/**
 * NovaSonic Backend Server
 * Downloads music via yt-dlp and saves directly into your Navidrome music library
 *
 * Requirements:
 *   - Node.js 18+
 *   - yt-dlp installed (https://github.com/yt-dlp/yt-dlp)
 *   - ffmpeg installed
 */

const express = require('express');
const { spawn, execSync } = require('child_process');
const path    = require('path');
const fs      = require('fs');
const https   = require('https');

// ─── CONFIG ───────────────────────────────────────────────────────────────────
const CONFIG = {
  port:         process.env.PORT            || 3700,
  musicPath:    process.env.MUSIC_PATH      || '/music',
  ytdlpBin:     process.env.YTDLP_BIN      || 'yt-dlp',
  audioFmt:     process.env.AUDIO_FMT      || 'mp3',
  audioQuality: process.env.AUDIO_QUALITY  || '0',
  maxParallel:  parseInt(process.env.MAX_PARALLEL || '2'),
};

// ─── INIT ─────────────────────────────────────────────────────────────────────
const app = express();
app.use((req, res, next) => {
  res.setHeader('Access-Control-Allow-Origin', '*');
  res.setHeader('Access-Control-Allow-Methods', 'GET,POST,OPTIONS');
  res.setHeader('Access-Control-Allow-Headers', 'Content-Type,Authorization');
  res.setHeader('Access-Control-Allow-Private-Network', 'true');
  if (req.method === 'OPTIONS') { res.sendStatus(204); return; }
  next();
});
app.use(express.json());

const jobs = new Map();

let ytdlpVersion = 'unknown';
try {
  ytdlpVersion = execSync(`${CONFIG.ytdlpBin} --version`, { timeout: 5000 }).toString().trim();
  console.log(`✅ yt-dlp ${ytdlpVersion} found`);
} catch {
  console.warn('⚠️  yt-dlp not found!');
}

if (!fs.existsSync(CONFIG.musicPath)) {
  console.warn(`⚠️  Music path "${CONFIG.musicPath}" does not exist — creating it`);
  fs.mkdirSync(CONFIG.musicPath, { recursive: true });
}

// ─── HELPERS ──────────────────────────────────────────────────────────────────
function sanitize(s) {
  return (s || 'Unknown').replace(/[\\/:*?"<>|]/g, '_').trim().slice(0, 100);
}

// Convert "Artist feat. B" / "Artist ft. B" / "Artist featuring B" → "Artist / B"
// so Navidrome splits on "/" and lists each as a separate artist
function navidromeArtist(name) {
  if (!name) return name;
  return name
    .replace(/\s+feat\.?\s+/gi, ' / ')
    .replace(/\s+ft\.?\s+/gi, ' / ')
    .replace(/\s+featuring\s+/gi, ' / ');
}

function updateJob(id, update) {
  const job = jobs.get(id);
  if (job) jobs.set(id, { ...job, ...update, updatedAt: Date.now() });
}

function log(jobId, msg) {
  const j = jobs.get(jobId);
  if (j) jobs.set(jobId, { ...j, log: [...(j.log || []), msg], message: msg });
  console.log(`[${jobId}] ${msg}`);
}

// Download hi-res iTunes artwork (1000x1000) to cover.jpg, return path or null
async function downloadArtwork(url, dir) {
  if (!url) return null;
  const dest = path.join(dir, 'cover.jpg');
  // Upgrade to 1000x1000 — iTunes URL pattern: ...100x100bb.jpg
  const hiRes = url.replace(/\d+x\d+bb\./, '1000x1000bb.');
  return new Promise(resolve => {
    const tryUrl = (u, fallback) => {
      const file = fs.createWriteStream(dest);
      https.get(u, res => {
        if (res.statusCode !== 200) {
          res.resume();
          file.close();
          try { fs.unlinkSync(dest); } catch {}
          if (fallback) tryUrl(fallback, null);
          else resolve(null);
          return;
        }
        res.pipe(file);
        file.on('finish', () => resolve(dest));
        file.on('error', () => resolve(null));
      }).on('error', () => {
        if (fallback) tryUrl(fallback, null);
        else resolve(null);
      });
    };
    tryUrl(hiRes, url !== hiRes ? url : null);
  });
}

const AUDIO_EXTS = ['mp3', 'flac', 'opus', 'm4a', 'ogg', 'wav'];

function findExistingTrack(dir, trackPrefix, safeTitle) {
  return AUDIO_EXTS
    .map(ext => path.join(dir, `${trackPrefix}${safeTitle}.${ext}`))
    .find(f => fs.existsSync(f)) || null;
}

