autocomplete: In @-mention results, match insensitively to diacritics

Fixes zulip#237

Author: Khader-1

lib/model/autocomplete.dart

@@ -1,3 +1,4 @@
+import 'package:diacritic/diacritic.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
 
@@ -301,7 +302,7 @@ class MentionAutocompleteQuery {
         return false;
       }
 
-      if (nameWords[nameWordsIndex].startsWith(_lowercaseWords[queryWordsIndex])) {
+      if (nameWords[nameWordsIndex].startsWith(removeDiacritics(_lowercaseWords[queryWordsIndex]))) {
         queryWordsIndex++;
       }
       nameWordsIndex++;
@@ -326,7 +327,7 @@ class AutocompleteDataCache {
   final Map<int, List<String>> _nameWordsByUser = {};
 
   List<String> nameWordsForUser(User user) {
-    return _nameWordsByUser[user.userId] ??= user.fullName.toLowerCase().split(' ');
+    return _nameWordsByUser[user.userId] ??= removeDiacritics(user.fullName.toLowerCase()).split(' ');
   }
 
   void invalidateUser(int userId) {

pubspec.lock

@@ -273,6 +273,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "7.0.0"
+  diacritic:
+    dependency: "direct main"
+    description:
+      name: diacritic
+      sha256: "96db5db6149cbe4aa3cfcbfd170aca9b7648639be7e48025f9d458517f807fe4"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.1.5"
   drift:
     dependency: "direct main"
     description:

pubspec.yaml

@@ -65,6 +65,7 @@ dependencies:
   url_launcher: ^6.1.11
   url_launcher_android: ">=6.1.0"
   sqlite3: ^2.4.0
+  diacritic: ^0.1.5
 
 dev_dependencies:
   flutter_driver:

test/model/autocomplete_test.dart

@@ -327,6 +327,11 @@ void main() {
     doCheck('full full', eg.user(fullName: 'Full Full Name'), true);
     doCheck('full full', eg.user(fullName: 'Full Name Full'), true);
 
+    // assert that name checking is diacritic insensitive
+    doCheck('fűll ñámé', eg.user(fullName: 'Full Name'), true);
+    doCheck('fűll', eg.user(fullName: 'Full Name'), true);
+    doCheck('ñámé', eg.user(fullName: 'Full Name'), true);
+
     doCheck('F', eg.user(fullName: ''), false); // Unlikely case, but should not crash
     doCheck('Fully Named', eg.user(fullName: 'Full Name'), false);
     doCheck('Full Name', eg.user(fullName: 'Full'), false);