package com.guwan.backend.handler;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.guwan.backend.service.CourseService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.socket.CloseStatus;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.TextWebSocketHandler;

import java.io.IOException;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

@Slf4j
@Component
public class CoursesWebSocketHandler extends TextWebSocketHandler {

    @Autowired
    private CourseService courseService;
    private static final Set<WebSocketSession> sessions = ConcurrentHashMap.newKeySet();

    @Override
    public void afterConnectionEstablished(WebSocketSession session) {
        log.info("Home page WebSocket connection established: {}", session.getId());
        sessions.add(session);
        // 连接建立时，发送所有课程的当前学习人数
        sendAllCourseCounts(session);
    }

    @Override
    protected void handleTextMessage(WebSocketSession session, TextMessage message) {
        log.info("Home page received message from {}: {}", session.getId(), message.getPayload());
        try {
            JsonNode jsonNode = new ObjectMapper().readTree(message.getPayload());
            String type = jsonNode.get("type").asText();

            if ("STUDENT_COUNT_UPDATE".equals(type)) {
                // 转发消息给所有首页连接的客户端
                broadcastMessage(message.getPayload());
            }
        } catch (Exception e) {
            log.error("Error handling home page message", e);
        }
    }

    @Override
    public void afterConnectionClosed(WebSocketSession session, CloseStatus status) {
        log.info("Home page WebSocket connection closed: {}, status: {}", session.getId(), status);
        sessions.remove(session);
    }

    public void broadcastMessage(String message) {
        sessions.forEach(session -> {
            try {
                if (session.isOpen()) {
                    session.sendMessage(new TextMessage(message));
                }
            } catch (IOException e) {
                log.error("Error broadcasting to home page", e);
            }
        });
    }


    private void sendAllCourseCounts(WebSocketSession session) {
        try {
            // 获取所有课程的学习人数
            Map<String, Integer> allCounts = courseService.getAllCourseCounts();

            // 发送每个课程的学习人数
            allCounts.forEach((courseId, count) -> {
                String message = String.format(
                        "{\"type\":\"STUDENT_COUNT_UPDATE\",\"courseId\":\"%s\",\"count\":%d}",
                        courseId, count
                );
                try {
                    if (session.isOpen()) {
                        session.sendMessage(new TextMessage(message));
                    }
                } catch (IOException e) {
                    log.error("Error sending course count", e);
                }
            });
        } catch (Exception e) {
            log.error("Error sending all course counts", e);
        }
    }
}