/*
 *      Copyright (c) 2018-2028, DreamLu All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions are met:
 *
 *  Redistributions of source code must retain the above copyright notice,
 *  this list of conditions and the following disclaimer.
 *  Redistributions in binary form must reproduce the above copyright
 *  notice, this list of conditions and the following disclaimer in the
 *  documentation and/or other materials provided with the distribution.
 *  Neither the name of the dreamlu.net developer nor the names of its
 *  contributors may be used to endorse or promote products derived from
 *  this software without specific prior written permission.
 *  Author: DreamLu 卢春梦 (596392912@qq.com)
 */

package org.springblade.core.redis.ratelimiter;

import lombok.RequiredArgsConstructor;
import org.springblade.core.tool.utils.CharPool;
import org.springframework.core.env.Environment;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.RedisScript;

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

/**
 * redis 限流服务
 *
 * @author dream.lu
 */
@RequiredArgsConstructor
public class RedisRateLimiterClient implements RateLimiterClient {
	/**
	 * redis 限流 key 前缀
	 */
	private static final String REDIS_KEY_PREFIX = "limiter:";
	/**
	 * 失败的默认返回值
	 */
	private static final long FAIL_CODE = 0;
	/**
	 * redisTemplate
	 */
	private final StringRedisTemplate redisTemplate;
	/**
	 * redisScript
	 */
	private final RedisScript<List<Long>> script;
	/**
	 * env
	 */
	private final Environment environment;

	@Override
	public boolean isAllowed(String key, long max, long ttl, TimeUnit timeUnit) {
		// redis key
		String redisKeyBuilder = REDIS_KEY_PREFIX +
			getApplicationName(environment) + CharPool.COLON + key;
		List<String> keys = Collections.singletonList(redisKeyBuilder);
		// 毫秒，考虑主从策略和脚本回放机制，这个time由客户端获取传入
		long now = System.currentTimeMillis();
		// 转为毫秒，pexpire
		long ttlMillis = timeUnit.toMillis(ttl);
		// 执行命令
		List<Long> results = this.redisTemplate.execute(this.script, keys, max + "", ttlMillis + "", now + "");
		// 结果为空返回失败
		if (results == null || results.isEmpty()) {
			return false;
		}
		// 判断返回成功
		Long result = results.get(0);
		return result != FAIL_CODE;
	}

	private static String getApplicationName(Environment environment) {
		return environment.getProperty("spring.application.name", "");
	}

}