] = metadataPacket.TrackEntry.Metadata.Art
						}
						return nil
					}

					p := packet.GetData()
					var data []byte
					for len(p) > 0 {
						l := icyInterval - icyCounter
						if l <= len(p) {
							data = append(data, p[:l]...)
							data = append(data, writeIcy()...)
							icyCounter = 0
							p = p[l:]
						} else {
							data = append(data, p...)
							icyCounter += len(p)
							p = p[:0]
						}
					}

					if len(writeChannel) >= byteSliceChannelBuffer-1 {
						requestDone = errors.New("client ran out of buffer")
						return requestDone
					}
					writeChannel <- data
					return nil
				}
			} else {
				packetWriteCallback = func(packet packetizer.Packet) error {
					if requestDone != nil {
						return requestDone
					}
					if _, ok := packet.(*QueueMetadataPacket); ok {
						return nil
					}

					if len(writeChannel) >= byteSliceChannelBuffer-1 {
						requestDone = errors.New("client ran out of buffer")
						return requestDone
					}
					writeChannel <- packet.GetData()
					return nil
				}
			}

			wgClient.Add(1)
			go func() {
				defer wgClient.Done()
				var flusher http.Flusher
				if httpFlusher, ok := writer.(http.Flusher); ok {
					flusher = httpFlusher
				}

				for byteSlice := range writeChannel {
					if _, requestDone = writer.Write(byteSlice); requestDone != nil {
						break
					}
					//try flush
					if flusher != nil {
						flusher.Flush()
					}
				}

			}()

			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))
			}

			wgClient.Add(1)
			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].GetStartSampleNumber() - sampleBufferLimit
						for _, p := range packets {
							if p.KeepMode() != packetizer.Discard || p.GetEndSampleNumber() >= sampleBufferMin {
								if err := packetWriteCallback(p); err != nil {
									return err
								}
							}
						}
					}
					return nil
				},
				Write: packetWriteCallback,
				Close: func() {
					defer wgClient.Done()
					close(writeChannel)
				},
			})
			wgClient.Wait()
			return
		}
	}

	writer.WriteHeader(http.StatusNotFound)
	return
}