#!/usr/bin/env node
const stylelint = require('stylelint')
const {readFileSync, writeFileSync} = require('fs')

const files = process.argv.slice(2)
if (files.length === 0) {
  files.push('src/**/*.scss')
}

// we use an empty "marker" to delineate removed lines
const REMOVED = `===REMOVED@${Date.now()}===`

stylelint.lint({files, reportNeedlessDisables: true}).then(({needlessDisables}) => {
  for (const {source, ranges} of needlessDisables) {
    const lines = readFileSync(source, 'utf8').split(/\n/)
    let offset = 0
    for (const {start, unusedRule} of ranges) {
      let index = start - 1
      let line = lines[index]
      let disable = parseDisableComment(line)
      if (!disable) {
        console.warn(`unable to parse disable on line ${start}: ${lines[start - 1]}; trying previous line...`)
        index--
        line = lines[index]
        disable = parseDisableComment(line)
        if (!disable) {
          console.warn(`unable to parse disable on line ${index + 1}: ${lines}`)
          continue
        }
      }

      const rules = new Set(disable.rules)
      rules.delete(unusedRule)

      if (rules.size === 0) {
        console.log(`- ${line}`)
        lines[index] = REMOVED
      } else {
        const replacement = line.replace(disable.content, `${disable.type} ${Array.from(rules).join(', ')}`)
        lines[index] = replacement
        console.log(`- ${line}`)
        console.log(`+ ${replacement}`)
      }
    }
    const output = lines.filter(line => line !== REMOVED).join('\n')
    writeFileSync(source, output, 'utf8')
  }
})

function parseDisableComment(str) {
  const match = str.match(/(stylelint-disable((-next)?-line)?)\s+(.+)$/)
  return match
    ? {
        content: match[0],
        type: match[1],
        rules: match[4].split(/,\s+/)
      }
    : false
}