package queue

import (
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"git.gammaspectra.live/S.O.N.G/Kirika/audio"
	"git.gammaspectra.live/S.O.N.G/Kirika/audio/filter"
	"git.gammaspectra.live/S.O.N.G/Kirika/audio/queue"
	"git.gammaspectra.live/S.O.N.G/Kirika/audio/replaygain"
	"git.gammaspectra.live/S.O.N.G/MeteorLight/config"
	"git.gammaspectra.live/S.O.N.G/MeteorLight/listener"
	"git.gammaspectra.live/S.O.N.G/MeteorLight/listener/aps1"
	"git.gammaspectra.live/S.O.N.G/MeteorLight/listener/icy"
	"git.gammaspectra.live/S.O.N.G/MeteorLight/listener/plain"
	"git.gammaspectra.live/S.O.N.G/MeteorLight/queue/metadata"
	"git.gammaspectra.live/S.O.N.G/MeteorLight/queue/track"
	"git.gammaspectra.live/S.O.N.G/MeteorLight/stream"
	"git.gammaspectra.live/S.O.N.G/MeteorLight/util"
	"golang.org/x/exp/slices"
	"log"
	"net/http"
	"strconv"
	"strings"
	"sync"
	"sync/atomic"
	"time"
)

type Queue struct {
	NowPlaying    chan *track.Entry
	QueueEmpty    chan *track.Entry
	duration      atomic.Int64
	durationError int64
	audioQueue    *queue.Queue
	mounts        []*stream.Mount
	queue         []*track.Entry
	mutex         sync.RWMutex
	config        *config.Config
	wg            sync.WaitGroup
}

func NewQueue(conf *config.Config) *Queue {
	if conf.Queue.SampleRate <= 0 {
		conf.Queue.SampleRate = 44100
	}

	sampleFormat := audio.SourceInt16
	bitDepth := 16
	switch conf.Queue.SampleFormat {
	case "f32", "float", "float32", "f32le":
		sampleFormat = audio.SourceFloat32
		bitDepth = 0
	case "i32", "s32", "int32", "int", "s32le":
		sampleFormat = audio.SourceInt32
		bitDepth = 32
	case "i16", "s16", "int16", "s16le":
		sampleFormat = audio.SourceInt16
		bitDepth = 16
	}
	if conf.Queue.BitDepth > 0 {
		bitDepth = conf.Queue.BitDepth
	}

	q := &Queue{
		NowPlaying: make(chan *track.Entry, 1),
		QueueEmpty: make(chan *track.Entry),
		config:     conf,
		audioQueue: queue.NewQueue(sampleFormat, bitDepth, conf.Queue.SampleRate, 2),
	}
	blocksPerSecond := 20

	sources := filter.NewFilterChain(q.audioQueue.GetSource(), filter.NewBufferFilter(16), filter.NewRealTimeFilter(blocksPerSecond), filter.NewBufferFilter(config.MaxBufferSize*blocksPerSecond)).Split(len(conf.Streams))
	for i, s := range q.config.Streams {
		mount := stream.NewStreamMount(sources[i], s)
		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) GetDuration() time.Duration {
	return time.Duration(q.duration.Load())
}

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

func (q *Queue) AddTrack(entry *track.Entry, tail bool) error {

	if err := entry.Load(); err != nil {
		return err
	}

	startCallback := func(queue *queue.Queue, queueEntry *queue.Entry) {
		if e := q.Get(queueEntry.Identifier); e != nil { //is this needed?
			log.Printf("now playing \"%s\": %s - %s (%s)\n", e.Path, e.Metadata.Title, e.Metadata.Artist, e.Metadata.Album)
			q.NowPlaying <- e
			for _, mount := range q.mounts {
				mount.QueueMetadata(&metadata.Packet{
					//TODO: carry sample rate error
					SampleNumber: (q.duration.Load() * int64(queue.GetSampleRate())) / int64(time.Second),
					TrackEntry:   e,
				})
			}
		} else {
			log.Printf("now playing \"%s\": %s - %s (%s)\n", entry.Path, entry.Metadata.Title, entry.Metadata.Artist, entry.Metadata.Album)
		}
	}

