// fetch_assets.js - 从 3dtank.com 镜像本地可运行客户端所需文件
// 用法: node fetch_assets.js [--index i.html] [--out web] [--concurrency 8] [--base https://3dtank.com]
// 内容:
//   1) index.html 里引用的 /play/**（字体、图标、manifest；main.js 跳过，用本地切割版）
//   2) src/resources.json 里的 1218 个资源（static/**.svg|webp|json|mp3|webm|3ds...）
const fs = require('fs');
const path = require('path');

const PROJECT = path.resolve(__dirname, '..');
const ROOT = path.resolve(PROJECT, '..');
const Argv = process.argv.slice(2);
const Arg = (Name, Def) => {
  const I = Argv.indexOf('--' + Name);
  return I >= 0 && Argv[I + 1] ? Argv[I + 1] : Def;
};

const BASE = Arg('base', 'https://3dtank.com');
const INDEX_HTML = path.resolve(Arg('index', path.join(ROOT, 'i.html')));
const OUT_DIR = path.resolve(Arg('out', path.join(PROJECT, 'web')));
const CONCURRENCY = Number(Arg('concurrency', '8'));
const RESOURCES = path.join(PROJECT, 'src', 'resources.json');

// 与 curlcmd 一致的请求头
const HEADERS = {
  accept: '*/*',
  'accept-language': 'zh-CN,zh;q=0.9,en-GB;q=0.8,en;q=0.7,en-US;q=0.6',
  'cache-control': 'no-cache',
  pragma: 'no-cache',
  origin: BASE,
  referer: BASE + '/',
  'user-agent':
    'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/152.0.0.0 Safari/537.36 Edg/152.0.0.0',
};

// 收集待下载路径（不含域名，形如 /play/xxx）
function CollectPaths() {
  const Paths = new Set();
  const Html = fs.readFileSync(INDEX_HTML, 'utf8');
  for (const M of Html.matchAll(/["'(](\/play\/[^"')]+)["')]/g)) Paths.add(M[1]);
  for (const M of Html.matchAll(/url\(['"]?(\/play\/[^'")]+)['"]?\)/g)) Paths.add(M[1]);

  const Res = JSON.parse(fs.readFileSync(RESOURCES, 'utf8')).resourceMap;
  for (const K of Object.keys(Res)) Paths.add('/play/' + Res[K]);

  // main.js 用本地切割版，不覆盖
  const List = [...Paths].filter((P) => !/\/play\/static\/js\/main\.[0-9a-f]+\.js$/.test(P));
  // 本地已存在的 hornet 文件也不要覆盖
  return List.filter((P) => !/\/hornet_[^/]*\.js$/.test(P));
}

async function DownloadOne(PathName) {
  const Rel = PathName.replace(/^\/+/, '');
  const File = path.join(OUT_DIR, Rel);
  if (fs.existsSync(File) && fs.statSync(File).size > 0) return { PathName, skipped: true };
  fs.mkdirSync(path.dirname(File), { recursive: true });
  const Url = BASE + PathName;
  for (let Attempt = 1; Attempt <= 3; Attempt++) {
    try {
      const Resp = await fetch(Url, { headers: HEADERS, redirect: 'follow' });
      if (!Resp.ok) throw new Error('HTTP ' + Resp.status);
      const Buf = Buffer.from(await Resp.arrayBuffer());
      if (Buf.length === 0) throw new Error('empty body');
      fs.writeFileSync(File, Buf);
      return { PathName, bytes: Buf.length };
    } catch (Err) {
      if (Attempt === 3) return { PathName, error: String(Err.message || Err) };
      await new Promise((R) => setTimeout(R, 300 * Attempt));
    }
  }
  return { PathName, error: 'unreachable' };
}

async function Pool(Items, Worker, Concurrency) {
  let Next = 0;
  const Results = [];
  const Runners = new Array(Math.min(Concurrency, Items.length)).fill(0).map(async () => {
    while (true) {
      const I = Next++;
      if (I >= Items.length) return;
      Results[I] = await Worker(Items[I]);
    }
  });
  await Promise.all(Runners);
  return Results;
}

(async () => {
  const Paths = CollectPaths();
  console.log('待下载: ' + Paths.length + ' 个（并发 ' + CONCURRENCY + '）');
  console.log('来源: ' + BASE + '  输出: ' + OUT_DIR);

  // 首页就地复制一份（i.html 即 index.html）
  fs.mkdirSync(OUT_DIR, { recursive: true });
  fs.copyFileSync(INDEX_HTML, path.join(OUT_DIR, 'index.html'));

  const Started = Date.now();
  let Done = 0;
  const Results = await Pool(
    Paths,
    async (P) => {
      const R = await DownloadOne(P);
      Done++;
      if (Done % 100 === 0 || R.error) {
        console.log('  进度 ' + Done + '/' + Paths.length + (R.error ? ('  [失败] ' + R.PathName + ' ' + R.error) : ''));
      }
      return R;
    },
    CONCURRENCY
  );

  const Failed = Results.filter((R) => R && R.error);
  const Skipped = Results.filter((R) => R && R.skipped).length;
  const Bytes = Results.reduce((S, R) => S + (R && R.bytes ? R.bytes : 0), 0);
  console.log('=== 完成 ===');
  console.log('  成功下载: ' + (Results.length - Failed.length - Skipped) + '  跳过(已存在): ' + Skipped + '  失败: ' + Failed.length);
  console.log('  新增体积: ' + (Bytes / 1024 / 1024).toFixed(1) + ' MB   用时: ' + ((Date.now() - Started) / 1000).toFixed(0) + ' s');
  if (Failed.length) {
    fs.writeFileSync(path.join(OUT_DIR, '..', 'names', 'fetch_failed.txt'), Failed.map((F) => F.PathName + '  ' + F.error).join('\n'), 'utf8');
    console.log('  失败清单: 3DTank/names/fetch_failed.txt');
  }
})();