// Fetch plain + synced lyrics from LRCLIB
async function fetchLyrics(artist, title, album) {
  try {
    const p = new URLSearchParams({ artist_name: artist, track_name: title });
    if (album) p.set('album_name', album);
    const r = await fetch(`https://lrclib.net/api/get?${p}`, {
      headers: { 'User-Agent': 'NovaSonic/1.0' },
      signal: AbortSignal.timeout(8000),
    });
    if (!r.ok) return null;
    const d = await r.json();
    return { plain: d.plainLyrics || null, synced: d.syncedLyrics || null };
  } catch { return null; }
}

// iTunes track lookup — fills in album, year, trackNum, totalTracks, genre when missing
async function lookupItunesTrackMeta(artist, title) {
  try {
    const url = `https://itunes.apple.com/search?term=${encodeURIComponent(artist + ' ' + title)}&media=music&entity=musicTrack&limit=5&country=us&explicit=Yes`;
    const results = await new Promise((resolve, reject) => {
      https.get(url, res => {
        let d = ''; res.on('data', c => d += c);
        res.on('end', () => { try { resolve(JSON.parse(d).results || []); } catch { reject(new Error('parse')); } });
      }).on('error', reject);
    });
    const norm = s => s?.toLowerCase().trim() || '';
    const match = results.find(t =>
      norm(t.trackName) === norm(title) &&
      norm(t.artistName).split(' ')[0] === norm(artist).split(' ')[0]
    ) || results[0];
    if (!match) return {};
    return {
      album:       match.collectionName || '',
      year:        match.releaseDate ? new Date(match.releaseDate).getFullYear() : undefined,
      trackNum:    match.trackNumber   || undefined,
      totalTracks: match.trackCount    || undefined,
      discNum:     match.discNumber    || undefined,
      discTotal:   match.discCount     || undefined,
      genre:       match.primaryGenreName || undefined,
      artworkUrl:  (match.artworkUrl100 || '').replace('100x100bb', '1000x1000bb'),
    };
  } catch { return {}; }
}

// Download a single track: yt-dlp audio + ffmpeg clean metadata + iTunes cover embedded
async function downloadTrack({ jobId, artist, albumArtist, title, album, year, trackNum, totalTracks, discNum, discTotal, compilation, genre, artworkUrl, explicit, outputDir }) {
  const mainArtist = albumArtist || artist;
  const safeArtist = sanitize(mainArtist);
  const safeAlbum  = sanitize(album || 'Singles');
  const dir = path.join(outputDir || CONFIG.musicPath, safeArtist, safeAlbum);
  fs.mkdirSync(dir, { recursive: true });

  const safeTitle   = sanitize(title);
  const trackPrefix = trackNum ? String(trackNum).padStart(2, '0') + ' - ' : '';

  const existing = findExistingTrack(dir, trackPrefix, safeTitle);
  if (existing) {
    log(jobId, `⏭ Bereits vorhanden: ${path.basename(existing)} — übersprungen`);
    return { success: true, dir, skipped: true };
  }

  const outputTemplate = path.join(dir, `${trackPrefix}${safeTitle}.%(ext)s`);
  const query          = `${mainArtist} - ${title} official audio`;
  log(jobId, `🔍 Suche: "${query}"`);

