package com.tcm.training.admin.live.service;

import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.tcm.training.admin.live.entity.LiveSession;
import com.tcm.training.admin.live.mapper.LiveSessionMapper;
import com.tcm.training.admin.live.vo.LiveSessionStatusVO;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Service;

import java.time.LocalDateTime;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;

@Service
public class LiveSessionStatusSyncService {

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

    private final LiveSessionMapper liveSessionMapper;
    private final LiveSessionAppService liveSessionAppService;

    /**
     * 注入直播场次查询能力与状态流转服务。
     */
    public LiveSessionStatusSyncService(LiveSessionMapper liveSessionMapper,
                                        LiveSessionAppService liveSessionAppService) {
        this.liveSessionMapper = liveSessionMapper;
        this.liveSessionAppService = liveSessionAppService;
    }

    /**
     * 扫描已到开播时间的未开始场次，并自动切换为直播中。
     */
    @Scheduled(fixedDelayString = "${app.live.session-status-sync-interval-ms:60000}")
    public void syncDueSessions() {
        LocalDateTime now = LocalDateTime.now();
        List<LiveSession> dueSessions = liveSessionMapper.selectList(new LambdaQueryWrapper<LiveSession>()
                .eq(LiveSession::getDeleted, 0)
                .eq(LiveSession::getLiveStatus, 0)
                .isNotNull(LiveSession::getStartTime)
                .le(LiveSession::getStartTime, now)
                .orderByAsc(LiveSession::getStartTime)
                .orderByAsc(LiveSession::getId));
        int startedCount = 0;
        if (dueSessions != null && !dueSessions.isEmpty()) {
            for (LiveSession dueSession : dueSessions) {
                // 定时任务与人工开播共用同一套状态迁移逻辑，避免状态口径分叉。
                LiveSessionStatusVO statusVO = liveSessionAppService.autoStart(dueSession.getId(), now);
                if (statusVO == null) {
                    log.warn("live session auto start skipped, sessionId={}, courseId={}",
                            dueSession.getId(), dueSession.getLiveCourseId());
                    continue;
                }
                startedCount++;
            }

            if (startedCount > 0) {
                log.info("live session auto start finished, scanned={}, started={}", dueSessions.size(), startedCount);
            }
        }

        reconcileLivingCourses(now);
    }

    /**
     * 定时收敛历史残留的直播中场次，避免同课程出现多条或过期直播中状态。
     */
    private void reconcileLivingCourses(LocalDateTime now) {
        List<LiveSession> livingSessions = liveSessionMapper.selectList(new LambdaQueryWrapper<LiveSession>()
                .eq(LiveSession::getDeleted, 0)
                .eq(LiveSession::getLiveStatus, 1)
                .orderByAsc(LiveSession::getLiveCourseId)
                .orderByAsc(LiveSession::getId));
        if (livingSessions == null || livingSessions.isEmpty()) {
            return;
        }

        Set<Long> courseIds = new LinkedHashSet<Long>();
        for (LiveSession livingSession : livingSessions) {
            if (livingSession == null || livingSession.getLiveCourseId() == null) {
                continue;
            }
            courseIds.add(livingSession.getLiveCourseId());
        }

        int repairedCount = 0;
        for (Long courseId : courseIds) {
            repairedCount += liveSessionAppService.reconcileCourseLivingSessions(courseId, now);
        }
        if (repairedCount > 0) {
            log.info("live session reconcile finished, livingCourses={}, repaired={}", courseIds.size(), repairedCount);
        }
    }
}