const fs = require('node:fs')
const path = require('node:path')
const { spawnSync } = require('node:child_process')
const runner = require.resolve('@tarojs/webpack5-runner')
const postcss = require(require.resolve('postcss', { paths: [runner] }))
const parseSelector = require(require.resolve('postcss-selector-parser', { paths: [runner] }))
const dist = path.resolve(__dirname, '../dist')

function collect(folder) {
  return fs.readdirSync(folder, { withFileTypes: true }).flatMap(entry => {
    const file = path.join(folder, entry.name)
    return entry.isDirectory() ? collect(file) : file.endsWith('.wxss') ? [file] : []
  })
}

function validateWxss(css, label) {
  postcss.parse(css).walkRules(rule => {
    if (rule.parent.type === 'atrule' && /keyframes$/i.test(rule.parent.name)) return
    parseSelector(selectors => selectors.walkUniversals(() => {
      throw new Error(`${label}：WXSS 不支持通配选择器 ${rule.selector}`)
    })).processSync(rule.selector)
    parseSelector(selectors => selectors.walkPseudos(pseudo => {
      if (/^:(?:first|last|nth|only)-(?:child|of-type)$/.test(pseudo.value)
        && (!pseudo.prev() || pseudo.prev().type === 'combinator')) {
        throw new Error(`${label}：WXSS 结构伪类前需明确元素或类名 ${rule.selector}`)
      }
    })).processSync(rule.selector)
  })
}

function main() {
  if (!fs.existsSync(path.join(dist, 'app.wxss'))) throw new Error('请先构建微信小程序')
  const files = collect(dist)
  for (const file of files) validateWxss(fs.readFileSync(file, 'utf8'), path.relative(dist, file))
  console.log(`WXSS 选择器兼容检查通过：${files.length} 个文件`)

  const compiler = process.env.WECHAT_WXSS_COMPILER
    || '/Applications/wechatwebdevtools.app/Contents/Resources/app.asar.unpacked/node_modules/wcc-exec/wcsc'
  if (!fs.existsSync(compiler)) {
    if (process.env.WECHAT_WXSS_COMPILER) throw new Error('指定的微信 WXSS 编译器不存在')
    console.warn('未找到微信原生 WXSS 编译器：本次仅完成静态检查，仍需开发者工具编译验收。可设置 WECHAT_WXSS_COMPILER。')
  } else {
    // The native compiler resolves @import from its supplied file collection.
    const result = spawnSync(compiler, ['-lc', '-pc', String(files.length), ...files.map(file => `./${path.relative(dist, file)}`)], {
      cwd: dist, encoding: 'utf8', maxBuffer: 16 * 1024 * 1024
    })
    if (result.error) throw result.error
    if (result.status !== 0) throw new Error(`微信原生编译失败：${result.stderr.slice(0, 3000)}`)
    console.log(`微信原生 WXSS 编译通过：${files.length} 个文件`)
  }
}

module.exports = { validateWxss }
if (require.main === module) main()