Store resources in generic inventories

Inventory.gd

@@ -0,0 +1,79 @@
+class_name Inventory
+extends RefCounted
+
+var total_capacity: int = -1
+var resource_capacities: Dictionary = {}
+var _amounts: Dictionary = {}
+
+
+func _init(initial: Dictionary = {}, capacity: int = -1) -> void:
+	total_capacity = capacity
+	for resource_id in initial:
+		set_amount(String(resource_id), int(initial[resource_id]))
+
+
+func amount(resource_id: String) -> int:
+	return int(_amounts.get(resource_id, 0))
+
+
+func total() -> int:
+	var result: int = 0
+	for value in _amounts.values():
+		result += int(value)
+	return result
+
+
+func capacity_for(resource_id: String) -> int:
+	return int(resource_capacities.get(resource_id, -1))
+
+
+func space_for(resource_id: String) -> int:
+	var space: int = 1 << 30
+	if total_capacity >= 0:
+		space = maxi(total_capacity - total(), 0)
+	var resource_capacity: int = capacity_for(resource_id)
+	if resource_capacity >= 0:
+		space = mini(space, maxi(resource_capacity - amount(resource_id), 0))
+	return space
+
+
+func set_amount(resource_id: String, value: int) -> int:
+	_amounts.erase(resource_id)
+	var accepted: int = mini(maxi(value, 0), space_for(resource_id))
+	if accepted > 0:
+		_amounts[resource_id] = accepted
+	return amount(resource_id)
+
+
+func deposit(resource_id: String, requested: int) -> int:
+	var moved: int = mini(maxi(requested, 0), space_for(resource_id))
+	if moved > 0:
+		_amounts[resource_id] = amount(resource_id) + moved
+	return moved
+
+
+func withdraw(resource_id: String, requested: int) -> int:
+	var moved: int = mini(maxi(requested, 0), amount(resource_id))
+	if moved <= 0:
+		return 0
+	var remaining: int = amount(resource_id) - moved
+	if remaining > 0:
+		_amounts[resource_id] = remaining
+	else:
+		_amounts.erase(resource_id)
+	return moved
+
+
+func transfer_to(destination: Inventory, resource_id: String, requested: int) -> int:
+	if destination == null:
+		return 0
+	var moved: int = mini(mini(maxi(requested, 0), amount(resource_id)), destination.space_for(resource_id))
+	if moved <= 0:
+		return 0
+	withdraw(resource_id, moved)
+	destination.deposit(resource_id, moved)
+	return moved
+
+
+func snapshot() -> Dictionary:
+	return _amounts.duplicate()