frontend/src/hooks/useChat.js

import { useState, useEffect } from 'react';
import { useQuery, useMutation, useQueryClient } from 'react-query';
import { conversationAPI, chatAPI } from '../services/api';
import { useSocket } from './useSocket';
import toast from 'react-hot-toast';

export const useChat = () => {
  const [currentConversationId, setCurrentConversationId] = useState(null);
  const [messages, setMessages] = useState([]);
  const [isTyping, setIsTyping] = useState(false);
  const queryClient = useQueryClient();
  const socket = useSocket();

  // Get conversations
  const {
    data: conversations = [],
    isLoading: conversationsLoading,
    refetch: refetchConversations
  } = useQuery('conversations', () => conversationAPI.getConversations().then(res => res.data.conversations));

  // Get messages for current conversation
  const {
    data: messagesData,
    isLoading: messagesLoading,
    refetch: refetchMessages
  } = useQuery(
    ['messages', currentConversationId],
    () => chatAPI.getMessages(currentConversationId).then(res => res.data.messages),
    {
      enabled: !!currentConversationId,
      onSuccess: (data) => {
        setMessages(data);
      }
    }
  );

  // Create conversation mutation
  const createConversationMutation = useMutation(
    (title) => conversationAPI.createConversation(title),
    {
      onSuccess: (response) => {
        const newConversation = response.data.conversation;
        setCurrentConversationId(newConversation._id);
        queryClient.invalidateQueries('conversations');
        toast.success('New conversation created');
      },
      onError: (error) => {
        toast.error(error.response?.data?.error || 'Failed to create conversation');
      }
    }
  );

  // Send message mutation
  const sendMessageMutation = useMutation(
    ({ conversationId, content }) => chatAPI.sendMessage(conversationId, content),
    {
      onSuccess: (response) => {
        const { userMessage, assistantMessage } = response.data;
        setMessages(prev => [...prev, userMessage, assistantMessage]);
        queryClient.invalidateQueries('conversations');
      },
      onError: (error) => {
        toast.error(error.response?.data?.error || 'Failed to send message');
      }
    }
  );

  // Delete message mutation
  const deleteMessageMutation = useMutation(
    (messageId) => chatAPI.deleteMessage(messageId),
    {
      onSuccess: () => {
        refetchMessages();
        queryClient.invalidateQueries('conversations');
        toast.success('Message deleted');
      },
      onError: (error) => {
        toast.error(error.response?.data?.error || 'Failed to delete message');
      }
    }
  );

  // Update conversation mutation
  const updateConversationMutation = useMutation(
    ({ id, updates }) => conversationAPI.updateConversation(id, updates),
    {
      onSuccess: () => {
        queryClient.invalidateQueries('conversations');
        toast.success('Conversation updated');
      },
      onError: (error) => {
        toast.error(error.response?.data?.error || 'Failed to update conversation');
      }
    }
  );

  // Delete conversation mutation
  const deleteConversationMutation = useMutation(
    (id) => conversationAPI.deleteConversation(id),
    {
      onSuccess: () => {
        if (currentConversationId === id) {
          setCurrentConversationId(null);
          setMessages([]);
        }
        queryClient.invalidateQueries('conversations');
        toast.success('Conversation deleted');
      },
      onError: (error) => {
        toast.error(error.response?.data?.error || 'Failed to delete conversation');
      }
    }
  );

  // Socket event handlers
  useEffect(() => {
    if (!socket) return;

    const handleNewMessage = (data) => {
      const { userMessage, assistantMessage } = data;
      setMessages(prev => [...prev, userMessage, assistantMessage]);
      queryClient.invalidateQueries('conversations');
    };

    const handleUserTyping = (data) => {
      if (data.conversationId === currentConversationId) {
        setIsTyping(data.isTyping);
      }
    };

    socket.on('newMessage', handleNewMessage);
    socket.on('userTyping', handleUserTyping);

    return () => {
      socket.off('newMessage', handleNewMessage);
      socket.off('userTyping', handleUserTyping);
    };
  }, [socket, currentConversationId, queryClient]);

  // Helper functions
  const createConversation = (title = 'New Chat') => {
    createConversationMutation.mutate(title);
  };

  const sendMessage = (content) => {
    if (!currentConversationId) {
      // Create new conversation first
      const title = content.length > 50 ? content.substring(0, 50) + '...' : content;
      createConversationMutation.mutate(title);
      // The message will be sent after conversation is created
      return;
    }
    
    sendMessageMutation.mutate({
      conversationId: currentConversationId,
      content
    });
  };

  const deleteMessage = (messageId) => {
    deleteMessageMutation.mutate(messageId);
  };

  const updateConversation = (id, updates) => {
    updateConversationMutation.mutate({ id, updates });
  };

  const deleteConversation = (id) => {
    deleteConversationMutation.mutate(id);
  };

  const switchConversation = (conversationId) => {
    setCurrentConversationId(conversationId);
    setMessages([]);
  };

  const emitTyping = (isTyping) => {
    if (socket && currentConversationId) {
      socket.emit('typing', {
        conversationId: currentConversationId,
        isTyping
      });
    }
  };

  return {
    // Data
    conversations,
    messages,
    currentConversationId,
    isTyping,
    
    // Loading states
    conversationsLoading,
    messagesLoading,
    sendingMessage: sendMessageMutation.isLoading,
    creatingConversation: createConversationMutation.isLoading,
    
    // Actions
    createConversation,
    sendMessage,
    deleteMessage,
    updateConversation,
    deleteConversation,
    switchConversation,
    emitTyping,
    
    // Utilities
    refetchConversations,
    refetchMessages
  };
};