Add shop supplies and rebalance early economy

economy/fishing_shop_stock.gd

@@ -0,0 +1,58 @@
+class_name FishingShopStock
+extends RefCounted
+
+const ItemCatalogType = preload("res://items/item_catalog.gd")
+const ItemDataType = preload("res://items/item_data.gd")
+const PlayerBagType = preload("res://inventory/player_bag.gd")
+const PlayerWalletType = preload("res://economy/player_wallet.gd")
+
+const ITEM_PRICES: Dictionary[StringName, int] = {
+	&"coffee": 20,
+	&"energy_drink": 35,
+	&"snack": 30,
+	&"fish_finder": 60,
+}
+const ITEM_ORDER: Array[StringName] = [
+	&"coffee",
+	&"energy_drink",
+	&"snack",
+	&"fish_finder",
+]
+
+
+static func get_price(item_id: StringName) -> int:
+	return ITEM_PRICES.get(item_id, -1)
+
+
+static func get_stock_item_ids() -> Array[StringName]:
+	return ITEM_ORDER.duplicate()
+
+
+static func purchase_one(
+	item_id: StringName,
+	wallet: PlayerWalletType,
+	bag: PlayerBagType,
+	catalog: ItemCatalogType,
+) -> bool:
+	if wallet == null or bag == null or catalog == null:
+		return false
+	var price: int = get_price(item_id)
+	var item: ItemDataType = catalog.get_item_by_id(item_id)
+	if (
+		price < 0
+		or item == null
+		or not item.is_valid()
+		or item.category != ItemDataType.Category.CONSUMABLE
+		or not item.stackable
+		or not item.usable
+		or not bag.can_add_item(item_id, 1)
+		or not wallet.can_afford(price)
+	):
+		return false
+	if not wallet.debit(price):
+		return false
+	if bag.add_item(item_id, 1):
+		return true
+	if not wallet.credit(price):
+		push_error("Fishing Shop failed to roll back an item purchase.")
+	return false