const path = require('path')
const config = require('../config')
const ExtractTextPlugin = require('extract-text-webpack-plugin')

exports.assetsPath = function(_path) {
  const assetsSubDirectory =
    process.env.NODE_ENV === 'production'
      ? config.build.assetsSubDirectory
      : config.dev.assetsSubDirectory
  return path.posix.join(assetsSubDirectory, _path)
}

exports.cssLoaders = function(options) {
  options = options || {}
  // generate loader string to be used with extract text plugin
  function generateLoaders (loaders) {
    const sourceLoader = loaders
      .map(loader => {
        let extraParamChar
        if (/\?/.test(loader)) {
          loader = loader.replace(/\?/, '-loader?')
          extraParamChar = '&'
        } else {
          loader += '-loader'
          extraParamChar = '?'
        }
        return loader + (options.sourceMap ? `${extraParamChar}sourceMap` : '')
      })
      .join('!')

    // Extract CSS when that option is specified
    // (which is the case during production build)
    if (options.extract) {
      return ExtractTextPlugin.extract({
        use: sourceLoader,
        fallback: 'vue-style-loader'
      })
    }
    return ['vue-style-loader', sourceLoader].join('!')
  }

  // http://vuejs.github.io/vue-loader/en/configurations/extract-css.html
  return {
    css: generateLoaders(['css']),
    postcss: generateLoaders(['css']),
    less: generateLoaders(['css', 'less']),
    sass: generateLoaders(['css', 'sass?indentedSyntax']),
    scss: generateLoaders(['css', 'sass']),
    stylus: generateLoaders(['css', 'stylus']),
    styl: generateLoaders(['css', 'stylus'])
  }
}

// Generate loaders for standalone style files (outside of .vue)
exports.styleLoaders = function(options) {
  const output = []
  const loaders = exports.cssLoaders(options)
  for (const extension in loaders) {
    const loader = loaders[extension]
    output.push({
      test: new RegExp(`\\.${extension}$`),
      loader
    })
  }
  return output
}
