extends Path3D

@export var speed: float = 1.0
@export var item_offset: Vector3 = Vector3(0,2.0,0)
@export var extra_distance_start: float = 1.0
@export var extra_distance_end: float = 1.0
	
var transported_items: Dictionary[Item, PackedFloat64Array] = {}

@onready var consumer: Consumer = $Consumer
@onready var producer: Producer = $Producer
@onready var multimesh: MultiMeshInstance3D = $MultiMeshInstance3D

var test_timer: float = 0
@onready var test_item: Item = load("res://items/metal.tres")

func _ready() -> void:
	multimesh.multimesh = multimesh.multimesh.duplicate()

func _process(delta: float) -> void:
	#test_timer += delta
	#if test_timer >= 2.0:
		#test_timer -= 2.0
		#add_item(test_item)
	
	var belt_moving: bool = check_items_at_end()
	if belt_moving:
		for transported_item_type in transported_items.keys():
			var offsets: PackedFloat64Array = transported_items[transported_item_type]
			multimesh.multimesh.instance_count = offsets.size()
			for i in range(offsets.size()):
				offsets[i] += (delta * speed)
				position_item(i, transported_item_type, offsets[i])
				
func consumer_has_item(item: Item) -> void:
	if consumer.take_item_from_storage(item):
		add_item(item)

func add_item(item: Item) -> void:
	if item.model != multimesh.multimesh.mesh:
		multimesh.multimesh.mesh = item.model
	
	var offsets: PackedFloat64Array
	if transported_items.has(item):
		offsets = transported_items[item]
	else:
		offsets = []
	offsets.append(get_start_offset())
	transported_items[item] = offsets

func check_items_at_end() -> bool:
	var length: float = get_end_offset()
	var belt_moving: bool = true
	for transported_item_type in transported_items.keys():
		var offsets: PackedFloat64Array = transported_items[transported_item_type]
		var to_delete: Array[int] = []
		for i in range(offsets.size()):
			if offsets[i] >= length:
				var sent: bool = producer.send_item(transported_item_type)
				if !sent:
					belt_moving = false
				else:
					to_delete.append(i)
		for d in to_delete:
			offsets.remove_at(d)
	return belt_moving
	
func get_start_offset() -> float:
	return -extra_distance_start
	
func get_end_offset() -> float:
	return curve.get_baked_length() + extra_distance_end
		
func position_item(instance: int, item: Item, offset: float) -> void:
	var trans: Transform3D
	trans = sample_curve_with_extrapolation(offset).translated_local(item_offset)
	multimesh.multimesh.set_instance_transform(instance, trans)
	
func sample_curve_with_extrapolation(offset: float) -> Transform3D:
	var end_offset: float = curve.get_baked_length()
	if offset <= 0:
		var zero: Transform3D = curve.sample_baked_with_rotation(0)
		var almost_zero: Transform3D = curve.sample_baked_with_rotation(0.1)
		return almost_zero.interpolate_with(zero, (0.1-offset) * 10)
	elif offset > end_offset:
		var end: Transform3D = curve.sample_baked_with_rotation(end_offset)
		var almost_end: Transform3D = curve.sample_baked_with_rotation(end_offset-0.1)
		return almost_end.interpolate_with(end, (offset - (end_offset - 0.1)) * 10)
	else:
		return curve.sample_baked_with_rotation(offset)