package com.tcm.training.admin.app.course.service;

import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.tcm.training.admin.app.course.vo.AppHealthCourseDetailVO;
import com.tcm.training.admin.app.course.vo.AppHealthCourseExpertVO;
import com.tcm.training.admin.app.course.vo.AppHealthCourseVideoVO;
import com.tcm.training.admin.live.entity.Expert;
import com.tcm.training.admin.live.entity.HealthCourseVideo;
import com.tcm.training.admin.live.mapper.ExpertMapper;
import com.tcm.training.admin.live.mapper.HealthCourseVideoMapper;
import com.tcm.training.admin.live.service.HealthCourseAppService;
import com.tcm.training.admin.live.vo.HealthCourseDetailVO;
import org.springframework.stereotype.Service;

import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/**
 * APP 养生课程详情聚合服务。
 */
@Service
public class AppHealthCourseService {

    private static final int COURSE_STATUS_ENABLED = 1;
    private static final int VIDEO_STATUS_ENABLED = 1;

    private final HealthCourseAppService healthCourseAppService;
    private final HealthCourseVideoMapper healthCourseVideoMapper;
    private final ExpertMapper expertMapper;

    /**
     * 注入 APP 养生课程详情所需依赖。
     */
    public AppHealthCourseService(HealthCourseAppService healthCourseAppService,
                                  HealthCourseVideoMapper healthCourseVideoMapper,
                                  ExpertMapper expertMapper) {
        this.healthCourseAppService = healthCourseAppService;
        this.healthCourseVideoMapper = healthCourseVideoMapper;
        this.expertMapper = expertMapper;
    }

    /**
     * 获取 APP 养生课程详情页数据。
     */
    public AppHealthCourseDetailVO detail(Long courseId) {
        HealthCourseDetailVO courseDetail = healthCourseAppService.detail(courseId);
        if (courseDetail.getStatus() == null || courseDetail.getStatus().intValue() != COURSE_STATUS_ENABLED) {
            throw new IllegalArgumentException("养生课程不存在");
        }

        List<HealthCourseVideo> enabledVideos = listEnabledVideos(courseId);
        AppHealthCourseDetailVO detailVO = new AppHealthCourseDetailVO();
        detailVO.setId(courseDetail.getId());
        detailVO.setTitle(trimToEmpty(courseDetail.getTitle()));
        detailVO.setBannerImages(resolveBannerImages(courseDetail));
        detailVO.setLevelName(trimToEmpty(courseDetail.getLevelName()));
        detailVO.setDifficultyName(trimToEmpty(courseDetail.getDifficultyName()));
        detailVO.setSalePrice(defaultPrice(courseDetail.getSalePrice()));
        detailVO.setLearnUserCount(defaultNumber(courseDetail.getLearnUserCount()));
        detailVO.setSummary(trimToEmpty(courseDetail.getSummary()));
        detailVO.setTargetUsers(trimToEmpty(courseDetail.getTargetUsers()));
        detailVO.setContent(trimToEmpty(courseDetail.getContent()));
        detailVO.setVideoCount(Integer.valueOf(enabledVideos.size()));
        detailVO.setTotalDurationSeconds(resolveTotalDurationSeconds(courseDetail, enabledVideos));
        detailVO.setTotalDurationText(formatCourseDuration(detailVO.getTotalDurationSeconds()));
        detailVO.setExpert(resolveExpert(courseDetail.getExpert() == null ? null : courseDetail.getExpert().getId()));

        List<AppHealthCourseVideoVO> videoVOList = toVideoVOList(enabledVideos);
        detailVO.setVideos(videoVOList);
        detailVO.setFreeVideoCount(countFreeVideos(videoVOList));
        detailVO.setPaidVideoCount(countPaidVideos(videoVOList));
        return detailVO;
    }

    /**
     * 查询课程下启用的视频章节。
     */
    private List<HealthCourseVideo> listEnabledVideos(Long courseId) {
        List<HealthCourseVideo> records = healthCourseVideoMapper.selectList(new LambdaQueryWrapper<HealthCourseVideo>()
                .eq(HealthCourseVideo::getCourseId, courseId)
                .eq(HealthCourseVideo::getDeleted, 0)
                .eq(HealthCourseVideo::getStatus, VIDEO_STATUS_ENABLED)
                .orderByAsc(HealthCourseVideo::getSort)
                .orderByAsc(HealthCourseVideo::getId));
        return records == null ? Collections.<HealthCourseVideo>emptyList() : records;
    }

    /**
     * 组装课程详情页需要展示的轮播图列表。
     */
    private List<String> resolveBannerImages(HealthCourseDetailVO courseDetail) {
        List<String> bannerImages = new ArrayList<String>();
        if (courseDetail.getBannerImgs() != null) {
            for (String bannerImage : courseDetail.getBannerImgs()) {
                String normalizedImage = trimToEmpty(bannerImage);
                if (!normalizedImage.isEmpty()) {
                    bannerImages.add(normalizedImage);
                }
            }
        }
        // 课程未配置轮播图时，回退到封面图，避免前端轮播组件出现空白页。
        if (bannerImages.isEmpty()) {
            String coverImage = trimToEmpty(courseDetail.getCoverImg());
            if (!coverImage.isEmpty()) {
                bannerImages.add(coverImage);
            }
        }
        return bannerImages;
    }

