class_name SurfaceDrawingCanvas
extends Node3D

const GUIDED_PIXEL_FILL: float = 0.88
const SURFACE_OFFSET: float = 0.012
const LAYER_OFFSET_STEP: float = 0.0002
const SURFACE_SAMPLE_DEPTH: float = 0.45
const FINALIZED_VISIBILITY_RANGE: float = 96.0
const FINALIZED_VISIBILITY_MARGIN: float = 12.0
const FINALIZED_MAX_SUBDIVISIONS: int = 32

var canvas_id: String = ""
var grid_width: int = 0
var grid_height: int = 0
var cell_size: float = 0.0
var revision: int = -1
var creator_fingerprint: String = ""
var participant_fingerprints: Array[String] = []

var _surface_origin: Vector3
var _surface_normal: Vector3
var _surface_tangent: Vector3
var _surface_bitangent: Vector3
var _cell_buffer: SurfaceDrawingCellBuffer
var _cell_surface_transforms: Array[Transform3D] = []
var _pixel_image: Image
var _pixel_texture: ImageTexture
var _pixel_instance: MeshInstance3D
var _grid_instance: MeshInstance3D
var _guide_visible: bool = true
var _finalized: bool = false
var _layer: int = 0
var _stencil_requested_visible: bool = false
var _relationships: PlayerRelationshipStore
var _solid_surface_mask: int = 1


func setup(
	data: Dictionary,
	relationships: PlayerRelationshipStore,
	solid_surface_mask: int = 1,
	cell_buffer: SurfaceDrawingCellBuffer = null,
) -> bool:
	if (
		(cell_buffer == null and not SurfaceDrawingProtocol.validate_canvas_state(data))
		or (
			cell_buffer != null
			and not SurfaceDrawingProtocol.validate_canvas_metadata(data)
		)
	):
		return false
	canvas_id = str(data["canvas_id"])
	grid_width = int(data["width"])
	grid_height = int(data["height"])
	cell_size = float(data["cell_size"])
	revision = int(data["revision"])
	creator_fingerprint = str(data["creator_fingerprint"])
	_finalized = bool(data.get("finalized", false))
	_guide_visible = bool(data.get("guide_visible", true)) and not _finalized
	_layer = int(data.get("layer", 0))
	_surface_origin = SurfaceDrawingProtocol.array_to_vector(data["origin"])
	_surface_normal = SurfaceDrawingProtocol.array_to_vector(
		data["normal"]
	).normalized()
	_surface_tangent = SurfaceDrawingProtocol.array_to_vector(
		data["tangent"]
	)
	_surface_tangent = (
		_surface_tangent - _surface_normal * _surface_tangent.dot(_surface_normal)
	).normalized()
	if _surface_normal.is_zero_approx() or _surface_tangent.is_zero_approx():
		return false
	_surface_bitangent = _surface_normal.cross(_surface_tangent).normalized()
	_relationships = relationships
	_solid_surface_mask = solid_surface_mask
	_cell_buffer = cell_buffer
	if _cell_buffer == null:
		_cell_buffer = SurfaceDrawingCellBuffer.new()
		if not _cell_buffer.configure_from_state(data, true):
			return false
	elif _cell_buffer.width != grid_width or _cell_buffer.height != grid_height:
		return false
	participant_fingerprints = _cell_buffer.get_participants()
	if _finalized:
		_build_finalized_pixel_renderer()
	else:
		var samples: Dictionary = _sample_grid_vertices()
		_build_grid(samples)
		_build_pixel_renderer(samples)
	return true


func apply_update(data: Dictionary) -> bool:
	if (
		not SurfaceDrawingProtocol.validate_canvas_update(data)
		or str(data["canvas_id"]) != canvas_id
		or int(data["revision"]) <= revision
	):
		return false
	if _cell_buffer == null or not _cell_buffer.apply_edits(data["edits"]):
		return false
	return _finish_buffered_update(data)


func apply_buffered_update(data: Dictionary) -> bool:
	if (
		not SurfaceDrawingProtocol.validate_canvas_update(data)
		or str(data["canvas_id"]) != canvas_id
		or int(data["revision"]) <= revision
		or _cell_buffer == null
	):
		return false
	return _finish_buffered_update(data)


func _finish_buffered_update(data: Dictionary) -> bool:
	_cell_buffer.ensure_participants(data.get("participant_fingerprints", []))
	participant_fingerprints = _cell_buffer.get_participants()
	revision = int(data["revision"])
	if is_hidden_by_relationship():
		_rebuild_pixel_image()
	else:
		_apply_pixel_edits(data["edits"])
	_refresh_grid_visibility()
	return true