  // Step 1: yt-dlp — audio only, no thumbnail (we embed iTunes artwork ourselves)
  await new Promise((resolve, reject) => {
    const args = [
      `ytsearch1:${query}`,
      '--extract-audio',
      '--audio-format',   CONFIG.audioFmt,
      '--audio-quality',  CONFIG.audioQuality,
      '-o',               outputTemplate,
      '--no-playlist',
      '--playlist-items', '1',
      '--no-warnings',
      '--newline',
    ];
    const proc = spawn(CONFIG.ytdlpBin, args, { env: { ...process.env, PYTHONUNBUFFERED: '1' } });
    let stderr = '', lastPct = '';
    proc.stdout.on('data', d => {
      d.toString().split('\n').filter(l => l.trim()).forEach(line => {
        if (line.includes('%') && line === lastPct) return;
        if (line.includes('%')) lastPct = line;
        log(jobId, line.trim());
      });
    });
    proc.stderr.on('data', d => {
      stderr += d.toString();
      d.toString().split('\n')
        .filter(l => l.trim() && !l.startsWith('[debug]'))
        .forEach(l => log(jobId, l.trim()));
    });
    proc.on('error', reject);
    proc.on('close', code =>
      code === 0 ? resolve() : reject(new Error(`yt-dlp code ${code}: ${stderr.slice(-300)}`))
    );
  });

  // Step 2: find the audio file yt-dlp wrote (newest audio file in dir)
  const audioFile = fs.readdirSync(dir)
    .filter(f => AUDIO_EXTS.some(e => f.endsWith(`.${e}`)))
    .map(f => path.join(dir, f))
    .sort((a, b) => fs.statSync(b).mtimeMs - fs.statSync(a).mtimeMs)[0];

  if (!audioFile) {
    log(jobId, '⚠️  Keine Audio-Datei gefunden');
    return { success: true, dir };
  }

  // Step 3: download artwork + fetch lyrics in parallel
  const [coverPath, lyricsData] = await Promise.all([
    downloadArtwork(artworkUrl, dir),
    fetchLyrics(artist, title, album),
  ]);
  const hasCover = !!(coverPath && fs.existsSync(coverPath));

  if (lyricsData?.synced) {
    const lrcPath = path.join(dir, `${trackPrefix}${safeTitle}.lrc`);
    fs.writeFileSync(lrcPath, lyricsData.synced, 'utf8');
    log(jobId, '🎵 Synced lyrics gefunden');
  } else if (lyricsData?.plain) {
    log(jobId, '📝 Lyrics gefunden');
  }

  log(jobId, `🏷  Metadaten + Cover → ${path.basename(audioFile)}`);

  // Step 4: ffmpeg — strip old tags, write clean ID3, embed hi-res artwork
  const fileExt = path.extname(audioFile);
  const tmpFile = audioFile.slice(0, -fileExt.length) + '.metatmp' + fileExt;
  await new Promise(resolve => {
    const ffArgs = ['-i', audioFile];
    if (hasCover) ffArgs.push('-i', coverPath);

    // Map: audio from input 0, artwork from input 1 (if available)
    ffArgs.push('-map', '0:a');
    if (hasCover) ffArgs.push('-map', '1:v');

    ffArgs.push(
      '-c',             'copy',
      '-map_metadata',  '-1',         // strip all existing tags (removes blurry YT thumbnail)
      '-id3v2_version', '3',
      '-metadata', `title=${title}`,
      '-metadata', `artist=${navidromeArtist(artist)}`,
      '-metadata', `album_artist=${mainArtist}`,
    );
    if (album)       ffArgs.push('-metadata', `album=${album}`);
    if (year)        ffArgs.push('-metadata', `date=${String(year)}`);
    if (trackNum)    ffArgs.push('-metadata', `track=${totalTracks ? `${trackNum}/${totalTracks}` : String(trackNum)}`);
    if (totalTracks) ffArgs.push('-metadata', `totaltracks=${String(totalTracks)}`);
    if (genre)         ffArgs.push('-metadata', `genre=${genre}`);
    if (discNum)       ffArgs.push('-metadata', `disc=${discTotal ? `${discNum}/${discTotal}` : String(discNum)}`);
    if (compilation)   ffArgs.push('-metadata', `compilation=1`);
    if (explicit)      ffArgs.push('-metadata', 'ITUNESADVISORY=1');
    if (lyricsData?.plain) ffArgs.push('-metadata', `lyrics=${lyricsData.plain}`);
    if (hasCover) {
      ffArgs.push(
        '-metadata:s:v', 'title=Album cover',
        '-metadata:s:v', 'comment=Cover (front)',
      );
    }
    ffArgs.push(tmpFile, '-y');

