import 'dart:async';
import 'package:flutter_bloc/flutter_bloc.dart';
import '../../domain/entities/chat.dart';
import '../../domain/entities/message.dart';
import '../../domain/repositories/chat_repository.dart';
import 'chat_event.dart';
import 'chat_state.dart';

class ChatBloc extends Bloc<ChatEvent, ChatState> {
  final ChatRepository chatRepository;
  StreamSubscription? _messageSubscription;
  StreamSubscription? _typingSubscription;

  ChatBloc({required this.chatRepository}) : super(const ChatState.initial()) {
    on<ChatEventStarted>(_onStarted);
    on<ChatEventChatsLoaded>(_onChatsLoaded);
    on<ChatEventChatSelected>(_onChatSelected);
    on<ChatEventMessagesRequested>(_onMessagesRequested);
    on<ChatEventMessageReceived>(_onMessageReceived);
    on<ChatEventMessageSent>(_onMessageSent);
    on<ChatEventFavoritesRequested>(_onFavoritesRequested);
    on<ChatEventTypingUpdated>(_onTypingUpdated);
    on<ChatEventSendTypingStatus>(_onSendTypingStatus);
    on<ChatEventCacheCleared>(_onCacheCleared);
    
    _messageSubscription = chatRepository.messageStream.listen((message) {
      add(ChatEvent.messageReceived(message));
    });

    _typingSubscription = chatRepository.typingStream.listen((data) {
      add(ChatEvent.typingUpdated(data['chatId'], data['userId'], data['isTyping']));
    });
  }

  Future<void> _onStarted(ChatEventStarted event, Emitter<ChatState> emit) async {
    // ignore: avoid_print
    print('[DEBUG] ChatBloc._onStarted for user: ${event.userId}');
    // Start SignalR in background
    chatRepository.initSignalR().catchError((e) {
      // Log or handle SignalR init error
    });
    // Immediately trigger chats loading
    add(ChatEvent.chatsLoaded(currentUserId: event.userId));
  }

  Future<void> _onChatsLoaded(ChatEventChatsLoaded event, Emitter<ChatState> emit) async {
    emit(const ChatState.loading());
    final result = await chatRepository.getChats(currentUserId: event.currentUserId);
    result.fold(
      (error) => emit(ChatState.error(error.message ?? 'Failed to load chats')),
      (chats) => emit(ChatState.chatsLoaded(chats)),
    );
  }

  Future<void> _onChatSelected(ChatEventChatSelected event, Emitter<ChatState> emit) async {
    final currentChatId = state.maybeMap(
      chatSelected: (s) => s.chat.id,
      messagesLoaded: (s) => s.chat.id,
      orElse: () => null,
    );

    if (currentChatId == event.chatId) {
      // Already in this chat, just refresh messages
      final messagesResult = await chatRepository.getMessages(event.chatId);
      messagesResult.fold(
        (error) => null,
        (messages) {
          final currentChat = state.maybeMap(
            chatSelected: (s) => s.chat,
            messagesLoaded: (s) => s.chat,
            orElse: () => null,
          );
          if (currentChat != null) {
            emit(ChatState.messagesLoaded(currentChat, messages, typingUsers: state.typingUsers));
          }
        },
      );
      return;
    }

    emit(ChatState.loading(typingUsers: state.typingUsers));
    final chatResult = await chatRepository.getChatById(event.chatId);
    final messagesResult = await chatRepository.getMessages(event.chatId);
    
    chatResult.fold(
      (error) => emit(ChatState.error(error.message ?? 'Failed to load chat', typingUsers: state.typingUsers)),
      (chat) {
        messagesResult.fold(
          (error) => emit(ChatState.chatSelected(chat, [], typingUsers: state.typingUsers)),
          (messages) => emit(ChatState.chatSelected(chat, messages, typingUsers: state.typingUsers)),
        );
      },
    );
  }

  Future<void> _onMessagesRequested(ChatEventMessagesRequested event, Emitter<ChatState> emit) async {
    final currentChat = state.maybeMap(
      chatSelected: (s) => s.chat,
      messagesLoaded: (s) => s.chat,
      orElse: () => null,
    );

    // Only fetch if it's the current chat or we are in chats list
    final result = await chatRepository.getMessages(event.chatId);
    result.fold(
      (error) => null, // Don't emit error state for background updates to avoid UI flickering
      (messages) {
        if (currentChat != null && currentChat.id == event.chatId) {
          // If we are in the chat, update messages and switch to messagesLoaded (stable state)
          emit(ChatState.messagesLoaded(currentChat, messages, typingUsers: state.typingUsers));
        }
        // If we are in the list, the list will update via local cache anyway or on next fetch
      },
    );
  }

