import sharp from 'sharp'
import { readdir, stat, rename, unlink } from 'fs/promises'
import { join, extname } from 'path'

const IMAGE_DIR = 'src/assets/images'
const IMAGE_EXTENSIONS = ['.png', '.jpg', '.jpeg']
const SIZE_THRESHOLD = 500 * 1024 // 500KB

// 计算文件大小（KB）
function formatSize(bytes) {
  return (bytes / 1024).toFixed(2) + ' KB'
}

// 压缩单个图片 - 更激进的压缩策略
async function compressImage(fileName) {
  const ext = extname(fileName).toLowerCase()
  const inputPath = join(IMAGE_DIR, fileName)
  const tempPath = join(IMAGE_DIR, 'temp_' + fileName)

  try {
    const inputStats = await stat(inputPath)
    const inputSize = inputStats.size

    // 如果文件小于 500KB，跳过
    if (inputSize < SIZE_THRESHOLD) {
      console.log(`⏭️  ${fileName} (${formatSize(inputSize)}) - 跳过`)
      return null
    }

    let pipeline = sharp(inputPath)

    // 首先调整尺寸（如果图片太大）
    const metadata = await pipeline.metadata()
    const maxWidth = 1920
    const maxHeight = 1080

    if (metadata.width > maxWidth || metadata.height > maxHeight) {
      pipeline = pipeline.resize(maxWidth, maxHeight, {
        fit: 'inside',
        withoutEnlargement: true
      })
    }

    // 根据图片类型设置更激进的压缩参数
    if (ext === '.png') {
      // PNG 转为 PNG 但使用更激进的设置
      pipeline = pipeline.png({
        compressionLevel: 9,
        palette: true,
        quality: 60,
        dither: 1
      })
    } else if (ext === '.jpg' || ext === '.jpeg') {
      pipeline = pipeline.jpeg({
        quality: 70,
        mozjpeg: true,
        progressive: true
      })
    }

    // 执行压缩到临时文件
    await pipeline.toFile(tempPath)

    const outputStats = await stat(tempPath)
    const outputSize = outputStats.size

    // 如果压缩后仍然很大，考虑转为 WebP
    if (outputSize > SIZE_THRESHOLD && ext === '.png') {
      console.log(`🔄 ${fileName} - 转为 WebP 格式`)
      await pipeline.webp({ quality: 75 }).toFile(tempPath)
      const webpStats = await stat(tempPath)
      console.log(`   原始：${formatSize(inputSize)} → WebP: ${formatSize(webpStats.size)}`)
    }

    // 删除原文件并重命名临时文件
    await unlink(inputPath)
    await rename(tempPath, inputPath)

    const finalStats = await stat(inputPath)
    const finalSize = finalStats.size

    const savings = ((inputSize - finalSize) / inputSize * 100).toFixed(1)

    console.log(`✅ ${fileName}`)
    console.log(`   原始：${formatSize(inputSize)} → 压缩后：${formatSize(finalSize)} (节省 ${savings}%)`)

    return { inputSize, outputSize: finalSize, savings }
  } catch (error) {
    console.error(`❌ 压缩失败 ${fileName}:`, error.message)
    // 清理临时文件（如果存在）
    try {
      await unlink(tempPath)
    } catch (e) {
      // 忽略
    }
    return null
  }
}

// 主函数
async function main() {
  console.log('🚀 开始优化大图片（>500KB）...\n')

  const files = await readdir(IMAGE_DIR)
  const imageFiles = files.filter(file => 
    IMAGE_EXTENSIONS.includes(extname(file).toLowerCase())
  )
  
  if (imageFiles.length === 0) {
    console.log('⚠️  未找到图片')
    return
  }

  // 先找出所有大于 500KB 的图片
  const largeImages = []
  for (const file of imageFiles) {
    const stats = await stat(join(IMAGE_DIR, file))
    if (stats.size > SIZE_THRESHOLD) {
      largeImages.push({ name: file, size: stats.size })
    }
  }

  if (largeImages.length === 0) {
    console.log('✅ 所有图片都已小于 500KB，无需进一步优化！')
    return
  }

  console.log(`📁 找到 ${largeImages.length} 张大图片需要优化：\n`)
  largeImages.forEach(img => {
    console.log(`   - ${img.name}: ${formatSize(img.size)}`)
  })
  console.log()

  let totalInput = 0
  let totalOutput = 0
  let successCount = 0

  for (const file of imageFiles) {
    const result = await compressImage(file)
    if (result) {
      totalInput += result.inputSize
      totalOutput += result.outputSize
      successCount++
      console.log()
    }
  }

  if (successCount === 0) {
    console.log('\n✅ 没有需要优化的大图片')
    return
  }

  const totalSavings = ((totalInput - totalOutput) / totalInput * 100).toFixed(1)

  console.log('='.repeat(50))
  console.log(`📊 优化完成！`)
  console.log(`   成功：${successCount} 张`)
  console.log(`   原始总大小：${formatSize(totalInput)}`)
  console.log(`   优化后总大小：${formatSize(totalOutput)}`)
  console.log(`   总计节省：${totalSavings}% (${formatSize(totalInput - totalOutput)})`)
  console.log('='.repeat(50))
}

// 运行
main().catch(console.error)