    const ff = spawn('ffmpeg', ffArgs);
    let ffErr = '';
    ff.stderr.on('data', d => ffErr += d.toString());
    ff.on('error', () => resolve());
    ff.on('close', code => {
      if (code === 0 && fs.existsSync(tmpFile)) {
        fs.renameSync(tmpFile, audioFile);
        log(jobId, `✅ Fertig${hasCover ? ' (Cover 1000x1000 eingebettet)' : ''}`);
      } else {
        try { fs.unlinkSync(tmpFile); } catch {}
        log(jobId, `⚠️  ffmpeg code ${code}`);
        if (ffErr) log(jobId, ffErr.slice(-200));
      }
      resolve();
    });
  });

  return { success: true, dir };
}

// Download all tracks of an album sequentially
async function downloadAlbumTracks({ jobId, artist, albumTitle, tracks, artworkUrl }) {
  const total = tracks.length;
  log(jobId, `📀 Album "${albumTitle}" — ${total} Tracks`);
  let done = 0, skipped = 0;

  for (const track of tracks) {
    try {
      const result = await downloadTrack({
        jobId,
        artist:      track.artistName  || artist,  // track artist (may include feat.)
        albumArtist: artist,                        // always the main artist → consistent grouping
        title:       track.trackName   || track.title,
        album:       albumTitle,
        year:        track.releaseDate ? new Date(track.releaseDate).getFullYear() : undefined,
        trackNum:    track.trackNumber     || undefined,
        totalTracks: total,
        discNum:     track.discNumber      || undefined,
        discTotal:   track.discCount       || undefined,
        compilation: track.collectionType === 'Compilation' || undefined,
        genre:       track.primaryGenreName || undefined,
        artworkUrl:  artworkUrl || track.artworkUrl100,
        explicit:    track.trackExplicitness === 'explicit',
        outputDir:   CONFIG.musicPath,
      });
      if (result?.skipped) skipped++; else done++;
      updateJob(jobId, { progress: Math.round(((done + skipped) / total) * 90) });
    } catch (e) {
      log(jobId, `⚠️  Fehler bei "${track.trackName || track.title}": ${e.message}`);
    }
  }
  return { done, skipped };
}

// Search iTunes for album tracks by artist + album name (fallback when no collectionId)
async function searchItunesAlbumTracks(artist, album) {
  return new Promise(resolve => {
    const q = encodeURIComponent(`${artist} ${album}`);
    https.get(`https://itunes.apple.com/search?term=${q}&media=music&entity=album&limit=5&country=us&explicit=Yes`, res => {
      let d = '';
      res.on('data', c => d += c);
      res.on('end', () => {
        try {
          const results = JSON.parse(d).results || [];
          const match = results.find(r =>
            r.collectionName?.toLowerCase().includes(album.toLowerCase()) ||
            r.artistName?.toLowerCase().includes(artist.toLowerCase())
          );
          if (match) fetchItunesTracks(match.collectionId).then(resolve).catch(() => resolve([]));
          else resolve([]);
        } catch { resolve([]); }
      });
    }).on('error', () => resolve([]));
  });
}

// Fetch individual tracks for an iTunes collectionId
async function fetchItunesTracks(collectionId) {
  return new Promise((resolve, reject) => {
    const url = `https://itunes.apple.com/lookup?id=${collectionId}&entity=song&explicit=Yes`;
    https.get(url, res => {
      let data = '';
      res.on('data', d => data += d);
      res.on('end', () => {
        try {
          const parsed = JSON.parse(data);
          resolve((parsed.results || []).filter(r => r.wrapperType === 'track'));
        } catch { reject(new Error('iTunes API parse error')); }
      });
    }).on('error', reject);
  });
}

