package com.xuqm.im.service;

import com.xuqm.im.cluster.ImClusterPublisher;
import com.xuqm.im.entity.ImMessageEntity;
import com.xuqm.im.entity.ImOfflineMessageEntity;
import com.xuqm.im.repository.ImMessageRepository;
import com.xuqm.im.repository.ImOfflineMessageRepository;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.List;
import java.util.UUID;

@Service
public class OfflineMessageSyncService {

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

    private final ImOfflineMessageRepository offlineMessageRepository;
    private final ImMessageRepository messageRepository;
    private final ImClusterPublisher clusterPublisher;

    public OfflineMessageSyncService(ImOfflineMessageRepository offlineMessageRepository,
                                      ImMessageRepository messageRepository,
                                      ImClusterPublisher clusterPublisher) {
        this.offlineMessageRepository = offlineMessageRepository;
        this.messageRepository = messageRepository;
        this.clusterPublisher = clusterPublisher;
    }

    @Transactional
    public void storeOfflineMessage(String appId, String userId, String messageId) {
        ImOfflineMessageEntity entity = new ImOfflineMessageEntity();
        entity.setId(UUID.randomUUID().toString());
        entity.setAppId(appId);
        entity.setUserId(userId);
        entity.setMessageId(messageId);
        entity.setDelivered(false);
        entity.setCreatedAt(LocalDateTime.now());
        offlineMessageRepository.save(entity);
        log.debug("Stored offline message appId={} userId={} messageId={}", appId, userId, messageId);
    }

    @Transactional
    public void syncAndDeliver(String appId, String userId) {
        List<ImOfflineMessageEntity> offlineMessages = offlineMessageRepository
                .findByAppIdAndUserIdAndDeliveredFalse(appId, userId);
        if (offlineMessages.isEmpty()) {
            return;
        }

        List<String> deliveredIds = new ArrayList<>();
        for (ImOfflineMessageEntity offline : offlineMessages) {
            ImMessageEntity message = messageRepository.findById(offline.getMessageId()).orElse(null);
            if (message != null) {
                clusterPublisher.publish("/user/" + userId + "/queue/messages", message);
                deliveredIds.add(offline.getId());
                log.debug("Delivered offline message appId={} userId={} messageId={}", appId, userId, message.getId());
            }
        }

        if (!deliveredIds.isEmpty()) {
            offlineMessageRepository.markDeliveredByIds(deliveredIds);
            log.info("Synced {} offline messages for appId={} userId={}", deliveredIds.size(), appId, userId);
        }

        offlineMessageRepository.deleteByAppIdAndUserIdAndDeliveredTrue(appId, userId);
    }

    public long countUndelivered(String appId, String userId) {
        return offlineMessageRepository.countUndeliveredByAppIdAndUserId(appId, userId);
    }

    @Transactional
    public List<ImMessageEntity> syncAndReturn(String appId, String userId) {
        List<ImOfflineMessageEntity> offlineMessages = offlineMessageRepository
                .findByAppIdAndUserIdAndDeliveredFalse(appId, userId);
        List<ImMessageEntity> result = new ArrayList<>();
        List<String> deliveredIds = new ArrayList<>();
        for (ImOfflineMessageEntity offline : offlineMessages) {
            ImMessageEntity message = messageRepository.findById(offline.getMessageId()).orElse(null);
            if (message != null) {
                result.add(message);
                deliveredIds.add(offline.getId());
            }
        }
        if (!deliveredIds.isEmpty()) {
            offlineMessageRepository.markDeliveredByIds(deliveredIds);
        }
        offlineMessageRepository.deleteByAppIdAndUserIdAndDeliveredTrue(appId, userId);
        return result;
    }
}