Fix empty link bug and proper error logging in highlightMentions.js (#12228)

* fix(chat) - Don't insert user link in url-less link and properly log source-mapping failures

* fix(chat) - Add link to markdown spec and list of known issues

* fix(chat) - Log regular expression as String

test/api/unit/libs/highlightMentions.test.js

@@ -1,4 +1,5 @@
 import mongoose from 'mongoose';
+
 import highlightMentions from '../../../../website/server/libs/highlightMentions';
 
 describe('highlightMentions', () => {
@@ -101,12 +102,28 @@ describe('highlightMentions', () => {
       expect(result[0]).to.equal('http://www.medium.com/@user/blog [@user](/profile/111)');
     });
 
+    // https://spec.commonmark.org/0.29/#example-483
+    it('doesn\'t highlight user in a link without url', async () => {
+      const text = '[@user2]()';
+      const result = await highlightMentions(text);
+      expect(result[0]).to.equal(text);
+    });
+
     // https://github.com/HabitRPG/habitica/issues/12217
     it('doesn\'t highlight user in link with url-escapable characters', async () => {
       const text = '[test](https://habitica.fandom.com/ru/@wiki/Снаряжение)';
       const result = await highlightMentions(text);
       expect(result[0]).to.equal(text);
     });
+
+    // https://github.com/HabitRPG/habitica/issues/12223
+    it('matches a link in between two the same links', async () => {
+      const text = '[here](http://habitica.wikia.com/wiki/The_Keep:Pirate_Cove/FAQ)\n@user\n[hier](http://habitica.wikia.com/wiki/The_Keep:Pirate_Cove/FAQ)';
+
+      const result = await highlightMentions(text);
+
+      expect(result[0]).to.equal('[here](http://habitica.wikia.com/wiki/The_Keep:Pirate_Cove/FAQ)\n[@user](/profile/111)\n[hier](http://habitica.wikia.com/wiki/The_Keep:Pirate_Cove/FAQ)');
+    });
   });
 
   describe('exceptions in code blocks', () => {
@@ -149,14 +166,6 @@ describe('highlightMentions', () => {
 
       expect(result[0]).to.equal('[@user](/profile/111) `@user`');
     });
-
-    it('matches a link in between two the same links', async () => {
-      const text = '[here](http://habitica.wikia.com/wiki/The_Keep:Pirate_Cove/FAQ)\n@user\n[hier](http://habitica.wikia.com/wiki/The_Keep:Pirate_Cove/FAQ)';
-
-      const result = await highlightMentions(text);
-
-      expect(result[0]).to.equal('[here](http://habitica.wikia.com/wiki/The_Keep:Pirate_Cove/FAQ)\n[@user](/profile/111)\n[hier](http://habitica.wikia.com/wiki/The_Keep:Pirate_Cove/FAQ)');
-    });
   });
 
   it('github issue 12118, method crashes when square brackets are used', async () => {

website/server/libs/highlightMentions.js

@@ -2,6 +2,7 @@ import escapeRegExp from 'lodash/escapeRegExp';
 import habiticaMarkdown from 'habitica-markdown';
 
 import { model as User } from '../models/user';
+import logger from './logger';
 
 const mentionRegex = /\B@[-\w]+/g;
 const ignoreTokenTypes = ['code_block', 'code_inline', 'fence', 'link_open'];
@@ -70,8 +71,17 @@ function withOptionalIndentation (content) {
   return content.split('\n').map(line => `\\s*${line}`).join('\n');
 }
 
-// This is essentially a workaround around the fact that markdown-it doesn't
+/* This is essentially a workaround around the fact that markdown-it doesn't
-// provide sourcemap functionality and is the most brittle part of this code.
+ * provide sourcemap functionality and is the most brittle part of this code.
+ *
+ * Known errors (Not supported markdown link variants):
+ * - [a](<b)c>) https://spec.commonmark.org/0.29/#example-489
+ * - [link](\(foo\)) https://spec.commonmark.org/0.29/#example-492
+ * - [link](foo(and(bar))) https://spec.commonmark.org/0.29/#example-493
+ * - [link](foo\(and\(bar\)) https://spec.commonmark.org/0.29/#example-494
+ * - [link](<foo(and(bar)>) https://spec.commonmark.org/0.29/#example-495
+ * - [link](foo\)\:) https://spec.commonmark.org/0.29/#example-496
+ */
 function toSourceMapRegex (token) {
   const { type, content, markup } = token;
   const contentRegex = escapeRegExp(content);
@@ -86,7 +96,7 @@ function toSourceMapRegex (token) {
   } else if (type === 'link_open') {
     const texts = token.textContents.map(escapeRegExp);
     regexStr = markup === 'linkify' || markup === 'autolink' ? texts[0]
-      : `\\[[^\\]]*${texts.join('[^\\]]*')}[^\\]]*\\]\\([^)]+\\)`;
+      : `\\[[^\\]]*${texts.join('[^\\]]*')}[^\\]]*\\]\\([^)]*\\)`;
   } else {
     throw new Error(`No source mapping regex defined for ignore blocks of type ${type}`);
   }
@@ -112,7 +122,10 @@ function findTextBlocks (text) {
     const match = targetText.match(regex);
 
     if (!match) {
-      // Should not happen, but insert to handle bugs gracefully
+      logger.error(
+        new Error('Failed to match source-mapping regex to find ignore block'),
+        { text, targetText, regex: String(regex) },
+      );
       return;
     }