const fs = require('fs');
const path = require('path');
const { execSync, execFileSync } = require('child_process');
const { downloadBuffer } = require('./network');

function hasFFmpeg() {
  try { execSync('ffmpeg -version', { stdio: 'ignore' }); return true; } catch { return false; }
}

function hasNodeID3() {
  try { require.resolve('node-id3'); return true; } catch { return false; }
}

async function embedCover(audioPath, coverUrl, meta) {
  const ext = path.extname(audioPath).toLowerCase();
  const coverPath = audioPath + '.cover.jpg';

  try {
    const coverBuf = await downloadBuffer(coverUrl);
    fs.writeFileSync(coverPath, coverBuf);

    if (ext === '.mp3' && hasNodeID3()) {
      const NodeID3 = require('node-id3');
      const tags = {
        title: meta.name,
        artist: meta.artist,
        album: meta.album,
        image: coverPath,
      };
      if (meta.albumArtist) tags.performerInfo = meta.albumArtist;
      if (meta.year) tags.year = String(meta.year);
      if (meta.date) tags.date = String(meta.date);
      if (meta.trackNo) tags.trackNumber = String(meta.trackNo);
      if (meta.disc) tags.partOfSet = String(meta.disc);
      if (meta.genre) tags.genre = meta.genre;
      if (meta.composer) tags.composer = meta.composer;
      if (meta.lyricist) tags.textWriter = meta.lyricist;
      if (meta.publisher) tags.publisher = meta.publisher;

      const userTexts = [];
      if (meta.arranger) userTexts.push({ description: 'ARRANGER', value: meta.arranger });
      if (meta.producer) userTexts.push({ description: 'PRODUCER', value: meta.producer });
      if (meta.mixer) userTexts.push({ description: 'MIXER', value: meta.mixer });
      if (userTexts.length) tags.userDefinedText = userTexts;
      if (meta.lyrics) tags.unsynchronisedLyrics = { language: 'chi', text: meta.lyrics };
      const ok = NodeID3.write(tags, audioPath);
      if (ok === true) {
        console.log('  ✅ 封面+标签+歌词已嵌入 (node-id3)');
        return;
      }
    }

    if (hasFFmpeg()) {
      const tmpPath = audioPath + '.tmp' + ext;
      const args = [
        '-y', '-i', audioPath, '-i', coverPath,
        '-map', '0:a', '-map', '1:0', '-c', 'copy',
        '-disposition:v:0', 'attached_pic',
      ];
      const addMeta = (key, value) => {
        if (value !== undefined && value !== null && value !== '') {
          args.push('-metadata', `${key}=${value}`);
        }
      };
      addMeta('title', meta.name);
      addMeta('artist', meta.artist);
      addMeta('album', meta.album);
      addMeta('album_artist', meta.albumArtist || meta.artist);
      addMeta('date', meta.date || meta.year);
      addMeta('track', meta.trackNo);
      addMeta('disc', meta.disc);
      addMeta('genre', meta.genre);
      addMeta('composer', meta.composer);
      addMeta('publisher', meta.publisher);
      addMeta('lyricist', meta.lyricist);
      addMeta('arranger', meta.arranger);
      addMeta('producer', meta.producer);
      addMeta('mixer', meta.mixer);
      if (meta.lyrics && meta.lyrics.length <= 8000) addMeta('lyrics', meta.lyrics);
      args.push('-metadata:s:v', 'title=Album cover', '-metadata:s:v', 'comment=Cover (front)');
      if (ext === '.mp3') args.push('-id3v2_version', '3');
      args.push(tmpPath);

      execFileSync('ffmpeg', args, { stdio: 'ignore' });
      fs.renameSync(tmpPath, audioPath);
      console.log('  ✅ 封面+标签+歌词已嵌入 (ffmpeg)');
    } else {
      console.log('  ⚠️  跳过封面: 需要 node-id3 (npm i node-id3) 或 ffmpeg');
    }
  } catch (e) {
    console.error(`  ⚠️  封面嵌入失败: ${e.message}`);
  } finally {
    if (fs.existsSync(coverPath)) fs.unlinkSync(coverPath);
  }
}

module.exports = { hasFFmpeg, hasNodeID3, embedCover };