SearckKeywordBloc

//EVENT

part of 'search_keyword_bloc.dart';

abstract class SearchKeywordEvent extends Equatable {
  const SearchKeywordEvent();

  @override
  List<Object> get props => [];
}

class OnChangeKeyword extends SearchKeywordEvent {
  final String? keyword;

  const OnChangeKeyword(this.keyword);
}

//STATE

part of 'search_keyword_bloc.dart';

class SearchKeywordState {
  final String? keyword;
  final TextEditingController? controller;

  const SearchKeywordState({
    this.keyword,
    this.controller,
  });

  SearchKeywordState copyWith({
    String? keyword,
    TextEditingController? controller,
  }) {
    return SearchKeywordState(
      keyword: keyword ?? this.keyword,
      controller: controller ?? this.controller,
    );
  }

  factory SearchKeywordState.initial() {
    return SearchKeywordState(
      keyword: '',
      controller: TextEditingController(text: ''),
    );
  }
}

//BLOC
import 'package:bloc/bloc.dart';
import 'package:equatable/equatable.dart';
import 'package:flutter/widgets.dart';
import 'package:rxdart/rxdart.dart';

part 'search_keyword_event.dart';
part 'search_keyword_state.dart';

class SearchKeywordBloc extends Bloc<SearchKeywordEvent, SearchKeywordState> {
  SearchKeywordBloc() : super(SearchKeywordState.initial()) {
    on<OnChangeKeyword>(
      (event, emit) {
        if (event.keyword?.isNotEmpty == true) {
          emit(
            state.copyWith(
              keyword: event.keyword,
              controller: TextEditingController(text: event.keyword)
                ..selection = TextSelection.fromPosition(
                  TextPosition(offset: event.keyword?.length ?? 0),
                ),
            ),
          );
        } else {
          emit(
            state.copyWith(
              keyword: '',
              controller: TextEditingController(text: ''),
            ),
          );
        }
      },
      transformer: debounce(const Duration(milliseconds: 500)),
    );
  }
}

EventTransformer<MyEvent> debounce<MyEvent>(Duration duration) {
  return (events, mapper) => events.debounceTime(duration).flatMap(mapper);
}