extends Building
class_name ItemSpawner

# TODO: Use CustomResources to set item types
@export var item_type_to_spawn: String = "TestItem"
@export var spawn_interval_seconds: float = 1.0

@onready var spawn_timer: Timer = $SpawnTimer
#@onready var spawn_point_offset: Vector2 = Vector2(0, -32)

var _spawned_item_scene: PackedScene = preload("res://Item.tscn")

func _ready():
	super()
	
	_on_grid_position_changed()
	
	if spawn_timer:
		spawn_timer.one_shot = true
		spawn_timer.wait_time = spawn_interval_seconds
		spawn_timer.timeout.connect(_on_spawn_timer_timeout)
		spawn_timer.start()

func _on_grid_position_changed():
	super()
	
	name = "ItemSpawner_%s,%s" % [current_grid_pos.x, current_grid_pos.y]

# Can never accept items
func can_accept_item() -> bool:
	return false


func handle_item_entry(item: Item, remaining_delta_from_previous: float = 0.0):
	# Should never happen since can_accept_item() is always false
	#item.queue_free() 
	print("Item %s tried to enter spawner at %s." % [item.type, current_grid_pos])

func _on_spawn_timer_timeout():
	set_physics_process(true)
	var next_grid_cell_pos = current_grid_pos + direction
	var next_entity: Building = game_grid.get_content_at_grid(next_grid_cell_pos)

	if not next_entity:
		print("Spawner at %s is blocked: no entity at next cell." % current_grid_pos)
		return
		
	if not next_entity.can_accept_item():
		# pause future spawning and "buffer" current item spawn until the space is free
		# TODO: Use a signal FROM the belt here (belt should signal when it is free instead
		# of the spawner checking every tick...
		print("Spawner at %s is blocked: next entity (%s) cannot accept item. Pausing spawn." % [current_grid_pos, next_entity.name])
		return
		
	var new_item: Item = _spawned_item_scene.instantiate()
	new_item.modulate = modulate
	new_item.type = item_type_to_spawn
	game_grid.add_child(new_item)

	new_item.global_position = global_position # + spawn_point_offset
	new_item.reset_physics_interpolation()

	print("Spawner at %s is spawned item (%s) for next_entity (%s)." % [current_grid_pos, new_item.name, next_entity.name])

	next_entity.handle_item_entry(new_item, 0.0) # TOOO: Use actual item pixel size
	# Maybe have up to 4 or 8 items on a belt like factorio?
	# Currently all items are in the center (easier), but we still
	# need to use size to check if we are backed up and can't move
	# Easierst would be to have ALL items be the same size, and use factorios approach of distances
	# between items for checks
	spawn_timer.start()

func _physics_process(delta: float) -> void:
	# We could disable physics_process() while the timer is running
	if not spawn_timer.is_stopped():
		set_physics_process(false)
		return

	_on_spawn_timer_timeout()