// extract.js - 把 webpack bundle 拆成可读源码工程
// 用法: node extract.js [bundle路径] [输出目录]
//   默认 bundle = ../../main.6469b966.js（TankIC 根目录）
//   默认输出  = ../src
// 输出:
//   src/module_<id>.js      每个代码模块（prettier 美化）
//   src/resources.json      资源模块 ID → 路径
//   src/index.json          模块索引（id / 文件 / 是否资源）
const fs = require('fs');
const path = require('path');
const acorn = require('acorn');
const walk = require('acorn-walk');
const prettier = require('prettier');

const PROJECT = path.resolve(__dirname, '..');
const argv = process.argv.slice(2).filter((a) => !a.startsWith('--'));
const BUNDLE_PATH = path.resolve(argv[0] || path.join(PROJECT, '..', 'main.6469b966.js'));
const SRC_DIR = path.resolve(argv[1] || path.join(PROJECT, 'src'));
const RESOURCES_JSON = path.join(SRC_DIR, 'resources.json');
const INDEX_JSON = path.join(SRC_DIR, 'index.json');

function tryExtractResource(valueSrc) {
  let m = valueSrc.match(/\{\s*"use strict";\s*(?:t|n|i)\.exports\s*=\s*(?:t|n|i)\.p\+"([^"]+)"\s*;?\s*\}/);
  if (m) return m[1];
  m = valueSrc.match(/(?:t|n|i)\.exports\s*=\s*(?:t|n|i)\.p\+"([^"]+)"\s*;?/);
  if (m && valueSrc.length < 200) return m[1];
  return null;
}

(async () => {
  if (!fs.existsSync(BUNDLE_PATH)) {
    console.error('找不到 bundle: ' + BUNDLE_PATH);
    process.exit(1);
  }
  if (!fs.existsSync(SRC_DIR)) fs.mkdirSync(SRC_DIR, { recursive: true });
  // 清理旧产物
  for (const f of fs.readdirSync(SRC_DIR)) {
    if (/^module_\d+\.js$/.test(f) || f === 'resources.json' || f === 'index.json') {
      fs.unlinkSync(path.join(SRC_DIR, f));
    }
  }

  console.log('[1/4] 读取 bundle: ' + BUNDLE_PATH);
  const source = fs.readFileSync(BUNDLE_PATH, 'utf8');
  console.log('      大小: ' + (source.length / 1024 / 1024).toFixed(2) + ' MB');

  console.log('[2/4] 解析 AST...');
  const ast = acorn.parse(source, {
    ecmaVersion: 'latest',
    sourceType: 'script',
    allowReturnOutsideFunction: true,
  });
  let modulesDecl = null;
  walk.simple(ast, {
    VariableDeclarator(node) {
      if (node.id && node.id.name === '__webpack_modules__' && node.init && node.init.type === 'ObjectExpression') {
        modulesDecl = node;
      }
    },
  });
  if (!modulesDecl) throw new Error('未找到 __webpack_modules__');

  console.log('[3/4] 拆分模块...');
  const props = modulesDecl.init.properties;
  const resourceMap = {};
  const index = [];
  let codeCount = 0, resourceCount = 0, failCount = 0;

  for (const prop of props) {
    let keyRaw, keyNum;
    if (prop.key.type === 'Identifier') {
      keyRaw = prop.key.name;
      keyNum = Number(keyRaw);
    } else {
      keyRaw = String(prop.key.value);
      keyNum = typeof prop.key.value === 'number' ? prop.key.value : keyRaw;
    }
    const valueSrc = source.slice(prop.value.start, prop.value.end);
    const resourcePath = tryExtractResource(valueSrc);
    if (resourcePath) {
      resourceMap[keyNum] = resourcePath;
      resourceCount++;
      index.push({ id: keyNum, type: 'resource', path: resourcePath });
      continue;
    }

    let beautified = valueSrc;
    try {
      beautified = await prettier.format('(' + valueSrc + ')', {
        parser: 'babel',
        semi: true,
        singleQuote: false,
        printWidth: 110,
        tabWidth: 2,
      });
      beautified = beautified.trim();
      if (beautified.startsWith('(') && beautified.endsWith(')')) beautified = beautified.slice(1, -1).trim();
      while (beautified.endsWith(';')) beautified = beautified.slice(0, -1).trimEnd();
    } catch (e) {
      failCount++;
    }

    const padded = String(keyNum).padStart(5, '0');
    const file = 'module_' + padded + '.js';
    const header =
      '// ============================================================\n' +
      '// Module ID: ' + keyRaw + '\n' +
      '// ============================================================\n';
    fs.writeFileSync(path.join(SRC_DIR, file), header + ';(window.__modules__ = window.__modules__ || {})[' + keyNum + '] = ' + beautified + ';\n', 'utf8');
    codeCount++;
    index.push({ id: keyNum, type: 'code', file });
  }

  console.log('[4/4] 写 resources.json / index.json...');
  fs.writeFileSync(RESOURCES_JSON, JSON.stringify({ type: 'webpack-resource-map', resourceMap }, null, 0), 'utf8');
  fs.writeFileSync(INDEX_JSON, JSON.stringify({ bundle: path.basename(BUNDLE_PATH), modules: index }, null, 1), 'utf8');

  console.log('代码模块 ' + codeCount + ' / 资源模块 ' + resourceCount + ' / 美化失败 ' + failCount);
  console.log('输出目录: ' + SRC_DIR);
})().catch((err) => {
  console.error('Fatal:', err);
  process.exit(1);
});