@tool
class_name BoneFlipper
extends SkeletonModifier3D

@export var flip: bool = false

@export_enum(" ") var _bones_to_flip: Array[String] = []
@export var _flip_all_bones: bool = true
@export_enum(" ") var _bones_to_exclude: Array[String] = []
@export var _bone_prefixes_to_exclude: Array[String] = []

var _skeleton: Skeleton3D


func _validate_property(property: Dictionary) -> void:
	if property.name in ["_bones_to_flip", "_bones_to_exclude"]:
		if _skeleton:
			property.hint = PROPERTY_HINT_TYPE_STRING
			property.hint_string = (
				"%d/%d:%s"
				% [
					TYPE_STRING,
					PROPERTY_HINT_ENUM,
					_skeleton.get_concatenated_bone_names()
				]
			)


func _ready() -> void:
	_skeleton = get_skeleton()
	assert(_skeleton, str(self) + ": _skeleton missing!")

	for bone_name in _bones_to_flip:
		var bone_idx := _skeleton.find_bone(bone_name)
		assert(bone_idx != -1, str(self) + ": bone " + bone_name + " missing!")
	for bone_name in _bones_to_exclude:
		var bone_idx := _skeleton.find_bone(bone_name)
		assert(bone_idx != -1, str(self) + ": bone " + bone_name + " missing!")


func _process_modification() -> void:
	if !_skeleton:
		return

	if !flip:
		for bone_idx in range(_skeleton.get_bone_count()):
			_skeleton.set_bone_pose(bone_idx, _skeleton.get_bone_pose(bone_idx))
		return

	if _flip_all_bones:
		for bone_idx in range(_skeleton.get_bone_count()):
			_flip_bone_if_not_excluded(bone_idx)
	else:
		for bone_name in _bones_to_flip:
			var bone_idx := _skeleton.find_bone(bone_name)
			if bone_idx == -1:
				continue
			_flip_bone(bone_idx, bone_name)


func _flip_bone_if_not_excluded(bone_idx: int) -> void:
	var bone_name := _skeleton.get_bone_name(bone_idx)
	if bone_name in _bones_to_exclude:
		return
	for bone_prefix in _bone_prefixes_to_exclude:
		if bone_prefix and bone_name.begins_with(bone_prefix):
			return
	_flip_bone(bone_idx, bone_name)


func _flip_bone(bone_idx: int, bone_name: String) -> void:
	var pose: Transform3D = _skeleton.get_bone_pose(bone_idx)

	if bone_name.ends_with("_R") or (bone_name.ends_with("_L") and !_flip_all_bones):
		var other_side_bone_name: String = (
			bone_name.replace("_R", "_L")
			if bone_name.ends_with("_R")
			else bone_name.replace("_L", "_R")
		)
		var other_side_bone_idx := _skeleton.find_bone(other_side_bone_name)
		if other_side_bone_idx == -1:
			return
		var other_side_pose: Transform3D = _skeleton.get_bone_pose(other_side_bone_idx)
		_mirror_bone_transform(bone_idx, other_side_pose)
		_mirror_bone_transform(other_side_bone_idx, pose)
	elif !bone_name.ends_with("_R") and !bone_name.ends_with("_L"):
		_mirror_bone_transform(bone_idx, pose)


func _mirror_bone_transform(bone_idx: int, pose: Transform3D) -> void:
	pose.origin.x = -pose.origin.x
	var pose_rot := pose.basis.get_euler()
	var pose_scale := pose.basis.get_scale()
	pose_rot.y = -pose_rot.y
	pose_rot.z = -pose_rot.z
	pose.basis = Basis.from_euler(pose_rot)
	pose.basis = pose.basis.scaled(pose_scale)
	_skeleton.set_bone_pose(bone_idx, pose)