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

	}

	removeCallback := func(queue *queue.Queue, entry *queue.Entry) {
		//TODO: carry sample rate error
		q.duration.Add(int64((time.Second * time.Duration(entry.ReadSamples.Load())) / time.Duration(entry.Source.GetSampleRate())))

		q.Remove(entry.Identifier)
		q.HandleQueue()
	}

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

	if q.config.Queue.Length > 0 && len(q.queue) >= q.config.Queue.Length {
		return errors.New("queue too long")
	}

	source := entry.Source()
	if q.config.Queue.ReplayGain {
		if entry.Metadata.ReplayGain.TrackPeak != 0 {
			source = replaygain.NewReplayGainFilter(entry.Metadata.ReplayGain.TrackGain, entry.Metadata.ReplayGain.TrackPeak, 0).Process(source)
		} else {
			source = replaygain.NewNormalizationFilter(5).Process(source)
		}
	}

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

	entry.Original["queue_id"] = entry.Identifier

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

	return nil
}

func (q *Queue) HandleQueue() {
	if q.audioQueue.GetQueueSize() == 0 {
		if err := q.AddTrack(<-q.QueueEmpty, true); err != nil {
			log.Printf("track addition error: \"%s\"", err)

			//TODO: maybe fail after n tries
			time.Sleep(time.Second)

			q.HandleQueue()
		}
	}
}

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

	if len(q.queue) > 1 {
		result = slices.Clone(q.queue[1:])
	}

	return
}

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

	return nil
}

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

	return nil
}

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

	return nil
}

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

	return nil
}

func (q *Queue) Remove(identifier queue.Identifier) bool {
	var entry *track.Entry
	func() {
		defer q.audioQueue.Remove(identifier)
		q.mutex.Lock()
		defer q.mutex.Unlock()

		for i, e := range q.queue {
			if e.Identifier == identifier {
				q.queue = slices.Delete(q.queue, i, i+1)
				entry = e
				return
			}
		}
	}()

	if entry != nil {
		_ = entry.Close()
		return true
	}
	return false
}

func (q *Queue) RemoveListener(identifier string) bool {
	q.mutex.RLock()
	defer q.mutex.RUnlock()
	for _, mount := range q.mounts {
		if mount.RemoveListener(identifier) {
			return true
		}
	}
	return false
}

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

	listeners = make([]*listener.Information, 0, 1)

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

func (q *Queue) HandleRadioRequest(writer http.ResponseWriter, request *http.Request) {
	writer.Header().Set("Server", "MeteorLight/radio")
	writer.Header().Set("Connection", "close")
	writer.Header().Set("X-Content-Type-Options", "nosniff")
	writer.Header().Set("Access-Control-Allow-Origin", "*")
	writer.Header().Set("Access-Control-Allow-Headers", "Accept, Content-Type, Icy-Metadata")
	writer.Header().Set("Accept-Ranges", "none")
	writer.Header().Set("Connection", "close")

	if strings.HasSuffix(request.URL.Path, "mounts") {
		writer.Header().Set("Content-Type", "application/json; charset=utf-8")
		writer.Header().Set("Access-Control-Expose-Headers", "Accept-Ranges, Server, Content-Type")

		type mountData struct {
			Path              string                 `json:"mount"`
			MimeType          string                 `json:"mime"`
			FormatDescription string                 `json:"formatDescription"`
			SampleRate        int                    `json:"sampleRate"`
			Channels          int                    `json:"channels"`
			Listeners         int                    `json:"listeners"`
			Options           map[string]interface{} `json:"options"`
		}

		var mounts []mountData

		for _, mount := range q.mounts {
			mounts = append(mounts, mountData{
				Path:              strings.TrimSuffix(request.URL.Path, "mounts") + mount.Mount,
				MimeType:          mount.MimeType,
				SampleRate:        mount.SampleRate,
				FormatDescription: mount.FormatDescription,
				Channels:          mount.Channels,
				Listeners:         len(mount.GetListeners()),
				Options:           mount.Options,
			})
		}

		jsonBytes, _ := json.MarshalIndent(mounts, "", " ")

