feat: add inventory domain

backend/internal/domain/inventory.go

@@ -0,0 +1,61 @@
+package domain
+
+import (
+	"context"
+	"time"
+
+	validation "github.com/go-ozzo/ozzo-validation/v4"
+)
+
+type InventoryStatus string
+
+const (
+	StatusInStock    InventoryStatus = "In Stock"
+	StatusLowStock   InventoryStatus = "Low Stock"
+	StatusOutOfStock InventoryStatus = "Out of Stock"
+)
+
+type InventoryItem struct {
+	ID        string
+	Name      string
+	Category  string
+	Type      string
+	Quantity  float64
+	Unit      string
+	DateAdded time.Time
+	Status    InventoryStatus
+	CreatedAt time.Time
+	UpdatedAt time.Time
+}
+
+type InventoryFilter struct {
+	Category    string
+	Type        string
+	Status      InventoryStatus
+	StartDate   time.Time
+	EndDate     time.Time
+	SearchQuery string
+}
+
+type InventorySort struct {
+	Field     string
+	Direction string
+}
+
+func (i *InventoryItem) Validate() error {
+	return validation.ValidateStruct(i,
+		validation.Field(&i.Name, validation.Required),
+		validation.Field(&i.Category, validation.Required),
+		validation.Field(&i.Type, validation.Required),
+		validation.Field(&i.Quantity, validation.Required, validation.Min(0.0)),
+		validation.Field(&i.Unit, validation.Required),
+		validation.Field(&i.Status, validation.Required, validation.In(StatusInStock, StatusLowStock, StatusOutOfStock)),
+	)
+}
+
+type InventoryRepository interface {
+	GetByID(ctx context.Context, id string) (InventoryItem, error)
+	GetWithFilter(ctx context.Context, filter InventoryFilter, sort InventorySort) ([]InventoryItem, error)
+	CreateOrUpdate(ctx context.Context, item *InventoryItem) error
+	Delete(ctx context.Context, id string) error
+}