package com.yunhai.cms.service.impl;

import com.yunhai.cms.entity.CmsBanner;
import com.yunhai.cms.entity.CmsSite;
import com.yunhai.cms.enums.LinkTypeEnum;
import com.yunhai.cms.event.SiteContentChangedEvent;
import com.yunhai.cms.model.dto.BannerSaveRequest;
import com.yunhai.cms.model.dto.DeleteRequest;
import com.yunhai.cms.model.vo.BannerVo;
import com.yunhai.cms.repository.CmsArticleRepository;
import com.yunhai.cms.repository.CmsBannerRepository;
import com.yunhai.cms.repository.CmsCategoryRepository;
import com.yunhai.platform.apistd.BizException;
import com.yunhai.platform.utils.exception.ErrorCode;
import com.yunhai.platform.utils.model.BoaUser;
import lombok.RequiredArgsConstructor;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.util.StringUtils;

import java.util.ArrayList;
import java.util.List;

/**
 * 轮播/推荐位管理（方案 §9.1 轮播管理）。保存时校验 link_type/link_value 匹配。
 */
@Service
@RequiredArgsConstructor
public class BannerService {

    private final CmsBannerRepository bannerRepository;
    private final CmsArticleRepository articleRepository;
    private final CmsCategoryRepository categoryRepository;
    private final SiteService siteService;
    private final ApplicationEventPublisher eventPublisher;
    private final AttachmentService attachmentService;

    public List<BannerVo> list(BoaUser user, Integer siteId, String position) {
        siteService.requireManageable(user, siteId);
        List<CmsBanner> banners = StringUtils.hasText(position)
                ? bannerRepository.findBySiteIdAndPositionOrderBySortNoAscIdAsc(siteId, position)
                : bannerRepository.findBySiteIdOrderByPositionAscSortNoAscIdAsc(siteId);
        List<BannerVo> result = new ArrayList<>();
        for (CmsBanner b : banners) {
            result.add(BannerVo.of(b));
        }
        return result;
    }

    @Transactional
    public BannerVo save(BoaUser user, BannerSaveRequest req) {
        CmsSite site = siteService.requireManageable(user, req.getSiteId());
        LinkTypeEnum linkType = LinkTypeEnum.ofCode(req.getLinkType());
        if (linkType == null) {
            throw new BizException(ErrorCode.PARAM_ERROR, "跳转类型非法：" + req.getLinkType() + "（仅 1=文章 2=栏目 3=外链）");
        }
        validateLink(site.getId(), linkType, req.getLinkValue());

        CmsBanner banner;
        if (req.getId() == null) {
            banner = new CmsBanner();
            banner.setSiteId(site.getId());
        } else {
            banner = bannerRepository.findById(req.getId())
                    .orElseThrow(() -> new BizException(ErrorCode.PARAM_ERROR, "轮播不存在"));
            if (!banner.getSiteId().equals(site.getId())) {
                throw new BizException(ErrorCode.FORBIDDEN, "无权修改该轮播");
            }
        }
        banner.setPosition(StringUtils.hasText(req.getPosition()) ? req.getPosition() : "home");
        banner.setTitle(req.getTitle());
        banner.setImageUrl(req.getImageUrl());
        banner.setLinkType(linkType.getCode());
        banner.setLinkValue(req.getLinkValue());
        banner.setSortNo(req.getSortNo() == null ? 0 : req.getSortNo());
        banner.setStartTime(req.getStartTime());
        banner.setEndTime(req.getEndTime());
        if (banner.getStartTime() != null && banner.getEndTime() != null
                && banner.getEndTime().isBefore(banner.getStartTime())) {
            throw new BizException(ErrorCode.PARAM_ERROR, "下线时间不能早于上线时间");
        }
        banner.setStatus(req.getStatus() == null ? 1 : req.getStatus());
        // docs/20 D-3/D-6：topic/event 位扩展字段透传（其余位一并落库，渲染端按位消费）
        banner.setDescription(req.getDescription());
        banner.setCtaText(req.getCtaText());
        banner.setCtaUrl(req.getCtaUrl());
        banner.setEventDate(req.getEventDate());
        banner.setLocation(req.getLocation());
        banner = bannerRepository.save(banner);
        // B2 附件引用：先解引用再回写新图（编辑换图时旧图回未使用）；幂等
        attachmentService.release("banner", banner.getId());
        attachmentService.markUsed(site.getId(), req.getImageUrl(), "banner", banner.getId());
        eventPublisher.publishEvent(new SiteContentChangedEvent(site.getId(), "banner"));
        return BannerVo.of(banner);
    }

    @Transactional
    public void delete(BoaUser user, DeleteRequest req) {
        CmsSite site = siteService.requireManageable(user, req.getSiteId());
        CmsBanner banner = bannerRepository.findById(req.getId())
                .orElseThrow(() -> new BizException(ErrorCode.PARAM_ERROR, "轮播不存在"));
        if (!banner.getSiteId().equals(site.getId())) {
            throw new BizException(ErrorCode.FORBIDDEN, "无权删除该轮播");
        }
        bannerRepository.delete(banner);
        attachmentService.release("banner", banner.getId());
        eventPublisher.publishEvent(new SiteContentChangedEvent(site.getId(), "banner"));
    }

    /**
     * link_type/link_value 匹配校验：1=文章 2=栏目（须存在且属于本站，禁止跨站引用）
     * 3=外链（必须 http/https 开头）。
     */
    private void validateLink(Integer siteId, LinkTypeEnum linkType, String linkValue) {
        if (linkType == LinkTypeEnum.EXTERNAL) {
            if (!StringUtils.hasText(linkValue)
                    || !(linkValue.startsWith("http://") || linkValue.startsWith("https://"))) {
                throw new BizException(ErrorCode.PARAM_ERROR, "外链地址必须以 http(s):// 开头");
            }
            return;
        }
        if (!StringUtils.hasText(linkValue)) {
            throw new BizException(ErrorCode.PARAM_ERROR, "跳转目标不能为空");
        }
        Integer targetId;
        try {
            targetId = Integer.valueOf(linkValue.trim());
        } catch (NumberFormatException e) {
            throw new BizException(ErrorCode.PARAM_ERROR, "跳转目标必须是数字 ID");
        }
        if (linkType == LinkTypeEnum.ARTICLE) {
            articleRepository.findByIdAndSiteId(targetId, siteId)
                    .orElseThrow(() -> new BizException(ErrorCode.PARAM_ERROR, "跳转文章不存在"));
        } else if (linkType == LinkTypeEnum.CATEGORY) {
            categoryRepository.findById(targetId)
                    .filter(c -> c.getSiteId().equals(siteId))
                    .orElseThrow(() -> new BizException(ErrorCode.PARAM_ERROR, "跳转栏目不存在"));
        }
    }
}