index.js

'use strict'

const assign = require('object-assign')
const Filter = require('broccoli-persistent-filter')
const Funnel = require('broccoli-funnel')
const postcss = require('postcss')

module.exports = class extends Filter {
  constructor (inputNode, options = {}) {
    if (options.exclude || options.include) {
      inputNode = new Funnel(inputNode, {
        exclude: options.exclude,
        include: options.include
      })
    }

    super(inputNode, options)
    this.inputNode = inputNode
    this.options = options
    this.warningStream = process.stderr
  }

  get extensions () {
    return ['css']
  }

  get targetExtension () {
    return 'css'
  }

  processString (content, relativePath) {
    const warningStream = this.warningStream
    const processor = postcss()
    const opts = assign({
      from: relativePath,
      to: relativePath,
      map: {
        inline: false,
        annotation: false
      },
      errors: {
        showSourceCode: true,
        terminalColors: true
      }
    }, this.options)

    if (!opts.plugins || opts.plugins.length < 1) {
      throw new Error('You must provide at least 1 plugin in the plugin array')
    }

    opts.plugins.forEach((plugin) => {
      let pluginInstance

      if (plugin.module) {
        const pluginOptions = assign(opts, plugin.options || {})
        pluginInstance = plugin.module(pluginOptions)
      } else {
        pluginInstance = plugin
      }

      processor.use(pluginInstance)
    })

    return processor.process(content, opts)
      .then((result) => {
        result.warnings().forEach(warn => warningStream.write(warn.toString()))

        return result.css
      })
      .catch((err) => {
        if (err.name === 'CssSyntaxError') {
          if (opts.errors.showSourceCode) {
            err.message += `\n${err.showSourceCode(opts.errors.terminalColors)}`
          }
        }

        throw err
      })
  }
}