dpot-frontend/hooks/useChat.ts

'use client';

import { useState, useEffect, useCallback, useRef } from 'react';
import { useSignalRContext } from '@/contexts/signalrProvider';
import type { ChatMessage } from '@/types/chat';

export type SystemMessage = {
	id: number;
	content: string;
	receivedAt: string;
};

export type ChatParticipant = {
	memberName: string;
	isGuest: boolean;
};

let systemMsgId = 0;

export default function useChat() {
	const { chatConnection, chatConnected } = useSignalRContext();
	const [messages, setMessages] = useState<ChatMessage[]>([]);
	const [systemMessages, setSystemMessages] = useState<SystemMessage[]>([]);
	const [participantCount, setParticipantCount] = useState(0);
	const [participants, setParticipants] = useState<ChatParticipant[]>([]);
	const prevConnectionRef = useRef<typeof chatConnection>(null);

	useEffect(() => {
		if (!chatConnection || !chatConnected) return;
		// 같은 connection 객체면 중복 등록 방지
		if (prevConnectionRef.current === chatConnection) return;
		prevConnectionRef.current = chatConnection;

		chatConnection.on('ReceiveHistory', (history: ChatMessage[]) => {
			setMessages(history);
		});

		chatConnection.on('ReceiveMessage', (message: ChatMessage) => {
			setMessages((prev) => [...prev, message]);
		});

		chatConnection.on('ReceiveSystemMessage', (content: string) => {
			setSystemMessages((prev) => [
				...prev,
				{ id: ++systemMsgId, content, receivedAt: new Date().toISOString() }
			]);
		});

		chatConnection.on('ReceiveParticipantCount', (count: number) => {
			setParticipantCount(count);
		});

		chatConnection.on('ReceiveParticipants', (list: ChatParticipant[]) => {
			setParticipants(list);
		});

		// 핸들러 등록 후 명시적으로 히스토리 + 접속자 수 요청
		chatConnection.invoke('RequestHistory').catch(() => {});
		chatConnection.invoke('RequestParticipantCount').catch(() => {});

		return () => {
			chatConnection.off('ReceiveHistory');
			chatConnection.off('ReceiveMessage');
			chatConnection.off('ReceiveSystemMessage');
			chatConnection.off('ReceiveParticipantCount');
			chatConnection.off('ReceiveParticipants');
			prevConnectionRef.current = null;
		};
	}, [chatConnection, chatConnected]);

	const sendMessage = useCallback(async (content: string) => {
		if (!chatConnection || !chatConnected) return;
		const trimmed = content.trim();
		if (!trimmed || trimmed.length > 500) return;

		try {
			await chatConnection.invoke('SendMessage', trimmed);
		} catch (error) {
			console.error('메시지 전송 실패:', error);
		}
	}, [chatConnection, chatConnected]);

	const clearMessages = useCallback(() => {
		setMessages([]);
		setSystemMessages([]);
	}, []);

	const refreshChat = useCallback(async () => {
		if (!chatConnection || !chatConnected) return;
		setMessages([]);
		setSystemMessages([]);
		try {
			await chatConnection.invoke('RequestHistory');
			await chatConnection.invoke('RequestParticipantCount');
		} catch {
			// ignore
		}
	}, [chatConnection, chatConnected]);

	const requestParticipants = useCallback(async () => {
		if (!chatConnection || !chatConnected) return;
		try {
			await chatConnection.invoke('RequestParticipants');
		} catch {
			// ignore
		}
	}, [chatConnection, chatConnected]);

	return {
		messages,
		systemMessages,
		participantCount,
		participants,
		sendMessage,
		clearMessages,
		refreshChat,
		requestParticipants,
		chatConnected
	};
}