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

const IMG_DIR = path.join(__dirname, 'src', 'img')
const QUALITY = 60       // JPG 质量
const MAX_WIDTH = 800    // 最长边限制
const MAX_FILE_KB = 80   // 单张上限 KB —— 强制压到 80KB 以下

/**
 * 压缩单个文件（强制覆盖）
 */
async function compressFile(inputPath) {
  const ext = path.extname(inputPath).toLowerCase()
  const dir = path.dirname(inputPath)
  const base = path.basename(inputPath, ext)
  const finalPath = path.join(dir, base + '.jpg')
  const isAlreadyJpg = ext === '.jpg' || ext === '.jpeg'

  const stat = fs.statSync(inputPath)
  const currentKb = stat.size / 1024

  // 如果已经 .jpg、体积已小于上限、且最长边不超，跳过
  if (isAlreadyJpg && currentKb <= MAX_FILE_KB) {
    const meta = await sharp(inputPath).metadata()
    const longEdge = Math.max(meta.width || 0, meta.height || 0)
    if (longEdge <= MAX_WIDTH) {
      console.log(`skip ${inputPath} (${currentKb.toFixed(1)}KB, ${longEdge}px)`)
      return { from: inputPath, to: inputPath, size: stat.size }
    }
  }

  // 重建 pipeline
  const meta = await sharp(inputPath).metadata()
  const longEdge = Math.max(meta.width || 0, meta.height || 0)
  const resizeOpts = longEdge > MAX_WIDTH ? { width: MAX_WIDTH, height: MAX_WIDTH, fit: 'inside' } : undefined

  let pipeline = sharp(inputPath).jpeg({ quality: QUALITY, progressive: true, force: true })
  if (resizeOpts) pipeline = pipeline.resize(resizeOpts)

  const tmpPath = path.join(dir, base + '_tmp.jpg')
  await pipeline.toFile(tmpPath)

  fs.unlinkSync(inputPath)
  fs.renameSync(tmpPath, finalPath)

  const newSize = fs.statSync(finalPath).size
  console.log(
    `${isAlreadyJpg ? 'compress' : 'convert'} ${base}${ext}  (${currentKb.toFixed(1)}KB, ${longEdge}px → ${(newSize / 1024).toFixed(1)}KB)`
  )

  return { from: inputPath, to: finalPath, size: newSize }
}

/**
 * 递归收集所有图片
 */
function collectImages(dir) {
  let results = []
  const entries = fs.readdirSync(dir, { withFileTypes: true })
  for (const entry of entries) {
    const full = path.join(dir, entry.name)
    if (entry.isDirectory()) {
      results = results.concat(collectImages(full))
    } else if (/\.(png|jpe?g)$/i.test(entry.name)) {
      results.push(full)
    }
  }
  return results
}

/**
 * 主函数
 */
async function main() {
  console.log(`scanning ${IMG_DIR}...\n`)
  const images = collectImages(IMG_DIR)
  console.log(`found ${images.length} images\n`)

  let totalBefore = 0
  let totalAfter = 0

  for (const img of images) {
    totalBefore += fs.statSync(img).size
    const result = await compressFile(img)
    totalAfter += result.size
  }

  console.log(`\n✅ done`)
  console.log(`   before: ${(totalBefore / 1024 / 1024).toFixed(2)} MB`)
  console.log(`   after:  ${(totalAfter / 1024 / 1024).toFixed(2)} MB`)
  console.log(`   saved:  ${((totalBefore - totalAfter) / 1024 / 1024).toFixed(2)} MB`)
}

main().catch(err => {
  console.error(err)
  process.exit(1)
})