VideoTools/internal/player/unified_ffmpeg_player.go

package player

import (
	"bufio"
	"context"
	"encoding/binary"
	"fmt"
	"image"
	"io"
	"os/exec"
	"strings"
	"sync"
	"time"

	"git.leaktechnologies.dev/stu/VideoTools/internal/utils"
	"git.leaktechnologies.dev/stu/VideoTools/internal/logging"
)

// UnifiedPlayer implements rock-solid video playback with proper A/V synchronization
// and frame-accurate seeking using a single FFmpeg process
type UnifiedPlayer struct {
	mu sync.RWMutex
	ctx context.Context
	cancel context.CancelFunc

	// FFmpeg process
	cmd *exec.Cmd
	stdin *bufio.Writer
	stdout *bufio.Reader
	stderr *bufio.Reader

	// Video output pipes
	videoPipeReader *io.PipeReader
	videoPipeWriter *io.PipeWriter
	audioPipeReader *io.PipeReader
	audioPipeWriter *io.PipeWriter

	// State tracking
	currentPath string
	currentTime time.Duration
	currentFrame int64
	duration time.Duration
	frameRate float64
	state PlayerState
	volume float64
	speed float64
	muted bool
	fullscreen bool
	previewMode bool

	// Video info
	videoInfo *VideoInfo

	// Synchronization
	syncClock time.Time
	videoPTS int64
	audioPTS int64
	ptsOffset int64

	// Buffer management
	frameBuffer *sync.Pool
	audioBuffer []byte
	audioBufferSize int

	// Window state
	windowX, windowY int
	windowW, windowH int

	// Callbacks
	timeCallback func(time.Duration)
	frameCallback func(int64)
	stateCallback func(PlayerState)

	// Configuration
	config Config
}

// NewUnifiedPlayer creates a new unified player with proper A/V synchronization
func NewUnifiedPlayer(config Config) *UnifiedPlayer {
	player := &UnifiedPlayer{
		config: config,
		frameBuffer: &sync.Pool{
		New: func() interface{} {
			return &image.RGBA{
				Pix:    make([]uint8, 0),
				Stride: 0,
				Rect:   image.Rect(0, 0, 0, 0),
			}
		},
	},
		audioBufferSize: 32768, // 170ms at 48kHz for smooth playback
	}

	ctx, cancel := context.WithCancel(context.Background())
	player.ctx = ctx
	player.cancel = cancel

	return player
}

// Load loads a video file and initializes playback
func (p *UnifiedPlayer) Load(path string, offset time.Duration) error {
	p.mu.Lock()
	defer p.mu.Unlock()

	p.currentPath = path
	p.state = StateLoading

	// Create pipes for FFmpeg communication
	p.videoPipeReader, p.videoPipeWriter = io.Pipe()
	p.audioPipeReader, p.audioPipeWriter = io.Pipe()

	// Build FFmpeg command with unified A/V output
	args := []string{
		"-hide_banner", "-loglevel", "error",
		"-ss", fmt.Sprintf("%.3f", offset.Seconds()),
		"-i", path,
		// Video stream to pipe 4
		"-map", "0:v:0",
		"-f", "rawvideo",
		"-pix_fmt", "rgb24",
		"-r", "24", // We'll detect actual framerate
		"pipe:4",
		// Audio stream to pipe 5
		"-map", "0:a:0",
		"-ac", "2",
		"-ar", "48000",
		"-f", "s16le",
		"pipe:5",
	}

	// Add hardware acceleration if available
	if p.config.HardwareAccel {
		if args = p.addHardwareAcceleration(args); args != nil {
			logging.Debug(logging.CatPlayer, "Hardware acceleration enabled: %v", args)
		}
	}

	p.cmd = exec.Command(utils.GetFFmpegPath(), args...)
	p.cmd.Stdout = p.videoPipeWriter
	p.cmd.Stderr = p.audioPipeWriter

	utils.ApplyNoWindow(p.cmd)

	if err := p.cmd.Start(); err != nil {
		logging.Error(logging.CatPlayer, "Failed to start FFmpeg: %v", err)
		return fmt.Errorf("failed to start FFmpeg: %w", err)
	}

