import lombok.RequiredArgsConstructor;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.data.redis.core.script.RedisScript;
import org.springframework.stereotype.Service;

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

/**
 * Redis Lock
 **/
@Service
@RequiredArgsConstructor
public class RedisDistributedLockImpl implements DistributedLock {

    private static final Logger log = LoggerFactory.getLogger(RedisDistributedLockImpl.class);

    private static final String UNLOCK_SCRIPT = "if redis.call('get', KEYS[1]) == ARGV[1] then return redis.call('del', KEYS[1]) else return 0 end";
    private static final Long UNLOCK_SUCCESS = 1L;

    private final RedisTemplate<String, String> redisTemplate;

    @Override
    @SuppressWarnings({"BusyWait", "java:S2142"})
    public boolean lock(DistributedLockParam param) {
        final long tryLockEndTime = param.getTryLockTime() + System.currentTimeMillis();
        while (true) {
            //判断是否超过了，尝试获取锁的时间
            if (System.currentTimeMillis() > tryLockEndTime) {
                return false;
            }

            // 尝试获取锁
            Boolean ok = redisTemplate.opsForValue().setIfAbsent(param.getKey(), param.getValue(), param.getHoldLockTime(), TimeUnit.MILLISECONDS);
            if (Boolean.TRUE.equals(ok)) {
                return true;
            }

            try {
                //获得锁失败，休眠50毫秒再去尝试获得锁,避免一直请求redis，导致redis cpu飙升
                Thread.sleep(50);
            } catch (InterruptedException e) {
                log.info(e.getMessage());
            }
        }
    }

    @Override
    public boolean unlock(DistributedLockParam param) {
        if (StringUtils.isBlank(param.getKey()) || StringUtils.isBlank(param.getValue())) {
            return false;
        }
        RedisScript<Long> redisScript = new DefaultRedisScript<>(UNLOCK_SCRIPT, Long.class);
        Long result = redisTemplate.execute(redisScript, Collections.singletonList(param.getKey()), param.getValue());
        return UNLOCK_SUCCESS.equals(result);
    }
}