// Linux 打包：产出 dist/PeopleLib-linux-<arch>.tar.gz。
// 直接把官方 zip 里的条目转写进 tar，不落地中间目录：Linux 的可执行位存在
// zip 的 external attributes 里，先解到 NTFS 再打包会把这些位全部丢掉，
// 产物解压后 PeopleLib 与 chrome-sandbox 都不可执行。因此本脚本在任意平台
// 都能构建 x64 与 arm64 包。
const fs = require('fs');
const path = require('path');
const zlib = require('zlib');
const { spawnSync } = require('child_process');

const ROOT = __dirname;
const pkg = require('./package.json');
const PRODUCT = pkg.productName || 'PeopleLib';
const SUPPORTED_ARCHES = ['x64', 'arm64'];

// 固定时间戳让同一份源码重复构建得到逐字节一致的产物，便于用哈希核对发布件。
const MTIME = Number(process.env.SOURCE_DATE_EPOCH) || 1735689600;

const KEEP_LOCALES = new Set(['zh-CN.pak', 'en-US.pak']);
// 无扩展名的可执行文件与 .so 之外，这几个也必须带执行位
const FORCE_EXECUTABLE = new Set(['chrome-sandbox', 'chrome_crashpad_handler']);

function parseArch(argv) {
  const index = argv.indexOf('--arch');
  const value = index >= 0 ? argv[index + 1] : process.arch;
  if (!SUPPORTED_ARCHES.includes(value)) {
    throw new Error(`不支持的架构：${value || '未指定'}（可选 ${SUPPORTED_ARCHES.join(' / ')}）`);
  }
  return value;
}

function run(cmd, args) {
  const result = spawnSync(cmd, args, { stdio: 'inherit' });
  if (result.error) throw result.error;
  if (result.status !== 0) throw new Error(`${cmd} 失败（退出码 ${result.status}）`);
}

// 官方 zip 只在需要时下载一次，缓存在 node_modules/.cache 下按版本和架构分目录
function ensureRuntimeZip(arch) {
  const version = String(pkg.devDependencies && pkg.devDependencies.electron || '').replace(/^v/, '');
  if (!version) throw new Error('package.json 未锁定 electron 版本');
  const cacheDir = path.join(ROOT, 'node_modules', '.cache', `electron-linux-${arch}`, version);
  const zip = path.join(cacheDir, 'electron.zip');
  if (fs.existsSync(zip) && fs.statSync(zip).size > 0) return zip;

  const mirror = process.env.ELECTRON_MIRROR
    || process.env.npm_config_electron_mirror
    || 'https://npmmirror.com/mirrors/electron/';
  const url = `${mirror.replace(/\/?$/, '/')}v${version}/electron-v${version}-linux-${arch}.zip`;

  fs.mkdirSync(cacheDir, { recursive: true });
  const partial = `${zip}.download`;
  fs.rmSync(partial, { force: true });
  console.log(`下载 Electron ${version} (linux-${arch})...`);
  run('curl', ['-fSL', '--retry', '3', '-o', partial, url]);
  fs.renameSync(partial, zip);
  return zip;
}

function isExecutableName(name) {
  const base = path.posix.basename(name);
  if (FORCE_EXECUTABLE.has(base)) return true;
  if (/\.so(\.\d+)*$/.test(base)) return true;
  return !base.includes('.');
}

// jszip 会把 external attributes 的高 16 位解析成 unixPermissions；
// 个别条目缺失时按文件名兜底，宁可多给执行位也不能让主程序起不来。
function modeOf(entry, name) {
  const raw = entry.unixPermissions;
  const parsed = typeof raw === 'number' ? raw & 0o7777 : 0;
  if (parsed) return parsed;
  return isExecutableName(name) ? 0o755 : 0o644;
}

async function readRuntimeEntries(zipPath, arch) {
  const JSZip = require('jszip');
  const zip = await JSZip.loadAsync(fs.readFileSync(zipPath));
  const entries = [];
  let sawElectron = false;

  for (const name of Object.keys(zip.files)) {
    const entry = zip.files[name];
    if (entry.dir) continue;
    if (name.startsWith('locales/') && !KEEP_LOCALES.has(path.posix.basename(name))) continue;
    if (name === 'resources/default_app.asar') continue;

