Fine-tune linkification technique for link previews

js/modules/link_previews.js

@@ -1,5 +1,6 @@
 /* global URL */
 
+const { isNumber, compact } = require('lodash');
 const he = require('he');
 const LinkifyIt = require('linkify-it');
 
@@ -96,9 +97,28 @@ function getImageMetaTag(html) {
   return _getMetaTag(html, META_IMAGE);
 }
 
-function findLinks(text) {
+function findLinks(text, caretLocation) {
+  const haveCaretLocation = isNumber(caretLocation);
+  const textLength = text ? text.length : 0;
+
   const matches = linkify.match(text || '') || [];
-  return matches.map(match => match.text);
+  return compact(
+    matches.map(match => {
+      if (!haveCaretLocation) {
+        return match.text;
+      }
+
+      if (match.lastIndex === textLength && caretLocation === textLength) {
+        return match.text;
+      }
+
+      if (match.index > caretLocation || match.lastIndex < caretLocation) {
+        return match.text;
+      }
+
+      return null;
+    })
+  );
 }
 
 function getDomain(url) {

js/views/conversation_view.js

@@ -1700,6 +1700,7 @@
       }
 
       const messageText = this.$messageField.val().trim();
+      const caretLocation = this.$messageField.get(0).selectionStart;
 
       if (!messageText) {
         this.resetLinkPreview();
@@ -1709,7 +1710,10 @@
         return;
       }
 
-      const links = window.Signal.LinkPreviews.findLinks(messageText);
+      const links = window.Signal.LinkPreviews.findLinks(
+        messageText,
+        caretLocation
+      );
       const { currentlyMatchedLink } = this;
       if (links.includes(currentlyMatchedLink)) {
         return;

test/modules/link_previews_test.js

@@ -1,6 +1,7 @@
 const { assert } = require('chai');
 
 const {
+  findLinks,
   getTitleMetaTag,
   getImageMetaTag,
   isLinkInWhitelist,
@@ -228,4 +229,80 @@ describe('Link previews', () => {
       );
     });
   });
+
+  describe('#findLinks', () => {
+    it('returns all links if no caretLocation is provided', () => {
+      const text =
+        'Check out this link: https://github.com/signalapp/Signal-Desktop\nAnd this one too: https://github.com/signalapp/Signal-Android';
+
+      const expected = [
+        'https://github.com/signalapp/Signal-Desktop',
+        'https://github.com/signalapp/Signal-Android',
+      ];
+
+      const actual = findLinks(text);
+      assert.deepEqual(expected, actual);
+    });
+
+    it('includes all links if cursor is not in a link', () => {
+      const text =
+        'Check out this link: https://github.com/signalapp/Signal-Desktop\nAnd this one too: https://github.com/signalapp/Signal-Android';
+      const caretLocation = 10;
+
+      const expected = [
+        'https://github.com/signalapp/Signal-Desktop',
+        'https://github.com/signalapp/Signal-Android',
+      ];
+
+      const actual = findLinks(text, caretLocation);
+      assert.deepEqual(expected, actual);
+    });
+
+    it('excludes a link not at the end if the caret is inside of it', () => {
+      const text =
+        'Check out this link: https://github.com/signalapp/Signal-Desktop\nAnd this one too: https://github.com/signalapp/Signal-Android';
+      const caretLocation = 30;
+
+      const expected = ['https://github.com/signalapp/Signal-Android'];
+
+      const actual = findLinks(text, caretLocation);
+      assert.deepEqual(expected, actual);
+    });
+
+    it('excludes a link not at the end if the caret is at its end', () => {
+      const text =
+        'Check out this link: https://github.com/signalapp/Signal-Desktop\nAnd this one too: https://github.com/signalapp/Signal-Android';
+      const caretLocation = 64;
+
+      const expected = ['https://github.com/signalapp/Signal-Android'];
+
+      const actual = findLinks(text, caretLocation);
+      assert.deepEqual(expected, actual);
+    });
+
+    it('excludes a link at the end of the caret is inside of it', () => {
+      const text =
+        'Check out this link: https://github.com/signalapp/Signal-Desktop\nAnd this one too: https://github.com/signalapp/Signal-Android';
+      const caretLocation = 100;
+
+      const expected = ['https://github.com/signalapp/Signal-Desktop'];
+
+      const actual = findLinks(text, caretLocation);
+      assert.deepEqual(expected, actual);
+    });
+
+    it('includes link at the end if cursor is at its end', () => {
+      const text =
+        'Check out this link: https://github.com/signalapp/Signal-Desktop\nAnd this one too: https://github.com/signalapp/Signal-Android';
+      const caretLocation = text.length;
+
+      const expected = [
+        'https://github.com/signalapp/Signal-Desktop',
+        'https://github.com/signalapp/Signal-Android',
+      ];
+
+      const actual = findLinks(text, caretLocation);
+      assert.deepEqual(expected, actual);
+    });
+  });
 });