@tool
extends MeshInstance3D
class_name GridHighlightController

@export var grid_manager_path: NodePath
@export var camera_path: NodePath

var _grid_manager: GridPlaneManager = null
var _camera: Camera3D = null
var _hovered_cell: Vector2i = Vector2i(-1, -1)

func _ready() -> void:
	set_process(true)
	_resolve_references()
	_refresh_mesh()
	if _grid_manager:
		_grid_manager.grid_layout_changed.connect(_on_grid_layout_changed)

func _on_grid_layout_changed(_cells: Dictionary) -> void:
	_refresh_mesh()
	_hovered_cell = Vector2i(-1, -1)
	visible = false

func _process(_delta: float) -> void:
	if Engine.is_editor_hint():
		return
	if not _grid_manager or not _camera:
		return
	var viewport: Viewport = get_viewport()
	if viewport == null:
		return
	var mouse_position: Vector2 = viewport.get_mouse_position()
	_update_hovered_cell(mouse_position)

func _resolve_references() -> void:
	if grid_manager_path != NodePath():
		_grid_manager = get_node_or_null(grid_manager_path) as GridPlaneManager
	else:
		_grid_manager = get_parent() as GridPlaneManager
	if camera_path != NodePath():
		_camera = get_node_or_null(camera_path) as Camera3D

func _refresh_mesh() -> void:
	if not _grid_manager:
		return
	mesh = _grid_manager.make_highlight_mesh()
	visible = false

func _update_hovered_cell(mouse_position: Vector2) -> void:
	var ray_origin: Vector3 = _camera.project_ray_origin(mouse_position)
	var ray_direction: Vector3 = _camera.project_ray_normal(mouse_position)
	var plane_normal: Vector3 = _grid_manager.global_transform.basis.y.normalized()
	var plane_point: Vector3 = _grid_manager.global_transform.origin
	var denominator: float = plane_normal.dot(ray_direction)
	if abs(denominator) < 0.0001:
		_set_hover_visible(false)
		return
	var t: float = plane_normal.dot(plane_point - ray_origin) / denominator
	if t <= 0.0:
		_set_hover_visible(false)
		return
	var world_point: Vector3 = ray_origin + ray_direction * t
	var cell_index: Vector2i = _grid_manager.world_to_cell(world_point, false)
	if cell_index.x < 0 or cell_index.y < 0 or not _grid_manager.has_cell(cell_index):
		_set_hover_visible(false)
		return
	if cell_index == _hovered_cell:
		return
	_hovered_cell = cell_index
	var local_center: Vector3 = _grid_manager.cell_to_world(cell_index)
	var target_position: Vector3 = _grid_manager.to_global(local_center)
	global_position = target_position + plane_normal * 0.02
	_set_hover_visible(true)

func _set_hover_visible(state: bool) -> void:
	if not state:
		visible = false
		_hovered_cell = Vector2i(-1, -1)
	else:
		visible = true