Name change: better unicode handling (#3164)

* Name change: better unicode handling

Client-side:

* Changes the NameChangeModal to show text "Over limit" when a proposed display
name is too long.

* Allows names to go over limit to prevent splitting graphemes on input.

Server-side:

* Changes the MakeSafeStringOfLength to count number of unicode code points
instead of string bytes.

* name modal: check that newName is defined before iterating

utils/strings.go

@@ -18,10 +18,14 @@ func MakeSafeStringOfLength(s string, length int) string {
 	newString := s
 	newString = StripHTML(newString)
 
-	if len(newString) > length {
+	// Convert utf-8 string into Unicode code points.
-		newString = newString[:length]
+	codePoints := []rune(newString)
+
+	if len(codePoints) > length {
+		codePoints = codePoints[:length]
 	}
 
+	newString = string(codePoints)
 	newString = strings.ReplaceAll(newString, "\r", "")
 	newString = strings.TrimSpace(newString)
 

web/components/modals/NameChangeModal/NameChangeModal.tsx

@@ -31,14 +31,23 @@ export const NameChangeModal: FC<NameChangeModalProps> = ({ closeModal }) => {
   const websocketService = useRecoilValue<WebsocketService>(websocketServiceAtom);
   const [newName, setNewName] = useState<string>(currentUser?.displayName);
 
+  const characterLimit = 30;
+
   if (!currentUser) {
     return null;
   }
 
   const { displayName, displayColor } = currentUser;
 
-  const saveEnabled = () =>
+  const saveEnabled = () => {
-    newName !== displayName && newName !== '' && websocketService?.isConnected();
+    const count = newName !== undefined ? Array.from(newName).length : 0;
+    return (
+      newName !== displayName &&
+      count > 0 &&
+      count <= characterLimit &&
+      websocketService?.isConnected()
+    );
+  };
 
   const handleNameChange = () => {
     if (!saveEnabled()) return;
@@ -59,6 +68,8 @@ export const NameChangeModal: FC<NameChangeModalProps> = ({ closeModal }) => {
     websocketService.send(colorChange);
   };
 
+  const showCount = info => (info.count > characterLimit ? 'Over limit' : '');
+
   const maxColor = 8; // 0...n
   const colorOptions = [...Array(maxColor)].map((_, i) => i);
 
@@ -84,8 +95,7 @@ export const NameChangeModal: FC<NameChangeModalProps> = ({ closeModal }) => {
           onChange={e => setNewName(e.target.value)}
           placeholder="Your chat display name"
           aria-label="Your chat display name"
-          maxLength={30}
+          showCount={{ formatter: showCount }}
-          showCount
           defaultValue={displayName}
           className={styles.inputGroup}
         />