package audio

import (
	"fmt"
	"os"
	"time"

	"github.com/tcolgate/mp3"
)

func analyzeMP3(filePath string) (*TrackInfo, error) {
	f, err := os.Open(filePath)
	if err != nil {
		return nil, fmt.Errorf("opening MP3: %w", err)
	}
	defer f.Close()

	decoder := mp3.NewDecoder(f)
	var frame mp3.Frame
	var skipped int
	var totalDuration time.Duration
	var sampleRate, channels, bitrate int
	var frameCount int

	for {
		err := decoder.Decode(&frame, &skipped)
		if err != nil {
			break
		}
		if frameCount == 0 {
			sampleRate = int(frame.Header().SampleRate())
			channels = channelCount(frame.Header().ChannelMode())
			bitrate = int(frame.Header().BitRate()) / 1000
		}
		totalDuration += frame.Duration()
		frameCount++
	}

	return &TrackInfo{
		Format:      "MP3",
		SampleRate:  sampleRate,
		Channels:    channels,
		DurationMs:  int(totalDuration.Milliseconds()),
		BitrateKbps: bitrate,
		IsLossless:  false,
	}, nil
}

func channelCount(mode mp3.FrameChannelMode) int {
	if mode == mp3.SingleChannel {
		return 1
	}
	return 2
}