		writer.WriteHeader(http.StatusOK)
		_, _ = writer.Write(jsonBytes)
		return
	}

	for _, mount := range q.mounts {
		if strings.HasSuffix(request.URL.Path, mount.Mount) {
			writer.Header().Set("Content-Type", mount.MimeType)
			writer.Header().Set("Cache-Control", "no-store, max-age=604800")
			writer.Header().Set("Access-Control-Expose-Headers", "Accept-Ranges, Server, Content-Type, Icy-MetaInt, X-Listener-Identifier")
			writer.Header().Set("Vary", "*")

			rangeHeader := request.Header.Get("range")
			if rangeHeader != "" && rangeHeader != "bytes=0-" {
				//TODO: maybe should fail in case bytes are requested

				if strings.Index(request.UserAgent(), " Safari/") != -1 && mount.MimeType == "audio/flac" {
					//Safari special case, fake Range check so it decodes afterwards.
					//Safari creates a request with Range for 0-1, specifically for FLAC, and expects a result supporting range. Afterwards it requests the whole file.
					//However the decoder is able to decode FLAC livestreams. If we fake the initial range response, then afterwards serve normal responses, Safari will happily work.
					//TODO: remove this AS SOON as safari works on its own
					//safariLargeFileValue arbitrary large value, cannot be that large or iOS Safari fails.
					safariLargeFileValue := 1024 * 1024 * 1024 * 1024 * 16 // 16 TiB

					if rangeHeader == "bytes=0-1" {
						//first request
						writer.Header().Set("Accept-Ranges", "bytes")
						writer.Header().Set("Content-Range", fmt.Sprintf("bytes 0-1/%d", safariLargeFileValue)) //64 TiB max fake size
						writer.Header().Set("Content-Length", "2")
						writer.WriteHeader(http.StatusPartialContent)
						_, _ = writer.Write([]byte{'f', 'L'})
						return
					} else if rangeHeader == fmt.Sprintf("bytes=0-%d", safariLargeFileValue-1) {
						//second request, serve status 200 to keep retries to a minimum
						writer.Header().Set("Content-Length", fmt.Sprintf("%d", safariLargeFileValue))
						writer.WriteHeader(http.StatusOK)
					} else if strings.HasPrefix(rangeHeader, "bytes=") && strings.HasSuffix(rangeHeader, fmt.Sprintf("-%d", safariLargeFileValue-1)) {
						//any other requests, these should fail
						writer.Header().Set("Content-Range", fmt.Sprintf("bytes %s/%d", strings.TrimPrefix(rangeHeader, "bytes="), safariLargeFileValue))
						writer.Header().Set("Accept-Ranges", "bytes")
						writer.WriteHeader(http.StatusRequestedRangeNotSatisfiable)
						return
					}
				}
			}

			bitrate := 0
			if value, ok := mount.Options["bitrate"]; ok {
				if intValue, ok := value.(int); ok {
					bitrate = intValue
				} else if int64Value, ok := value.(int64); ok {
					bitrate = int(int64Value)
				}
			}

			//set some audiocast/icy radio headers
			writer.Header().Set("x-audiocast-name", q.config.Radio.Name)
			writer.Header().Set("x-audiocast-bitrate", fmt.Sprintf("%d", bitrate))
			writer.Header().Set("icy-name", q.config.Radio.Name)
			writer.Header().Set("icy-version", "2")
			writer.Header().Set("icy-index-metadata", "1")
			if q.config.Radio.Description != "" {
				writer.Header().Set("x-audiocast-description", q.config.Radio.Description)
				writer.Header().Set("icy-description", q.config.Radio.Description)
			}
			if q.config.Radio.URL != "" {
				writer.Header().Set("x-audiocast-url", q.config.Radio.URL)
				writer.Header().Set("icy-url", q.config.Radio.URL)
			}
			if q.config.Radio.Logo != "" {
				writer.Header().Set("icy-logo", q.config.Radio.Logo)
			}
			writer.Header().Set("icy-br", fmt.Sprintf("%d", bitrate))
			writer.Header().Set("icy-sr", fmt.Sprintf("%d", mount.SampleRate))
			writer.Header().Set("icy-audio-info", fmt.Sprintf("ice-channels=%d;ice-samplerate=%d;ice-bitrate=%d", mount.Channels, mount.SampleRate, bitrate))
			if q.config.Radio.Private {
				writer.Header().Set("icy-pub", "0")
				writer.Header().Set("icy-do-not-index", "1")
				writer.Header().Set("x-audiocast-public", "0")
				writer.Header().Set("x-robots-tag", "noindex, nofollow")
			} else {
				writer.Header().Set("icy-pub", "1")
				writer.Header().Set("icy-do-not-index", "0")
				writer.Header().Set("x-audiocast-public", "1")
			}

