import 'dart:developer';

import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:equatable/equatable.dart';
import 'package:chat_repository/chat_repository.dart';

part 'chat_event.dart';
part 'chat_state.dart';

class ChatBloc extends Bloc<ChatEvent, ChatState> {
  final ApiChatRepository _chatRepository;

  /// Resolved once per conversation. Every chat endpoint is keyed by the chat
  /// id, which the app used to confuse with the service id.
  String? _chatId;

  ChatBloc({
    required ApiChatRepository chatRepository,
  })  : _chatRepository = chatRepository,
        super(ChatInitial()) {
    on<LoadChatEvent>(_onLoadChatEvent);
    on<SendMessageEvent>(_onSendMessageEvent);
  }

  void _onLoadChatEvent(LoadChatEvent event, Emitter<ChatState> emit) async {
    emit(ChatLoading());
    try {
      final chat = await _chatRepository.loadConversation(event.professionalId);
      _chatId = chat.id;
      emit(ChatLoaded(chat: chat));
    } catch (e) {
      log(e.toString());
      emit(ChatFailure());
    }
  }

  void _onSendMessageEvent(
      SendMessageEvent event, Emitter<ChatState> emit) async {
    final current = state;
    // Show the message immediately; the reload below reconciles with the
    // backend. Previously nothing was emitted at all and the message vanished.
    if (current is ChatLoaded) {
      emit(ChatLoaded(
        chat: ChatEntity(
          id: current.chat.id,
          userId: current.chat.userId,
          professionalId: current.chat.professionalId,
          messages: [...current.chat.messages, event.message],
        ),
      ));
    }

    try {
      final chatId = _chatId;
      if (chatId == null || chatId.isEmpty) {
        throw Exception('El chat aún no está abierto');
      }
      await _chatRepository.sendMessage(chatId, event.message);

      final messages = await _chatRepository.fetchMessages(chatId);
      emit(ChatLoaded(
        chat: ChatEntity(
          id: chatId,
          userId: current is ChatLoaded ? current.chat.userId : '',
          professionalId:
              current is ChatLoaded ? current.chat.professionalId : '',
          messages: messages,
        ),
      ));
    } catch (e) {
      log(e.toString());
      // Roll the optimistic message back so nobody believes it was delivered.
      if (current is ChatLoaded) emit(ChatLoaded(chat: current.chat));
      emit(SendMessageFailure());
    }
  }
}