package com.sunyard.util;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.ReentrantLock;

/**
 * IP锁工具类 - 高并发安全实现
 *
 * 为每个IP地址提供唯一的可重入锁，确保同一IP的操作顺序执行
 */
public class IpLockUtils {

    private static final ConcurrentMap<String, ReentrantLock> LOCK_MAP = new ConcurrentHashMap<>();

    private static final Object CREATION_LOCK = new Object();

    /**
     * 获取IP对应的锁（保证唯一性）
     * @param ip IP地址
     * @return 可重入锁实例
     */
    public static ReentrantLock getLockForIp(String ip) {
        ReentrantLock lock = LOCK_MAP.get(ip);
        if (lock != null) {
            return lock;
        }

        synchronized (CREATION_LOCK) {
            // 双重检查
            lock = LOCK_MAP.get(ip);
            if (lock == null) {
                lock = new ReentrantLock(true); // 公平锁
                LOCK_MAP.put(ip, lock);
            }
            return lock;
        }
    }

    /**
     * 安全加锁（带超时机制）
     * @param ip IP地址
     * @param timeout 超时时间
     * @param unit 时间单位
     * @return 是否成功获取锁
     * @throws InterruptedException
     */
    public static boolean lockWithTimeout(String ip, long timeout, TimeUnit unit)
            throws InterruptedException {

        ReentrantLock lock = getLockForIp(ip);
        return lock.tryLock(timeout, unit);
    }

    /**
     * 解锁指定IP的锁
     * @param ip IP地址
     */
    public static void unlockForIp(String ip) {
        ReentrantLock lock = LOCK_MAP.get(ip);
        if (lock != null && lock.isHeldByCurrentThread()) {
            lock.unlock();
        }
    }

    /**
     * 清理未使用的锁（可选）
     */
    public static void cleanupUnusedLocks() {
        LOCK_MAP.entrySet().removeIf(entry ->
                !entry.getValue().isLocked() &&
                        entry.getValue().getQueueLength() == 0
        );
    }

    /**
     * 获取当前锁数量
     */
    public static int getLockCount() {
        return LOCK_MAP.size();
    }

    /**
     * 获取IP锁状态
     * @param ip IP地址
     * @return 锁状态字符串
     */
    public static String getLockStatus(String ip) {
        ReentrantLock lock = LOCK_MAP.get(ip);
        if (lock == null) {
            return "No lock exists";
        }

        return String.format("Locked: %s, Queue: %d, HoldCount: %d",
                lock.isLocked(), lock.getQueueLength(), lock.getHoldCount());
    }

    /**
     * 重置所有锁
     */
    public static void reset() {
        synchronized (CREATION_LOCK) {
            LOCK_MAP.clear();
        }
    }
}