const { BundleAnalyzerPlugin } = require('webpack-bundle-analyzer')
const webpack = require('webpack')
const path = require('path')
const fs = require('fs')

// 获取webpack配置
const webpackConfig = require('../webpack.config.js')

// 添加分析插件
const analyzeConfig = {
  ...webpackConfig,
  plugins: [
    ...webpackConfig.plugins,
    new BundleAnalyzerPlugin({
      analyzerMode: 'static',
      reportFilename: 'bundle-report.html',
      openAnalyzer: true,
      generateStatsFile: true,
      statsFilename: 'bundle-stats.json',
      statsOptions: null,
      logLevel: 'info'
    })
  ]
}

// 运行分析
console.log('🔍 开始分析打包结果...')

webpack(analyzeConfig, (err, stats) => {
  if (err) {
    console.error('❌ 分析失败:', err)
    return
  }

  if (stats.hasErrors()) {
    console.error('❌ 构建过程中出现错误:')
    stats.compilation.errors.forEach(error => {
      console.error(error)
    })
    return
  }

  console.log('✅ 分析完成!')
  console.log('📊 报告文件已生成:')
  console.log('  - bundle-report.html (可视化报告)')
  console.log('  - bundle-stats.json (详细统计)')

  // 生成简单的性能报告
  const statsData = stats.toJson()
  const report = generatePerformanceReport(statsData)
  
  fs.writeFileSync(
    path.join(__dirname, '../performance-report.md'),
    report,
    'utf8'
  )
  
  console.log('  - performance-report.md (性能报告)')
})

function generatePerformanceReport(stats) {
  const assets = stats.assets || []
  const chunks = stats.chunks || []
  const modules = stats.modules || []

  // 按类型分组资源
  const assetsByType = {
    js: assets.filter(asset => asset.name.endsWith('.js')),
    css: assets.filter(asset => asset.name.endsWith('.css')),
    images: assets.filter(asset => /\.(png|jpg|jpeg|gif|svg|webp)$/.test(asset.name)),
    fonts: assets.filter(asset => /\.(woff|woff2|eot|ttf|otf)$/.test(asset.name)),
    other: assets.filter(asset => 
      !asset.name.endsWith('.js') && 
      !asset.name.endsWith('.css') && 
      !/\.(png|jpg|jpeg|gif|svg|webp|woff|woff2|eot|ttf|otf)$/.test(asset.name)
    )
  }

  // 计算总大小
  const totalSize = assets.reduce((sum, asset) => sum + asset.size, 0)
  const jsSize = assetsByType.js.reduce((sum, asset) => sum + asset.size, 0)
  const cssSize = assetsByType.css.reduce((sum, asset) => sum + asset.size, 0)

  // 生成报告
  const report = `# 性能分析报告

## 📊 构建统计

- **总文件数**: ${assets.length}
- **总大小**: ${formatBytes(totalSize)}
- **JS文件**: ${assetsByType.js.length} 个，${formatBytes(jsSize)}
- **CSS文件**: ${assetsByType.css.length} 个，${formatBytes(cssSize)}
- **图片文件**: ${assetsByType.images.length} 个
- **字体文件**: ${assetsByType.fonts.length} 个
- **其他文件**: ${assetsByType.other.length} 个

## 🎯 主要JS文件

${assetsByType.js
  .sort((a, b) => b.size - a.size)
  .slice(0, 10)
  .map(asset => `- **${asset.name}**: ${formatBytes(asset.size)}`)
  .join('\n')}

## 🎨 CSS文件

${assetsByType.css
  .sort((a, b) => b.size - a.size)
  .map(asset => `- **${asset.name}**: ${formatBytes(asset.size)}`)
  .join('\n')}

## 📦 Chunk分析

${chunks
  .sort((a, b) => b.size - a.size)
  .slice(0, 10)
  .map(chunk => `- **${chunk.names.join(', ')}**: ${formatBytes(chunk.size)}`)
  .join('\n')}

## 🔍 大文件警告

${assets
  .filter(asset => asset.size > 1024 * 1024) // 1MB以上
  .sort((a, b) => b.size - a.size)
  .map(asset => `- ⚠️ **${asset.name}**: ${formatBytes(asset.size)} (建议优化)`)
  .join('\n') || '✅ 没有超过1MB的文件'}

## 📈 性能建议

### 🚀 已实施的优化
- ✅ 代码分割 (${chunks.length} 个chunk)
- ✅ 资源压缩
- ✅ 缓存策略
- ✅ 预加载关键资源

### 🎯 进一步优化建议
${generateOptimizationSuggestions(assets, chunks)}

---
*报告生成时间: ${new Date().toLocaleString()}*
`

  return report
}

function generateOptimizationSuggestions(assets, chunks) {
  const suggestions = []
  
  // 检查大文件
  const largeFiles = assets.filter(asset => asset.size > 500 * 1024) // 500KB以上
  if (largeFiles.length > 0) {
    suggestions.push('- 考虑进一步分割大文件或使用动态导入')
  }
  
  // 检查chunk数量
  if (chunks.length > 20) {
    suggestions.push('- Chunk数量较多，考虑合并相关功能')
  }
  
  // 检查图片优化
  const images = assets.filter(asset => /\.(png|jpg|jpeg|gif|svg)$/.test(asset.name))
  const largeImages = images.filter(asset => asset.size > 100 * 1024) // 100KB以上
  if (largeImages.length > 0) {
    suggestions.push('- 优化大图片，考虑使用WebP格式')
  }
  
  if (suggestions.length === 0) {
    suggestions.push('- 当前配置已经相当优化！')
  }
  
  return suggestions.join('\n')
}

function formatBytes(bytes) {
  if (bytes === 0) return '0 Bytes'
  const k = 1024
  const sizes = ['Bytes', 'KB', 'MB', 'GB']
  const i = Math.floor(Math.log(bytes) / Math.log(k))
  return parseFloat((bytes / Math.pow(k, i)).toFixed(2)) + ' ' + sizes[i]
}