const fs = require('fs');
const http = require('http');
const https = require('https');
const path = require('path');
const { API, DOWNLOAD_DIR, NETEASE_BASE_URL } = require('./config');
const { downloadBuffer, fetchJSON } = require('./network');
const { sanitizePathSegment } = require('./utils');

function requestNetease(pathname) {
  return new Promise((resolve) => {
    const requestUrl = new URL(pathname, `${NETEASE_BASE_URL}/`);
    const options = {
      method: 'GET',
      headers: {
        Referer: NETEASE_BASE_URL,
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36',
        Accept: 'application/json',
        Cookie: 'os=pc',
      },
    };
    const protocol = requestUrl.protocol === 'https:' ? https : http;
    const req = protocol.request(requestUrl, options, (res) => {
      let data = '';
      res.on('data', chunk => data += chunk);
      res.on('end', () => {
        try { resolve(JSON.parse(data)); }
        catch { resolve(null); }
      });
    });
    req.on('error', () => resolve(null));
    req.setTimeout(5000, () => { req.destroy(); resolve(null); });
    req.end();
  });
}

async function fetchNeteaseSongDetail(songId) {
  const data = await requestNetease(`/api/v1/song/detail?ids=[${songId}]`);
  const song = data?.songs?.[0];
  if (!song) return null;
  return {
    id: song.id,
    name: song.name,
    artists: song.ar?.map(artist => ({ id: artist.id, name: artist.name })) || [],
    album: song.al ? { id: song.al.id, name: song.al.name, cover: song.al.picUrl || song.al.cover } : null,
    duration: song.dt || 0,
    disc: song.cd || '',
    trackNo: song.no || 0,
    aliases: song.alia || [],
    transNames: song.tns || [],
    popularity: song.pop || 0,
    fee: song.fee,
    quality: {
      h: song.h ? { br: song.h.br, size: song.h.size, sr: song.h.sr } : null,
      m: song.m ? { br: song.m.br, size: song.m.size, sr: song.m.sr } : null,
      l: song.l ? { br: song.l.br, size: song.l.size, sr: song.l.sr } : null,
    },
  };
}

async function fetchNeteaseAlbumDetail(albumId) {
  const data = await requestNetease(`/api/v1/album/${albumId}`);
  if (!data) return null;
  const album = data.album || data;
  const albumArtists = (album.artists?.length ? album.artists : [album.artist])
    .filter(artist => artist?.name)
    .map(artist => ({ id: artist.id, name: artist.name, trans: artist.trans }));
  const albumArtist = albumArtists.map(artist => artist.name).join(' / ');
  const normalizedAlbumArtist = albumArtist.toLowerCase().replace(/[.\s]/g, '');
  const isCompilation = ['群星', 'variousartists', 'variousartist', 'va'].includes(normalizedAlbumArtist);
  return {
    id: album.id,
    name: album.name,
    publishTime: album.publishTime || null,
    company: album.company || '',
    description: album.description || '',
    tags: album.tags || [],
    type: album.type || '',
    size: album.size || 0,
    artist: albumArtists[0] || null,
    artists: albumArtists,
    albumArtist,
    isCompilation,
    picUrl: album.picUrl || '',
    tracks: (data.songs || album.songs || []).map(song => ({
      id: song.id,
      name: song.name,
      ar: song.ar || song.artists || [],
      al: song.al || song.album || null,
      dt: song.dt || song.duration || 0,
      disc: song.cd || '',
      trackNo: song.no || 0,
    })),
  };
}

function getAlbumDownloadTarget(album, track, index, trackCount = album.tracks?.length || 0) {
  const trackArtists = track.ar?.map(artist => artist.name).filter(Boolean).join(' / ');
  const artistDir = sanitizePathSegment(album.artist?.name || trackArtists, '未知歌手');
  const albumDir = sanitizePathSegment(album.name, '未知专辑');
  const numberWidth = Math.max(2, String(trackCount).length);
  const trackNumber = String(index + 1).padStart(numberWidth, '0');
  return {
    outputDir: path.join(DOWNLOAD_DIR, artistDir, albumDir),
    outputBaseName: `${trackNumber}. ${track.name || '未知歌曲'}`,
  };
}

async function saveAlbumCover(coverUrl, outputDir) {
  const coverPath = path.join(outputDir, 'cover.jpg');
  if (fs.existsSync(coverPath) && fs.statSync(coverPath).size > 0) {
    console.log('  ⏭️  专辑封面已存在: cover.jpg');
    return;
  }
  if (!coverUrl) {
    console.log('  ⚠️  未获取到专辑封面');
    return;
  }
  try {
    fs.mkdirSync(outputDir, { recursive: true });
    fs.writeFileSync(coverPath, await downloadBuffer(coverUrl));
    console.log('  🖼️  专辑封面已保存: cover.jpg');
  } catch (e) {
    console.error(`  ⚠️  专辑封面保存失败: ${e.message}`);
  }
}

async function fetchFullMetadata(songId) {
  const [songDetail, chkszData] = await Promise.all([
    fetchNeteaseSongDetail(songId),
    fetchJSON(`${API.music}?id=${songId}&level=standard`).catch(() => null),
  ]);
  if (!songDetail) return null;

  const albumDetail = songDetail.album?.id
    ? await fetchNeteaseAlbumDetail(songDetail.album.id)
    : null;
  const durationSec = Math.round(songDetail.duration / 1000);
  const publishDate = albumDetail?.publishTime
    ? new Date(albumDetail.publishTime).toISOString().slice(0, 10)
    : null;

  return {
    id: songId,
    name: songDetail.name,
    artists: songDetail.artists,
    artistStr: songDetail.artists.map(artist => artist.name).join(' / '),
    album: songDetail.album,
    albumStr: songDetail.album?.name || '',
    duration: songDetail.duration,
    durationStr: `${Math.floor(durationSec / 60)}:${String(durationSec % 60).padStart(2, '0')}`,
    disc: songDetail.disc,
    trackNo: songDetail.trackNo,
    aliases: songDetail.aliases,
    transNames: songDetail.transNames,
    popularity: songDetail.popularity,
    fee: songDetail.fee,
    publishTime: albumDetail?.publishTime,
    publishYear: albumDetail?.publishTime ? new Date(albumDetail.publishTime).getFullYear() : null,
    publishDate,
    company: albumDetail?.company || '',
    description: albumDetail?.description || '',
    tags: albumDetail?.tags || [],
    albumType: albumDetail?.type || '',
    albumSize: albumDetail?.size || 0,
    albumArtist: albumDetail?.artist,
    quality: songDetail.quality,
    chksz: chkszData?.code === 200 ? chkszData.data : null,
  };
}

module.exports = {
  fetchNeteaseSongDetail,
  fetchNeteaseAlbumDetail,
  getAlbumDownloadTarget,
  saveAlbumCover,
  fetchFullMetadata,
};