Custom Mentions Formatter

import 'dart:async';
import 'package:cometchat_chat_uikit/cometchat_chat_uikit.dart';
import 'package:flutter/material.dart';

/// Custom mentions formatter that filters out the logged-in user
/// from suggestions.
///
/// Wraps the parent's [suggestionListEventSink] with a filtering
/// proxy so that every suggestion list emitted by the base class
/// automatically excludes the currently logged-in user.
class CustomMentionsFormatter extends CometChatMentionsFormatter {
  CustomMentionsFormatter({
    super.trackingCharacter,
    super.pattern,
    super.showLoadingIndicator,
    super.onSearch,
    super.onError,
    super.message,
    super.messageBubbleTextStyle,
    super.messageInputTextStyle,
    super.composerId,
    super.suggestionListEventSink,
    super.previousTextEventSink,
    super.user,
    super.group,
    super.groupMembersRequestBuilder,
    super.usersRequestBuilder,
    super.mentionsType,
    super.onMentionTap,
    super.visibleIn,
    super.style,
    super.disableMentions,
    super.disableMentionAll,
    super.mentionAllLabel,
    super.mentionAllLabelId,
    super.mentionsLimit,
  });

  bool _sinkWrapped = false;

  /// Wraps the sink once before the parent starts using it.
  /// Re-wraps if the controller has reassigned a new sink.
  void _ensureSinkWrapped() {
    final currentSink = super.suggestionListEventSink;
    if (currentSink == null) return;

    // Wrap the raw sink from the controller.
    suggestionListEventSink = _FilteredSuggestionSink(currentSink);
    _sinkWrapped = true;
  }

  @override
  Future<void> initializeFetchRequest(
    String? searchKeyword,
    TextEditingController textEditingController,
  ) async {
    _ensureSinkWrapped();
    await super.initializeFetchRequest(
      searchKeyword,
      textEditingController,
    );
  }

  @override
  Future<void> fetchItems({
    bool firstTimeFetch = false,
    required TextEditingController textEditingController,
    String? searchKeyword,
  }) async {
    _ensureSinkWrapped();
    await super.fetchItems(
      firstTimeFetch: firstTimeFetch,
      textEditingController: textEditingController,
      searchKeyword: searchKeyword,
    );
  }

  @override
  void resetMentionsTracker() {
    _ensureSinkWrapped();
    super.resetMentionsTracker();
  }
}

/// A [StreamSink] wrapper that removes the logged-in user from every
/// suggestion list before forwarding it to the real sink.
class _FilteredSuggestionSink
    implements StreamSink<List<SuggestionListItem>> {
  final StreamSink<List<SuggestionListItem>> _delegate;

  _FilteredSuggestionSink(this._delegate);

  @override
  void add(List<SuggestionListItem> data) {
    final loggedInUid = CometChatUIKit.loggedInUser?.uid;

    if (loggedInUid == null || loggedInUid.isEmpty) {
      _delegate.add(data);
      return;
    }

    _delegate.add(
      data.where((item) => item.id != loggedInUid).toList(),
    );
  }

  @override
  void addError(Object error, [StackTrace? stackTrace]) =>
      _delegate.addError(error, stackTrace);

  @override
  Future addStream(Stream<List<SuggestionListItem>> stream) =>
      _delegate.addStream(stream);

  @override
  Future close() => _delegate.close();

  @override
  Future get done => _delegate.done;
}

import 'package:your_app/utils/custom_mentions_formatter.dart';

CometChatMessageComposer(
  user: user,       // pass user for 1-on-1 chats
  group: group,     // pass group for group chats
  textFormatters: [
    CustomMentionsFormatter(
      user: user,
      group: group,
      onMentionTap: (mention, mentionedUser, {message}) {
        if (mentionedUser.uid != CometChatUIKit.loggedInUser!.uid) {
          // Navigate to your own user profile screen
          debugPrint('Mentioned user: ${mentionedUser.name}');
        }
      },
    ),
  ],
  disableMentions: false,
  parentMessageId: 0, // non-zero for thread replies
)