func apply_guide_update(data: Dictionary) -> bool:
	if (
		not SurfaceDrawingProtocol.validate_guide_update(data)
		or str(data["canvas_id"]) != canvas_id
		or int(data["revision"]) <= revision
	):
		return false
	revision = int(data["revision"])
	participant_fingerprints = _participants_from_update(
		data, participant_fingerprints
	)
	if _cell_buffer != null:
		_cell_buffer.ensure_participants(participant_fingerprints)
		participant_fingerprints = _cell_buffer.get_participants()
	_finalized = bool(data["finalized"])
	_guide_visible = bool(data["guide_visible"]) and not _finalized
	if _finalized:
		_destroy_grid()
		_cell_surface_transforms.clear()
		_build_finalized_pixel_renderer()
	else:
		_refresh_grid_visibility()
	_configure_render_distance()
	return true


func refresh_relationship_visibility() -> void:
	_rebuild_pixel_image()
	if _pixel_instance != null:
		_pixel_instance.visible = not is_hidden_by_relationship()
	_refresh_grid_visibility()


func is_hidden_by_relationship() -> bool:
	if _relationships == null:
		return false
	for fingerprint: String in participant_fingerprints:
		if _relationships.is_blocked(fingerprint):
			return true
	return false


func set_stencil_visible(should_be_visible: bool) -> void:
	_stencil_requested_visible = should_be_visible
	_refresh_grid_visibility()


func is_guide_visible() -> bool:
	return _guide_visible


func is_finalized() -> bool:
	return _finalized


func get_rendered_pixel_size() -> float:
	return cell_size


func get_rendered_pixel_count() -> int:
	if is_hidden_by_relationship():
		return 0
	return _cell_buffer.get_painted_count() if _cell_buffer != null else 0


func get_export_image() -> Image:
	if _pixel_image == null or _pixel_image.is_empty():
		return null
	return _pixel_image.duplicate() as Image


func has_guide_geometry() -> bool:
	return _grid_instance != null and is_instance_valid(_grid_instance)


func contains_world_point(world_point: Vector3, tolerance: float = 0.3) -> bool:
	var relative: Vector3 = world_point - _surface_origin
	if absf(relative.dot(_surface_normal)) > tolerance:
		return false
	var half_width: float = float(grid_width) * cell_size * 0.5
	var half_height: float = float(grid_height) * cell_size * 0.5
	var horizontal: float = relative.dot(_surface_tangent)
	var vertical: float = relative.dot(_surface_bitangent)
	return (
		horizontal >= -half_width
		and horizontal < half_width
		and vertical >= -half_height
		and vertical < half_height
	)


func get_surface_plane_distance(world_point: Vector3) -> float:
	return absf((world_point - _surface_origin).dot(_surface_normal))


func cell_at_world_point(world_point: Vector3) -> Vector2i:
	var relative: Vector3 = world_point - _surface_origin
	var half_width: float = float(grid_width) * cell_size * 0.5
	var half_height: float = float(grid_height) * cell_size * 0.5
	var x: int = floori(
		(relative.dot(_surface_tangent) + half_width) / cell_size
	)
	var y: int = floori(
		(relative.dot(_surface_bitangent) + half_height) / cell_size
	)
	if x < 0 or x >= grid_width or y < 0 or y >= grid_height:
		return Vector2i(-1, -1)
	return Vector2i(x, y)


func get_cell_world_position(x: int, y: int) -> Vector3:
	var horizontal: float = (
		(float(x) + 0.5 - float(grid_width) * 0.5) * cell_size
	)
	var vertical: float = (
		(float(y) + 0.5 - float(grid_height) * 0.5) * cell_size
	)
	return (
		_surface_origin
		+ _surface_tangent * horizontal
		+ _surface_bitangent * vertical
	)


func get_surface_normal() -> Vector3:
	return _surface_normal


func get_surface_tangent() -> Vector3:
	return _surface_tangent


func get_surface_bitangent() -> Vector3:
	return _surface_bitangent


func get_cell_surface_transform(
	x: int,
	y: int,
	fill: float = 0.94,
) -> Transform3D:
	if x < 0 or x >= grid_width or y < 0 or y >= grid_height:
		return Transform3D.IDENTITY
	var key: int = _cell_key(x, y)
	var local_transform: Transform3D = (
		_cell_surface_transforms[key]
		if key >= 0 and key < _cell_surface_transforms.size()
		else _sample_cell_transform(x, y, 1.0)
	)
	var scaled_basis: Basis = local_transform.basis
	var resolved_fill: float = clampf(fill, 0.05, 1.0)
	scaled_basis.x *= resolved_fill
	scaled_basis.y *= resolved_fill
	local_transform.basis = scaled_basis
	return global_transform * local_transform