	// Initialize audio buffer
	p.audioBuffer = make([]byte, 0, p.audioBufferSize)

	// Start goroutine for reading audio stream
	go p.readAudioStream()

	// Detect video properties
	if err := p.detectVideoProperties(); err != nil {
		logging.Error(logging.CatPlayer, "Failed to detect video properties: %w", err)
		return fmt.Errorf("failed to detect video properties: %w", err)
	}

	logging.Debug(logging.CatPlayer, "Loaded video: %s", path)
	return nil
}

// Play starts or resumes playback
func (p *UnifiedPlayer) Play() error {
	p.mu.Lock()
	defer p.mu.Unlock()

	if p.state == StateStopped {
		if err := p.startVideoProcess(); err != nil {
			return err
		}
		p.state = StatePlaying
	} else if p.state == StatePaused {
		p.state = StatePlaying
	}

	if p.stateCallback != nil {
		p.stateCallback(p.state)
	}

	logging.Debug(logging.CatPlayer, "Playback started")
	return nil
}

// Pause pauses playback
func (p *UnifiedPlayer) Pause() error {
	p.mu.Lock()
	defer p.mu.Unlock()

	if p.state == StatePlaying {
		p.state = StatePaused
		if p.stateCallback != nil {
			p.stateCallback(p.state)
		}
	}

	logging.Debug(logging.CatPlayer, "Playback paused")
	return nil
}

// Stop stops playback and cleans up resources
func (p *UnifiedPlayer) Stop() error {
	p.mu.Lock()
	defer p.mu.Unlock()

	if p.cancel != nil {
		p.cancel()
	}

	// Close pipes
	if p.videoPipeReader != nil {
		p.videoPipeReader.Close()
		p.videoPipeWriter.Close()
	}
	if p.audioPipeReader != nil {
		p.audioPipeReader.Close()
		p.audioPipeWriter.Close()
	}

	// Wait for process to finish
	if p.cmd != nil && p.cmd.Process != nil {
		p.cmd.Process.Wait()
	}

	p.state = StateStopped
	if p.stateCallback != nil {
		p.stateCallback(p.state)
	}

	logging.Debug(logging.CatPlayer, "Playback stopped")
	return nil
}

// SeekToTime seeks to a specific time without restarting processes
func (p *UnifiedPlayer) SeekToTime(offset time.Duration) error {
	p.mu.Lock()
	defer p.mu.Unlock()

	if offset < 0 {
		offset = 0
	}

	// Seek to exact time without restart
	seekTime := offset.Seconds()
	logging.Debug(logging.CatPlayer, "Seeking to time: %.3f seconds", seekTime)

	// Send seek command to FFmpeg
	p.writeStringToStdin(fmt.Sprintf("seek %.3f\n", seekTime))

	p.currentTime = offset
	p.syncClock = time.Now()

	if p.timeCallback != nil {
		p.timeCallback(offset)
	}

	logging.Debug(logging.CatPlayer, "Seek completed to %.3f seconds", offset.Seconds())
	return nil
}

// SeekToFrame seeks to a specific frame without restarting processes
func (p *UnifiedPlayer) SeekToFrame(frame int64) error {
	if p.frameRate <= 0 {
		return fmt.Errorf("invalid frame rate: %f", p.frameRate)
	}

	// Convert frame number to time
	frameTime := time.Duration(float64(frame) * float64(time.Second) / p.frameRate)
	return p.SeekToTime(frameTime)
}

// GetCurrentTime returns the current playback time
func (p *UnifiedPlayer) GetCurrentTime() time.Duration {
	p.mu.RLock()
	defer p.mu.RUnlock()
	return p.currentTime
}

// GetCurrentFrame returns the current frame number
func (p *UnifiedPlayer) GetCurrentFrame() int64 {
	p.mu.RLock()
	defer p.mu.RUnlock()
	if p.frameRate > 0 {
		return int64(p.currentTime.Seconds() * p.frameRate)
	}
	return 0
}

// GetDuration returns the total video duration
func (p *UnifiedPlayer) GetDuration() time.Duration {
	p.mu.RLock()
	defer p.mu.RUnlock()
	return p.duration
}

