package playlists

import (
	"context"
	"errors"
	"io"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/navidrome/navidrome/conf"
	"github.com/navidrome/navidrome/log"
	"github.com/navidrome/navidrome/model"
	"github.com/navidrome/navidrome/model/request"
	"github.com/navidrome/navidrome/utils/ioutils"
	"golang.org/x/text/unicode/norm"
)

func (s *playlists) ImportFile(ctx context.Context, folder *model.Folder, filename string) (*model.Playlist, error) {
	pls, err := s.parsePlaylist(ctx, filename, folder)
	if err != nil {
		log.Error(ctx, "Error parsing playlist", "path", filepath.Join(folder.AbsolutePath(), filename), err)
		return nil, err
	}
	log.Debug(ctx, "Found playlist", "name", pls.Name, "lastUpdated", pls.UpdatedAt, "path", pls.Path, "numTracks", len(pls.Tracks))
	err = s.updatePlaylist(ctx, pls)
	if err != nil {
		log.Error(ctx, "Error updating playlist", "path", filepath.Join(folder.AbsolutePath(), filename), err)
	}
	return pls, err
}

func (s *playlists) ImportM3U(ctx context.Context, reader io.Reader) (*model.Playlist, error) {
	owner, _ := request.UserFrom(ctx)
	pls := &model.Playlist{
		OwnerID: owner.ID,
		Public:  false,
		Sync:    false,
	}
	err := s.parseM3U(ctx, pls, nil, reader)
	if err != nil {
		log.Error(ctx, "Error parsing playlist", err)
		return nil, err
	}
	err = s.ds.Playlist(ctx).Put(pls)
	if err != nil {
		log.Error(ctx, "Error saving playlist", err)
		return nil, err
	}
	return pls, nil
}

func (s *playlists) parsePlaylist(ctx context.Context, playlistFile string, folder *model.Folder) (*model.Playlist, error) {
	pls, err := s.newSyncedPlaylist(folder.AbsolutePath(), playlistFile)
	if err != nil {
		return nil, err
	}

	file, err := os.Open(pls.Path)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	reader := ioutils.UTF8Reader(file)
	extension := strings.ToLower(filepath.Ext(playlistFile))
	switch extension {
	case ".nsp":
		err = s.parseNSP(ctx, pls, reader)
	default:
		err = s.parseM3U(ctx, pls, folder, reader)
	}
	return pls, err
}

func (s *playlists) updatePlaylist(ctx context.Context, newPls *model.Playlist) error {
	owner, _ := request.UserFrom(ctx)

	// Try to find existing playlist by path. Since filesystem normalization differs across
	// platforms (macOS uses NFD, Linux/Windows use NFC), we try both forms to match
	// playlists that may have been imported on a different platform.
	pls, err := s.ds.Playlist(ctx).FindByPath(newPls.Path)
	if errors.Is(err, model.ErrNotFound) {
		// Try alternate normalization form
		altPath := norm.NFD.String(newPls.Path)
		if altPath == newPls.Path {
			altPath = norm.NFC.String(newPls.Path)
		}
		if altPath != newPls.Path {
			pls, err = s.ds.Playlist(ctx).FindByPath(altPath)
		}
	}
	if err != nil && !errors.Is(err, model.ErrNotFound) {
		return err
	}
	if err == nil && !pls.Sync {
		log.Debug(ctx, "Playlist already imported and not synced", "playlist", pls.Name, "path", pls.Path)
		return nil
	}

	if err == nil {
		log.Info(ctx, "Updating synced playlist", "playlist", pls.Name, "path", newPls.Path)
		newPls.ID = pls.ID
		newPls.Name = pls.Name
		newPls.Comment = pls.Comment
		newPls.OwnerID = pls.OwnerID
		newPls.Public = pls.Public
		newPls.UploadedImage = pls.UploadedImage // Preserve manual upload
		newPls.EvaluatedAt = &time.Time{}
	} else {
		log.Info(ctx, "Adding synced playlist", "playlist", newPls.Name, "path", newPls.Path, "owner", owner.UserName)
		newPls.OwnerID = owner.ID
		// For NSP files, Public may already be set from the file; for M3U, use server default
		if !newPls.IsSmartPlaylist() {
			newPls.Public = conf.Server.DefaultPlaylistPublicVisibility
		}
	}
	return s.ds.Playlist(ctx).Put(newPls)
}