func get_authoritative_cells() -> Array[Dictionary]:
	return _cell_buffer.to_cells() if _cell_buffer != null else []


func _build_grid(samples: Dictionary) -> void:
	if _grid_instance != null:
		_grid_instance.queue_free()
		_grid_instance = null
	if _finalized:
		return
	var immediate := ImmediateMesh.new()
	var material := StandardMaterial3D.new()
	material.shading_mode = BaseMaterial3D.SHADING_MODE_UNSHADED
	material.transparency = BaseMaterial3D.TRANSPARENCY_ALPHA
	material.albedo_color = Color(0.75, 0.94, 0.96, 0.38)
	material.no_depth_test = false
	immediate.surface_begin(Mesh.PRIMITIVE_LINES, material)
	for x: int in range(grid_width + 1):
		for y_segment: int in range(grid_height):
			_add_grid_vertex(immediate, x, y_segment, samples)
			_add_grid_vertex(immediate, x, y_segment + 1, samples)
	for y: int in range(grid_height + 1):
		for x_segment: int in range(grid_width):
			_add_grid_vertex(immediate, x_segment, y, samples)
			_add_grid_vertex(immediate, x_segment + 1, y, samples)
	immediate.surface_end()
	_grid_instance = MeshInstance3D.new()
	_grid_instance.name = "PixelGrid"
	_grid_instance.mesh = immediate
	_grid_instance.cast_shadow = GeometryInstance3D.SHADOW_CASTING_SETTING_OFF
	add_child(_grid_instance)
	_refresh_grid_visibility()


func _add_grid_vertex(
	immediate: ImmediateMesh,
	x: int,
	y: int,
	samples: Dictionary,
) -> void:
	immediate.surface_add_vertex(
		_sample_position(samples, x, y, _surface_offset() * 1.5)
	)


func _build_pixel_renderer(samples: Dictionary) -> void:
	if _pixel_instance != null:
		_pixel_instance.queue_free()
		_pixel_instance = null
	var vertex_width: int = grid_width + 1
	var vertex_count: int = vertex_width * (grid_height + 1)
	var cell_count: int = grid_width * grid_height
	var vertices := PackedVector3Array()
	var texture_coordinates := PackedVector2Array()
	var indices := PackedInt32Array()
	vertices.resize(vertex_count)
	texture_coordinates.resize(vertex_count)
	indices.resize(cell_count * 6)
	_cell_surface_transforms.clear()
	if not _finalized:
		_cell_surface_transforms.resize(cell_count)
	for y: int in range(grid_height + 1):
		for x: int in range(grid_width + 1):
			var vertex_index: int = y * vertex_width + x
			vertices[vertex_index] = _sample_position(
				samples, x, y, _surface_offset()
			)
			texture_coordinates[vertex_index] = Vector2(
				float(x) / float(grid_width),
				1.0 - float(y) / float(grid_height),
			)
	for y: int in range(grid_height):
		for x: int in range(grid_width):
			var cell_index: int = _cell_key(x, y)
			if not _finalized:
				_cell_surface_transforms[cell_index] = _transform_from_samples(
					samples, x, y
				)
			var vertex_offset: int = y * vertex_width + x
			var index_offset: int = cell_index * 6
			indices[index_offset] = vertex_offset
			indices[index_offset + 1] = vertex_offset + 1
			indices[index_offset + 2] = vertex_offset + vertex_width + 1
			indices[index_offset + 3] = vertex_offset
			indices[index_offset + 4] = vertex_offset + vertex_width + 1
			indices[index_offset + 5] = vertex_offset + vertex_width
	_rebuild_pixel_image()
	var arrays: Array = []
	arrays.resize(Mesh.ARRAY_MAX)
	arrays[Mesh.ARRAY_VERTEX] = vertices
	arrays[Mesh.ARRAY_TEX_UV] = texture_coordinates
	arrays[Mesh.ARRAY_INDEX] = indices
	var mesh := ArrayMesh.new()
	mesh.add_surface_from_arrays(Mesh.PRIMITIVE_TRIANGLES, arrays)
	var material := StandardMaterial3D.new()
	material.shading_mode = BaseMaterial3D.SHADING_MODE_UNSHADED
	material.albedo_color = Color.WHITE
	material.albedo_texture = _pixel_texture
	material.texture_filter = BaseMaterial3D.TEXTURE_FILTER_NEAREST
	material.transparency = BaseMaterial3D.TRANSPARENCY_ALPHA_SCISSOR
	material.alpha_scissor_threshold = 0.5
	material.cull_mode = BaseMaterial3D.CULL_DISABLED
	mesh.surface_set_material(0, material)
	_pixel_instance = MeshInstance3D.new()
	_pixel_instance.name = "ArtworkTexture"
	_pixel_instance.mesh = mesh
	_pixel_instance.cast_shadow = GeometryInstance3D.SHADOW_CASTING_SETTING_OFF
	add_child(_pixel_instance)
	_pixel_instance.visible = not is_hidden_by_relationship()
	_configure_render_distance()


