backend_v2/internal/service/article_service.go

package service

import (
	"context"
	"errors"
	"net/http"

	"fashionapi/internal/dto"
	"fashionapi/internal/model"
	"fashionapi/internal/pkg/hashid"
	"fashionapi/internal/pkg/textutil"
	"fashionapi/internal/repository"
)

// summaryLength 对外摘要的截断长度（rune 数），与原项目一致。
const summaryLength = 140

// ArticleService 文章业务接口。
type ArticleService interface {
	List(ctx context.Context, q dto.ArticleQuery) ([]dto.PublicArticle, int64, error)
	Detail(ctx context.Context, id string, locale string) (*dto.PublicArticleDetail, error)
	// IDs 返回全部文章的编码 uid，供 SSG 路径枚举（getStaticPaths）。
	IDs(ctx context.Context) ([]string, error)
}

type articleService struct {
	articles repository.ArticleRepository
}

// NewArticleService 创建文章服务。
func NewArticleService(articles repository.ArticleRepository) ArticleService {
	return &articleService{articles: articles}
}

// List 查询文章列表，并按需附带每篇的前 N 张图。
func (s *articleService) List(ctx context.Context, q dto.ArticleQuery) ([]dto.PublicArticle, int64, error) {
	q.Normalize()

	rows, total, err := s.articles.List(ctx, q)
	if err != nil {
		return nil, 0, internalErr(err.Error())
	}

	list := make([]dto.PublicArticle, 0, len(rows))
	ids := make([]uint32, 0, len(rows))
	for _, r := range rows {
		ids = append(ids, r.ID)
		list = append(list, dto.PublicArticle{
			UID:            hashid.Encode(r.ID),
			BrandUID:       hashid.Encode(r.BrandID),
			Title:          pickLocale(r.TitleEn, r.TitleCn, q.Locale),
			Summary:        textutil.Summarize(pickLocale(r.DescriptionEn, r.DescriptionCn, q.Locale), summaryLength),
			Cover:          r.Cover,
			BrandName:      pickLocale(r.BrandNameEn, r.BrandNameCn, q.Locale),
			Year:           r.Year,
			ImageCount:     r.ImageCount,
			CollectionType: r.CollectionType,
			Season:         r.Season,
			SeasonCode:     r.SeasonCode,
			PublishedAt:    r.CreatedAt,
		})
	}

	if q.WithImages > 0 && len(list) > 0 {
		if err := s.attachImages(ctx, list, ids, q.WithImages); err != nil {
			return nil, 0, internalErr(err.Error())
		}
	}
	return list, total, nil
}

// attachImages 用单次 IN 查询为列表批量补齐图片，避免前端逐篇请求详情。
// ids 是与之对应的数字主键（对外已编码为 UID，此处用数字主键查库）。
func (s *articleService) attachImages(ctx context.Context, list []dto.PublicArticle, ids []uint32, limit int) error {
	grouped, err := s.articles.ImagesByRunwayIDs(ctx, ids)
	if err != nil {
		return err
	}
	for i := range list {
		imgs, ok := grouped[ids[i]]
		if !ok {
			continue
		}
		if len(imgs) > limit {
			imgs = imgs[:limit]
		}
		list[i].Images = toPublicImages(imgs)
	}
	return nil
}

// Detail 查询文章详情，含完整图片集。locale 决定标题/描述/品牌名的展示语言。
func (s *articleService) Detail(ctx context.Context, id string, locale string) (*dto.PublicArticleDetail, error) {
	row, err := s.articles.FindByID(ctx, id)
	if err != nil {
		if errors.Is(err, repository.ErrNotFound) {
			return nil, ErrArticleNotFound
		}
		return nil, NewError(http.StatusInternalServerError, err.Error())
	}

	imgs, err := s.articles.ListImages(ctx, id)
	if err != nil {
		return nil, internalErr(err.Error())
	}

	return &dto.PublicArticleDetail{
		UID:         hashid.Encode(row.ID),
		BrandUID:    hashid.Encode(row.BrandID),
		Title:       pickLocale(row.TitleEn, row.TitleCn, locale),
		Summary:     textutil.Summarize(pickLocale(row.DescriptionEn, row.DescriptionCn, locale), summaryLength),
		Description: pickLocale(row.DescriptionEn, row.DescriptionCn, locale),
		Cover:       row.Cover,
		BrandName:   pickLocale(row.BrandNameEn, row.BrandNameCn, locale),
		Year:        row.Year,
		ImageCount:  row.ImageCount,
		SourceURL:   row.SourceURL,
		PublishedAt: row.CreatedAt,
		Images:      toPublicImages(imgs),
	}, nil
}

// IDs 返回全部文章的编码 uid（供 SSG 枚举详情页路径使用，对外暴露的即编码串）。
func (s *articleService) IDs(ctx context.Context) ([]string, error) {
	ids, err := s.articles.IDs(ctx)
	if err != nil {
		return nil, internalErr(err.Error())
	}
	out := make([]string, 0, len(ids))
	for _, id := range ids {
		out = append(out, hashid.Encode(id))
	}
	return out, nil
}

// toPublicImages 把图片实体映射为对外结构（只保留 url 与名称）。
func toPublicImages(imgs []model.BrandRunwayImage) []dto.PublicArticleImage {
	if len(imgs) == 0 {
		return nil
	}
	out := make([]dto.PublicArticleImage, 0, len(imgs))
	for _, im := range imgs {
		out = append(out, dto.PublicArticleImage{Image: im.Image, Name: im.Name})
	}
	return out
}