extends ColorRect

enum LOAD_STATE { NO_LOAD, BASIC_LOAD, MAP_LOAD, MAP_LOADED }

const worldManager = preload("res://Levels/world_manager.tscn")

@export var opaque := 0.0
@export var transparent := 11.0
var duration := .5

var target_scene_path : String
var mapScene : PackedScene
var loadState : LOAD_STATE = LOAD_STATE.NO_LOAD
var loading_status : int
var progress : Array[float]

var tween : Tween

func goto(scene_path : String, _loadState : LOAD_STATE = LOAD_STATE.BASIC_LOAD):
	loadState = _loadState
	target_scene_path = scene_path

	fade_in()
	tween.tween_callback(load_scene)


func gotoLevel(mapSceneToLoad : String) -> void :
	goto(mapSceneToLoad, LOAD_STATE.MAP_LOAD)


func load_scene() -> void:
	ResourceLoader.load_threaded_request(target_scene_path) #Fetch loading status and loading scene


func animate() -> void:
	if tween:
		tween.kill() # Abort the previous animation.
	tween = create_tween()


func fade_in() -> void:
	animate()
	tween.tween_method(shader_transition, transparent, opaque, duration)


func fade_out() -> void:
	animate()
	tween.tween_method(shader_transition, opaque, transparent, duration)


func shader_transition(value) -> void:
	material.set_shader_parameter("progress", value)


func _process(_delta: float) -> void:
	if loadState == LOAD_STATE.NO_LOAD:
		return

	# Update the status:
	loading_status = ResourceLoader.load_threaded_get_status(target_scene_path, progress)

	if loadState == LOAD_STATE.MAP_LOADED:
		injectMap()
		fade_out()
		loadState = LOAD_STATE.NO_LOAD

	# Check the loading status:
	match loading_status:
		ResourceLoader.THREAD_LOAD_IN_PROGRESS:
			pass
		ResourceLoader.THREAD_LOAD_LOADED:
			# When done loading, change to the target scene:
			var scene = ResourceLoader.load_threaded_get(target_scene_path)
			if loadState == LOAD_STATE.MAP_LOAD:
				mapScene = scene
				get_tree().change_scene_to_packed(worldManager)
				loadState = LOAD_STATE.MAP_LOADED
			if loadState == LOAD_STATE.BASIC_LOAD:
				get_tree().change_scene_to_packed(scene)
				loadState = LOAD_STATE.NO_LOAD
				fade_out()

		ResourceLoader.THREAD_LOAD_FAILED:
			# Well some error happend:
			printerr("Error. Could not load Resource")
			loadState = LOAD_STATE.NO_LOAD


func injectMap() -> void:
	var node : Node = get_tree().current_scene
	if node is WorldManager:
		node.addMap(mapScene)