index.js

const defined = require('defined')
const postcss = require('postcss')
const extend = require('xtend')
const resolve = require('resolve')
const postcssrc = require('postcss-load-config')

module.exports = transform

function transform (filename, source, options, done) {
 options = defined(options, {})

 const basedir = options.basedir

 const plugins = defined(options.plugins, [])
 .map(plugin => {
 if (typeof plugin === 'string') {
 plugin = [plugin]
 }

 return {
 path: resolve.sync(plugin[0], { basedir }),
 options: plugin[1]
 }
 })
 .map(plugin => require(plugin.path)(plugin.options))

 const ctx = extend({
 sourcemap: true,
 from: filename,
 messages: {
 browser: true,
 console: false
 }
 }, options)

 delete ctx.plugins

 postcssrc(ctx, basedir).then(compile, function () {
 return compile({ options: ctx })
 }).then(function (result) {
 done(null, result)
 }, done)

 function compile (config) {
 return postcss(plugins.concat(config.plugins).filter(Boolean))
 .process(source, config.options)
 .then(function (result) {
 // Collect imported files for watchify
 const files = [filename]
 result.messages.forEach(function (msg) {
 if (msg.type === 'dependency') {
 files.push(msg.file)
 }
 })

 return {
 css: result.css,
 files: files
 }
 })
 }
}