			requestDone := util.RequestDone{}

			var headers []listener.HeaderEntry
			for k, v := range request.Header {
				for _, s := range v {
					headers = append(headers, listener.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 * 4000
				} 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 * config.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))
			}

			startStamp := time.Now().Unix()
			hashSum := sha256.Sum256([]byte(fmt.Sprintf("%s-%s-%s-%s-%d", request.RequestURI, request.RemoteAddr, request.Proto, request.Header.Get("user-agent"), startStamp)))
			listenerIdentifier := hex.EncodeToString(hashSum[16:])

			listenerInformation := listener.Information{
				Identifier: listenerIdentifier,
				Mount:      mount.Mount,
				Path:       uriPath,
				Headers:    headers,
				Start:      startStamp,
			}

			var mountListener listener.Listener
			var extraHeaders map[string]string

			ctx := request.Context()
			//buffer a bit, drop channels when buffer grows to not lock others. They will get disconnected elsewhere
			const byteSliceChannelBuffer = 1024 * 16
			writeChannel := make(chan []byte, byteSliceChannelBuffer)

			go func() {
				var flusher http.Flusher
				if httpFlusher, ok := writer.(http.Flusher); ok {
					flusher = httpFlusher
				}

				for !requestDone.Done() {
					select {
					case byteSlice := <-writeChannel:
						if _, err := writer.Write(byteSlice); err != nil {
							requestDone.Fail(err)
							break
						}
						//try flush
						if flusher != nil {
							flusher.Flush()
						}
					case <-ctx.Done():
						requestDone.Fail(ctx.Err())
						break
					}

				}
			}()

			funcWriter := func(byteSlice []byte) error {
				if requestDone.Done() {
					return requestDone.Error()
				}

				if len(byteSlice) > 0 {
					if len(writeChannel) >= (cap(writeChannel) - 1) {
						requestDone.Fail(errors.New("client ran out of writer buffer"))
						return requestDone.Error()
					}

					writeChannel <- byteSlice
				}

				return nil
			}

			//set X-Audio-Packet-Stream for strictly timed packets and metadata
			if numberValue, err := strconv.Atoi(request.Header.Get("x-audio-packet-stream")); err == nil && numberValue == 1 {
				//version 1
				mountListener, extraHeaders = aps1.NewListener(listenerInformation, funcWriter, sampleBufferLimit, mount.OffsetStart, mount.Channels, mount.SampleRate, mount.MimeType)
			} else if numberValue, err = strconv.Atoi(request.Header.Get("icy-metadata")); err == nil && numberValue >= 1 {
				mountListener, extraHeaders = icy.NewListener(listenerInformation, funcWriter, sampleBufferLimit, mount.OffsetStart)
			} else {
				mountListener, extraHeaders = plain.NewListener(listenerInformation, funcWriter, sampleBufferLimit, mount.OffsetStart)
			}

			if mountListener == nil {
				writer.WriteHeader(http.StatusInternalServerError)
				return
			}

			for k, v := range extraHeaders {
				writer.Header().Set(k, v)
			}

			writer.Header().Set("x-listener-identifier", listenerIdentifier)

			log.Printf("adding %s client to stream %s (%s, %s, agent \"%s\", buffer %.2f seconds)\n", listenerIdentifier, mount.Mount, request.RemoteAddr, request.Proto, request.Header.Get("user-agent"), float64(sampleBufferLimit)/float64(mount.SampleRate))
			mount.AddListener(mountListener)

			mountListener.Wait()

			requestDone.Complete()

			log.Printf("removing %s client from stream %s\n", listenerIdentifier, mount.Mount)
			return
		}
	}

	writer.WriteHeader(http.StatusNotFound)
	return
}