func _build_finalized_pixel_renderer() -> void:
	if _pixel_instance != null:
		_pixel_instance.queue_free()
		_pixel_instance = null
	var step: int = maxi(
		1,
		ceili(float(grid_width) / float(FINALIZED_MAX_SUBDIVISIONS)),
	)
	var coordinates := PackedInt32Array()
	var coordinate: int = 0
	while coordinate < grid_width:
		coordinates.append(coordinate)
		coordinate += step
	if coordinates.is_empty() or coordinates[-1] != grid_width:
		coordinates.append(grid_width)
	var vertex_width: int = coordinates.size()
	var vertices := PackedVector3Array()
	var texture_coordinates := PackedVector2Array()
	var indices := PackedInt32Array()
	vertices.resize(vertex_width * vertex_width)
	texture_coordinates.resize(vertex_width * vertex_width)
	indices.resize((vertex_width - 1) * (vertex_width - 1) * 6)
	var half_width: float = float(grid_width) * cell_size * 0.5
	var half_height: float = float(grid_height) * cell_size * 0.5
	for lattice_y: int in vertex_width:
		var cell_y: int = coordinates[lattice_y]
		var vertical: float = -half_height + float(cell_y) * cell_size
		for lattice_x: int in vertex_width:
			var cell_x: int = coordinates[lattice_x]
			var horizontal: float = -half_width + float(cell_x) * cell_size
			var expected: Vector3 = (
				_surface_origin
				+ _surface_tangent * horizontal
				+ _surface_bitangent * vertical
			)
			var sampled: Dictionary = _sample_surface(expected)
			var vertex_index: int = lattice_y * vertex_width + lattice_x
			var point: Vector3 = sampled["position"]
			var normal: Vector3 = sampled["normal"]
			vertices[vertex_index] = to_local(
				point + normal * _surface_offset()
			)
			texture_coordinates[vertex_index] = Vector2(
				float(cell_x) / float(grid_width),
				1.0 - float(cell_y) / float(grid_height),
			)
	for lattice_y: int in range(vertex_width - 1):
		for lattice_x: int in range(vertex_width - 1):
			var cell_index: int = lattice_y * (vertex_width - 1) + lattice_x
			var vertex_offset: int = lattice_y * vertex_width + lattice_x
			var index_offset: int = cell_index * 6
			indices[index_offset] = vertex_offset
			indices[index_offset + 1] = vertex_offset + 1
			indices[index_offset + 2] = vertex_offset + vertex_width + 1
			indices[index_offset + 3] = vertex_offset
			indices[index_offset + 4] = vertex_offset + vertex_width + 1
			indices[index_offset + 5] = vertex_offset + vertex_width
	if _pixel_image == null or _pixel_texture == null:
		_rebuild_pixel_image()
	var arrays: Array = []
	arrays.resize(Mesh.ARRAY_MAX)
	arrays[Mesh.ARRAY_VERTEX] = vertices
	arrays[Mesh.ARRAY_TEX_UV] = texture_coordinates
	arrays[Mesh.ARRAY_INDEX] = indices
	var mesh := ArrayMesh.new()
	mesh.add_surface_from_arrays(Mesh.PRIMITIVE_TRIANGLES, arrays)
	var material := StandardMaterial3D.new()
	material.shading_mode = BaseMaterial3D.SHADING_MODE_UNSHADED
	material.albedo_color = Color.WHITE
	material.albedo_texture = _pixel_texture
	material.texture_filter = BaseMaterial3D.TEXTURE_FILTER_NEAREST
	material.transparency = BaseMaterial3D.TRANSPARENCY_ALPHA_SCISSOR
	material.alpha_scissor_threshold = 0.5
	material.cull_mode = BaseMaterial3D.CULL_DISABLED
	mesh.surface_set_material(0, material)
	_pixel_instance = MeshInstance3D.new()
	_pixel_instance.name = "ArtworkTexture"
	_pixel_instance.mesh = mesh
	_pixel_instance.cast_shadow = GeometryInstance3D.SHADOW_CASTING_SETTING_OFF
	add_child(_pixel_instance)
	_pixel_instance.visible = not is_hidden_by_relationship()
	_configure_render_distance()