// ─── QUEUE ────────────────────────────────────────────────────────────────────
let activeDownloads = 0;
const downloadQueue = [];

function processQueue() {
  if (activeDownloads >= CONFIG.maxParallel || downloadQueue.length === 0) return;
  const task = downloadQueue.shift();
  activeDownloads++;
  task().finally(() => { activeDownloads--; processQueue(); });
}

function enqueue(task) {
  downloadQueue.push(task);
  processQueue();
}

// ─── SPOTIFY ──────────────────────────────────────────────────────────────────
let _spTok = null, _spTokExp = 0, _spCachedId = '';

async function getSpotifyToken(clientId, clientSecret) {
  if (_spTok && clientId === _spCachedId && Date.now() < _spTokExp - 30000) return _spTok;
  const creds = Buffer.from(`${clientId}:${clientSecret}`).toString('base64');
  const r = await fetch('https://accounts.spotify.com/api/token', {
    method: 'POST',
    headers: { Authorization: `Basic ${creds}`, 'Content-Type': 'application/x-www-form-urlencoded' },
    body: 'grant_type=client_credentials',
    signal: AbortSignal.timeout(8000),
  });
  if (!r.ok) throw new Error(`Spotify Auth fehlgeschlagen (${r.status}) — Client ID/Secret prüfen`);
  const d = await r.json();
  _spTok = d.access_token; _spTokExp = Date.now() + d.expires_in * 1000; _spCachedId = clientId;
  return _spTok;
}

function parseSpotifyUrl(url) {
  const m = url.match(/open\.spotify\.com\/(track|album|playlist)\/([A-Za-z0-9]+)/);
  if (!m) throw new Error('Ungültige Spotify-URL — erwartet: open.spotify.com/track|album|playlist/...');
  return { type: m[1], id: m[2] };
}

// ─── ROUTES ──────────────────────────────────────────────────────────────────

app.get('/api/health', (req, res) => {
  res.json({ status: 'ok', ytdlpVersion, musicPath: CONFIG.musicPath, audioFormat: CONFIG.audioFmt, activeJobs: activeDownloads, queueLength: downloadQueue.length });
});

app.post('/api/spotify/resolve', async (req, res) => {
  const { url, clientId, clientSecret } = req.body;
  if (!url)                       return res.status(400).json({ error: 'url required' });
  if (!clientId || !clientSecret) return res.status(400).json({ error: 'Spotify credentials fehlen (clientId + clientSecret in Einstellungen eintragen)' });
  try {
    const { type, id } = parseSpotifyUrl(url);
    const tok  = await getSpotifyToken(clientId, clientSecret);
    const spH  = { Authorization: `Bearer ${tok}` };
    const spFetch = (u) => fetch(u, { headers: spH, signal: AbortSignal.timeout(10000) });

    if (type === 'track') {
      const r = await spFetch(`https://api.spotify.com/v1/tracks/${id}`);
      if (!r.ok) throw new Error(`Spotify API ${r.status}`);
      const d = await r.json();
      return res.json({ type: 'track', name: d.name, artist: d.artists?.[0]?.name || '', artworkUrl: d.album?.images?.[0]?.url || '',
        tracks: [{ trackName: d.name, artistName: d.artists?.[0]?.name || '', collectionName: d.album?.name || '',
          artworkUrl100: d.album?.images?.[0]?.url || '', releaseDate: d.album?.release_date || '',
          trackNumber: d.track_number, trackExplicitness: d.explicit ? 'explicit' : 'notExplicit', previewUrl: d.preview_url || null }] });
    }

    if (type === 'album') {
      const r = await spFetch(`https://api.spotify.com/v1/albums/${id}`);
      if (!r.ok) throw new Error(`Spotify API ${r.status}`);
      const d = await r.json();
      const art = d.images?.[0]?.url || '';
      return res.json({ type: 'album', name: d.name, artist: d.artists?.[0]?.name || '', artworkUrl: art,
        tracks: (d.tracks?.items || []).map(t => ({ trackName: t.name, artistName: t.artists?.[0]?.name || d.artists?.[0]?.name || '',
          collectionName: d.name, artworkUrl100: art, releaseDate: d.release_date || '',
          trackNumber: t.track_number, trackExplicitness: t.explicit ? 'explicit' : 'notExplicit', previewUrl: t.preview_url || null })) });
    }

