class_name Inventory
extends RefCounted

const MAX_STACK: int = 64
const TOTAL_SLOTS: int = 36
const HOTBAR_SIZE: int = 9

signal inventory_changed

var slots: Array = []
var selected_hotbar: int = 0


func _init() -> void:
	slots.resize(TOTAL_SLOTS)
	for i: int in range(TOTAL_SLOTS):
		slots[i] = null


func add_item(item_id: int, count: int = 1) -> int:
	var remaining: int = count
	# First pass: stack into existing slots
	for i: int in range(TOTAL_SLOTS):
		if remaining <= 0:
			break
		if slots[i] != null and slots[i]["item_id"] == item_id:
			var space: int = MAX_STACK - slots[i]["count"]
			if space > 0:
				var add_amount: int = mini(space, remaining)
				slots[i]["count"] += add_amount
				remaining -= add_amount
	# Second pass: fill empty slots
	for i: int in range(TOTAL_SLOTS):
		if remaining <= 0:
			break
		if slots[i] == null:
			var add_amount: int = mini(MAX_STACK, remaining)
			slots[i] = {"item_id": item_id, "count": add_amount}
			remaining -= add_amount
	inventory_changed.emit()
	return remaining


func remove_item_from_slot(slot_index: int, count: int = 1) -> bool:
	if slot_index < 0 or slot_index >= TOTAL_SLOTS:
		return false
	if slots[slot_index] == null:
		return false
	if slots[slot_index]["count"] < count:
		return false
	slots[slot_index]["count"] -= count
	if slots[slot_index]["count"] <= 0:
		slots[slot_index] = null
	inventory_changed.emit()
	return true


func get_selected_item() -> Variant:
	return slots[selected_hotbar]


func scroll_hotbar(direction: int) -> void:
	selected_hotbar = (selected_hotbar + direction + HOTBAR_SIZE) % HOTBAR_SIZE
	inventory_changed.emit()


func has_items(requirements: Array) -> bool:
	for req: Dictionary in requirements:
		var needed: int = req["count"]
		for i: int in range(TOTAL_SLOTS):
			if slots[i] != null and slots[i]["item_id"] == req["item_id"]:
				needed -= slots[i]["count"]
		if needed > 0:
			return false
	return true


func get_all_slots() -> Array:
	return slots.duplicate(true)


func load_slots(saved_slots: Array) -> void:
	for i: int in range(min(saved_slots.size(), TOTAL_SLOTS)):
		slots[i] = saved_slots[i]
	inventory_changed.emit()


func consume_items(requirements: Array) -> bool:
	if not has_items(requirements):
		return false
	for req: Dictionary in requirements:
		var to_consume: int = req["count"]
		for i: int in range(TOTAL_SLOTS):
			if to_consume <= 0:
				break
			if slots[i] != null and slots[i]["item_id"] == req["item_id"]:
				var take: int = mini(slots[i]["count"], to_consume)
				slots[i]["count"] -= take
				to_consume -= take
				if slots[i]["count"] <= 0:
					slots[i] = null
	inventory_changed.emit()
	return true