    /**
     * 组装课程详情页专家卡片信息。
     */
    private AppHealthCourseExpertVO resolveExpert(Long expertId) {
        if (expertId == null) {
            return null;
        }
        Expert expert = expertMapper.selectOne(new LambdaQueryWrapper<Expert>()
                .eq(Expert::getId, expertId)
                .eq(Expert::getDeleted, 0)
                .eq(Expert::getStatus, COURSE_STATUS_ENABLED)
                .last("LIMIT 1"));
        if (expert == null) {
            return null;
        }
        AppHealthCourseExpertVO expertVO = new AppHealthCourseExpertVO();
        expertVO.setId(expert.getId());
        expertVO.setName(trimToEmpty(expert.getName()));
        expertVO.setAvatar(trimToEmpty(expert.getAvatar()));
        expertVO.setSpecialty(trimToEmpty(expert.getSpecialty()));
        return expertVO;
    }

    /**
     * 将启用视频列表转换为 APP 详情页可直接渲染的数据结构。
     */
    private List<AppHealthCourseVideoVO> toVideoVOList(List<HealthCourseVideo> videos) {
        if (videos == null || videos.isEmpty()) {
            return Collections.emptyList();
        }
        List<AppHealthCourseVideoVO> result = new ArrayList<AppHealthCourseVideoVO>(videos.size());
        for (HealthCourseVideo video : videos) {
            AppHealthCourseVideoVO videoVO = new AppHealthCourseVideoVO();
            videoVO.setId(video.getId());
            videoVO.setChapterName(trimToEmpty(video.getChapterName()));
            videoVO.setDurationSeconds(defaultNumber(video.getDurationSeconds()));
            videoVO.setDurationText(formatVideoDuration(videoVO.getDurationSeconds()));
            videoVO.setSalePrice(defaultPrice(video.getSalePrice()));
            // 前端课程列表直接按该字段切分免费/付费列表，避免再次复制业务判断。
            videoVO.setFreeAccess(Boolean.valueOf(isFreeVideo(videoVO.getSalePrice())));
            result.add(videoVO);
        }
        return result;
    }

    /**
     * 统计免费章节数量。
     */
    private Integer countFreeVideos(List<AppHealthCourseVideoVO> videos) {
        int count = 0;
        for (AppHealthCourseVideoVO video : videos) {
            if (Boolean.TRUE.equals(video.getFreeAccess())) {
                count++;
            }
        }
        return Integer.valueOf(count);
    }

    /**
     * 统计付费章节数量。
     */
    private Integer countPaidVideos(List<AppHealthCourseVideoVO> videos) {
        int count = 0;
        for (AppHealthCourseVideoVO video : videos) {
            if (!Boolean.TRUE.equals(video.getFreeAccess())) {
                count++;
            }
        }
        return Integer.valueOf(count);
    }

    /**
     * 解析课程总时长，优先复用课程表已汇总的时长字段。
     */
    private Integer resolveTotalDurationSeconds(HealthCourseDetailVO courseDetail, List<HealthCourseVideo> videos) {
        Integer totalDurationSeconds = courseDetail.getTotalDurationSeconds();
        if (totalDurationSeconds != null && totalDurationSeconds.intValue() > 0) {
            return totalDurationSeconds;
        }
        int sum = 0;
        for (HealthCourseVideo video : videos) {
            sum += defaultNumber(video.getDurationSeconds());
        }
        return Integer.valueOf(sum);
    }

    /**
     * 判断视频是否属于免费章节。
     */
    private boolean isFreeVideo(BigDecimal salePrice) {
        return salePrice == null || salePrice.compareTo(BigDecimal.ZERO) <= 0;
    }

    /**
     * 兜底空价格字段，避免前端价格区展示异常。
     */
    private BigDecimal defaultPrice(BigDecimal price) {
        return price == null ? BigDecimal.ZERO : price;
    }

    /**
     * 兜底空数字字段。
     */
    private Integer defaultNumber(Integer value) {
        return value == null ? 0 : value;
    }

    /**
     * 将总时长秒数格式化为适合页头展示的简要文案。
     */
    private String formatCourseDuration(Integer durationSeconds) {
        int totalSeconds = defaultNumber(durationSeconds);
        if (totalSeconds <= 0) {
            return "0分钟";
        }
        int hours = totalSeconds / 3600;
        int minutes = (totalSeconds % 3600) / 60;
        if (hours > 0 && minutes > 0) {
            return hours + "小时" + minutes + "分钟";
        }
        if (hours > 0) {
            return hours + "小时";
        }
        if (minutes > 0) {
            return minutes + "分钟";
        }
        return totalSeconds + "秒";
    }

    /**
     * 将章节时长格式化为 `HH:MM:SS`，便于与当前 APP 设计稿对齐。
     */
    private String formatVideoDuration(Integer durationSeconds) {
        int totalSeconds = defaultNumber(durationSeconds);
        int hours = totalSeconds / 3600;
        int minutes = (totalSeconds % 3600) / 60;
        int seconds = totalSeconds % 60;
        return String.format("%02d:%02d:%02d", hours, minutes, seconds);
    }

    /**
     * 将可空文本转换为空字符串。
     */
    private String trimToEmpty(String value) {
        if (value == null) {
            return "";
        }
        String trimmed = value.trim();
        return trimmed.isEmpty() ? "" : trimmed;
    }
}