import fs from 'fs'
import { existsFileSync } from '../../../../util/exists'
import parseArgv from '../../parseArgv'

const defaultConfig = 'mochapack.opts'

function handleMissingConfig(config) {
  if (config) {
    throw new Error(`Options file '${config}' not found`)
  }

  return {}
}

const createStripSurroundingChar = c => s => {
  if (
    s.indexOf(c) === 0 &&
    s.lastIndexOf(c) === s.length - 1 &&
    s.indexOf(c) !== s.lastIndexOf(c)
  ) {
    return s.substring(1, s.length - 1)
  }
  return s
}

const stripSingleQuotes = createStripSurroundingChar("'")
const stripDoubleQuotes = createStripSurroundingChar('"')

const removeSurroundingQuotes = str => {
  const stripped = stripDoubleQuotes(str)

  if (stripped !== str) {
    // strip only once
    return stripped
  }
  return stripSingleQuotes(str)
}

export default function parseMochaOptsFile(explicitConfig?: any) {
  const config = explicitConfig || defaultConfig

  if (!existsFileSync(config)) {
    return handleMissingConfig(explicitConfig)
  }

  const argv = fs
    .readFileSync(config, 'utf8')
    .replace(/\\\s/g, '%20')
    .split(/\s/)
    .filter(Boolean)
    .map(value => value.replace(/%20/g, ' '))
    .map(removeSurroundingQuotes)
  const defaultOptions = parseArgv(argv)
  return defaultOptions
}