/**
 * 微信小程序主包体积分析
 * 用法：先执行发行构建（微信小程序），再运行：node scripts/analyze-mp-main.js
 * 输出：主包总大小、超过 2MB 时告警、主包内大文件列表
 */
const fs = require('fs');
const path = require('path');

const BUILD_DIR = path.join(__dirname, '../unpackage/dist/build/mp-weixin');
const MAIN_PACKAGE_LIMIT_KB = 2048;

function getSubPackageRoots() {
  const appJsonPath = path.join(BUILD_DIR, 'app.json');
  if (!fs.existsSync(appJsonPath)) {
    console.error('未找到 app.json，请先执行：发行 -> 微信小程序');
    process.exit(1);
  }
  const app = JSON.parse(fs.readFileSync(appJsonPath, 'utf8'));
  let roots = (app.subPackages || []).map((p) => p.root);
  // 若构建产物尚未包含最新分包，则按源码 pages.json 补充（如 goods_cate）
  const pagesJsonPath = path.join(__dirname, '../pages.json');
  if (fs.existsSync(pagesJsonPath)) {
    let raw = fs.readFileSync(pagesJsonPath, 'utf8');
    // 只去掉行尾 // 注释（不删字符串内的 //）
    raw = raw.replace(/\s*\/\/[^\n"']*$/gm, '');
    try {
      const pagesJson = JSON.parse(raw);
      const subRoots = (pagesJson.subPackages || []).map((p) => p.root);
      subRoots.forEach((r) => {
        if (!roots.includes(r)) roots = roots.concat(r);
      });
    } catch (_) {}
  }
  return roots;
}

function isInMainPackage(filePath, subRoots) {
  const normalized = filePath.replace(BUILD_DIR + path.sep, '').replace(/\\/g, '/');
  for (const root of subRoots) {
    if (normalized === root || normalized.startsWith(root + '/')) return false;
  }
  return true;
}

function walkDir(dir, subRoots, list) {
  if (!fs.existsSync(dir)) return;
  const entries = fs.readdirSync(dir, { withFileTypes: true });
  for (const e of entries) {
    const full = path.join(dir, e.name);
    const rel = path.relative(BUILD_DIR, full).replace(/\\/g, '/');
    if (e.isDirectory()) {
      walkDir(full, subRoots, list);
    } else {
      if (!isInMainPackage(full, subRoots)) continue;
      try {
        const stat = fs.statSync(full);
        list.push({ path: rel, size: stat.size });
      } catch (_) {}
    }
  }
}

function main() {
  const subRoots = getSubPackageRoots();
  const files = [];
  walkDir(BUILD_DIR, subRoots, files);

  const totalBytes = files.reduce((s, f) => s + f.size, 0);
  const totalKB = Math.round(totalBytes / 1024);
  const totalMB = (totalBytes / 1024 / 1024).toFixed(2);

  console.log('========== 微信小程序主包体积分析 ==========\n');
  console.log('主包总大小:', totalKB, 'KB', '(' + totalMB + ' MB)');
  console.log('微信主包上限:', MAIN_PACKAGE_LIMIT_KB, 'KB (2 MB)\n');

  if (totalKB > MAIN_PACKAGE_LIMIT_KB) {
    console.log('⚠️  主包超出限制', totalKB - MAIN_PACKAGE_LIMIT_KB, 'KB，需优化后再上传。\n');
  } else {
    console.log('✓ 主包未超限。\n');
  }

  const sorted = files.slice().sort((a, b) => b.size - a.size);
  console.log('主包内大文件（按体积排序，前 30）：');
  console.log('----------------------------------------');
  sorted.slice(0, 30).forEach((f) => {
    const kb = (f.size / 1024).toFixed(1);
    console.log(kb.padStart(8) + ' KB  ' + f.path);
  });

  console.log('\n主包页面（来自 app.json）：');
  const app = JSON.parse(fs.readFileSync(path.join(BUILD_DIR, 'app.json'), 'utf8'));
  (app.pages || []).forEach((p) => console.log('  -', p));
}

main();