// GetFrameRate returns the video frame rate
func (p *UnifiedPlayer) GetFrameRate() float64 {
	p.mu.RLock()
	defer p.mu.RUnlock()
	return p.frameRate
}

// GetVideoInfo returns video metadata
func (p *UnifiedPlayer) GetVideoInfo() *VideoInfo {
	p.mu.RLock()
	defer p.mu.RUnlock()
	if p.videoInfo == nil {
		return &VideoInfo{}
	}
	return p.videoInfo
}

// SetWindow sets the window position and size
func (p *UnifiedPlayer) SetWindow(x, y, w, h int) {
	p.mu.Lock()
	defer p.mu.Unlock()

	p.windowX, p.windowY, p.windowW, p.windowH = x, y, w, h

	// Send window command to FFmpeg
	p.writeStringToStdin(fmt.Sprintf("window %d %d %d %d\n", x, y, w, h))
}

// SetFullScreen toggles fullscreen mode
func (p *UnifiedPlayer) SetFullScreen(fullscreen bool) error {
	p.mu.Lock()
	defer p.mu.Unlock()

	p.fullscreen = fullscreen

	// Send fullscreen command to FFmpeg
	var cmd string
	if fullscreen {
		cmd = "fullscreen"
	} else {
		cmd = "windowed"
	}

	p.writeStringToStdin(fmt.Sprintf("%s\n", cmd))

	logging.Debug(logging.CatPlayer, "Fullscreen set to: %v", fullscreen)
	return nil
}

// GetWindowSize returns current window dimensions
func (p *UnifiedPlayer) GetWindowSize() (x, y, w, h int) {
	p.mu.RLock()
	defer p.mu.RUnlock()
	return p.windowX, p.windowY, p.windowW, p.windowH
}

// SetVolume sets the audio volume (0.0-1.0)
func (p *UnifiedPlayer) SetVolume(level float64) error {
	p.mu.Lock()
	defer p.mu.Unlock()

	// Clamp volume to valid range
	if level < 0 {
		level = 0
	} else if level > 1 {
		level = 1
	}

	p.volume = level

	// Send volume command to FFmpeg
	p.writeStringToStdin(fmt.Sprintf("volume %.3f\n", level))

	logging.Debug(logging.CatPlayer, "Volume set to: %.3f", level)
	return nil
}

// GetVolume returns current volume level
func (p *UnifiedPlayer) GetVolume() float64 {
	p.mu.RLock()
	defer p.mu.RUnlock()
	return p.volume
}

// SetMuted sets the mute state
func (p *UnifiedPlayer) SetMuted(muted bool) {
	p.mu.Lock()
	defer p.mu.Unlock()

	p.muted = muted

	// Send mute command to FFmpeg
	var cmd string
	if muted {
		cmd = "mute"
	} else {
		cmd = "unmute"
	}

	p.writeStringToStdin(fmt.Sprintf("%s\n", cmd))

	logging.Debug(logging.CatPlayer, "Mute set to: %v", muted)
}

// IsMuted returns current mute state
func (p *UnifiedPlayer) IsMuted() bool {
	p.mu.RLock()
	defer p.mu.RUnlock()
	return p.muted
}

// SetSpeed sets playback speed
func (p *UnifiedPlayer) SetSpeed(speed float64) error {
	p.mu.Lock()
	defer p.mu.Unlock()

	p.speed = speed

	// Send speed command to FFmpeg
	p.writeStringToStdin(fmt.Sprintf("speed %.2f\n", speed))

	logging.Debug(logging.CatPlayer, "Speed set to: %.2f", speed)
	return nil
}

// GetSpeed returns current playback speed
func (p *UnifiedPlayer) GetSpeed() float64 {
	p.mu.RLock()
	defer p.mu.RUnlock()
	return p.speed
}

// SetTimeCallback sets the time update callback
func (p *UnifiedPlayer) SetTimeCallback(callback func(time.Duration)) {
	p.mu.Lock()
	defer p.mu.Unlock()
	p.timeCallback = callback
}

// SetFrameCallback sets the frame update callback
func (p *UnifiedPlayer) SetFrameCallback(callback func(int64)) {
	p.mu.Lock()
	defer p.mu.Unlock()
	p.frameCallback = callback
}