    // Electron Linux 包不该有符号链接；真出现了要显式失败，静默展开成副本
    // 会让产物体积翻倍且行为不可预期。
    const unixMode = typeof entry.unixPermissions === 'number' ? entry.unixPermissions : 0;
    if ((unixMode & 0o170000) === 0o120000) {
      throw new Error(`运行时包含未预期的符号链接：${name}`);
    }

    const target = name === 'electron' ? PRODUCT : name;
    if (name === 'electron') sawElectron = true;
    entries.push({
      name: target,
      mode: name === 'electron' ? 0o755 : modeOf(entry, name),
      data: await entry.async('nodebuffer')
    });
  }

  if (!sawElectron) throw new Error(`Electron 运行时缺少主可执行文件（linux-${arch}）`);
  return entries;
}

function skipDevFiles(e) {
  const name = e.name.toLowerCase();
  if (e.isDirectory()) return false;
  if (/\.(d\.ts|d\.ts\.map|ts|tsx|map|flow)$/.test(name)) return true;
  if (/^(readme|changelog|history|license|licence|notice|authors|contributing|security)/.test(name)) return true;
  if (/\.(md|markdown)$/.test(name)) return true;
  return false;
}

function collectDir(src, prefix, skip) {
  const out = [];
  for (const e of fs.readdirSync(src, { withFileTypes: true })) {
    if (skip && skip(e)) continue;
    const from = path.join(src, e.name);
    const to = path.posix.join(prefix, e.name);
    if (e.isDirectory()) out.push(...collectDir(from, to, skip));
    else out.push({ name: to, mode: 0o644, data: fs.readFileSync(from) });
  }
  return out;
}

function collectFile(src, name, mode = 0o644) {
  return { name, mode, data: fs.readFileSync(src) };
}

function appEntries() {
  const app = 'resources/app';
  const entries = [
    collectFile(path.join(ROOT, 'main.js'), `${app}/main.js`),
    collectFile(path.join(ROOT, 'preload.js'), `${app}/preload.js`),
    collectFile(
      path.join(ROOT, 'manga-online-preload.js'),
      `${app}/manga-online-preload.js`
    ),
    ...collectDir(path.join(ROOT, 'src'), `${app}/src`, (e) => e.name.startsWith('_test'))
  ];

  for (const name of ['book-ai-dark.ico', 'book-ai-light.ico']) {
    entries.push(collectFile(path.join(ROOT, 'icons', 'dist', name), `${app}/icons/dist/${name}`));
  }
  for (const theme of ['dark', 'light']) {
    // Linux 的 BrowserWindow 图标用 PNG：256 供窗口，32 供渲染层复用
    for (const size of [32, 256]) {
      entries.push(collectFile(
        path.join(ROOT, 'icons', 'dist', theme, `icon-${size}.png`),
        `${app}/icons/dist/${theme}/icon-${size}.png`
      ));
    }
  }

  const undici = path.join(ROOT, 'node_modules', 'undici');
  for (const name of ['package.json', 'index.js', 'index-fetch.js', 'LICENSE']) {
    const file = path.join(undici, name);
    if (fs.existsSync(file)) {
      entries.push(collectFile(file, `${app}/node_modules/undici/${name}`));
    }
  }
  entries.push(...collectDir(
    path.join(undici, 'lib'), `${app}/node_modules/undici/lib`, skipDevFiles
  ));

  const foliate = path.join(ROOT, 'node_modules', 'foliate-js');
  for (const name of ['package.json', 'LICENSE', 'mobi.js']) {
    entries.push(collectFile(path.join(foliate, name), `${app}/node_modules/foliate-js/${name}`));
  }
  entries.push(collectFile(
    path.join(foliate, 'vendor', 'fflate.js'),
    `${app}/node_modules/foliate-js/vendor/fflate.js`
  ));

  entries.push({
    name: `${app}/package.json`,
    mode: 0o644,
    data: Buffer.from(`${JSON.stringify({
      name: pkg.name, version: pkg.version, description: pkg.description,
      productName: PRODUCT,
      main: 'main.js', author: pkg.author, license: pkg.license,
      dependencies: {
        undici: pkg.dependencies.undici,
        'foliate-js': pkg.dependencies['foliate-js']
      }
    }, null, 2)}\n`, 'utf8')
  });

  return entries;
}

// 桌面集成留给用户自行安装，这里只给出可直接使用的启动脚本与 .desktop 模板。
// 不加 --no-sandbox：多数发行版开启了非特权用户命名空间，Electron 能正常起沙箱；
// 内核禁用该特性时才需要按 BUILD.md 给 chrome-sandbox 补 setuid。
function launcherEntries() {
  const launcher = `#!/bin/sh
set -e
HERE="$(dirname "$(readlink -f "$0")")"
exec "$HERE/${PRODUCT}" "$@"
`;
  const desktop = `[Desktop Entry]
Type=Application
Name=${PRODUCT}
Comment=${pkg.description}
Exec=${PRODUCT}.sh %U
Icon=${PRODUCT.toLowerCase()}
Terminal=false
Categories=Office;Viewer;
`;
  return [
    { name: `${PRODUCT}.sh`, mode: 0o755, data: Buffer.from(launcher, 'utf8') },
    { name: `${PRODUCT}.desktop`, mode: 0o644, data: Buffer.from(desktop, 'utf8') },
    collectFile(path.join(ROOT, 'icons', 'dist', 'dark', 'icon-256.png'), `${PRODUCT.toLowerCase()}.png`)
  ];
}

