perf: apply perfpsrint linter (#33967) (#34632)

* perf: apply perfpsrint linter (#33967)

* perf: apply perfpsrint linter

* further simplifications

* improved TestParseHashtags coverage

* more simplifications

* simplify renderBlockHTML further

---------

Co-authored-by: Jesse Hallam <jesse@mattermost.com>

* Fixed a bad merge

---------

Co-authored-by: Catena cyber <35799796+catenacyber@users.noreply.github.com>
Co-authored-by: Jesse Hallam <jesse@mattermost.com>

server/public/model/utils.go

@@ -717,8 +717,8 @@ var (
 func ParseHashtags(text string) (string, string) {
 	words := strings.Fields(text)
 
-	hashtagString := ""
-	plainString := ""
+	var hashtagStringSb strings.Builder
+	var plainString strings.Builder
 	for _, word := range words {
 		// trim off surrounding punctuation
 		word = puncStart.ReplaceAllString(word, "")
@@ -728,11 +728,12 @@ func ParseHashtags(text string) (string, string) {
 		word = hashtagStart.ReplaceAllString(word, "#")
 
 		if validHashtag.MatchString(word) {
-			hashtagString += " " + word
+			hashtagStringSb.WriteString(" " + word)
 		} else {
-			plainString += " " + word
+			plainString.WriteString(" " + word)
 		}
 	}
+	hashtagString := hashtagStringSb.String()
 
 	if len(hashtagString) > 1000 {
 		hashtagString = hashtagString[:999]
@@ -744,7 +745,7 @@ func ParseHashtags(text string) (string, string) {
 		}
 	}
 
-	return strings.TrimSpace(hashtagString), strings.TrimSpace(plainString)
+	return strings.TrimSpace(hashtagString), strings.TrimSpace(plainString.String())
 }
 
 func ClearMentionTags(post string) string {

server/public/model/utils_test.go

@@ -541,10 +541,58 @@ func TestStringArray_Equal(t *testing.T) {
 }
 
 func TestParseHashtags(t *testing.T) {
-	for input, output := range hashtags {
-		o, _ := ParseHashtags(input)
-		require.Equal(t, o, output, "failed to parse hashtags from input="+input+" expected="+output+" actual="+o)
-	}
+	t.Run("basic hashtag extraction", func(t *testing.T) {
+		for input, output := range hashtags {
+			o, _ := ParseHashtags(input)
+			require.Equal(t, o, output, "failed to parse hashtags from input="+input+" expected="+output+" actual="+o)
+		}
+	})
+
+	t.Run("long hashtag string truncation", func(t *testing.T) {
+		// Test case where hashtag string exceeds 1000 characters with a space to truncate at
+		longHashtags := "#test " + strings.Repeat("#verylonghashtag ", 50)
+		hashtagString, plainString := ParseHashtags(longHashtags)
+		require.NotEmpty(t, hashtagString)
+		require.LessOrEqual(t, len(hashtagString), 1000)
+		require.Empty(t, plainString)
+		// Ensure it truncated at a space
+		require.NotEqual(t, "", hashtagString)
+		require.True(t, hashtagString[len(hashtagString)-1] != ' ')
+	})
+
+	t.Run("long hashtag string truncation without spaces", func(t *testing.T) {
+		// Test case where hashtag string exceeds 1000 characters with no space after position 999
+		// Create a single very long hashtag that will be truncated
+		veryLongHashtag := "#" + strings.Repeat("a", 1010)
+		hashtagString, plainString := ParseHashtags(veryLongHashtag)
+		// Should be empty because no space was found to truncate at
+		require.Equal(t, "", hashtagString)
+		require.Empty(t, plainString)
+	})
+
+	t.Run("plain text extraction", func(t *testing.T) {
+		hashtagString, plainString := ParseHashtags("hello #world this is #test plain text")
+		require.Equal(t, "#world #test", hashtagString)
+		require.Equal(t, "hello this is plain text", plainString)
+	})
+
+	t.Run("only plain text", func(t *testing.T) {
+		hashtagString, plainString := ParseHashtags("no hashtags here")
+		require.Empty(t, hashtagString)
+		require.Equal(t, "no hashtags here", plainString)
+	})
+
+	t.Run("only hashtags", func(t *testing.T) {
+		hashtagString, plainString := ParseHashtags("#one #two #three")
+		require.Equal(t, "#one #two #three", hashtagString)
+		require.Empty(t, plainString)
+	})
+
+	t.Run("empty string", func(t *testing.T) {
+		hashtagString, plainString := ParseHashtags("")
+		require.Empty(t, hashtagString)
+		require.Empty(t, plainString)
+	})
 }
 
 func TestIsValidAlphaNum(t *testing.T) {