package com.ard.sample.component.websocket.handler;

import com.alibaba.fastjson2.JSON;
import com.ard.sample.component.websocket.enums.MessageType;
import com.ard.sample.component.websocket.model.Payload;
import com.ard.sample.component.websocket.model.WebSocketMessage;
import com.ard.sample.manage.service.IControlService;
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 javax.annotation.PreDestroy;
import java.io.IOException;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

/**
 * WebSocket处理器（设备对接）
 * 核心能力：心跳检测、订阅/取消订阅、定向消息推送、广播消息
 */
@Slf4j
@Component
public class DockWebSocketHandler extends TextWebSocketHandler {

    @Autowired
    private LiveStreamHandler _liveStreamService;

    @Autowired
    private IControlService _controlService;

    // ====================== 心跳相关常量（可配置化建议放到配置文件） ======================
    /** 心跳间隔（秒）：客户端需每隔此时间发送一次PING消息 */
    private static final long HEARTBEAT_INTERVAL = 30;
    /** 心跳超时阈值（秒）：超过此时间未收到PING则判定连接失效 */
    private static final long HEARTBEAT_TIMEOUT = 90;
    /** 心跳检测任务间隔（秒）：定时扫描超时连接 */
    private static final long HEARTBEAT_CHECK_INTERVAL = 10;

    // ====================== 核心存储（线程安全） ======================
    /** 用户会话映射：userId -> WebSocketSession */
    private final Map<String, WebSocketSession> userSessions = new ConcurrentHashMap<>();
    /** 订阅关系映射：订阅标识(sn:type) -> 订阅用户ID集合 */
    private final Map<String, Set<String>> subscriptions = new ConcurrentHashMap<>();
    /** 会话锁映射：WebSocketSession -> 独立锁对象（防止并发写冲突） */
    private final Map<WebSocketSession, Object> sessionLocks = new ConcurrentHashMap<>();
    /** 用户最后心跳时间：userId -> 最后心跳时间戳（毫秒） */
    private final Map<String, Long> userLastHeartbeatTime = new ConcurrentHashMap<>();

    // ====================== 线程池 ======================
    /** 心跳检测线程池（单线程守护线程） */
    private final ScheduledExecutorService heartbeatCheckExecutor = Executors.newSingleThreadScheduledExecutor(runnable -> {
        Thread thread = new Thread(runnable, "websocket-heartbeat-check-thread");
        thread.setDaemon(true); // 守护线程，不阻塞JVM退出
        return thread;
    });

    // ====================== 初始化 ======================
    public DockWebSocketHandler() {
        // 启动心跳检测定时任务：首次延迟CHECK_INTERVAL执行，之后每隔CHECK_INTERVAL执行
        heartbeatCheckExecutor.scheduleAtFixedRate(
                this::checkHeartbeatTimeout,
                HEARTBEAT_CHECK_INTERVAL,
                HEARTBEAT_CHECK_INTERVAL,
                TimeUnit.SECONDS
        );
        log.info("WebSocket心跳检测任务已启动，检测间隔：{}秒，超时阈值：{}秒",
                HEARTBEAT_CHECK_INTERVAL, HEARTBEAT_TIMEOUT);
    }

    // ====================== 连接生命周期 ======================
    /**
     * 连接建立成功回调
     */
    @Override
    public void afterConnectionEstablished(WebSocketSession session) throws Exception {
        // 从会话属性获取认证后的用户ID（需前置拦截器完成认证）
        String userId = (String) session.getAttributes().get("userId");
        if (userId == null) {
            session.close(CloseStatus.POLICY_VIOLATION.withReason("未认证，拒绝连接"));
            log.warn("WebSocket连接建立失败：会话无用户认证信息");
            return;
        }

        // 初始化会话相关存储
        userSessions.put(userId, session);
        sessionLocks.put(session, new Object());
        userLastHeartbeatTime.put(userId, System.currentTimeMillis());

        log.info("用户[{}]WebSocket连接建立成功，当前在线人数：{}", userId, userSessions.size());
    }

    /**
     * 连接关闭回调（同步清理，无延时）
     */
    @Override
    public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception {
        String userId = (String) session.getAttributes().get("userId");
        if (userId != null) {
            // 同步清理所有关联数据
            userSessions.remove(userId);
            sessionLocks.remove(session);
            userLastHeartbeatTime.remove(userId);
            removeUserAllSubscriptions(userId);

            log.info("用户[{}]WebSocket连接关闭（状态码：{}，原因：{}），当前在线人数：{}",
                    userId, status.getCode(), status.getReason(), userSessions.size());
        } else {
            // 无认证用户直接清理锁
            sessionLocks.remove(session);
            log.warn("无认证用户WebSocket连接关闭，状态码：{}", status.getCode());
        }
    }

    // ====================== 消息处理 ======================
    /**
     * 处理客户端文本消息（包含心跳、订阅/取消订阅）
     */
    @Override
    protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
        String userId = (String) session.getAttributes().get("userId");
        if (userId == null) {
            sendMessage(session, "未认证，无法处理消息");
            return;
        }

