/**
 * Build script: copy src → dist, minify JS/CSS, inline critical CSS (Critters).
 * Run with: pnpm build
 */
import {
  rmSync,
  mkdirSync,
  readFileSync,
  writeFileSync,
  cpSync,
  readdirSync
} from 'fs'
import { join, dirname, extname } from 'path'
import { fileURLToPath } from 'url'
import Critters from 'critters'
import { minify as minifyJs } from 'terser'
import CleanCSS from 'clean-css'

const __dirname = dirname(fileURLToPath(import.meta.url))
const root = join(__dirname, '..')
const srcDir = join(root, 'src')
const distDir = join(root, 'dist')

function getFiles(dir, files = []) {
  const entries = readdirSync(dir, { withFileTypes: true })
  for (const e of entries) {
    const full = join(dir, e.name)
    if (e.isDirectory()) getFiles(full, files)
    else files.push(full)
  }
  return files
}

async function main() {
  // 1. Clean and copy src → dist
  rmSync(distDir, { recursive: true, force: true })
  mkdirSync(distDir, { recursive: true })
  cpSync(srcDir, distDir, { recursive: true })

  const distFiles = getFiles(distDir)

  // 2. Minify JS
  const jsFiles = distFiles.filter((f) => extname(f) === '.js')
  for (const f of jsFiles) {
    const code = readFileSync(f, 'utf8')
    const result = await minifyJs(code, { format: { comments: false } })
    if (result.code) writeFileSync(f, result.code)
  }

  // 3. Minify CSS
  const cleanCss = new CleanCSS({ level: 2 })
  const cssFiles = distFiles.filter((f) => extname(f) === '.css')
  for (const f of cssFiles) {
    const code = readFileSync(f, 'utf8')
    const result = cleanCss.minify(code)
    if (!result.errors.length) writeFileSync(f, result.styles)
  }

  // 4. Inline critical CSS with Critters (no browser; works in CI)
  const critters = new Critters({
    path: distDir,
    preload: 'default',
    logLevel: 'warn'
  })
  const indexPath = join(distDir, 'index.html')
  const html = readFileSync(indexPath, 'utf8')
  const inlined = await critters.process(html)
  writeFileSync(indexPath, inlined)

  console.log('Build complete: dist/')
}

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