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

import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.tcm.training.admin.app.notice.service.AppSystemNoticeDispatchCommand;
import com.tcm.training.admin.app.notice.service.AppSystemNoticeDispatchService;
import com.tcm.training.admin.app.notice.service.AppSystemNoticeType;
import com.tcm.training.admin.app.settings.entity.AppUserNotificationSetting;
import com.tcm.training.admin.app.settings.mapper.AppUserNotificationSettingMapper;
import com.tcm.training.admin.live.entity.LiveCourse;
import com.tcm.training.admin.live.entity.LiveReserve;
import com.tcm.training.admin.live.entity.LiveSession;
import com.tcm.training.admin.live.mapper.LiveCourseMapper;
import com.tcm.training.admin.live.mapper.LiveReserveMapper;
import com.tcm.training.admin.live.mapper.LiveSessionMapper;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Service;

import java.time.LocalDateTime;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

/**
 * 直播提醒通知分发服务。
 */
@Service
public class LiveRemindDispatchService {

    private final LiveSessionMapper liveSessionMapper;
    private final LiveReserveMapper liveReserveMapper;
    private final LiveCourseMapper liveCourseMapper;
    private final AppUserNotificationSettingMapper appUserNotificationSettingMapper;
    private final AppSystemNoticeDispatchService appSystemNoticeDispatchService;

    /**
     * 注入直播提醒分发所需依赖。
     */
    public LiveRemindDispatchService(LiveSessionMapper liveSessionMapper,
                                     LiveReserveMapper liveReserveMapper,
                                     LiveCourseMapper liveCourseMapper,
                                     AppUserNotificationSettingMapper appUserNotificationSettingMapper,
                                     AppSystemNoticeDispatchService appSystemNoticeDispatchService) {
        this.liveSessionMapper = liveSessionMapper;
        this.liveReserveMapper = liveReserveMapper;
        this.liveCourseMapper = liveCourseMapper;
        this.appUserNotificationSettingMapper = appUserNotificationSettingMapper;
        this.appSystemNoticeDispatchService = appSystemNoticeDispatchService;
    }

    /**
     * 定时扫描即将开播的预约用户，并按用户设置的提前提醒时间发放通知。
     */
    @Scheduled(fixedDelayString = "${app.live.remind-dispatch-interval-ms:60000}")
    public void dispatchScheduledReminds() {
        LocalDateTime now = LocalDateTime.now();
        List<LiveSession> sessions = liveSessionMapper.selectList(new LambdaQueryWrapper<LiveSession>()
                .eq(LiveSession::getDeleted, 0)
                .eq(LiveSession::getLiveStatus, 0)
                .isNotNull(LiveSession::getStartTime)
                .gt(LiveSession::getStartTime, now)
                .orderByAsc(LiveSession::getStartTime)
                .orderByAsc(LiveSession::getId));
        for (LiveSession session : sessions) {
            dispatchRemindsForSession(session, now, false);
        }
    }

    /**
     * 手动触发指定场次的直播提醒发放。
     */
    public long dispatchManualRemind(LiveSession session) {
        if (session == null) {
            return 0L;
        }
        return dispatchRemindsForSession(session, LocalDateTime.now(), true);
    }

    /**
     * 根据预约记录与提醒时间配置发放直播提醒。
     */
    private long dispatchRemindsForSession(LiveSession session, LocalDateTime now, boolean ignoreReminderWindow) {
        if (session == null || session.getId() == null || session.getStartTime() == null) {
            return 0L;
        }
        List<LiveReserve> reserves = liveReserveMapper.selectList(new LambdaQueryWrapper<LiveReserve>()
                .eq(LiveReserve::getSessionId, session.getId())
                .eq(LiveReserve::getIsCancel, 0));
        if (reserves.isEmpty()) {
            return 0L;
        }
        LiveCourse liveCourse = liveCourseMapper.selectById(session.getLiveCourseId());
        long dispatchedCount = 0L;
        for (LiveReserve reserve : reserves) {
            if (reserve.getUserId() == null) {
                continue;
            }
            Integer advanceMinutes = resolveAdvanceMinutes(reserve.getUserId());
            if (!ignoreReminderWindow && !isWithinReminderWindow(session.getStartTime(), now, advanceMinutes)) {
                continue;
            }
            AppSystemNoticeDispatchCommand command = new AppSystemNoticeDispatchCommand();
            command.setAppUserId(reserve.getUserId());
            command.setNoticeTypeCode(AppSystemNoticeType.LIVE_REMIND);
            command.setTitle("直播提醒");
            command.setContent(defaultCourseTitle(liveCourse) + " 即将开播");
            command.setReferenceType("LIVE_SESSION");
            command.setReferenceId(session.getId());
            command.setRequireUserSetting(Boolean.TRUE);
            Map<String, String> payload = new LinkedHashMap<String, String>();
            payload.put("courseId", session.getLiveCourseId() == null ? "" : String.valueOf(session.getLiveCourseId()));
            payload.put("sessionId", String.valueOf(session.getId()));
            payload.put("startTime", String.valueOf(session.getStartTime()));
            payload.put("courseTitle", defaultCourseTitle(liveCourse));
            command.setPayload(payload);
            appSystemNoticeDispatchService.createAndPush(command);
            dispatchedCount++;
        }
        return dispatchedCount;
    }

    /**
     * 读取用户设置的提前提醒分钟数，未配置时默认按 60 分钟处理。
     */
    private Integer resolveAdvanceMinutes(Long appUserId) {
        AppUserNotificationSetting setting = appUserNotificationSettingMapper.selectOne(new LambdaQueryWrapper<AppUserNotificationSetting>()
                .eq(AppUserNotificationSetting::getAppUserId, appUserId)
                .eq(AppUserNotificationSetting::getDeleted, 0)
                .last("limit 1"));
        if (setting == null || setting.getAdvanceNoticeMinutes() == null || setting.getAdvanceNoticeMinutes().intValue() <= 0) {
            return 60;
        }
        return setting.getAdvanceNoticeMinutes();
    }

    /**
     * 判断当前时间是否已进入当前用户对应的提醒发送窗口。
     */
    private boolean isWithinReminderWindow(LocalDateTime startTime, LocalDateTime now, Integer advanceMinutes) {
        if (startTime == null || now == null) {
            return false;
        }
        LocalDateTime remindTime = startTime.minusMinutes(advanceMinutes == null ? 60L : advanceMinutes.longValue());
        return !now.isBefore(remindTime) && now.isBefore(startTime);
    }

    /**
     * 返回安全的直播课程标题。
     */
    private String defaultCourseTitle(LiveCourse liveCourse) {
        if (liveCourse == null || liveCourse.getTitle() == null) {
            return "您预约的直播";
        }
        return liveCourse.getTitle();
    }
}