@tool
class_name ItemGrid
extends GridContainer

signal item_selected

@export var slot_scene:PackedScene
@export var allow_selection:bool = false
@export var allow_drag_drop:bool = false

@export var rows:int:
	get:
		return rows
	set(value):
		if value == rows:
			return

		rows = value

		if slot_scene == null or not is_node_ready():
			return

		resize_grid()

var _slots:Array = []
var _item_slot_to_index:Dictionary = {}
var _highlighted_slot_index = -1
var _highlighted_slot:ItemSlot = null
var selected_slot:ItemSlot = null
var _selected_slot_index:int = -1

func _ready() -> void:
	resize_grid()

func resize_grid() -> void:
	_item_slot_to_index.clear()
	
	for child in get_children():
		child.get_parent().remove_child(child)
		child.queue_free()
	
	_slots.clear()
	while get_child_count() < rows * columns:
		var slot_instance = slot_scene.instantiate() as ItemSlot
		if allow_drag_drop:
			slot_instance.set_drag_drop_flags(ItemSlot.ALLOW_DRAG | ItemSlot.ALLOW_DROP)
		add_child(slot_instance)
		_slots.append(slot_instance)
		if allow_selection and not Engine.is_editor_hint():
			slot_instance.connect("mouse_entered_slot", _on_slot_mouse_entered)
			slot_instance.connect("mouse_left_pressed", _on_slot_mouse_left_pressed)
		_item_slot_to_index[slot_instance] = _item_slot_to_index.size()

func clear_slots() -> void:
	for slot:ItemSlot in _slots:
		slot.display(ItemStack.new())

func get_slot_index(slot:ItemSlot) -> int:
	if _item_slot_to_index.has(slot):
		return _item_slot_to_index[slot]
	
	return -1

func _on_slot_mouse_entered(slot:ItemSlot):
	if _highlighted_slot != null:
		_highlighted_slot.highlighted = false
	
	_highlighted_slot_index = -1
	_highlighted_slot = null
	
	if _item_slot_to_index.has(slot):
		_highlighted_slot_index = _item_slot_to_index[slot]
		_highlighted_slot = slot
		_highlighted_slot.highlighted = true

func select_slot(index:int) -> void:
	if index < 0 or index > _slots.size():
		item_selected.emit(null)
		return
	
	_selected_slot_index = index
	selected_slot = _slots[_selected_slot_index]	
	selected_slot.selected = true
	item_selected.emit(selected_slot)

func _on_slot_mouse_left_pressed(slot:ItemSlot):
	if selected_slot:
		selected_slot.selected = false
		
	if slot == _highlighted_slot:
		_highlighted_slot.highlighted = false
		select_slot(get_slot_index(slot))

func displayStacks(item_stacks:Array[ItemStack]):
	var item_stack_index = 0
	
	for slot:ItemSlot in _slots:
		if item_stack_index < item_stacks.size():
			slot.display(item_stacks[item_stack_index])
		else:
			var item_stack:ItemStack = ItemStack.new()
			item_stack.item = null
			slot.display(item_stack)	
		
		item_stack_index = item_stack_index + 1

func display(item_stacks:Array[ItemResource]):
	var item_stack_index = 0
	
	for slot:ItemSlot in _slots:
		var item_stack:ItemStack = ItemStack.new()
		
		if item_stack_index < item_stacks.size():
			item_stack.item = item_stacks[item_stack_index]
			item_stack.count = 1
		else:
			item_stack.item = null
		
		item_stack_index = item_stack_index + 1
		
		slot.display(item_stack)