        String jsonPayload = message.getPayload();
        try {
            // 解析WebSocket消息体
            WebSocketMessage webSocketMessage = JSON.parseObject(jsonPayload, WebSocketMessage.class);
            String messageType = webSocketMessage.getType();
            Payload payload = webSocketMessage.getPayload();

            // 1. 处理心跳PING消息
            if (MessageType.PING.getType().equals(messageType)) {
                handleHeartbeatPing(session, userId);
                return;
            }

            // 2. 验证消息类型合法性
            if (!MessageType.fromString(messageType)) {
                sendMessage(session, "不支持的消息类型：" + messageType);
                log.warn("用户[{}]发送非法消息类型：{}", userId, messageType);
                return;
            }

            // 3. 处理订阅/取消订阅逻辑
            handleSubscription(userId, messageType, payload);

        } catch (Exception e) {
            log.error("用户[{}]消息处理异常", userId, e);
            sendMessage(session, "消息格式错误或处理失败：" + e.getMessage());
        }
    }

    /**
     * 处理心跳PING消息
     */
    private void handleHeartbeatPing(WebSocketSession session, String userId) throws IOException {
        // 更新最后心跳时间
        userLastHeartbeatTime.put(userId, System.currentTimeMillis());
        // 回复PONG消息
        WebSocketMessage pongMessage = new WebSocketMessage();
        pongMessage.setType(MessageType.PONG.getType());
        pongMessage.setPayload(new Payload());
        sendMessage(session, JSON.toJSONString(pongMessage));

        log.debug("用户[{}]心跳PING接收成功，已回复PONG", userId);
    }

    /**
     * 处理订阅/取消订阅逻辑
     */
    private void handleSubscription(String userId, String type, Payload payload) {
        String sn = payload.getSn();
        boolean isSubscribe = payload.isSubscribe();
        String subscriptionKey = getSubscriptionKey(sn, type);

        if (isSubscribe) {
            // 订阅操作：不存在则创建，存在则添加用户
            subscriptions.computeIfAbsent(subscriptionKey, k -> ConcurrentHashMap.newKeySet()).add(userId);
            log.info("用户[{}]订阅设备[{}]的[{}]类型消息", userId, sn, type);

            // 直播类型订阅：触发开启直播
            if (MessageType.LIVESTREAM.getType().equals(type)) {
                _liveStreamService.StartLiveStreaming(sn);
                log.info("设备[{}]直播流已开启（用户[{}]订阅触发）", sn, userId);
            }
        } else {
            // 取消订阅操作
            if (subscriptions.containsKey(subscriptionKey)) {
                Set<String> subscriberIds = subscriptions.get(subscriptionKey);
                subscriberIds.remove(userId);
                log.info("用户[{}]取消订阅设备[{}]的[{}]类型消息", userId, sn, type);

                // 订阅组为空时移除，并停止直播（直播类型）
                if (subscriberIds.isEmpty()) {
                    subscriptions.remove(subscriptionKey);
                    if (MessageType.LIVESTREAM.getType().equals(type)) {
                        _liveStreamService.StopLiveStreaming(sn);
                        log.info("设备[{}]直播流已停止（无订阅用户）", sn);
                    }
                }
            }
        }
    }

    // ====================== 心跳检测 ======================
    /**
     * 检测心跳超时连接并主动关闭
     */
    private void checkHeartbeatTimeout() {
        long currentTime = System.currentTimeMillis();
        // 遍历所有用户心跳记录，检查超时
        for (Map.Entry<String, Long> entry : userLastHeartbeatTime.entrySet()) {
            String userId = entry.getKey();
            long lastHeartbeatTime = entry.getValue();
            long timeoutMs = currentTime - lastHeartbeatTime;

            // 判定超时：超过阈值则主动关闭连接
            if (timeoutMs > HEARTBEAT_TIMEOUT * 1000) {
                WebSocketSession session = userSessions.get(userId);
                log.warn("用户[{}]心跳超时（{}秒未发送PING），将主动关闭连接",
                        userId, timeoutMs / 1000);

                try {
                    // 主动关闭连接
                    if (session != null && session.isOpen()) {
                        session.close(CloseStatus.SESSION_NOT_RELIABLE.withReason(
                                String.format("心跳超时：%d秒未收到PING", timeoutMs / 1000)
                        ));
                    }
                } catch (IOException e) {
                    log.error("主动关闭用户[{}]超时连接失败", userId, e);
                } finally {
                    // 强制清理用户所有关联数据
                    userSessions.remove(userId);
                    sessionLocks.remove(session);
                    userLastHeartbeatTime.remove(userId);
                    removeUserAllSubscriptions(userId);
                }
            }
        }
    }

