package com.example.idgenerate.config;

import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;

@Component
public class RedisIdWorker {
    /**
     * 開始時間戳,此處的時間戳為預生成
     */
    private static final long BEGIN_TIMESTAMP = 1640995200L;
    /**
     * 序列號的位數(shù)
     */
    private static final int COUNT_BITS = 32;

    private StringRedisTemplate stringRedisTemplate;

    public RedisIdWorker(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    /**
      * 描述信息: 生成唯一id
      *
      * @date  2023/05/21
      * @param keyPrefix 前綴，用于區(qū)分不同的業(yè)務
      * @return long id
      **/
    public long nextId(String keyPrefix) {
        // 1.生成時間戳
        LocalDateTime now = LocalDateTime.now();
        long nowSecond = now.toEpochSecond(ZoneOffset.UTC);
        long timestamp = nowSecond - BEGIN_TIMESTAMP;

        // 2.生成序列號
        // 2.1.獲取當前日期，精確到天
        String date = now.format(DateTimeFormatter.ofPattern("yyyy:MM:dd"));
        // 2.2.自增長 key格式：icr:order:2023:05:21
        long count = stringRedisTemplate.opsForValue().increment("icr:" + keyPrefix + ":" + date);

        // 3.拼接并返回，目的是讓時間戳存放在32上，序列號在低32位
        return timestamp << COUNT_BITS | count;
    }
}

 @Autowired
    private RedisIdWorker redisIdWorker;

    /**
      * 描述信息:將日期時間轉成秒級數(shù)字
      *
      * @date  2023/05/21
      * @return void
      **/
    @Test
    void contextLoads() {
        LocalDateTime time = LocalDateTime.of(2023, 5, 20, 0, 0,0);
        //將時間轉成秒數(shù)
        long second = time.toEpochSecond(ZoneOffset.UTC);
        System.out.println("second = " + second);
    }
    //實際項目中應使用自定義的線程池
    private ExecutorService es = Executors.newFixedThreadPool(500);

    /**
      * 描述信息: 測試redis生成3w條id所需要的時間
      *
      * @date  2023/05/21
      * @return void
      **/
    @Test
    void testIdWorker() throws InterruptedException {
        CountDownLatch latch = new CountDownLatch(300);

        Runnable task = () -> {
            for (int i = 0; i < 100; i++) {
                long id = redisIdWorker.nextId("order");
                System.out.println("id = " + id);
            }
            latch.countDown();
        };
        long begin = System.currentTimeMillis();
        for (int i = 0; i < 300; i++) {
            es.submit(task);
        }
        latch.await();
        long end = System.currentTimeMillis();
        System.out.println("time = " + (end - begin));
    }