feat(ui): improve add support for mentionAllAppUsers in UserMentionsOverlay.

Signed-off-by: xsahil03x <[email protected]>

packages/stream_chat_flutter/lib/src/utils.dart

@@ -1,10 +1,11 @@
 import 'dart:async';
+import 'dart:math' as math;
 
 import 'package:flutter/material.dart';
+import 'package:stream_chat_flutter/src/extension.dart';
 import 'package:stream_chat_flutter/stream_chat_flutter.dart';
 import 'package:stream_chat_flutter_core/stream_chat_flutter_core.dart';
 import 'package:url_launcher/url_launcher.dart';
-import 'package:stream_chat_flutter/src/extension.dart';
 
 /// Launch URL
 Future<void> launchURL(BuildContext context, String url) async {
@@ -388,3 +389,39 @@ class Tuple2<T1, T2> {
   @override
   int get hashCode => item1.hashCode ^ item2.hashCode;
 }
+
+/// Levenshtein algorithm implementation based on:
+/// http://en.wikipedia.org/wiki/Levenshtein_distance#Iterative_with_two_matrix_rows
+int levenshtein(String s, String t, {bool caseSensitive = true}) {
+  if (!caseSensitive) {
+    // ignore: parameter_assignments
+    s = s.toLowerCase();
+    // ignore: parameter_assignments
+    t = t.toLowerCase();
+  }
+  if (s == t) return 0;
+  if (s.isEmpty) return t.length;
+  if (t.isEmpty) return s.length;
+
+  final v0 = List<int>.filled(t.length + 1, 0);
+  final v1 = List<int>.filled(t.length + 1, 0);
+
+  for (var i = 0; i < t.length + 1; i < i++) {
+    v0[i] = i;
+  }
+
+  for (var i = 0; i < s.length; i++) {
+    v1[0] = i + 1;
+
+    for (var j = 0; j < t.length; j++) {
+      final cost = (s[i] == t[j]) ? 0 : 1;
+      v1[j + 1] = math.min(v1[j] + 1, math.min(v0[j + 1] + 1, v0[j] + cost));
+    }
+
+    for (var j = 0; j < t.length + 1; j++) {
+      v0[j] = v1[j];
+    }
+  }
+
+  return v1[t.length];
+}