package backend

import (
	"fmt"
	"os"
	"strconv"

	"github.com/go-flac/flacpicture"
	"github.com/go-flac/flacvorbis"
	"github.com/go-flac/go-flac"
)

type Metadata struct {
	Title       string
	Artist      string
	Album       string
	Date        string
	TrackNumber int
	DiscNumber  int
	ISRC        string
}

func EmbedMetadata(filepath string, metadata Metadata, coverPath string) error {
	f, err := flac.ParseFile(filepath)
	if err != nil {
		return fmt.Errorf("failed to parse FLAC file: %w", err)
	}

	var cmtIdx = -1
	for idx, block := range f.Meta {
		if block.Type == flac.VorbisComment {
			cmtIdx = idx
			break
		}
	}

	cmt := flacvorbis.New()

	if metadata.Title != "" {
		_ = cmt.Add(flacvorbis.FIELD_TITLE, metadata.Title)
	}
	if metadata.Artist != "" {
		_ = cmt.Add(flacvorbis.FIELD_ARTIST, metadata.Artist)
	}
	if metadata.Album != "" {
		_ = cmt.Add(flacvorbis.FIELD_ALBUM, metadata.Album)
	}
	if metadata.Date != "" {
		_ = cmt.Add(flacvorbis.FIELD_DATE, metadata.Date)
	}
	if metadata.TrackNumber > 0 {
		_ = cmt.Add(flacvorbis.FIELD_TRACKNUMBER, strconv.Itoa(metadata.TrackNumber))
	}
	if metadata.DiscNumber > 0 {
		_ = cmt.Add("DISCNUMBER", strconv.Itoa(metadata.DiscNumber))
	}
	if metadata.ISRC != "" {
		_ = cmt.Add(flacvorbis.FIELD_ISRC, metadata.ISRC)
	}

	cmtBlock := cmt.Marshal()
	if cmtIdx < 0 {
		f.Meta = append(f.Meta, &cmtBlock)
	} else {
		f.Meta[cmtIdx] = &cmtBlock
	}

	if coverPath != "" && fileExists(coverPath) {
		if err := embedCoverArt(f, coverPath); err != nil {
			fmt.Printf("Warning: Failed to embed cover art: %v\n", err)
		}
	}

	if err := f.Save(filepath); err != nil {
		return fmt.Errorf("failed to save FLAC file: %w", err)
	}

	return nil
}

func embedCoverArt(f *flac.File, coverPath string) error {
	imgData, err := os.ReadFile(coverPath)
	if err != nil {
		return fmt.Errorf("failed to read cover image: %w", err)
	}

	picture, err := flacpicture.NewFromImageData(
		flacpicture.PictureTypeFrontCover,
		"Cover",
		imgData,
		"image/jpeg",
	)
	if err != nil {
		return fmt.Errorf("failed to create picture block: %w", err)
	}

	pictureBlock := picture.Marshal()

	for i := len(f.Meta) - 1; i >= 0; i-- {
		if f.Meta[i].Type == flac.Picture {
			f.Meta = append(f.Meta[:i], f.Meta[i+1:]...)
		}
	}

	f.Meta = append(f.Meta, &pictureBlock)

	return nil
}

func fileExists(path string) bool {
	_, err := os.Stat(path)
	return err == nil
}