import { writeFile } from '@tauri-apps/plugin-fs';
import { sanitizeFilename } from '$lib/services/deezer/paths';
import { encodeEmojis } from '$lib/utils/emoji';

export interface M3U8Track {
  duration: number; // in seconds
  artist: string;
  title: string;
  path: string; // relative path from playlist file (e.g., ../Music/Artist/Album/01 - Track.flac)
}

/**
 * Write an M3U8 playlist file
 * Format: Extended M3U format with EXTINF metadata
 *
 * @param playlistName - Name of the playlist (will be sanitized)
 * @param tracks - Array of tracks to include
 * @param playlistsFolder - Absolute path to playlists folder
 * @returns Absolute path to created m3u8 file
 */
export async function writeM3U8(
  playlistName: string,
  tracks: M3U8Track[],
  playlistsFolder: string
): Promise<string> {
  // Encode emojis and sanitize playlist name for filename
  const encodedName = encodeEmojis(playlistName);
  const sanitizedName = sanitizeFilename(encodedName);
  const playlistPath = `${playlistsFolder}/${sanitizedName}.m3u8`;

  // Build m3u8 content
  const lines: string[] = [
    '#EXTM3U',
    `#PLAYLIST:${encodedName}`,
    '#EXTENC:UTF-8',
    ''
  ];

  for (const track of tracks) {
    // EXTINF format: #EXTINF:duration,artist - title
    const durationSeconds = Math.round(track.duration);
    const extinf = `#EXTINF:${durationSeconds},${track.artist} - ${track.title}`;
    lines.push(extinf);
    lines.push(track.path);
  }

  // Add trailing newline
  lines.push('');

  const content = lines.join('\n');
  const encoder = new TextEncoder();
  const data = encoder.encode(content);

  await writeFile(playlistPath, data);

  return playlistPath;
}

/**
 * Convert absolute music file path to relative path from playlists folder
 * Assumes music folder and playlists folder are siblings:
 *   /path/to/Music/Artist/Album/Track.flac
 *   /path/to/Playlists/playlist.m3u8
 * Becomes: ../Music/Artist/Album/Track.flac
 *
 * @param absoluteMusicPath - Absolute path to music file
 * @param musicFolderName - Name of music folder (default: 'Music')
 * @returns Relative path from playlists folder
 */
export function makeRelativePath(
  absoluteMusicPath: string,
  musicFolderName: string = 'Music'
): string {
  // Split path into parts
  const parts = absoluteMusicPath.split('/');

  // Find the music folder index
  const musicIndex = parts.findIndex(part => part === musicFolderName);

  if (musicIndex === -1) {
    // Fallback: if music folder not found, use the path as-is
    console.warn(`[M3U8] Could not find "${musicFolderName}" in path: ${absoluteMusicPath}`);
    return absoluteMusicPath;
  }

  // Take everything from music folder onwards
  const relativeParts = parts.slice(musicIndex);

  // Prepend ../ to go up from playlists folder
  return `../${relativeParts.join('/')}`;
}