From 3c80f63a55168ddc152c9a695722c6c5f1f7b361 Mon Sep 17 00:00:00 2001
From: Leon Mika <lmika@lmika.org>
Date: Wed, 18 Mar 2026 21:38:41 +1100
Subject: [PATCH] feat: add categories service with CRUD and slug validation

---
 services/categories/service.go | 162 +++++++++++++++++++++++++++++++++
 1 file changed, 162 insertions(+)
 create mode 100644 services/categories/service.go

diff --git a/services/categories/service.go b/services/categories/service.go
new file mode 100644
index 0000000..57b509d
--- /dev/null
+++ b/services/categories/service.go
@@ -0,0 +1,162 @@
+package categories
+
+import (
+	"context"
+	"time"
+
+	"lmika.dev/lmika/weiro/models"
+	"lmika.dev/lmika/weiro/providers/db"
+	"lmika.dev/lmika/weiro/services/publisher"
+)
+
+type CreateCategoryParams struct {
+	GUID        string `form:"guid" json:"guid"`
+	Name        string `form:"name" json:"name"`
+	Slug        string `form:"slug" json:"slug"`
+	Description string `form:"description" json:"description"`
+}
+
+type Service struct {
+	db        *db.Provider
+	publisher *publisher.Queue
+}
+
+func New(db *db.Provider, publisher *publisher.Queue) *Service {
+	return &Service{db: db, publisher: publisher}
+}
+
+func (s *Service) ListCategories(ctx context.Context) ([]*models.Category, error) {
+	site, ok := models.GetSite(ctx)
+	if !ok {
+		return nil, models.SiteRequiredError
+	}
+	return s.db.SelectCategoriesOfSite(ctx, site.ID)
+}
+
+// ListCategoriesWithCounts returns all categories for the site with published post counts.
+func (s *Service) ListCategoriesWithCounts(ctx context.Context) ([]models.CategoryWithCount, error) {
+	site, ok := models.GetSite(ctx)
+	if !ok {
+		return nil, models.SiteRequiredError
+	}
+
+	cats, err := s.db.SelectCategoriesOfSite(ctx, site.ID)
+	if err != nil {
+		return nil, err
+	}
+
+	result := make([]models.CategoryWithCount, len(cats))
+	for i, cat := range cats {
+		count, err := s.db.CountPostsOfCategory(ctx, cat.ID)
+		if err != nil {
+			return nil, err
+		}
+		result[i] = models.CategoryWithCount{
+			Category:         *cat,
+			PostCount:        int(count),
+			DescriptionBrief: models.BriefDescription(cat.Description),
+		}
+	}
+	return result, nil
+}
+
+func (s *Service) GetCategory(ctx context.Context, id int64) (*models.Category, error) {
+	return s.db.SelectCategory(ctx, id)
+}
+
+func (s *Service) CreateCategory(ctx context.Context, params CreateCategoryParams) (*models.Category, error) {
+	site, ok := models.GetSite(ctx)
+	if !ok {
+		return nil, models.SiteRequiredError
+	}
+
+	now := time.Now()
+	slug := params.Slug
+	if slug == "" {
+		slug = models.GenerateCategorySlug(params.Name)
+	}
+
+	// Check for slug collision
+	if _, err := s.db.SelectCategoryBySlugAndSite(ctx, site.ID, slug); err == nil {
+		return nil, models.SlugConflictError
+	}
+
+	cat := &models.Category{
+		SiteID:      site.ID,
+		GUID:        params.GUID,
+		Name:        params.Name,
+		Slug:        slug,
+		Description: params.Description,
+		CreatedAt:   now,
+		UpdatedAt:   now,
+	}
+	if cat.GUID == "" {
+		cat.GUID = models.NewNanoID()
+	}
+
+	if err := s.db.SaveCategory(ctx, cat); err != nil {
+		return nil, err
+	}
+
+	s.publisher.Queue(site)
+	return cat, nil
+}
+
+func (s *Service) UpdateCategory(ctx context.Context, id int64, params CreateCategoryParams) (*models.Category, error) {
+	site, ok := models.GetSite(ctx)
+	if !ok {
+		return nil, models.SiteRequiredError
+	}
+
+	cat, err := s.db.SelectCategory(ctx, id)
+	if err != nil {
+		return nil, err
+	}
+	if cat.SiteID != site.ID {
+		return nil, models.NotFoundError
+	}
+
+	slug := params.Slug
+	if slug == "" {
+		slug = models.GenerateCategorySlug(params.Name)
+	}
+
+	// Check slug collision (exclude self)
+	if existing, err := s.db.SelectCategoryBySlugAndSite(ctx, site.ID, slug); err == nil && existing.ID != cat.ID {
+		return nil, models.SlugConflictError
+	}
+
+	cat.Name = params.Name
+	cat.Slug = slug
+	cat.Description = params.Description
+	cat.UpdatedAt = time.Now()
+
+	if err := s.db.SaveCategory(ctx, cat); err != nil {
+		return nil, err
+	}
+
+	s.publisher.Queue(site)
+	return cat, nil
+}
+
+func (s *Service) DeleteCategory(ctx context.Context, id int64) error {
+	site, ok := models.GetSite(ctx)
+	if !ok {
+		return models.SiteRequiredError
+	}
+
+	cat, err := s.db.SelectCategory(ctx, id)
+	if err != nil {
+		return err
+	}
+	if cat.SiteID != site.ID {
+		return models.NotFoundError
+	}
+
+	if err := s.db.DeleteCategory(ctx, id); err != nil {
+		return err
+	}
+
+	s.publisher.Queue(site)
+	return nil
+}