    if (type === 'playlist') {
      const r = await spFetch(`https://api.spotify.com/v1/playlists/${id}?fields=name,description,images,owner,tracks.total`);
      if (!r.ok) throw new Error(`Spotify API ${r.status}`);
      const pl = await r.json();
      const tracks = [];
      let nextUrl = `https://api.spotify.com/v1/playlists/${id}/tracks?limit=100&fields=next,items(is_local,track(name,artists,album,track_number,explicit,preview_url))`;
      while (nextUrl) {
        const tr = await spFetch(nextUrl);
        if (!tr.ok) break;
        const td = await tr.json();
        for (const item of (td.items || [])) {
          if (!item?.track || item.is_local) continue;
          tracks.push({ trackName: item.track.name, artistName: item.track.artists?.[0]?.name || '',
            collectionName: item.track.album?.name || '', artworkUrl100: item.track.album?.images?.[0]?.url || '',
            releaseDate: item.track.album?.release_date || '', trackNumber: item.track.track_number,
            trackExplicitness: item.track.explicit ? 'explicit' : 'notExplicit', previewUrl: item.track.preview_url || null });
        }
        nextUrl = td.next || null;
      }
      return res.json({ type: 'playlist', name: pl.name, artist: pl.owner?.display_name || '',
        artworkUrl: pl.images?.[0]?.url || '', description: pl.description || '', tracks });
    }

    res.status(400).json({ error: `Unbekannter Typ: ${type}` });
  } catch(e) {
    console.error('[spotify/resolve]', e.message);
    res.status(500).json({ error: e.message });
  }
});

app.post('/api/download', async (req, res) => {
  const { type, artist, title, album, artworkUrl, collectionId, jobId: clientJobId, explicit } = req.body;
  if (!artist || !title) return res.status(400).json({ error: 'artist and title required' });

  const jobId = clientJobId || ('job_' + Date.now());
  jobs.set(jobId, {
    id: jobId, type, artist, title, album,
    status: 'queued', progress: 0, message: 'In Warteschlange…',
    log: [], createdAt: Date.now(), updatedAt: Date.now(),
  });
  res.json({ jobId, status: 'queued' });

  enqueue(async () => {
    updateJob(jobId, { status: 'running', progress: 5, message: 'Gestartet…' });
    try {
      if (type === 'track') {
        let meta = { album, year: undefined, trackNum: undefined, totalTracks: undefined, discNum: undefined, discTotal: undefined, genre: undefined };
        if (!album) {
          log(jobId, '📋 Suche Album-Metadaten von iTunes…');
          const extra = await lookupItunesTrackMeta(artist, title);
          if (extra.album) log(jobId, `📋 Album: "${extra.album}" (${extra.year || '?'})`);
          meta = { ...extra, artworkUrl: artworkUrl || extra.artworkUrl || '' };
        }
        const result = await downloadTrack({ jobId, artist, title, artworkUrl: artworkUrl || meta.artworkUrl || '', explicit: !!explicit, ...meta });
        if (result?.skipped) {
          updateJob(jobId, { status: 'done', progress: 100, message: 'Bereits vorhanden – übersprungen', skipped: true });
        } else {
          updateJob(jobId, { status: 'done', progress: 100, message: 'Fertig!' });
        }

      } else if (type === 'album') {
        let tracks = [];
        if (collectionId) {
          log(jobId, '📋 Lade Track-Liste von iTunes…');
          tracks = await fetchItunesTracks(collectionId);
        }
        if (!tracks.length) {
          log(jobId, '🔍 Suche Album auf iTunes…');
          tracks = await searchItunesAlbumTracks(artist, album || title);
        }
        if (!tracks.length) {
          throw new Error(`Keine einzelnen Tracks für "${album || title}" gefunden. Bitte über iTunes Global-Suche herunterladen.`);
        }
        const { done: dlDone, skipped: dlSkipped } = await downloadAlbumTracks({ jobId, artist, albumTitle: album || title, tracks, artworkUrl });
        const allSkipped = dlSkipped === tracks.length;
        const someSkipped = dlSkipped > 0 && !allSkipped;
        const msg = allSkipped
          ? `Album bereits vorhanden – alle ${dlSkipped} Tracks übersprungen`
          : someSkipped
            ? `Album fertig! (${dlDone} geladen, ${dlSkipped} bereits vorhanden)`
            : `Album "${album || title}" fertig!`;
        updateJob(jobId, { status: 'done', progress: 100, message: msg, skipped: allSkipped });

