markdown.js: Allow Dovecot markdown generated URLs to be rewritten

Author: slusarz

README.md

@@ -219,6 +219,13 @@ Paths are relative to project base.
 
 Supports fast-glob: https://github.com/mrmlnc/fast-glob#pattern-syntax
 
+#### url_rewrite
+
+A callback where Markdown generated URLs can be rewritten.
+Function is called the original URL and returns the (modified) URL.
+
+Example: `url_rewrite: (url) => { return url + '.foo' }`
+
 #### watch_paths
 
 An array of file patterns to watch to refresh data loaders in dev mode.

lib/markdown.js

@@ -435,8 +435,14 @@ function dovecot_markdown(md, opts) {
 	}
 
 	function resolveURL(url) {
-		return (opts.base.endsWith('/') ? opts.base.slice(0, -1) : opts.base) +
+		if (!('url_rewrite' in opts)) {
+			opts.url_rewrite = dovecotSetting('url_rewrite')
+		}
+
+		const new_url =
+			(opts.base.endsWith('/') ? opts.base.slice(0, -1) : opts.base) +
 			'/' + url
+		return (opts.url_rewrite) ? opts.url_rewrite(new_url) : new_url
 	}
 
 	md.inline.ruler.after('emphasis', 'dovecot_brackets', process_brackets)