  Future<void> _onMessageReceived(ChatEventMessageReceived event, Emitter<ChatState> emit) async {
    final message = event.message;
    final currentChat = state.maybeMap(
      chatSelected: (s) => s.chat,
      messagesLoaded: (s) => s.chat,
      orElse: () => null,
    );

    if (currentChat != null && currentChat.id == message.chatId) {
      final List<Message> currentMessages = state.maybeMap(
        chatSelected: (s) => s.messages,
        messagesLoaded: (s) => s.messages,
        orElse: () => [],
      );

      // Check for duplicates
      if (currentMessages.any((m) => m.id == message.id)) return;

      final updatedMessages = List<Message>.from(currentMessages)..insert(0, message);
      // Ensure sorting if needed (usually messages are already in order from stream)
      
      emit(ChatState.messagesLoaded(currentChat, updatedMessages, typingUsers: state.typingUsers));
    }
    
    // Also trigger chats refresh if we are in chatsLoaded state to update last message/unread
    state.maybeMap(
      chatsLoaded: (_) => add(ChatEvent.chatsLoaded(currentUserId: currentChat?.participants?.firstWhere((p) => p.id != '').id)), // userId logic might need to be better
      orElse: () => null,
    );
  }

  Future<void> _onMessageSent(ChatEventMessageSent event, Emitter<ChatState> emit) async {
    final result = await chatRepository.sendMessage(event.chatId, event.content);
    result.fold(
      (error) => emit(ChatState.error(error.message ?? 'Failed to send message', typingUsers: state.typingUsers)),
      (_) {
        // Optimistically or via refresh
        add(ChatEvent.messagesRequested(event.chatId));
      },
    );
  }

  Future<void> _onFavoritesRequested(ChatEventFavoritesRequested event, Emitter<ChatState> emit) async {
    emit(ChatState.loading(typingUsers: state.typingUsers));
    final result = await chatRepository.getOrCreateFavorites();
    result.fold(
      (error) => emit(ChatState.error(error.message ?? 'Failed to open Favorites', typingUsers: state.typingUsers)),
      (chat) => add(ChatEvent.chatSelected(chat.id)),
    );
  }

  Future<void> _onTypingUpdated(ChatEventTypingUpdated event, Emitter<ChatState> emit) async {
    final Map<String, Set<String>> newTypingUsers = Map.from(state.typingUsers);
    final Set<String> chatTypingUsers = Set.from(newTypingUsers[event.chatId] ?? {});
    
    if (event.isTyping) {
      chatTypingUsers.add(event.userId);
    } else {
      chatTypingUsers.remove(event.userId);
    }
    
    if (chatTypingUsers.isEmpty) {
      newTypingUsers.remove(event.chatId);
    } else {
      newTypingUsers[event.chatId] = chatTypingUsers;
    }
    
    state.maybeMap(
      chatSelected: (s) {
        // If it's the current chat, transition to stable state
        if (s.chat.id == event.chatId) {
          emit(ChatState.messagesLoaded(s.chat, s.messages, typingUsers: newTypingUsers));
        } else {
          emit(s.copyWith(typingUsers: newTypingUsers));
        }
      },
      messagesLoaded: (s) => emit(s.copyWith(typingUsers: newTypingUsers)),
      chatsLoaded: (s) => emit(s.copyWith(typingUsers: newTypingUsers)),
      orElse: () => emit(state.copyWith(typingUsers: newTypingUsers)),
    );
  }

  Future<void> _onSendTypingStatus(ChatEventSendTypingStatus event, Emitter<ChatState> emit) async {
    await chatRepository.sendTypingStatus(event.chatId, event.isTyping);
  }

  Future<void> _onCacheCleared(ChatEventCacheCleared event, Emitter<ChatState> emit) async {
    // ignore: avoid_print
    print('[DEBUG] ChatBloc._onCacheCleared START');
    await chatRepository.clearCache();
    // ignore: avoid_print
    print('[DEBUG] ChatBloc._onCacheCleared END');
    emit(const ChatState.initial());
  }

  @override
  Future<void> close() {
    _messageSubscription?.cancel();
    _typingSubscription?.cancel();
    chatRepository.disposeSignalR();
    return super.close();
  }
}