package service

import (
	"butterfliu/config"
	"butterfliu/internal/model"
	"butterfliu/internal/repository"
	"butterfliu/internal/scanner"
	"errors"
	"fmt"
	"log"
	"path"
	"path/filepath"
	"strconv"
	"strings"
)

// ScanReport holds the result of a library scan.
type ScanReport struct {
	TotalFiles  int
	Added       int
	Skipped     int
	FailedFiles []string
}

type LibraryService struct {
	repo *repository.LibraryRepository
}

func NewLibraryService(repo *repository.LibraryRepository) *LibraryService {
	return &LibraryService{repo: repo}
}

func (s *LibraryService) GetAll() ([]model.Library, error) {
	return s.repo.GetAll()
}

func (s *LibraryService) GetByID(id int) (model.Library, error) {
	return s.repo.GetByID(id)
}

func (s *LibraryService) Create(name, path string) (model.Library, error) {
	if name = strings.TrimSpace(name); name == "" {
		return model.Library{}, errors.New("library name cannot be empty")
	}
	if path = strings.TrimSpace(path); path == "" {
		return model.Library{}, errors.New("library path cannot be empty")
	}
	return s.repo.Create(name, path)
}

func (s *LibraryService) UpdateName(id int, name string) error {
	if name = strings.TrimSpace(name); name == "" {
		return errors.New("library name cannot be empty")
	}
	return s.repo.UpdateName(id, name)
}

func (s *LibraryService) UpdatePath(id int, path string) error {
	if path = strings.TrimSpace(path); path == "" {
		return errors.New("library path cannot be empty")
	}
	return s.repo.UpdatePath(id, path)
}

func (s *LibraryService) Delete(id int) error {
	return s.repo.Delete(id)
}

func (s *LibraryService) GetSongs(id int) ([]repository.SongDetail, error) {
	return s.repo.GetSongsByLibraryWithDetails(id)
}

func (s *LibraryService) GetSongsByArtist(id int) ([]repository.SongDetail, error) {
	return s.repo.GetSongsByArtistWithDetails(id)
}

func (s *LibraryService) GetSongsByAlbum(id int) ([]repository.SongDetail, error) {
	return s.repo.GetSongsByAlbumWithDetails(id)
}

func (s *LibraryService) GetSongIDsByAlbum(id int) ([]repository.SongDetail, error) {
	return s.repo.GetSongsByAlbumWithDetails(id)
}

func (s *LibraryService) GetArtists() ([]model.Artist, error) {
	return s.repo.GetArtists()
}

func (s *LibraryService) GetArtist(id int) (model.ArtistDetail, error) {
	artist, err := s.repo.GetArtist(id)
	if err != nil {
		return model.ArtistDetail{}, err
	}
	albums, err := s.repo.GetAlbumIDsByArtist(id)
	if err != nil {
		return model.ArtistDetail{}, err
	}
	songs, err := s.repo.GetSongIDsByArtist(id)
	if err != nil {
		return model.ArtistDetail{}, err
	}
	return model.ArtistDetail{
		ID:     artist.ID,
		Name:   artist.Name,
		Songs:  songs,
		Albums: albums,
	}, nil
}

func (s *LibraryService) GetAlbums() ([]model.Album, error) {
	return s.repo.GetAlbums()
}

func (s *LibraryService) GetAlbumsByArtistWithDetail(artistID int) ([]model.AlbumDetail, error) {
	albums, err := s.repo.GetAlbumsByArtist(artistID)
	if err != nil {
		return nil, err
	}
	details := []model.AlbumDetail{}
	for _, a := range albums {
		songs, err := s.repo.GetSongIDsByAlbum(a.ID)
		if err != nil {
			break
		}
		artist, err := s.repo.GetArtist(artistID)
		if err != nil {
			break
		}
		details = append(details, model.AlbumDetail{
			ID:     a.ID,
			Title:  a.Title,
			Artist: artist.Name,
			Songs:  songs,
		})
	}
	return details, nil
}

func (s *LibraryService) GetAlbum(id int) (model.AlbumDetail, error) {
	album, err := s.repo.GetAlbum(id)
	if err != nil {
		return model.AlbumDetail{}, err
	}
	songs, err := s.repo.GetSongIDsByAlbum(id)
	if err != nil {
		return model.AlbumDetail{}, err
	}
	artist, err := s.repo.GetArtist(album.ArtistID)
	if err != nil {
		return model.AlbumDetail{}, err
	}
	return model.AlbumDetail{
		ID:     id,
		Title:  album.Title,
		Songs:  songs,
		Artist: artist.Name,
	}, nil
}

func (s *LibraryService) GetAlbumCover(id int) (string, error) {
	songs, err := s.repo.GetSongIDsByAlbum(id)
	if err != nil {
		return "", err
	}
	conf := config.LoadConfig()
	return path.Join(conf.GetCachePath("cover"), strconv.Itoa(songs[0])+".jpg"), nil
}

func (s *LibraryService) Scan(id int) (*ScanReport, error) {
	lib, err := s.repo.GetByID(id)
	if err != nil {
		return nil, fmt.Errorf("library %d not found: %w", id, err)
	}

	scannedSongs, err := scanner.ScanDirectory(lib.Path)
	if err != nil {
		return nil, fmt.Errorf("scan directory %s: %w", lib.Path, err)
	}

	report := &ScanReport{TotalFiles: len(scannedSongs)}

	for _, song := range scannedSongs {
		if err := s.addScannedSong(song, lib.ID, report); err != nil {
			log.Printf("Failed to add %s: %v", filepath.Base(song.Path), err)
			report.FailedFiles = append(report.FailedFiles, song.Path)
		}
	}

	log.Printf("Scan complete for library %d: %+v", id, report)
	return report, nil
}

// addScannedSong upserts a scanned song and its related artist, album, and media file.
func (s *LibraryService) addScannedSong(song scanner.ScannedSong, libraryID int, report *ScanReport) error {
	mediaFile, err := s.getOrCreateMediaFile(song.Path, libraryID)
	if err != nil {
		return fmt.Errorf("media file: %w", err)
	}

	artist, err := s.getOrCreateArtist(song.Artist)
	if err != nil {
		return fmt.Errorf("artist: %w", err)
	}

	album, err := s.getOrCreateAlbum(song.Album, artist.ID)
	if err != nil {
		return fmt.Errorf("album: %w", err)
	}

	if _, err := s.repo.CreateSong(song.Title, artist.ID, album.ID, song.Duration, mediaFile.ID); err != nil {
		return fmt.Errorf("song: %w", err)
	}

	report.Added++
	return nil
}

func (s *LibraryService) getOrCreateMediaFile(path string, libraryID int) (model.MediaFile, error) {
	mf, err := s.repo.GetMediaFileByPath(path)
	if err == nil {
		return mf, nil
	}
	return s.repo.CreateMediaFile(path, libraryID)
}

func (s *LibraryService) getOrCreateArtist(name string) (model.Artist, error) {
	a, err := s.repo.GetArtistByName(name)
	if err == nil {
		return a, nil
	}
	return s.repo.CreateArtist(name)
}

func (s *LibraryService) getOrCreateAlbum(title string, artistID int) (model.Album, error) {
	al, err := s.repo.GetAlbumByTitleAndArtist(title, artistID)
	if err == nil {
		return al, nil
	}
	return s.repo.CreateAlbum(title, artistID)
}