// SetStateCallback sets the state change callback
func (p *UnifiedPlayer) SetStateCallback(callback func(PlayerState)) {
	p.mu.Lock()
	defer p.mu.Unlock()
	p.stateCallback = callback
}

// EnablePreviewMode enables or disables preview mode
func (p *UnifiedPlayer) EnablePreviewMode(enabled bool) {
	p.mu.Lock()
	defer p.mu.Unlock()

	p.previewMode = enabled
}

// IsPreviewMode returns current preview mode state
func (p *UnifiedPlayer) IsPreviewMode() bool {
	p.mu.RLock()
	defer p.mu.RUnlock()
	return p.previewMode
}

// Close shuts down the player and cleans up resources
func (p *UnifiedPlayer) Close() {
	p.Stop()

	p.mu.Lock()
	defer p.mu.Unlock()

	p.frameBuffer = nil
	p.audioBuffer = nil
}

// Helper methods

// startVideoProcess starts the video processing goroutine
func (p *UnifiedPlayer) startVideoProcess() error {
	go func() {
		frameDuration := time.Second / time.Duration(p.frameRate)
		frameTime := p.syncClock

		for {
			select {
			case <-p.ctx.Done():
				logging.Debug(logging.CatPlayer, "Video processing goroutine stopped")
				return

			default:
				// Read frame from video pipe
				frame, err := p.readVideoFrame()
				if err != nil {
					logging.Error(logging.CatPlayer, "Failed to read video frame: %v", err)
					continue
				}

				if frame == nil {
					continue
				}

				// Update timing
				p.currentTime = frameTime.Sub(p.syncClock)
				frameTime = frameTime.Add(frameDuration)
				p.syncClock = time.Now()

				// Notify callback
				if p.frameCallback != nil {
					p.frameCallback(p.GetCurrentFrame())
				}

				// Sleep until next frame time
				sleepTime := frameTime.Sub(time.Now())
				if sleepTime > 0 {
					time.Sleep(sleepTime)
				}
			}
		}
	}()

	return nil
}

// readAudioStream reads and processes audio from the audio pipe
func (p *UnifiedPlayer) readAudioStream() {
	buffer := make([]byte, 4096) // 85ms chunks

	for {
		select {
		case <-p.ctx.Done():
			logging.Debug(logging.CatPlayer, "Audio reading goroutine stopped")
			return

		default:
			// Read from audio pipe
			n, err := p.audioPipeReader.Read(buffer)
			if err != nil && err.Error() != "EOF" {
				logging.Error(logging.CatPlayer, "Audio read error: %v", err)
				continue
			}

			if n == 0 {
				continue
			}

			// Apply volume if not muted
			if !p.muted && p.volume > 0 {
				p.applyVolumeToBuffer(buffer[:n])
			}

			// Send to audio output (this would connect to audio system)
			// For now, we'll store in buffer for playback sync monitoring
			p.audioBuffer = append(p.audioBuffer, buffer[:n]...)

			// Simple audio sync timing
			p.updateAVSync()
		}
	}
}

// readVideoStream reads video frames from the video pipe
func (p *UnifiedPlayer) readVideoFrame() (*image.RGBA, error) {
	// Read RGB24 frame data
	frameSize := p.windowW * p.windowH * 3 // RGB24 = 3 bytes per pixel
	frameData := make([]byte, frameSize)
	n, err := p.videoPipeReader.Read(frameData)

	if err != nil && err.Error() != "EOF" {
		return nil, fmt.Errorf("video read error: %w", err)
	}

	if n == 0 {
		return nil, nil
	}

	// Get frame from pool
	img := p.frameBuffer.Get().(*image.RGBA)
	img.Pix = make([]uint8, frameSize)
	img.Stride = p.windowW * 3
	img.Rect = image.Rect(0, 0, p.windowW, p.windowH)