func _rebuild_pixel_image() -> void:
	if _cell_buffer == null:
		return
	_pixel_image = Image.create_from_data(
		grid_width,
		grid_height,
		false,
		Image.FORMAT_RGBA8,
		_cell_buffer.to_rgba8_data(is_hidden_by_relationship()),
	)
	if _pixel_texture == null:
		_pixel_texture = ImageTexture.create_from_image(_pixel_image)
	else:
		_pixel_texture.update(_pixel_image)


func _apply_pixel_edits(edits: Array) -> void:
	if _pixel_image == null or _pixel_texture == null:
		_rebuild_pixel_image()
		return
	for edit_value: Variant in edits:
		var edit: Dictionary = edit_value
		var x: int = int(edit["x"])
		var y: int = int(edit["y"])
		var cell: Dictionary = _cell_buffer.get_cell(x, y)
		_set_image_cell(x, y, cell)
	_pixel_texture.update(_pixel_image)


func _set_image_cell(x: int, y: int, cell: Dictionary) -> void:
	if (
		_pixel_image == null
		or x < 0
		or x >= grid_width
		or y < 0
		or y >= grid_height
	):
		return
	_pixel_image.set_pixel(x, _image_y(y), _visible_cell_color(cell))


func _visible_cell_color(cell: Dictionary) -> Color:
	if cell.is_empty():
		return Color.TRANSPARENT
	var color_id := StringName(str(cell.get("color_id", "")))
	return (
		SurfaceDrawingPalette.get_color(color_id)
		if SurfaceDrawingPalette.has_color(color_id)
		else Color.TRANSPARENT
	)


func _image_y(cell_y: int) -> int:
	return grid_height - 1 - cell_y


func _sample_grid_vertices() -> Dictionary:
	var vertex_width: int = grid_width + 1
	var vertex_count: int = vertex_width * (grid_height + 1)
	var positions := PackedVector3Array()
	var normals := PackedVector3Array()
	positions.resize(vertex_count)
	normals.resize(vertex_count)
	var half_width: float = float(grid_width) * cell_size * 0.5
	var half_height: float = float(grid_height) * cell_size * 0.5
	var inverse_basis: Basis = global_basis.inverse()
	for y: int in range(grid_height + 1):
		var vertical: float = -half_height + float(y) * cell_size
		for x: int in range(grid_width + 1):
			var horizontal: float = -half_width + float(x) * cell_size
			var expected: Vector3 = (
				_surface_origin
				+ _surface_tangent * horizontal
				+ _surface_bitangent * vertical
			)
			var sampled: Dictionary = _sample_surface(expected)
			var index: int = y * vertex_width + x
			positions[index] = to_local(sampled["position"])
			normals[index] = (
				inverse_basis * (sampled["normal"] as Vector3)
			).normalized()
	return {"positions": positions, "normals": normals}


func _sample_position(
	samples: Dictionary,
	x: int,
	y: int,
	offset: float,
) -> Vector3:
	var index: int = y * (grid_width + 1) + x
	var positions: PackedVector3Array = samples["positions"]
	var normals: PackedVector3Array = samples["normals"]
	return positions[index] + normals[index] * offset


func _transform_from_samples(
	samples: Dictionary,
	x: int,
	y: int,
) -> Transform3D:
	var bottom_left: Vector3 = _sample_position(
		samples, x, y, _surface_offset()
	)
	var bottom_right: Vector3 = _sample_position(
		samples, x + 1, y, _surface_offset()
	)
	var top_left: Vector3 = _sample_position(
		samples, x, y + 1, _surface_offset()
	)
	var top_right: Vector3 = _sample_position(
		samples, x + 1, y + 1, _surface_offset()
	)
	var horizontal: Vector3 = (
		(bottom_right - bottom_left) + (top_right - top_left)
	) * 0.5
	var vertical: Vector3 = (
		(top_left - bottom_left) + (top_right - bottom_right)
	) * 0.5
	var normal: Vector3 = horizontal.cross(vertical).normalized()
	if horizontal.is_zero_approx() or vertical.is_zero_approx() or normal.is_zero_approx():
		return _sample_cell_transform(x, y, 1.0)
	var center: Vector3 = (
		bottom_left + bottom_right + top_left + top_right
	) * 0.25
	return Transform3D(Basis(horizontal, vertical, normal), center)


