#!/usr/bin/env node
/* 等价回归验证（UniForge verify 工具）
 * 用法：node scripts/equiv-regression.js <页面路径（相对 cfc-frontend）>
 * 例：node scripts/equiv-regression.js pages/index-home/index.vue
 *
 * 原理：uni-app 将 uni.scss prepend 到每个页面 style。
 * 取 HEAD 版与工作区版分别拼接 uni.scss 编译，hex 大小写/3-6 位归一后逐字节比对。
 * 全部令牌同值映射时，产物应完全相同 → 证明零观感变化。
 */
const { execSync } = require('child_process')
const fs = require('fs')
const path = require('path')

const PAGE = process.argv[2]
if (!PAGE) {
  console.error('用法: node scripts/equiv-regression.js <页面路径>')
  process.exit(2)
}

const ROOT = path.resolve(__dirname, '..')
const REPO = path.resolve(ROOT, '..')
const REL = path.relative(REPO, path.join(ROOT, PAGE)).split(path.sep).join('/')
const TMP = path.join(ROOT, '.tmp_equiv')
fs.mkdirSync(TMP, { recursive: true })

function extractStyle(src) {
  const m = src.match(/<style[^>]*>([\s\S]*?)<\/style>/)
  if (!m) throw new Error('未找到 style 块: ' + PAGE)
  return m[1]
}

const uniScss = fs.readFileSync(path.join(ROOT, 'uni.scss'), 'utf8')
const afterVue = fs.readFileSync(path.join(ROOT, PAGE), 'utf8')
const beforeVue = execSync(`git -C "${REPO}" show HEAD:${REL}`, { encoding: 'utf8', maxBuffer: 1e8 })

fs.writeFileSync(path.join(TMP, 'after.scss'), uniScss + '\n' + extractStyle(afterVue))
fs.writeFileSync(path.join(TMP, 'before.scss'), uniScss + '\n' + extractStyle(beforeVue))

const sass = path.join(ROOT, 'node_modules/.bin/sass.cmd')
execSync(`"${sass}" --no-source-map "${TMP}/after.scss" "${TMP}/after.out.css"`, { stdio: 'pipe' })
execSync(`"${sass}" --no-source-map "${TMP}/before.scss" "${TMP}/before.out.css"`, { stdio: 'pipe' })

function norm(s) {
  return s
    .replace(/#([0-9a-fA-F]{3,8})\b/g, (m) => {
      let h = m.slice(1).toUpperCase()
      if (h.length === 3) h = h.split('').map((c) => c + c).join('')
      return '#' + h
    })
    .split('\n').map((l) => l.trim()).filter(Boolean).join('\n')
}

const before = norm(fs.readFileSync(path.join(TMP, 'before.out.css'), 'utf8'))
const after = norm(fs.readFileSync(path.join(TMP, 'after.out.css'), 'utf8'))

if (before === after) {
  console.log(`等价回归 PASS（${PAGE}）：编译产物归一后逐字节相同，零观感变化`)
} else {
  const bl = before.split('\n'), al = after.split('\n')
  console.log(`等价回归 DIFF（${PAGE}）：before ${bl.length} 行 / after ${al.length} 行`)
  let shown = 0
  for (let i = 0; i < Math.max(bl.length, al.length) && shown < 40; i++) {
    if (bl[i] !== al[i]) {
      console.log(`L${i + 1}\n  before: ${bl[i]}\n  after:  ${al[i]}`)
      shown++
    }
  }
  if (shown >= 40) console.log('...（仅显示前 40 处差异）')
  process.exit(1)
}