const fs = require('fs');
const path = require('path');
const { API, DOWNLOAD_DIR } = require('./config');
const { fetchJSON } = require('./network');

async function fetchLyric(songId) {
  try {
    const res = await fetchJSON(`${API.lyric}?id=${songId}`);
    if (res.code !== 200) return null;
    return res.data;
  } catch {
    return null;
  }
}

function mergeLrc(lrc, tlyric) {
  if (!lrc) return '';
  if (!tlyric) return lrc;

  const transMap = new Map();
  for (const line of tlyric.split('\n')) {
    const match = line.match(/^\[(\d+:\d+[\.:]\d+)\](.*)/);
    if (match && match[2].trim()) transMap.set(match[1], match[2].trim());
  }

  const result = [];
  for (const line of lrc.split('\n')) {
    result.push(line);
    const match = line.match(/^\[(\d+:\d+[\.:]\d+)\]/);
    if (match && transMap.has(match[1])) result.push(`[${match[1]}]${transMap.get(match[1])}`);
  }
  return result.join('\n');
}

function parseCredits(lrcText) {
  const credits = {};
  if (!lrcText) return credits;
  const labels = {
    lyricist: /^(作词|作詞|词|填词|Lyricist|Lyrics? by|Written by)$/i,
    composer: /^(作曲|曲|Composer|Composed by|Music by)$/i,
    arranger: /^(编曲|編曲|Arranger|Arranged by)$/i,
    producer: /^(制作人|製作人|出品人|监制|Producer|Produced by)$/i,
    mixer: /^(混音|Mix(ing)?|Mixed by)$/i,
  };
  for (const raw of lrcText.split('\n')) {
    const line = raw.replace(/^(\s*\[[^\]]*\]\s*)+/, '').trim();
    const match = line.match(/^([^:：]{1,12})\s*[:：]\s*(.+)$/);
    if (!match) continue;
    const label = match[1].trim();
    const value = match[2].trim().replace(/\s*\/\s*/g, '/');
    if (!value) continue;
    for (const [key, pattern] of Object.entries(labels)) {
      if (pattern.test(label) && !credits[key]) {
        credits[key] = value;
        break;
      }
    }
  }
  return credits;
}

async function saveLyric(songId, fileName) {
  const data = await fetchLyric(songId);
  if (!data?.lrc) {
    console.log('  ⚠️  未获取到歌词');
    return;
  }

  const lrcPath = path.join(DOWNLOAD_DIR, fileName + '.lrc');
  fs.writeFileSync(lrcPath, data.lrc, 'utf-8');
  console.log(`  📄 歌词已保存: ${path.basename(lrcPath)}`);
  if (data.tlyric?.trim()) {
    const mergedPath = path.join(DOWNLOAD_DIR, fileName + '.合并翻译.lrc');
    fs.writeFileSync(mergedPath, mergeLrc(data.lrc, data.tlyric), 'utf-8');
    console.log(`  📄 翻译歌词已保存: ${path.basename(mergedPath)}`);
  }
}

module.exports = { fetchLyric, mergeLrc, parseCredits, saveLyric };