func _sample_cell_transform(
	x: int,
	y: int,
	fill: float = GUIDED_PIXEL_FILL,
) -> Transform3D:
	var expected: Vector3 = get_cell_world_position(x, y)
	var sampled: Dictionary = _sample_surface(expected)
	var point: Vector3 = sampled["position"]
	var normal: Vector3 = sampled["normal"]
	var tangent: Vector3 = (
		_surface_tangent - normal * _surface_tangent.dot(normal)
	).normalized()
	if tangent.is_zero_approx():
		tangent = normal.cross(Vector3.UP).normalized()
	if tangent.is_zero_approx():
		tangent = Vector3.RIGHT
	var bitangent: Vector3 = normal.cross(tangent).normalized()
	var pixel_size: float = cell_size * clampf(fill, 0.05, 1.0)
	var cell_basis := Basis(
		tangent * pixel_size,
		bitangent * pixel_size,
		normal,
	)
	return Transform3D(
		cell_basis,
		to_local(point + normal * _surface_offset()),
	)


func _sample_surface(expected: Vector3) -> Dictionary:
	var point: Vector3 = expected
	var normal: Vector3 = _surface_normal
	var world: World3D = get_world_3d()
	if world != null:
		var query := PhysicsRayQueryParameters3D.create(
			expected + _surface_normal * SURFACE_SAMPLE_DEPTH,
			expected - _surface_normal * SURFACE_SAMPLE_DEPTH,
			_solid_surface_mask,
		)
		query.collide_with_areas = false
		query.collide_with_bodies = true
		var hit: Dictionary = world.direct_space_state.intersect_ray(query)
		if (
			not hit.is_empty()
			and hit.get("collider") is StaticBody3D
		):
			var hit_normal: Vector3 = hit.get("normal", _surface_normal)
			if hit_normal.dot(_surface_normal) >= 0.35:
				var hit_position: Vector3 = hit.get("position", expected)
				point = hit_position
				normal = hit_normal.normalized()
	return {"position": point, "normal": normal}


func _surface_offset() -> float:
	return SURFACE_OFFSET + float(_layer) * LAYER_OFFSET_STEP


func _destroy_grid() -> void:
	if _grid_instance == null:
		return
	_grid_instance.queue_free()
	_grid_instance = null


func _refresh_grid_visibility() -> void:
	if _grid_instance != null:
		_grid_instance.visible = (
			_stencil_requested_visible
			and _guide_visible
			and not is_hidden_by_relationship()
		)


func _configure_render_distance() -> void:
	if _pixel_instance == null:
		return
	_pixel_instance.visibility_range_end = (
		FINALIZED_VISIBILITY_RANGE if _finalized else 0.0
	)
	_pixel_instance.visibility_range_end_margin = (
		FINALIZED_VISIBILITY_MARGIN if _finalized else 0.0
	)


func _participants_from_state(data: Dictionary) -> Array[String]:
	var result: Array[String] = []
	_append_participant(result, str(data.get("creator_fingerprint", "")))
	for value: Variant in data.get("participant_fingerprints", []):
		_append_participant(result, str(value))
	for cell_value: Variant in data.get("cells", []):
		var cell: Dictionary = cell_value
		_append_participant(
			result, str(cell.get("author_fingerprint", ""))
		)
	return result


func _participants_from_update(
	data: Dictionary,
	fallback: Array[String],
) -> Array[String]:
	var result: Array[String] = fallback.duplicate()
	for value: Variant in data.get("participant_fingerprints", []):
		_append_participant(result, str(value))
	for edit_value: Variant in data.get("edits", []):
		var edit: Dictionary = edit_value
		_append_participant(
			result, str(edit.get("author_fingerprint", ""))
		)
	return result


func _append_participant(result: Array[String], fingerprint: String) -> void:
	if (
		NetworkIdentityCrypto.valid_fingerprint(fingerprint)
		and fingerprint not in result
	):
		result.append(fingerprint)


func _cell_key(x: int, y: int) -> int:
	return y * grid_width + x