add create waste route

internal/services/category/category_service.go

@@ -41,3 +41,25 @@ func (s *CategoryService) AddCategory(ctx context.Context, category *CategoryEnt
 	}
 	return category, nil
 }
+
+func (s *CategoryService) GetCategory(ctx context.Context, categoryId int) (*CategoryEntity, error) {
+	query := `SELECT id, name, budget_id, favorite, monthly_limit FROM categories WHERE id = @id`
+	args := pgx.NamedArgs{
+		"id": categoryId,
+	}
+	rows, err := s.db.Query(ctx, query, args)
+	if err != nil {
+		return nil, err
+	}
+	categories := []*CategoryEntity{}
+	defer rows.Close()
+	for rows.Next() {
+		category := &CategoryEntity{}
+		err = rows.Scan(&category.Id, &category.Name, &category.BudgetId, &category.Favorite, &category.MonthlyLimit)
+		if err != nil {
+			return nil, err
+		}
+		categories = append(categories, category)
+	}
+	return categories[0], nil
+}

internal/services/waste/waste_service.go

@@ -0,0 +1,54 @@
+package waste
+
+import (
+	"context"
+	"fmt"
+
+	"git.3crabs.ru/save_my_money/smm_core/internal/services/category"
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+type WasteEntity struct {
+	Id         int
+	Name       string
+	Price      int
+	Amount     float32
+	BudgetId   int
+	CategoryId int
+}
+
+type WasteService struct {
+	db              *pgxpool.Pool
+	categoryService *category.CategoryService
+}
+
+func NewWasteService(
+	db *pgxpool.Pool,
+	categoryService *category.CategoryService,
+) *WasteService {
+	return &WasteService{
+		db:              db,
+		categoryService: categoryService,
+	}
+}
+
+func (s *WasteService) AddWaste(ctx context.Context, waste *WasteEntity) (*WasteEntity, error) {
+	category, err := s.categoryService.GetCategory(ctx, waste.CategoryId)
+	if err != nil {
+		return nil, err
+	}
+
+	query := `INSERT INTO wastes (name, price, amount, budget_id, category_id) VALUES (@name, @price, @amount, @budget_id, @category_id) RETURNING id`
+	args := pgx.NamedArgs{
+		"name":        waste.Name,
+		"price":       waste.Price,
+		"amount":      waste.Amount,
+		"budget_id":   category.BudgetId,
+		"category_id": waste.CategoryId,
+	}
+	if err := s.db.QueryRow(ctx, query, args).Scan(&waste.Id); err != nil {
+		return nil, fmt.Errorf("unable to insert row: %w", err)
+	}
+	return waste, nil
+}