package com.xiaopeng.admin.socketio;

import com.corundumstudio.socketio.SocketIOClient;
import org.springframework.stereotype.Component;

import java.util.Collections;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

/**
 * Socket.IO 会话管理
 *
 * @ClassName SocketIOSessionManager
 * @Description 跟踪连接、城市订阅与单车详情订阅
 */
@Component
public class SocketIOSessionManager {

    private final Map<String, SocketIOClient> clients = new ConcurrentHashMap<>();
    private final Map<String, Set<String>> clientCitySubscriptions = new ConcurrentHashMap<>();
    private final Map<String, Long> clientVehicleDetailSubscription = new ConcurrentHashMap<>();
    private final Map<Long, Set<String>> vehicleDetailSubscribers = new ConcurrentHashMap<>();

    /**
     * 注册客户端
     *
     * @param client Socket 客户端
     */
    public void register(SocketIOClient client) {
        clients.put(client.getSessionId().toString(), client);
    }

    /**
     * 注销客户端
     *
     * @param client Socket 客户端
     */
    public void unregister(SocketIOClient client) {
        unsubscribeVehicleDetail(client);
        clients.remove(client.getSessionId().toString());
        clientCitySubscriptions.remove(client.getSessionId().toString());
    }

    /**
     * 记录城市订阅
     *
     * @param client   Socket 客户端
     * @param cityCode 城市编码
     */
    public void trackSubscription(SocketIOClient client, String cityCode) {
        clientCitySubscriptions
                .computeIfAbsent(client.getSessionId().toString(), key -> ConcurrentHashMap.newKeySet())
                .add(cityCode);
    }

    /**
     * 移除城市订阅记录
     *
     * @param client   Socket 客户端
     * @param cityCode 城市编码
     */
    public void untrackSubscription(SocketIOClient client, String cityCode) {
        Set<String> cities = clientCitySubscriptions.get(client.getSessionId().toString());
        if (cities != null) {
            cities.remove(cityCode);
        }
    }

    /**
     * 订阅单车详情推送（同一客户端仅保留一个 vehicleId）
     *
     * @param client    Socket 客户端
     * @param vehicleId 车辆 ID
     */
    public void subscribeVehicleDetail(SocketIOClient client, Long vehicleId) {
        if (vehicleId == null) {
            return;
        }
        String sessionId = client.getSessionId().toString();
        Long previous = clientVehicleDetailSubscription.get(sessionId);
        if (previous != null) {
            removeVehicleSubscriber(previous, sessionId);
        }
        clientVehicleDetailSubscription.put(sessionId, vehicleId);
        vehicleDetailSubscribers.computeIfAbsent(vehicleId, key -> ConcurrentHashMap.newKeySet()).add(sessionId);
    }

    /**
     * 取消单车详情订阅
     *
     * @param client Socket 客户端
     */
    public void unsubscribeVehicleDetail(SocketIOClient client) {
        String sessionId = client.getSessionId().toString();
        Long vehicleId = clientVehicleDetailSubscription.remove(sessionId);
        if (vehicleId != null) {
            removeVehicleSubscriber(vehicleId, sessionId);
        }
    }

    /**
     * 当前被订阅的所有车辆 ID（去重）
     *
     * @return 车辆 ID 集合
     */
    public Set<Long> getSubscribedVehicleIds() {
        return new HashSet<>(vehicleDetailSubscribers.keySet());
    }

    /**
     * 订阅指定车辆详情的 sessionId 集合
     *
     * @param vehicleId 车辆 ID
     * @return sessionId 集合
     */
    public Set<String> getSubscriberSessionIds(Long vehicleId) {
        Set<String> subscribers = vehicleDetailSubscribers.get(vehicleId);
        return subscribers != null ? new HashSet<>(subscribers) : Collections.emptySet();
    }

    /**
     * 按 sessionId 获取客户端
     *
     * @param sessionId 会话 ID
     * @return 客户端，不存在返回 null
     */
    public SocketIOClient getClient(String sessionId) {
        return clients.get(sessionId);
    }

    private void removeVehicleSubscriber(Long vehicleId, String sessionId) {
        vehicleDetailSubscribers.computeIfPresent(vehicleId, (key, subscribers) -> {
            subscribers.remove(sessionId);
            return subscribers.isEmpty() ? null : subscribers;
        });
    }
}