package services

import (
	"context"

	"github.com/fish/language/backend/internal/models"
	"github.com/fish/language/backend/internal/repository/queries"
)

// CategoryService handles business logic for categories.
type CategoryService struct {
	q *queries.Queries
}

// NewCategoryService creates a new CategoryService.
func NewCategoryService(q *queries.Queries) *CategoryService {
	return &CategoryService{q: q}
}

// List returns all categories ordered by sort_order.
func (s *CategoryService) List(ctx context.Context) ([]models.Category, error) {
	rows, err := s.q.ListCategories(ctx)
	if err != nil {
		return nil, err
	}
	out := make([]models.Category, len(rows))
	for i, r := range rows {
		out[i] = toCategory(r)
	}
	return out, nil
}

// Get returns a single category by id.
func (s *CategoryService) Get(ctx context.Context, id int32) (models.Category, error) {
	row, err := s.q.GetCategory(ctx, id)
	if err != nil {
		return models.Category{}, err
	}
	return toCategory(row), nil
}

// Create creates a new category.
func (s *CategoryService) Create(ctx context.Context, req models.CreateCategoryRequest) (models.Category, error) {
	row, err := s.q.CreateCategory(ctx, queries.CreateCategoryParams{
		Name:      req.Name,
		SortOrder: req.SortOrder,
	})
	if err != nil {
		return models.Category{}, err
	}
	return toCategory(row), nil
}

// Update updates an existing category.
func (s *CategoryService) Update(ctx context.Context, id int32, req models.UpdateCategoryRequest) (models.Category, error) {
	row, err := s.q.UpdateCategory(ctx, queries.UpdateCategoryParams{
		ID:        id,
		Name:      req.Name,
		SortOrder: req.SortOrder,
	})
	if err != nil {
		return models.Category{}, err
	}
	return toCategory(row), nil
}

// Delete removes a category by id.
func (s *CategoryService) Delete(ctx context.Context, id int32) error {
	return s.q.DeleteCategory(ctx, id)
}

func toCategory(c queries.Category) models.Category {
	return models.Category{
		ID:        c.ID,
		Name:      c.Name,
		SortOrder: c.SortOrder,
		CreatedAt: c.CreatedAt,
		UpdatedAt: c.UpdatedAt,
	}
}