package edu.travel.cache.config;

import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.data.redis.core.script.RedisScript;
import org.springframework.stereotype.Component;

import java.util.Collections;
import java.util.UUID;
import java.util.concurrent.TimeUnit;

@Component
public class RedisLock {

    // 锁键的前缀，可根据业务自定义
    private static final String LOCK_PREFIX = "lock:";
    private final StringRedisTemplate redisTemplate;

    public RedisLock(StringRedisTemplate redisTemplate) {
        this.redisTemplate = redisTemplate;
    }

    /**
     * 获取分布式锁（使用SETNX和过期时间，保证原子性）
     *
     * @param lockKey 锁的键
     * @param expire  锁的过期时间（秒）
     * @return 锁的唯一标识（用于释放锁）
     */
    public String acquireLock(String lockKey, long expire) {
        String lockValue = UUID.randomUUID().toString();
        String key = LOCK_PREFIX + lockKey;
        // 使用SET命令：SET key value NX EX expire
        Boolean success = redisTemplate.opsForValue()
                .setIfAbsent(key, lockValue, expire, TimeUnit.SECONDS);
        return Boolean.TRUE.equals(success) ? lockValue : null;
    }

    /**
     * 释放分布式锁（使用Lua脚本保证原子性）
     *
     * @param lockKey   锁的键
     * @param lockValue 锁的唯一标识
     * @return 是否释放成功
     */
    public boolean releaseLock(String lockKey, String lockValue) {
        if (lockValue == null) return false;
        String key = LOCK_PREFIX + lockKey;
        String script = "if redis.call('get', KEYS[1]) == ARGV[1] then " +
                "return redis.call('del', KEYS[1]) " +
                "else return 0 end";
        RedisScript<Long> redisScript = new DefaultRedisScript<>(script, Long.class);
        Long result = redisTemplate.execute(redisScript, Collections.singletonList(key), lockValue);
        return result != null && result == 1;
    }
}