feat(index): add config callback

index.js

@@ -4,75 +4,87 @@
 
 'use strict'
 
-const assign = Object.assign
+const path = require('path')
 
-const dirname = require('path').dirname
-const extname = require('path').extname
-
-const Error = require('gulp-util').PluginError
 const transform = require('through2').obj
 
+const PLUGIN_NAME = 'gulp-posthtml'
+
 const posthtml = require('posthtml')
 const posthtmlrc = require('posthtml-load-config')
 
-const PLUGIN_NAME = 'gulp-posthtml'
+const Error = require('gulp-util').PluginError
 
+function rc (cb) {
+  return function (plugins, options) {
+    if (Array.isArray(plugins)) {
+      return cb(() => Promise.resolve({ plugins: plugins, options: options }))
+    } else if (typeof plugins === 'function') {
+      return cb((file) => Promise.resolve(plugins(file)))
+    } else {
+      const ctx = plugins || {}
+
+      return cb((file) => {
+        const config = {}
+
+        if (ctx.config) {
+          config.path = path.resolve(ctx.config)
+        } else {
+          config.path = file.dirname
+        }
+
+        config.ctx = { file: file, options: ctx }
+
+        return posthtmlrc(config.ctx, config.path)
+      })
+    }
+  }
+}
 /**
  * @author Ivan Voishev (@voishev) <voischev.ivan@ya.ru>
  * @description PostHTML Plugin for Gulp
  * @license MIT
  *
  * @module gulp-posthtml
- * @version 2.0.0
+ * @version 3.0.0
  *
  * @requires gulp-util
  * @requires through2
  * @requires posthtml
  * @requires posthtml-load-config
  *
+ * @method gulp-posthtml
+ *
  * @param  {Array}  plugins PostHTML Plugins
  * @param  {Object} options PostHTML Options
  *
  * @return {Function}       Stream (Transform)
  */
-module.exports = function (plugins, options) {
+module.exports = rc((loadConfig) => {
   return transform((file, enc, cb) => {
     if (file.isNull()) {
       return cb(null, file)
     }
 
-    const defaults = { from: file.path, to: file.path }
-
-    if (!plugins || !Array.isArray(plugins)) {
-      const ctx = assign(
-        defaults, plugins, { ext: extname(file.path), dir: dirname(file.path) }
-      )
-
-      posthtmlrc(ctx, ctx.dir).then((config) => {
-        posthtml(config.plugins)
-          .process(file.contents.toString(enc), config.options)
-          .then((result) => {
-            file.contents = new Buffer(result.html)
-            cb(null, file)
-          })
-          .catch((err) => {
-            cb(new Error(PLUGIN_NAME, err))
-          })
-      })
+    if (file.isStream()) {
+      return new Error(`Streams are not supported by ${PLUGIN_NAME}`)
     }
 
-    if (plugins && Array.isArray(plugins)) {
-      options = assign(defaults, options)
+    loadConfig(file).then((config) => {
+      config.options = Object.assign(
+        { from: file.path, to: file.path }, config.options
+      )
 
-      posthtml(plugins)
-        .process(file.contents.toString(enc), assign(options, defaults))
+      return posthtml(config.plugins)
+        .process(file.contents.toString(enc), config.options)
         .then((result) => {
+          // console.log(result.html)
           file.contents = new Buffer(result.html)
           cb(null, file)
         })
         .catch((err) => {
           cb(new Error(PLUGIN_NAME, err))
         })
-    }
+    })
   })
-}
+})