refactor(imgTag): utilize url_for (#3973)

lib/plugins/tag/img.js

@@ -1,7 +1,6 @@
 'use strict';
 
-const url = require('url');
-const { htmlTag } = require('hexo-util');
+const { htmlTag, url_for } = require('hexo-util');
 
 const rUrl = /((([A-Za-z]{3,9}:(?:\/\/)?)(?:[-;:&=+$,\w]+@)?[A-Za-z0-9.-]+|(?:www.|[-;:&=+$,\w]+@)[A-Za-z0-9.-]+)((?:\/[+~%/.\w-_]*)?\??(?:[-+=&;%@.\w_]*)#?(?:[.!/\\w]*))?)/;
 const rMeta = /["']?([^"']+)?["']?\s*["']?([^"']+)?["']?/;
@@ -13,23 +12,6 @@ const rMeta = /["']?([^"']+)?["']?\s*["']?([^"']+)?["']?/;
 *   {% img [class names] /path/to/image [width] [height] [title text [alt text]] %}
 */
 module.exports = ctx => {
-  const { config } = ctx;
-
-  function makeUrl(path) {
-    if (path[0] === '#' || path.startsWith('//')) {
-      return path;
-    }
-
-    const data = url.parse(path);
-
-    if (data && data.protocol) {
-      return path;
-    }
-
-    path = config.root + path;
-
-    return path.replace(/\/{2,}/g, '/');
-  }
 
   return function imgTag(args, content) {
     const classes = [];
@@ -39,7 +21,7 @@ module.exports = ctx => {
     while (args.length > 0) {
       const item = args.shift();
       if (rUrl.test(item) || item[0] === '/') {
-        src = makeUrl(item);
+        src = url_for.call(ctx, item);
         break;
       } else {
         classes.push(item);