package vidplayback

import (
	"bytes"
	"encoding/binary"
	"fmt"
	"image"
	"image/color"
	"math/rand"
	"os"
	"time"

	"fyne.io/fyne/v2"
	"fyne.io/fyne/v2/canvas"
	"fyne.io/fyne/v2/widget"
	"github.com/zergon321/reisen"
)

func staticNoiseImage(w, h int) *image.RGBA {
	i := image.NewRGBA(image.Rect(0, 0, w, h))
	for x := 0; x < w; x++ {
		for y := 0; y < h; y++ {
			lum := uint8(rand.Float32() * 255)
			i.Set(x, y, color.RGBA{lum, lum, lum, 255})
		}
	}
	return i
}

const (
	width            = 1280
	height           = 720
	frameBufferSize  = 1024
	sampleRate       = 44100
	channelCount     = 2
	bitDepth         = 8
	sampleBufferSize = 32 * channelCount * bitDepth * 1024
)

// player holds all the data
// necessary for playing video.
type player struct {
	pix         *image.NRGBA
	ticker      <-chan time.Time
	errs        <-chan error
	frameBuffer <-chan *image.RGBA
	audioBuffer <-chan [2]float64
	last        time.Time
	fps         int
	paused      bool
	frameCount  int64
}

// readVideoAndAudio reads video and audio frames
// from the opened media and sends the decoded
// data to che channels to be played.
func (p *player) readVideoAndAudio(media *reisen.Media) (<-chan *image.RGBA, <-chan [2]float64, chan error, error) {
	frameBuffer := make(chan *image.RGBA, frameBufferSize)
	sampleBuffer := make(chan [2]float64, sampleBufferSize)
	errs := make(chan error)

	err := media.OpenDecode()

	if err != nil {
		return nil, nil, nil, err
	}

	videoStream := media.VideoStreams()[0]
	err = videoStream.Open()
	p.frameCount = videoStream.FrameCount()

	if err != nil {
		return nil, nil, nil, err
	}

	audioStream := media.AudioStreams()[0]
	err = audioStream.Open()

	if err != nil {
		return nil, nil, nil, err
	}

	go func() {
		for {
			packet, gotPacket, err := media.ReadPacket()

			if err != nil {
				go func(err error) {
					errs <- err
				}(err)
			}

			if !gotPacket {
				break
			}

			switch packet.Type() {
			case reisen.StreamVideo:
				s := media.Streams()[packet.StreamIndex()].(*reisen.VideoStream)
				videoFrame, gotFrame, err := s.ReadVideoFrame()

				if err != nil {
					go func(err error) {
						errs <- err
					}(err)
				}

				if !gotFrame {
					break
				}

				if videoFrame == nil {
					continue
				}

				frameBuffer <- videoFrame.Image()

			case reisen.StreamAudio:
				s := media.Streams()[packet.StreamIndex()].(*reisen.AudioStream)
				audioFrame, gotFrame, err := s.ReadAudioFrame()

				if err != nil {
					go func(err error) {
						errs <- err
					}(err)
				}

				if !gotFrame {
					break
				}

				if audioFrame == nil {
					continue
				}

				// Turn the raw byte data into
				// audio samples of type [2]float64.
				reader := bytes.NewReader(audioFrame.Data())

				// See the README.md file for
				// detailed scheme of the sample structure.
				for reader.Len() > 0 {
					sample := [2]float64{0, 0}
					var result float64
					err = binary.Read(reader, binary.LittleEndian, &result)

					if err != nil {
						go func(err error) {
							errs <- err
						}(err)
					}

					sample[0] = result

					err = binary.Read(reader, binary.LittleEndian, &result)

					if err != nil {
						go func(err error) {
							errs <- err
						}(err)
					}

					sample[1] = result
					sampleBuffer <- sample
				}
			}
		}

		videoStream.Close()
		audioStream.Close()
		media.CloseDecode()
		close(frameBuffer)
		close(sampleBuffer)
		close(errs)
	}()

	return frameBuffer, sampleBuffer, errs, nil
}

// Starts reading samples and frames
// of the media file.
func (p *player) open(fname string) error {
	// Sprite for drawing video frames.
	p.pix = image.NewNRGBA(image.Rect(0, 0, width, height))