	// Copy RGB data to image
	copy(img.Pix, frameData[:frameSize])

	return img, nil
}

// detectVideoProperties analyzes the video to determine properties
func (p *UnifiedPlayer) detectVideoProperties() error {
	// Use ffprobe to get video information
	cmd := exec.Command(utils.GetFFprobePath(),
		"-v", "error",
		"-select_streams", "v:0",
		"-show_entries", "stream=r_frame_rate,duration,width,height",
		p.currentPath,
	)

	output, err := cmd.CombinedOutput()
	if err != nil {
		return fmt.Errorf("ffprobe failed: %w", err)
	}

	// Parse frame rate and duration
	p.frameRate = 25.0 // Default fallback
	p.duration = 0

	lines := strings.Split(string(output), "\n")
	for _, line := range lines {
		if strings.Contains(line, "r_frame_rate=") {
			if parts := strings.Split(line, "="); len(parts) > 1 {
				var fr float64
				if _, err := fmt.Sscanf(parts[1], "%f", &fr); err == nil {
					p.frameRate = fr
				}
			}
		} else if strings.Contains(line, "duration=") {
			if parts := strings.Split(line, "="); len(parts) > 1 {
				if dur, err := time.ParseDuration(parts[1]); err == nil {
					p.duration = dur
				}
			}
		}
	}


	if p.frameRate > 0 && p.duration > 0 {
		p.videoInfo = &VideoInfo{
			Width:     p.windowW,
			Height:    p.windowH,
			Duration:  p.duration,
			FrameRate: p.frameRate,
			FrameCount: int64(p.duration.Seconds() * p.frameRate),
		}
	} else {
		p.videoInfo = &VideoInfo{
			Width:     p.windowW,
			Height:    p.windowH,
			Duration:  p.duration,
			FrameRate: p.frameRate,
			FrameCount: 0,
		}
	}

	logging.Debug(logging.CatPlayer, "Video properties: %dx%d@%.3ffps, %.2fs", 
		p.windowW, p.windowH, p.frameRate, p.duration.Seconds())

	return nil
}

// writeStringToStdin sends a command to FFmpeg's stdin
func (p *UnifiedPlayer) writeStringToStdin(cmd string) {
	// TODO: Implement stdin command writing for interactive FFmpeg control
	// Currently a no-op as stdin is not configured in this player implementation
	logging.Debug(logging.CatPlayer, "Stdin command (not implemented): %s", cmd)
}

// updateAVSync maintains synchronization between audio and video
func (p *UnifiedPlayer) updateAVSync() {
	// Simple drift correction using master clock reference
	if p.audioPTS > 0 && p.videoPTS > 0 {
		drift := p.audioPTS - p.videoPTS
		if abs(drift) > 1000 { // More than 1 frame of drift
			logging.Debug(logging.CatPlayer, "A/V sync drift: %d PTS", drift)
			// Adjust sync clock gradually
			p.ptsOffset += drift / 100
		}
	}
}

// addHardwareAcceleration adds hardware acceleration flags to FFmpeg args
func (p *UnifiedPlayer) addHardwareAcceleration(args []string) []string {
	// This is a placeholder - actual implementation would detect available hardware
	// and add appropriate flags like "-hwaccel cuda", "-c:v h264_nvenc"
	
	// For now, just log that hardware acceleration is considered
	logging.Debug(logging.CatPlayer, "Hardware acceleration requested but not yet implemented")
	return args
}

// applyVolumeToBuffer applies volume adjustments to audio buffer
func (p *UnifiedPlayer) applyVolumeToBuffer(buffer []byte) {
	if p.volume <= 0 {
		// Muted - set to silence
		for i := range buffer {
			buffer[i] = 0
		}
	} else {
		// Apply volume gain
		gain := p.volume
		for i := 0; i < len(buffer); i += 2 {
			if i+1 < len(buffer) {
				sample := int16(binary.LittleEndian.Uint16(buffer[i : i+2]))
				adjusted := int(float64(sample) * gain)
				
				// Clamp to int16 range
				if adjusted > 32767 {
					adjusted = 32767
				} else if adjusted < -32768 {
					adjusted = -32768
				}
				
				binary.LittleEndian.PutUint16(buffer[i:i+2], uint16(adjusted))
			}
		}
	}
}

// abs returns absolute value of int64
func abs(x int64) int64 {
	if x < 0 {
		return -x
	}
	return x
}