#!/usr/bin/env node
/**
 * webpack bundle 解包器
 * 识别 __webpack_modules__ 结构，按模块 ID 拆分为独立文件
 * 
 * 用法: node unpack-webpack.js <bundle.js> <output-dir>
 */

const fs = require('fs');
const path = require('path');

function unpackWebpackBundle(bundlePath, outputDir) {
  const code = fs.readFileSync(bundlePath, 'utf-8');
  
  let modules = null;
  
  // 模式1: __webpack_modules__ = { 123: function(module, exports, __webpack_require__) {...}, ... }
  const modulesAssignMatch = code.match(/__webpack_modules__\s*=\s*(\{[\s\S]*?\});/);
  // 模式2: (function(modules) { ... })({ 123: function(...) {...}, ... })
  const iifeMatch = code.match(/\(function\(\s*\w+\s*\)\s*\{[\s\S]*?\}\s*\)\s*\(\s*(\{[\s\S]*?\})\s*\)\s*;/);
  
  if (modulesAssignMatch) {
    modules = eval('(' + modulesAssignMatch[1] + ')');
  } else if (iifeMatch) {
    modules = eval('(' + iifeMatch[1] + ')');
  } else {
    console.error('未识别到 webpack 模块结构，尝试按 function(module, exports) 正则提取');
    modules = extractByRegex(code);
  }
  
  if (!modules || Object.keys(modules).length === 0) {
    console.error('未能提取任何模块');
    process.exit(1);
  }
  
  fs.mkdirSync(outputDir, { recursive: true });
  
  let count = 0;
  for (const [id, factory] of Object.entries(modules)) {
    const moduleCode = typeof factory === 'function' 
      ? factory.toString() 
      : JSON.stringify(factory, null, 2);
    
    const safeId = String(id).replace(/[^a-zA-Z0-9_-]/g, '_');
    fs.writeFileSync(path.join(outputDir, `module_${safeId}.js`), moduleCode);
    count++;
  }
  
  console.log(`拆解完成: ${count} 个模块 → ${outputDir}`);
  return count;
}

function extractByRegex(code) {
  const modules = {};
  const re = /(\d+):\s*function\s*\(\s*\w+\s*,\s*\w+\s*,\s*\w+\s*\)\s*\{/g;
  
  let match;
  const matches = [];
  
  while ((match = re.exec(code)) !== null) {
    matches.push({ id: match[1], start: match.index });
  }
  
  for (let i = 0; i < matches.length; i++) {
    const current = matches[i];
    const next = matches[i + 1];
    const startIdx = current.start;
    const endIdx = next ? next.start : code.length;
    
    let depth = 1;
    let pos = startIdx + current[0].length;
    while (depth > 0 && pos < endIdx) {
      if (code[pos] === '{') depth++;
      if (code[pos] === '}') depth--;
      pos++;
    }
    
    const funcBody = code.substring(startIdx, pos);
    modules[current.id] = funcBody;
  }
  
  return modules;
}

// CLI
const args = process.argv.slice(2);
if (args.length < 2) {
  console.log('用法: node unpack-webpack.js <bundle.js> <output-dir>');
  process.exit(1);
}

unpackWebpackBundle(args[0], args[1]);