	// Open the media file.
	media, err := reisen.NewMedia(fname)

	if err != nil {
		fmt.Printf("Error %s\n", err.Error())
		return err
	}

	// Get the FPS for playing
	// video frames.
	videoFPS, _ := media.Streams()[0].FrameRate()
	fmt.Printf("Detected FPS of %d\n", videoFPS)
	if videoFPS == 0 {
		fmt.Println("Setting fps to 60 as no FPS found")
		videoFPS = 60
	}
	if videoFPS > 150 {
		fmt.Printf("FPS of %d seems way too high, assuming it's *1000, so we'll use %d", videoFPS, videoFPS/1000)
		videoFPS = videoFPS / 1000
	}
	p.fps = videoFPS

	if err != nil {
		fmt.Printf("Error %s\n", err.Error())
		return err
	}

	// SPF for frame ticker.
	spf := 1.0 / float64(videoFPS)
	frameDuration, err := time.
		ParseDuration(fmt.Sprintf("%fs", spf))

	if err != nil {
		fmt.Printf("Error %s\n", err.Error())
		return err
	}

	// Start decoding streams.
	p.frameBuffer, p.audioBuffer,
		p.errs, err = p.readVideoAndAudio(media)

	if err != nil {
		return err
	}

	p.ticker = time.Tick(frameDuration)

	// Setup metrics.
	p.last = time.Now()
	return nil
}

var _ fyne.WidgetRenderer = (*vidPlaybackRenderer)(nil)

type VidPlayback struct {
	widget.BaseWidget
	UpdateFPS     int64
	VideoFilename string

	fpsTimer       *time.Ticker
	videoOpened    bool
	playerStruct   player
	currentFrameID int64
}

func NewVidPlayback() *VidPlayback {
	w := &VidPlayback{}
	w.ExtendBaseWidget(w)
	w.UpdateFPS = 25
	w.videoOpened = false
	w.currentFrameID = 0

	return w
}

func fileIsOpenable(path string) bool {
	_, err := os.Open(path)
	if err != nil {
		return false
	}
	return true
}

func (w *VidPlayback) Play() {
	if !w.videoOpened {
		if fileIsOpenable(w.VideoFilename) {
			w.playerStruct.open(w.VideoFilename)
			w.videoOpened = true
			w.fpsTimer.Stop()
			spf := 1.0 / float64(w.playerStruct.fps)
			frameDuration, err := time.
				ParseDuration(fmt.Sprintf("%fs", spf))

			if err != nil {
				fmt.Printf("Error %s\n", err.Error())
			}
			w.fpsTimer.Reset(frameDuration)
			go func() {
				// constantly empty the audio buffer in case that's what's jamming things up.
				for {
					_ = <-w.playerStruct.audioBuffer
				}
			}()
		}
	}
	w.BaseWidget.Refresh()
}

func (w *VidPlayback) Resize(s fyne.Size) {
	w.BaseWidget.Resize(s)
}

func (w *VidPlayback) CreateRenderer() fyne.WidgetRenderer {
	w.fpsTimer = time.NewTicker(time.Duration(1000/25) * time.Millisecond)
	go func(v *VidPlayback) {
		for {
			_ = <-w.fpsTimer.C
			v.Refresh()
		}
	}(w)
	return newVidPlaybackRenderer(w)
}

type vidPlaybackRenderer struct {
	vidPlayback  *VidPlayback
	background   *canvas.Rectangle
	currentframe *canvas.Raster
}

func (r *vidPlaybackRenderer) actualrenderframe(w, h int) image.Image {
	var frameImage *image.RGBA
	if r.vidPlayback.videoOpened {
		frameImage = <-r.vidPlayback.playerStruct.frameBuffer
		r.vidPlayback.currentFrameID = r.vidPlayback.currentFrameID + 1
		fmt.Print(".")
		if r.vidPlayback.currentFrameID%int64(r.vidPlayback.playerStruct.fps) == 0 {
			fmt.Println(r.vidPlayback.currentFrameID)
		}
		if r.vidPlayback.currentFrameID > r.vidPlayback.playerStruct.frameCount-5 { //definitely stopping before the end
			r.vidPlayback.videoOpened = false
			fmt.Println("Almost at end of file!")
		}
	} else {
		frameImage = staticNoiseImage(w, h) //no point doing anything other than returning anyway!
	}
	return frameImage
}

func newVidPlaybackRenderer(w *VidPlayback) *vidPlaybackRenderer {
	renderer := &vidPlaybackRenderer{
		vidPlayback: w,
		background:  canvas.NewRectangle(color.RGBA{255, 0, 255, 255}),
	}
	renderer.currentframe = canvas.NewRaster(renderer.actualrenderframe)
	return renderer
}

func (r *vidPlaybackRenderer) Objects() []fyne.CanvasObject {
	// The order is critical, rect is drawn first then currentframe
	return []fyne.CanvasObject{r.background, r.currentframe}
}

func (r *vidPlaybackRenderer) Layout(s fyne.Size) {
	r.background.Resize(s)
	r.currentframe.Resize(s)
}

func (r *vidPlaybackRenderer) MinSize() fyne.Size {
	return fyne.NewSize(200, 200)
}

func (r *vidPlaybackRenderer) Refresh() {
	r.currentframe.Refresh()
}

func (r *vidPlaybackRenderer) Destroy() {
	r.vidPlayback.fpsTimer.Stop()
} // Called when the renderer is destroyed