extends Node3D
## Earth impostor — from Luna you are always far; show a disc inside far plane.

@export var real_earth_path: NodePath = ^".."
@export var surface_path: NodePath = ^"../EarthSurface"
@export var impostor_mesh_path: NodePath = ^"ImposterSphere"

@export var switch_distance: float = 150000.0
@export var visual_distance: float = 120000.0
@export var real_radius: float = 637100.0

var _real: Node3D
var _surface: Node3D
var _mesh: MeshInstance3D
var _base_radius: float = 0.5

func _ready() -> void:
	_real = get_node_or_null(real_earth_path) as Node3D
	_surface = get_node_or_null(surface_path) as Node3D
	_mesh = get_node_or_null(impostor_mesh_path) as MeshInstance3D

	if _mesh and _mesh.mesh is SphereMesh:
		_base_radius = maxf((_mesh.mesh as SphereMesh).radius, 0.5)

	if _mesh:
		_mesh.visible = false
		# Keep YOUR material/texture; only force unshaded so it reads in space
		var src_mat: Material = _mesh.get_active_material(0)
		if src_mat is StandardMaterial3D:
			var mat: StandardMaterial3D = (src_mat as StandardMaterial3D).duplicate()
			mat.shading_mode = BaseMaterial3D.SHADING_MODE_UNSHADED
			_mesh.material_override = mat

	print("EarthImposter ready | real=", _real, " surface=", _surface, " mesh=", _mesh)
	set_process(true)

func _process(_delta: float) -> void:
	if _real == null or _mesh == null:
		return

	var viewer: Node3D = FloatingOrigin.focus
	if viewer == null or not is_instance_valid(viewer):
		_mesh.visible = false
		return

	var to_body: Vector3 = _real.global_position - viewer.global_position
	var dist: float = to_body.length()
	if dist < 1.0:
		_mesh.visible = false
		return

	# Close approach only: real surface
	if dist < switch_distance:
		_mesh.visible = false
		if _surface:
			_surface.visible = true
		return

	# Far (normal from Luna): impostor on
	# Leave EarthSurface visible until you confirm the disc — then you can hide it
	var dir: Vector3 = to_body / dist
	_mesh.global_position = viewer.global_position + dir * visual_distance

	var visual_radius: float = real_radius * (visual_distance / dist)
	visual_radius = clampf(visual_radius, 8000.0, 150000.0)
	_mesh.scale = Vector3.ONE * (visual_radius / _base_radius)
	_mesh.visible = true