      } else if (type === 'artist') {
        log(jobId, `🎤 Künstler-Download: ${artist}`);
        const artistData = await new Promise((resolve, reject) => {
          https.get(`https://itunes.apple.com/search?term=${encodeURIComponent(artist)}&media=music&entity=album&limit=10&country=de`, res => {
            let d = ''; res.on('data', c => d += c); res.on('end', () => { try { resolve(JSON.parse(d).results || []); } catch { reject(new Error('parse')); } });
          }).on('error', reject);
        });
        const artistAlbums = artistData.filter(a => a.artistName?.toLowerCase() === artist.toLowerCase()).slice(0, 10);
        log(jobId, `📀 ${artistAlbums.length} Alben gefunden`);
        let done = 0;
        for (const alb of artistAlbums) {
          const tracks = await fetchItunesTracks(alb.collectionId).catch(() => []);
          if (tracks.length) {
            await downloadAlbumTracks({ jobId, artist, albumTitle: alb.collectionName, tracks, artworkUrl: alb.artworkUrl100 });
          }
          done++;
          updateJob(jobId, { progress: Math.round((done / artistAlbums.length) * 95) });
        }
        updateJob(jobId, { status: 'done', progress: 100, message: `Künstler "${artist}" fertig!` });

      } else if (type === 'playlist') {
        const plTracks = req.body.tracks || [];
        if (!plTracks.length) throw new Error('Keine Tracks übergeben');
        log(jobId, `🎵 Playlist "${title}" — ${plTracks.length} Tracks`);
        let done = 0, skipped = 0;
        for (const track of plTracks) {
          try {
            const result = await downloadTrack({
              jobId,
              artist:      track.artistName    || artist || '',
              albumArtist: track.artistName    || artist || '',
              title:       track.trackName     || '',
              album:       track.collectionName || '',
              year:        track.releaseDate ? new Date(track.releaseDate).getFullYear() : undefined,
              trackNum:    track.trackNumber   || undefined,
              genre:       track.primaryGenreName || undefined,
              artworkUrl:  track.artworkUrl100 || artworkUrl || '',
              explicit:    track.trackExplicitness === 'explicit',
            });
            if (result?.skipped) skipped++; else done++;
            updateJob(jobId, { progress: Math.round(((done + skipped) / plTracks.length) * 90) });
          } catch(e) {
            log(jobId, `⚠️  Fehler bei "${track.trackName || '?'}": ${e.message}`);
          }
        }
        const allSkipped = skipped === plTracks.length;
        updateJob(jobId, {
          status: 'done', progress: 100, skipped: allSkipped,
          message: allSkipped
            ? `Alle ${skipped} Tracks bereits vorhanden`
            : `Fertig! ${done} geladen${skipped ? `, ${skipped} übersprungen` : ''}`,
        });
      }
    } catch (err) {
      console.error(`[${jobId}] Error:`, err.message);
      updateJob(jobId, { status: 'error', message: err.message });
    }
  });
});

app.get('/api/status/:jobId', (req, res) => {
  const job = jobs.get(req.params.jobId);
  if (!job) return res.status(404).json({ error: 'Job not found' });
  res.json(job);
});

app.get('/api/jobs', (req, res) => {
  res.json(Array.from(jobs.values()).sort((a, b) => b.createdAt - a.createdAt).slice(0, 50));
});

// ─── START ────────────────────────────────────────────────────────────────────
app.listen(CONFIG.port, () => {
  console.log(`\n🎵 NovaSonic Backend running on port ${CONFIG.port}`);
  console.log(`   Music folder : ${CONFIG.musicPath}`);
  console.log(`   Audio format : ${CONFIG.audioFmt} (quality ${CONFIG.audioQuality})`);
  console.log(`   yt-dlp       : ${ytdlpVersion}`);
  console.log('');
});