package com.csitc.framework.mq.job;

import cn.hutool.core.collection.CollUtil;
import com.csitc.framework.mq.core.RedisMQTemplate;
import com.csitc.framework.mq.core.stream.AbstractStreamMessageListener;
import lombok.AllArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.data.redis.connection.stream.Consumer;
import org.springframework.data.redis.connection.stream.MapRecord;
import org.springframework.data.redis.connection.stream.PendingMessagesSummary;
import org.springframework.data.redis.connection.stream.ReadOffset;
import org.springframework.data.redis.connection.stream.StreamOffset;
import org.springframework.data.redis.connection.stream.StreamRecords;
import org.springframework.data.redis.core.StreamOperations;
import org.springframework.scheduling.annotation.Scheduled;

import java.util.List;
import java.util.Map;

/**
 * 这个任务用于处理，crash 之后的消费者未消费完的消息
 */
@Slf4j
@AllArgsConstructor
public class RedisPendingMessageResendJob {

    private static final String LOCK_KEY = "redis:pending:msg:lock";

    private final List<AbstractStreamMessageListener<?>> listeners;
    private final RedisMQTemplate redisTemplate;
    private final String groupName;
    private final RedissonClient redissonClient;

    /**
     * 一分钟执行一次,这里选择每分钟的35秒执行，是为了避免整点任务过多的问题
     */
    @Scheduled(cron = "35 * * * * ?")
    public void messageResend() {
        RLock lock = redissonClient.getLock(LOCK_KEY);
        // 尝试加锁
        if (lock.tryLock()) {
            try {
                execute();
            } catch (Exception ex) {
                log.error("[messageResend][执行异常]", ex);
            } finally {
                lock.unlock();
            }
        }
    }

    private void execute() {
        StreamOperations<String, Object, Object> ops = redisTemplate.getRedisTemplate().opsForStream();
        listeners.forEach(listener -> {
            PendingMessagesSummary pendingMessagesSummary = ops.pending(listener.getStreamKey(), groupName);
            // 每个消费者的 pending 队列消息数量
            Map<String, Long> pendingMessagesPerConsumer = pendingMessagesSummary.getPendingMessagesPerConsumer();
            pendingMessagesPerConsumer.forEach((consumerName, pendingMessageCount) -> {
                log.info("[processPendingMessage][消费者({}) 消息数量({})]", consumerName, pendingMessageCount);

                // 从消费者的 pending 队列中读取消息
                List<MapRecord<String, Object, Object>> records = ops.read(Consumer.from(groupName, consumerName), StreamOffset.create(listener.getStreamKey(), ReadOffset.from("0")));
                if (CollUtil.isEmpty(records)) {
                    return;
                }
                for (MapRecord<String, Object, Object> record : records) {
                    // 重新投递消息
                    redisTemplate.getRedisTemplate().opsForStream().add(StreamRecords.newRecord()
                            .ofObject(record.getValue()) // 设置内容
                            .withStreamKey(listener.getStreamKey()));

                    // ack 消息消费完成
                    redisTemplate.getRedisTemplate().opsForStream().acknowledge(groupName, record);
                }
            });
        });
    }
}
