const postcss = require('postcss')
const uniPostcss = require('@dcloudio/vue-cli-plugin-uni/packages/postcss')

function toVw(value) {
  return value.replace(/%\?([+-]?\d+(?:\.\d+)?)\?%/g, (match, number) => {
    const rpx = Number(number)
    if (!Number.isFinite(rpx)) {
      return match
    }
    const vw = Number((rpx / 7.5).toFixed(6)).toString()
    return vw === '0' ? '0' : `${vw}vw`
  })
}

const rpxPlaceholderToVw = postcss.plugin('rpx-placeholder-to-vw', () => {
  return root => {
    root.walkDecls(decl => {
      if (decl.value && decl.value.includes('%?')) {
        decl.value = toVw(decl.value)
      }
    })

    root.walkAtRules(atRule => {
      if (atRule.params && atRule.params.includes('%?')) {
        atRule.params = toVw(atRule.params)
      }
    })
  }
})

module.exports = {
  plugins: [
    uniPostcss(),
    rpxPlaceholderToVw()
  ]
}