function octal(value, length) {
  // tar 的数字字段是定长八进制串，末位留给 NUL
  return Buffer.from(value.toString(8).padStart(length - 1, '0') + '\0', 'ascii');
}

function tarHeader({ name, mode, size, typeflag }) {
  const header = Buffer.alloc(512);
  header.write(name, 0, 100, 'utf8');
  octal(mode & 0o7777, 8).copy(header, 100);
  octal(0, 8).copy(header, 108);          // uid
  octal(0, 8).copy(header, 116);          // gid
  octal(size, 12).copy(header, 124);
  octal(MTIME, 12).copy(header, 136);
  header.write('        ', 148, 8, 'ascii'); // 计算校验和时该字段视为空格
  header.write(typeflag, 156, 1, 'ascii');
  header.write('ustar\0', 257, 6, 'ascii');
  header.write('00', 263, 2, 'ascii');
  header.write('root', 265, 32, 'ascii');
  header.write('root', 297, 32, 'ascii');

  let sum = 0;
  for (const byte of header) sum += byte;
  header.write(sum.toString(8).padStart(6, '0') + '\0 ', 148, 8, 'ascii');
  return header;
}

function padding(size) {
  const remainder = size % 512;
  return remainder ? Buffer.alloc(512 - remainder) : Buffer.alloc(0);
}

// 路径超过 100 字节时用 PAX 扩展头承载完整路径。ustar 的 prefix 字段只能在
// 斜杠处切分，undici 与 vendor 里的深层路径切不出合法组合，必须走 PAX。
function paxRecords(fullName) {
  const record = (key, value) => {
    const body = ` ${key}=${value}\n`;
    let length = Buffer.byteLength(body) + 1;
    while (Buffer.byteLength(`${length}${body}`) !== length) length += 1;
    return Buffer.from(`${length}${body}`, 'utf8');
  };
  return record('path', fullName);
}

function tarEntry(fullName, mode, data, typeflag = '0') {
  const chunks = [];
  const nameBytes = Buffer.byteLength(fullName, 'utf8');

  if (nameBytes > 100) {
    const records = paxRecords(fullName);
    chunks.push(tarHeader({
      name: `PaxHeader/${path.posix.basename(fullName).slice(0, 80)}`,
      mode: 0o644,
      size: records.length,
      typeflag: 'x'
    }));
    chunks.push(records, padding(records.length));
  }

  chunks.push(tarHeader({
    // 超长路径已由 PAX 头给出，这里的截断名只是给不支持 PAX 的工具看的回退值
    name: nameBytes > 100 ? fullName.slice(-100) : fullName,
    mode,
    size: data.length,
    typeflag
  }));
  chunks.push(data, padding(data.length));
  return Buffer.concat(chunks);
}

function writeTarGz(entries, root, outFile) {
  const seen = new Set();
  const chunks = [];
  const sorted = [...entries].sort((a, b) => (a.name < b.name ? -1 : a.name > b.name ? 1 : 0));

  for (const entry of sorted) {
    const full = path.posix.join(root, entry.name);
    if (seen.has(full)) throw new Error(`打包条目重复：${full}`);
    seen.add(full);
    chunks.push(tarEntry(full, entry.mode, entry.data));
  }
  chunks.push(Buffer.alloc(1024)); // tar 以两个空块收尾

  const gz = zlib.gzipSync(Buffer.concat(chunks), { level: 9, mtime: 0 });
  fs.mkdirSync(path.dirname(outFile), { recursive: true });
  fs.writeFileSync(outFile, gz);
  return gz.length;
}

async function build() {
  const arch = parseArch(process.argv.slice(2));
  const target = `${PRODUCT}-linux-${arch}`;
  const outFile = path.join(ROOT, 'dist', `${target}.tar.gz`);

  const zip = ensureRuntimeZip(arch);
  console.log('读取 Electron 运行时（保留可执行位）...');
  const runtime = await readRuntimeEntries(zip, arch);

  console.log('组装 app 源码...');
  const entries = [...runtime, ...appEntries(), ...launcherEntries()];

  console.log('生成 tar.gz...');
  const size = writeTarGz(entries, target, outFile);

  console.log('\n构建完成:');
  console.log('  架构:', arch);
  console.log('  产物:', outFile, `(${(size / 1024 / 1024).toFixed(1)} MB)`);
  console.log('  解压后运行:', `./${target}/${PRODUCT}.sh`);
}

module.exports = { parseArch, isExecutableName, modeOf, tarEntry, writeTarGz };

if (require.main === module) {
  build().catch((error) => {
    console.error('构建失败:', error && error.message ? error.message : error);
    process.exitCode = 1;
  });
}