Added arn to the main repository

arn/InventorySlot.go

@@ -0,0 +1,44 @@
+package arn
+
+import "errors"
+
+// InventorySlot ...
+type InventorySlot struct {
+	ItemID   string `json:"itemId"`
+	Quantity uint   `json:"quantity"`
+}
+
+// IsEmpty ...
+func (slot *InventorySlot) IsEmpty() bool {
+	return slot.ItemID == ""
+}
+
+// Item ...
+func (slot *InventorySlot) Item() *ShopItem {
+	if slot.ItemID == "" {
+		return nil
+	}
+
+	item, _ := GetShopItem(slot.ItemID)
+	return item
+}
+
+// Decrease reduces the quantity by the given number.
+func (slot *InventorySlot) Decrease(count uint) error {
+	if slot.Quantity < count {
+		return errors.New("Not enough items")
+	}
+
+	slot.Quantity -= count
+
+	if slot.Quantity == 0 {
+		slot.ItemID = ""
+	}
+
+	return nil
+}
+
+// Increase increases the quantity by the given number.
+func (slot *InventorySlot) Increase(count uint) {
+	slot.Quantity += count
+}