    // ====================== 消息推送接口 ======================
    /**
     * 向订阅指定设备指定类型的用户推送消息
     *
     * @param sn      设备序列号
     * @param type    消息类型（对应MessageType）
     * @param content 消息内容（JSON字符串）
     */
    public void sendMessageToSubscribers(String sn, String type, String content) {
        String subscriptionKey = getSubscriptionKey(sn, type);
        Set<String> subscriberIds = subscriptions.getOrDefault(subscriptionKey, Collections.emptySet());

        if (subscriberIds.isEmpty()) {
            log.debug("设备[{}]的[{}]类型消息无订阅用户，无需推送", sn, type);
            return;
        }

        // 遍历订阅用户推送消息
        for (String userId : subscriberIds) {
            WebSocketSession session = userSessions.get(userId);
            if (session == null || !session.isOpen()) {
                // 清理无效会话
                userSessions.remove(userId);
                sessionLocks.remove(session);
                userLastHeartbeatTime.remove(userId);
                log.warn("用户[{}]会话无效，已清理", userId);
                continue;
            }

            // 线程安全发送消息
            try {
                sendMessage(session, content);
                log.debug("向用户[{}]推送设备[{}]的[{}]类型消息：{}", userId, sn, type, content);
            } catch (IOException e) {
                log.error("向用户[{}]推送消息失败", userId, e);
            }
        }
    }

    /**
     * 新增：向所有在线客户端广播消息
     *
     * @param content 消息内容（JSON字符串）
     */
    public void broadcastMessageToAllClients(String content) {
        if (userSessions.isEmpty()) {
            log.debug("无在线客户端，无需广播消息");
            return;
        }

        log.info("开始向所有在线客户端（{}人）广播消息", userSessions.size());
        // 遍历所有在线会话发送消息
        for (Map.Entry<String, WebSocketSession> entry : userSessions.entrySet()) {
            String userId = entry.getKey();
            WebSocketSession session = entry.getValue();

            if (session == null || !session.isOpen()) {
                // 清理无效会话
                userSessions.remove(userId);
                sessionLocks.remove(session);
                userLastHeartbeatTime.remove(userId);
                log.warn("用户[{}]会话无效，已清理", userId);
                continue;
            }

            // 线程安全发送广播消息
            try {
                sendMessage(session, content);
                log.debug("向用户[{}]广播消息成功", userId);
            } catch (IOException e) {
                log.error("向用户[{}]广播消息失败", userId, e);
            }
        }
    }

    // ====================== 通用工具方法 ======================
    /**
     * 线程安全发送消息（封装同步逻辑）
     */
    private void sendMessage(WebSocketSession session, String content) throws IOException {
        Object lock = sessionLocks.get(session);
        if (lock != null && session.isOpen()) {
            synchronized (lock) {
                session.sendMessage(new TextMessage(content));
            }
        }
    }

    /**
     * 生成订阅标识（设备SN + 消息类型）
     */
    private String getSubscriptionKey(String sn, String type) {
        return String.format("%s:%s", sn, type);
    }

    /**
     * 清除用户所有订阅关系
     */
    private void removeUserAllSubscriptions(String userId) {
        // 迭代器遍历，避免并发修改异常
        Iterator<Map.Entry<String, Set<String>>> iterator = subscriptions.entrySet().iterator();
        while (iterator.hasNext()) {
            Map.Entry<String, Set<String>> entry = iterator.next();
            Set<String> subscriberIds = entry.getValue();

            // 移除当前用户
            if (subscriberIds.remove(userId)) {
                log.debug("用户[{}]已移除订阅：{}", userId, entry.getKey());

                // 订阅组为空时移除，并停止直播（直播类型）
                if (subscriberIds.isEmpty()) {
                    String subscriptionKey = entry.getKey();
                    if (subscriptionKey.contains(MessageType.LIVESTREAM.getType())) {
                        String sn = subscriptionKey.split(":")[0];
                        _liveStreamService.StopLiveStreaming(sn);
                        log.info("设备[{}]无订阅用户，已停止直播流", sn);
                    }
                    iterator.remove(); // 安全移除空订阅组
                }
            }
        }
    }

    // ====================== 资源销毁 ======================
    /**
     * 容器销毁时关闭线程池，防止内存泄漏
     */
    @PreDestroy
    public void destroy() {
        // 关闭心跳检测线程池
        if (heartbeatCheckExecutor != null && !heartbeatCheckExecutor.isShutdown()) {
            heartbeatCheckExecutor.shutdown();
            try {
                // 等待1秒优雅关闭，超时则强制关闭
                if (!heartbeatCheckExecutor.awaitTermination(1, TimeUnit.SECONDS)) {
                    heartbeatCheckExecutor.shutdownNow();
                    log.warn("WebSocket心跳检测线程池强制关闭");
                }
            } catch (InterruptedException e) {
                heartbeatCheckExecutor.shutdownNow();
                Thread.currentThread().interrupt(); // 恢复中断状态
                log.error("WebSocket心跳检测线程池关闭被中断", e);
            }
        }
        log.info("WebSocket处理器资源已销毁");
    }
}