Added arn to the main repository

arn/Inventory.go

@@ -0,0 +1,88 @@
+package arn
+
+import (
+	"errors"
+)
+
+// DefaultInventorySlotCount tells you how many slots are available by default in an inventory.
+const DefaultInventorySlotCount = 24
+
+// Inventory has inventory slots that store shop item IDs and their quantity.
+type Inventory struct {
+	UserID UserID           `json:"userId"`
+	Slots  []*InventorySlot `json:"slots"`
+}
+
+// AddItem adds a given item to the inventory.
+func (inventory *Inventory) AddItem(itemID string, quantity uint) error {
+	if itemID == "" {
+		return nil
+	}
+
+	// Find the slot with the item
+	for _, slot := range inventory.Slots {
+		if slot.ItemID == itemID {
+			slot.Quantity += quantity
+			return nil
+		}
+	}
+
+	// If the item doesn't exist in the inventory yet, add it to the first free slot
+	for _, slot := range inventory.Slots {
+		if slot.ItemID == "" {
+			slot.ItemID = itemID
+			slot.Quantity = quantity
+			return nil
+		}
+	}
+
+	// If there is no free slot, return an error
+	return errors.New("Inventory is full")
+}
+
+// ContainsItem checks if the inventory contains the item ID already.
+func (inventory *Inventory) ContainsItem(itemID string) bool {
+	for _, slot := range inventory.Slots {
+		if slot.ItemID == itemID {
+			return true
+		}
+	}
+
+	return false
+}
+
+// SwapSlots swaps the slots with the given indices.
+func (inventory *Inventory) SwapSlots(a, b int) error {
+	if a < 0 || b < 0 || a >= len(inventory.Slots) || b >= len(inventory.Slots) {
+		return errors.New("Inventory slot index out of bounds")
+	}
+
+	// Swap
+	inventory.Slots[a], inventory.Slots[b] = inventory.Slots[b], inventory.Slots[a]
+	return nil
+}
+
+// NewInventory creates a new inventory with the default number of slots.
+func NewInventory(userID UserID) *Inventory {
+	inventory := &Inventory{
+		UserID: userID,
+		Slots:  make([]*InventorySlot, DefaultInventorySlotCount),
+	}
+
+	for i := 0; i < len(inventory.Slots); i++ {
+		inventory.Slots[i] = &InventorySlot{}
+	}
+
+	return inventory
+}
+
+// GetInventory ...
+func GetInventory(userID UserID) (*Inventory, error) {
+	obj, err := DB.Get("Inventory", userID)
+
+	if err != nil {
+		return nil, err
+	}
+
+	return obj.(*Inventory), nil
+}