playback/internal/audio/player.go

package audio

import (
	"fmt"
	"io"
	"os"
	"sync"
	"time"

	"github.com/gopxl/beep/v2"
	"github.com/gopxl/beep/v2/flac"
	"github.com/gopxl/beep/v2/mp3"
	"github.com/gopxl/beep/v2/speaker"
	"github.com/gopxl/beep/v2/vorbis"
	"github.com/gopxl/beep/v2/wav"
)

// Player handles audio playback
type Player struct {
	mu sync.Mutex

	filePath   string
	file       *os.File
	streamer   beep.StreamSeekCloser
	format     beep.Format
	ctrl       *beep.Ctrl
	resampler  *beep.Resampler

	playing    bool
	initialized bool
}

// NewPlayer creates a new audio player
func NewPlayer() *Player {
	return &Player{}
}

// Load opens an audio file for playback
func (p *Player) Load(path string) error {
	p.mu.Lock()
	defer p.mu.Unlock()

	// Close any existing file
	if p.file != nil {
		p.streamer.Close()
		p.file.Close()
	}

	format := DetectFormat(path)
	if format == FormatUnknown {
		return fmt.Errorf("unsupported audio format")
	}

	file, err := os.Open(path)
	if err != nil {
		return fmt.Errorf("failed to open audio file: %w", err)
	}

	var streamer beep.StreamSeekCloser
	var audioFormat beep.Format

	switch format {
	case FormatMP3:
		streamer, audioFormat, err = mp3.Decode(file)
	case FormatWAV:
		streamer, audioFormat, err = wav.Decode(file)
	case FormatFLAC:
		streamer, audioFormat, err = flac.Decode(file)
	case FormatOGG:
		streamer, audioFormat, err = vorbis.Decode(file)
	}

	if err != nil {
		file.Close()
		return fmt.Errorf("failed to decode audio: %w", err)
	}

	p.filePath = path
	p.file = file
	p.streamer = streamer
	p.format = audioFormat
	p.ctrl = &beep.Ctrl{Streamer: streamer, Paused: true}

	// Initialize speaker if not already done
	if !p.initialized {
		sampleRate := beep.SampleRate(44100)
		if err := speaker.Init(sampleRate, sampleRate.N(time.Second/10)); err != nil {
			return fmt.Errorf("failed to initialize speaker: %w", err)
		}
		p.initialized = true
	}

	// Resample if needed
	targetRate := beep.SampleRate(44100)
	if audioFormat.SampleRate != targetRate {
		p.resampler = beep.Resample(4, audioFormat.SampleRate, targetRate, p.ctrl)
		speaker.Play(p.resampler)
	} else {
		p.resampler = nil
		speaker.Play(p.ctrl)
	}

	return nil
}

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

	if p.ctrl == nil {
		return
	}

	speaker.Lock()
	p.ctrl.Paused = false
	speaker.Unlock()
	p.playing = true
}

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

	if p.ctrl == nil {
		return
	}

	speaker.Lock()
	p.ctrl.Paused = true
	speaker.Unlock()
	p.playing = false
}

// Toggle toggles between play and pause
func (p *Player) Toggle() {
	p.mu.Lock()
	if p.ctrl == nil {
		p.mu.Unlock()
		return
	}
	playing := p.playing
	p.mu.Unlock()

	if playing {
		p.Pause()
	} else {
		p.Play()
	}
}

// IsPlaying returns true if audio is currently playing
func (p *Player) IsPlaying() bool {
	p.mu.Lock()
	defer p.mu.Unlock()
	return p.playing
}

// Position returns the current playback position
func (p *Player) Position() time.Duration {
	p.mu.Lock()
	defer p.mu.Unlock()

	if p.streamer == nil {
		return 0
	}

	speaker.Lock()
	pos := p.format.SampleRate.D(p.streamer.Position())
	speaker.Unlock()

	return pos
}

// Duration returns the total duration
func (p *Player) Duration() time.Duration {
	p.mu.Lock()
	defer p.mu.Unlock()

	if p.streamer == nil {
		return 0
	}

	return p.format.SampleRate.D(p.streamer.Len())
}

// Seek moves to the specified position
func (p *Player) Seek(pos time.Duration) error {
	p.mu.Lock()
	defer p.mu.Unlock()

	if p.streamer == nil {
		return nil
	}

	sample := p.format.SampleRate.N(pos)
	if sample < 0 {
		sample = 0
	}
	if sample > p.streamer.Len() {
		sample = p.streamer.Len()
	}

	speaker.Lock()
	err := p.streamer.Seek(sample)
	speaker.Unlock()

	return err
}

// SeekRelative seeks relative to current position
func (p *Player) SeekRelative(delta time.Duration) error {
	pos := p.Position()
	return p.Seek(pos + delta)
}

// Close releases resources
func (p *Player) Close() {
	p.mu.Lock()
	defer p.mu.Unlock()

	if p.streamer != nil {
		p.streamer.Close()
	}
	if p.file != nil {
		p.file.Close()
	}
}

// Format returns the audio format info
func (p *Player) Format() beep.Format {
	p.mu.Lock()
	defer p.mu.Unlock()
	return p.format
}

// Streamer returns the underlying streamer (for waveform extraction)
func (p *Player) Streamer() beep.StreamSeekCloser {
	p.mu.Lock()
	defer p.mu.Unlock()
	return p.streamer
}

// GetSamples extracts sample data for waveform visualization
func (p *Player) GetSamples(numSamples int) ([]float64, error) {
	p.mu.Lock()
	defer p.mu.Unlock()

	if p.streamer == nil {
		return nil, fmt.Errorf("no audio loaded")
	}

	totalSamples := p.streamer.Len()
	if totalSamples == 0 {
		return nil, fmt.Errorf("empty audio")
	}

	samples := make([]float64, numSamples)
	samplesPerBucket := totalSamples / numSamples
	if samplesPerBucket < 1 {
		samplesPerBucket = 1
	}

	// Save current position
	speaker.Lock()
	currentPos := p.streamer.Position()
	speaker.Unlock()

	buf := make([][2]float64, samplesPerBucket)

	for i := 0; i < numSamples; i++ {
		targetPos := i * samplesPerBucket
		if targetPos >= totalSamples {
			break
		}

		speaker.Lock()
		p.streamer.Seek(targetPos)
		speaker.Unlock()

		speaker.Lock()
		n, ok := p.streamer.Stream(buf)
		speaker.Unlock()

		if !ok || n == 0 {
			if err, isErr := p.streamer.(interface{ Err() error }); isErr && err.Err() != nil {
				if err.Err() != io.EOF {
					continue
				}
			}
			continue
		}

		// Calculate average absolute amplitude
		var sum float64
		for j := 0; j < n; j++ {
			val := (buf[j][0] + buf[j][1]) / 2
			if val < 0 {
				val = -val
			}
			sum += val
		}
		samples[i] = sum / float64(n)
	}

	// Restore position
	speaker.Lock()
	p.streamer.Seek(currentPos)
	speaker.Unlock()

	return samples, nil
}