add shopping list and tag management

internal/service/tag.go

@@ -0,0 +1,77 @@
+package service
+
+import (
+	"fmt"
+	"strings"
+	"time"
+
+	"git.juancwu.dev/juancwu/budgit/internal/model"
+	"git.juancwu.dev/juancwu/budgit/internal/repository"
+	"github.com/google/uuid"
+)
+
+type TagService struct {
+	tagRepo repository.TagRepository
+}
+
+func NewTagService(tagRepo repository.TagRepository) *TagService {
+	return &TagService{tagRepo: tagRepo}
+}
+
+func (s *TagService) CreateTag(spaceID, name string, color *string) (*model.Tag, error) {
+	name = strings.TrimSpace(name)
+	if name == "" {
+		return nil, fmt.Errorf("tag name cannot be empty")
+	}
+
+	now := time.Now()
+	tag := &model.Tag{
+		ID:        uuid.NewString(),
+		SpaceID:   spaceID,
+		Name:      name,
+		Color:     color,
+		CreatedAt: now,
+		UpdatedAt: now,
+	}
+
+	err := s.tagRepo.Create(tag)
+	if err != nil {
+		return nil, err
+	}
+
+	return tag, nil
+}
+
+func (s *TagService) GetTagsForSpace(spaceID string) ([]*model.Tag, error) {
+	return s.tagRepo.GetBySpaceID(spaceID)
+}
+
+func (s *TagService) GetTagByID(id string) (*model.Tag, error) {
+	return s.tagRepo.GetByID(id)
+}
+
+func (s *TagService) UpdateTag(id, name string, color *string) (*model.Tag, error) {
+	name = strings.TrimSpace(name)
+	if name == "" {
+		return nil, fmt.Errorf("tag name cannot be empty")
+	}
+
+	tag, err := s.tagRepo.GetByID(id)
+	if err != nil {
+		return nil, err
+	}
+
+	tag.Name = name
+	tag.Color = color
+
+	err = s.tagRepo.Update(tag)
+	if err != nil {
+		return nil, err
+	}
+
+	return tag, nil
+}
+
+func (s *TagService) DeleteTag(id string) error {
+	return s.tagRepo.Delete(id)
+}