PLT-4454 Autolink anything that looks like an at mention (#4416)

* PLT-4454 Added autolinking for anything that looks like an at mention

* PLT-4454 Added unit tests for at mention autolinking

2 files changed, 92 insertions, 23 deletions

diff --git a/webapp/tests/formatting_at_mentions.test.jsx b/webapp/tests/formatting_at_mentions.test.jsx
new file mode 100644
index 000000000..babcb2ca9
--- /dev/null
+++ b/webapp/tests/formatting_at_mentions.test.jsx
@@ -0,0 +1,81 @@
+// Copyright (c) 2016 Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+import assert from 'assert';
+
+import * as TextFormatting from 'utils/text_formatting.jsx';
+
+describe('TextFormatting.AtMentions', function() {
+    this.timeout(10000);
+
+    it('At mentions', function() {
+        assert.equal(
+            TextFormatting.autolinkAtMentions('@user', new Map(), {user: {}}),
+            'MM_ATMENTION0',
+            'should replace explicit mention with token'
+        );
+
+        assert.equal(
+            TextFormatting.autolinkAtMentions('abc"@user"def', new Map(), {user: {}}),
+            'abc"MM_ATMENTION0"def',
+            'should replace explicit mention surrounded by punctuation with token'
+        );
+
+        assert.equal(
+            TextFormatting.autolinkAtMentions('@user1 @user2', new Map(), {user1: {}, user2: {}}),
+            'MM_ATMENTION0 MM_ATMENTION1',
+            'should replace multiple explicit mentions with tokens'
+        );
+
+        assert.equal(
+            TextFormatting.autolinkAtMentions('@us_-e.r', new Map(), {'us_-e.r': {}}),
+            'MM_ATMENTION0',
+            'should replace multiple explicit mentions containing punctuation with token'
+        );
+
+        assert.equal(
+            TextFormatting.autolinkAtMentions('@us_-e.r', new Map(), {'us_-e.r': {}}),
+            'MM_ATMENTION0',
+            'should replace multiple explicit mentions containing valid punctuation with token'
+        );
+
+        assert.equal(
+            TextFormatting.autolinkAtMentions('@user.', new Map(), {user: {}}),
+            'MM_ATMENTION0.',
+            'should replace explicit mention followed by period with token'
+        );
+
+        assert.equal(
+            TextFormatting.autolinkAtMentions('@user.', new Map(), {'user.': {}}),
+            'MM_ATMENTION0',
+            'should replace explicit mention ending with period with token'
+        );
+    });
+
+    it('Implied at mentions', function() {
+        // PLT-4454 Assume users exist for things that look like at mentions until we support the new mention syntax
+        assert.equal(
+            TextFormatting.autolinkAtMentions('@user', new Map(), {}),
+            'MM_ATMENTION0',
+            'should imply user exists and replace mention with token'
+        );
+
+        assert.equal(
+            TextFormatting.autolinkAtMentions('@user.', new Map(), {}),
+            'MM_ATMENTION0.',
+            'should assume username doesn\'t end in punctuation'
+        );
+    });
+
+    it('Not at mentions', function() {
+        assert.equal(
+            TextFormatting.autolinkAtMentions('user@host', new Map(), {user: {}, host: {}}),
+            'user@host'
+        );
+
+        assert.equal(
+            TextFormatting.autolinkAtMentions('user@email.com', new Map(), {user: {}, email: {}}),
+            'user@email.com'
+        );
+    });
+});
diff --git a/webapp/utils/text_formatting.jsx b/webapp/utils/text_formatting.jsx
index 9834f4b9b..dbd6a4e32 100644
--- a/webapp/utils/text_formatting.jsx
+++ b/webapp/utils/text_formatting.jsx
@@ -152,7 +152,7 @@ function autolinkEmails(text, tokens) {
 
 const punctuation = XRegExp.cache('[^\\pL\\d]');
 
-function autolinkAtMentions(text, tokens, usernameMap) {
+export function autolinkAtMentions(text, tokens, usernameMap) {
     // Test if provided text needs to be highlighted, special mention or current user
     function mentionExists(u) {
         return (Constants.SPECIAL_MENTIONS.indexOf(u) !== -1 || Boolean(usernameMap[u]));
@@ -169,30 +169,18 @@ function autolinkAtMentions(text, tokens, usernameMap) {
         return alias;
     }
 
-    function replaceAtMentionWithToken(fullMatch, mention, username) {
-        let usernameLower = username.toLowerCase();
-
-        if (mentionExists(usernameLower)) {
-            // Exact match
-            const alias = addToken(usernameLower, mention, '');
-            return alias;
-        }
-
-        // Not an exact match, attempt to truncate any punctuation to see if we can find a user
-        const originalUsername = usernameLower;
+    function replaceAtMentionWithToken(fullMatch, prefix, mention, username) {
+        const usernameLower = username.toLowerCase();
 
+        // Check if the text makes up an explicit mention, possible trimming extra punctuation from the end of the name if necessary
         for (let c = usernameLower.length; c > 0; c--) {
-            if (punctuation.test(usernameLower[c - 1])) {
-                usernameLower = usernameLower.substring(0, c - 1);
+            const truncated = usernameLower.substring(0, c);
+            const suffix = usernameLower.substring(c);
 
-                if (mentionExists(usernameLower)) {
-                    const suffix = originalUsername.substr(c - 1);
-                    const alias = addToken(usernameLower, '@' + usernameLower);
-                    return alias + suffix;
-                }
-            } else {
-                // If the last character is not punctuation, no point in going any further
-                break;
+            // If we've found a username or run out of punctuation to trim off, render it as an at mention
+            if (mentionExists(truncated) || !punctuation.test(truncated[truncated.length - 1])) {
+                const alias = addToken(truncated, '@' + truncated);
+                return prefix + alias + suffix;
             }
         }
 
@@ -200,7 +188,7 @@ function autolinkAtMentions(text, tokens, usernameMap) {
     }
 
     let output = text;
-    output = output.replace(/(@([a-z0-9.\-_]*))/gi, replaceAtMentionWithToken);
+    output = output.replace(/(^|\W)(@([a-z0-9.\-_]*))/gi, replaceAtMentionWithToken);
 
     return output;
 }