PLT-1626/PLT-1424/PLT-1473/PLT-1483 Improved search highlighting (#3171)

* PLT-1626 Stopped breaking up hyphenated hashtags when highlighting search terms

* Made hashtag search highlighting case independent

* PLT-1424 Improved search highlighting when searching for CJK characters

* PLT-1473 Added search term highlighting to single-line code blocks

* PLT-1473 Added search term highlighting to code blocks that don't use syntax highlighting

* PLT-1483 Added proper highlighting of at mentions

* Fixing formatting

webapp/utils/text_formatting.jsx

@@ -11,6 +11,10 @@ import UserStore from 'stores/user_store.jsx';
 import twemoji from 'twemoji';
 import * as Utils from './utils.jsx';
 
+// pattern to detect the existance of a Chinese, Japanese, or Korean character in a string
+// http://stackoverflow.com/questions/15033196/using-javascript-to-check-whether-a-string-contains-japanese-characters-includi
+const cjkPattern = /[\u3000-\u303f\u3040-\u309f\u30a0-\u30ff\uff00-\uff9f\u4e00-\u9faf\u3400-\u4dbf]/;
+
 // Performs formatting of user posts including highlighting mentions and search terms and converting urls, hashtags, and
 // @mentions to links by taking a user's message and returning a string of formatted html. Also takes a number of options
 // as part of the second parameter:
@@ -61,7 +65,7 @@ export function doFormatText(text, options) {
     }
 
     if (options.searchTerm) {
-        output = highlightSearchTerm(output, tokens, options.searchTerm);
+        output = highlightSearchTerms(output, tokens, options.searchTerm);
     }
 
     if (!('mentionHighlight' in options) || options.mentionHighlight) {
@@ -323,18 +327,27 @@ function parseSearchTerms(searchTerm) {
             continue;
         }
 
+        // capture at mentions differently from the server so we can highlight them with the preceeding at sign
+        captured = (/^@\w+\b/).exec(termString);
+        if (captured) {
+            termString = termString.substring(captured[0].length);
+
+            terms.push(captured[0]);
+            continue;
+        }
+
         // capture any plain text up until the next quote or search flag
         captured = (/^.+?(?=\bin|\bfrom|\bchannel|"|$)/).exec(termString);
         if (captured) {
             termString = termString.substring(captured[0].length);
 
             // break the text up into words based on how the server splits them in SqlPostStore.SearchPosts and then discard empty terms
-            terms.push(...captured[0].split(/[ <>+\-\(\)~@]/).filter((term) => !!term));
+            terms.push(...captured[0].split(/[ <>+\(\)~@]/).filter((term) => !!term));
             continue;
         }
 
         // we should never reach this point since at least one of the regexes should match something in the remaining text
-        throw new Error('Infinite loop in search term parsing: ' + termString);
+        throw new Error('Infinite loop in search term parsing: "' + termString + '"');
     }
 
     // remove punctuation from each term
@@ -345,16 +358,23 @@ function parseSearchTerms(searchTerm) {
 
 function convertSearchTermToRegex(term) {
     let pattern;
-    if (term.endsWith('*')) {
-        pattern = '\\b' + escapeRegex(term.substring(0, term.length - 1));
+
+    if (cjkPattern.test(term)) {
+        // term contains Chinese, Japanese, or Korean characters so don't mark word boundaries
+        pattern = '()(' + escapeRegex(term.replace(/\*/g, '')) + ')';
+    } else if (term.endsWith('*')) {
+        pattern = '\\b()(' + escapeRegex(term.substring(0, term.length - 1)) + ')';
+    } else if (term.startsWith('@')) {
+        // needs special handling of the first boundary because a word boundary doesn't work before an @ sign
+        pattern = '(\\W|^)(' + escapeRegex(term) + ')\\b';
     } else {
-        pattern = '\\b' + escapeRegex(term) + '\\b';
+        pattern = '\\b()(' + escapeRegex(term) + ')\\b';
     }
 
     return new RegExp(pattern, 'gi');
 }
 
-function highlightSearchTerm(text, tokens, searchTerm) {
+export function highlightSearchTerms(text, tokens, searchTerm) {
     const terms = parseSearchTerms(searchTerm);
 
     if (terms.length === 0) {
@@ -363,7 +383,7 @@ function highlightSearchTerm(text, tokens, searchTerm) {
 
     let output = text;
 
-    function replaceSearchTermWithToken(word) {
+    function replaceSearchTermWithToken(match, prefix, word) {
         const index = tokens.size;
         const alias = `MM_SEARCHTERM${index}`;
 
@@ -372,14 +392,14 @@ function highlightSearchTerm(text, tokens, searchTerm) {
             originalText: word
         });
 
-        return alias;
+        return prefix + alias;
     }
 
     for (const term of terms) {
         // highlight existing tokens matching search terms
         var newTokens = new Map();
         for (const [alias, token] of tokens) {
-            if (token.originalText === term.replace(/\*$/, '')) {
+            if (token.originalText.toLowerCase() === term.replace(/\*$/, '').toLowerCase()) {
                 const index = tokens.size + newTokens.size;
                 const newAlias = `MM_SEARCHTERM${index}`;
 
@@ -403,7 +423,7 @@ function highlightSearchTerm(text, tokens, searchTerm) {
     return output;
 }
 
-function replaceTokens(text, tokens) {
+export function replaceTokens(text, tokens) {
     let output = text;
 
     // iterate backwards through the map so that we do replacement in the opposite order that we added tokens