extends CanvasLayer

@export var config: SceneConfig
@onready var color_rect = $ColorRect
@onready var loading_screen = $LoadingScreen
@export var transition_duration: float = 3
const SHADER_PATH := "res://core/transition.gdshader"
var transaction_material: ShaderMaterial

func _ready() -> void:
	_build_material()
	_update_resolution()
	get_viewport().size_changed.connect(_update_resolution)
	_set_factor(0.0)
	color_rect.visible = false

func _build_material() -> void:
	transaction_material = ShaderMaterial.new()
	transaction_material.shader = load(SHADER_PATH)

	#directional gradient: bottom-left-> black; top-right -> white
	var g := Gradient.new()
	g.set_color(0, Color.BLACK)
	g.set_color(1, Color.WHITE)
	var grad_tex := GradientTexture2D.new()
	grad_tex.gradient = g
	grad_tex.fill = GradientTexture2D.FILL_LINEAR
	grad_tex.fill_from = Vector2(0.0, 1.0)   # bottom-left
	grad_tex.fill_to   = Vector2(1.0, 0.0)   # top-right
	grad_tex.width = 256
	grad_tex.height = 256

	#shape: sphere (white at the center, black around)
	var sg := Gradient.new()
	sg.set_color(0, Color.WHITE)
	sg.set_color(1, Color.BLACK)
	var shape_tex := GradientTexture2D.new()
	shape_tex.gradient = sg
	shape_tex.fill = GradientTexture2D.FILL_RADIAL
	shape_tex.fill_from = Vector2(0.5, 0.5)  # center
	shape_tex.fill_to   = Vector2(0.5, 0.0)  # ray
	shape_tex.width = 64
	shape_tex.height = 64

	transaction_material.set_shader_parameter("base_color", Color.BLACK)
	transaction_material.set_shader_parameter("gradient_texture", grad_tex)
	transaction_material.set_shader_parameter("gradient_fixed", false)
	transaction_material.set_shader_parameter("shape_texture", shape_tex)
	transaction_material.set_shader_parameter("shape_tiling", 16.0)
	transaction_material.set_shader_parameter("shape_rotation", 0.0)
	transaction_material.set_shader_parameter("shape_scroll", Vector2.ZERO)
	transaction_material.set_shader_parameter("shape_feathering", 0.05)
	transaction_material.set_shader_parameter("shape_treshold", 1.0)  # >=1 -> full at the end of the transation
	transaction_material.set_shader_parameter("width", 0.5)

	color_rect.material = transaction_material

func _update_resolution() -> void:
	var s := get_viewport().get_visible_rect().size
	if color_rect.material:
		color_rect.material.set_shader_parameter("node_resolution", s)

func _set_factor(v: float) -> void:
	if color_rect.material:
		color_rect.material.set_shader_parameter("factor", v)

func cover(duration := 0.5) -> void:
	color_rect.visible = true
	var t := create_tween()
	t.tween_method(_set_factor, 0.0, 1.0, duration)
	await t.finished

func reveal(duration := 0.5) -> void:
	var t := create_tween()
	t.tween_method(_set_factor, 1.0, 0.0, duration)
	await t.finished
	color_rect.visible = false

func change_scene_with_standard_fade(scene_enum: SceneConfig.SceneName, duration: float = transition_duration, show_loading_label: bool = false) -> void:	
	if not config or not config.scenes.has(scene_enum):
		return

	color_rect.material = null
	color_rect.color = Color(0,0,0)
	var target_scene: PackedScene = config.scenes[scene_enum]

	color_rect.mouse_filter = Control.MOUSE_FILTER_STOP
	if show_loading_label:
		loading_screen.visible = true
	
	await cover(duration)
	get_tree().change_scene_to_packed(target_scene)
	await reveal(duration)

	if show_loading_label:
		loading_screen.visible = false
	color_rect.mouse_filter = Control.MOUSE_FILTER_IGNORE
	
func change_scene(scene_enum: SceneConfig.SceneName, duration: float = transition_duration, show_loading_label: bool = false) -> void:	
	if not config or not config.scenes.has(scene_enum):
		return

	color_rect.material = transaction_material
	color_rect.color = Color(0,0,0,0)
	var target_scene: PackedScene = config.scenes[scene_enum]

	color_rect.mouse_filter = Control.MOUSE_FILTER_STOP
	if show_loading_label:
		loading_screen.visible = true
	
	await cover(duration)
	get_tree().change_scene_to_packed(target_scene)
	await reveal(duration)

	if show_loading_label:
		loading_screen.visible = false
	color_rect.mouse_filter = Control.MOUSE_FILTER_IGNORE

func quit_game() -> void:
	get_tree().quit()