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
}