class_name NodeUtils
extends RefCounted
## Static utility methods for node tree traversal.


static func find_child_of_type(node: Node, type_name: String) -> Node:
	if node.get_class() == type_name:
		return node
	for child: Node in node.get_children():
		var found := find_child_of_type(child, type_name)
		if found != null:
			return found
	return null


static func find_first_mesh_with_blendshapes(
	node: Node,
) -> MeshInstance3D:
	if node is MeshInstance3D:
		var mi: MeshInstance3D = node as MeshInstance3D
		if mi.mesh != null and mi.mesh.get_blend_shape_count() > 0:
			return mi
	for child: Node in node.get_children():
		var found := find_first_mesh_with_blendshapes(child)
		if found != null:
			return found
	return null


static func find_blend_shape_index(mesh: MeshInstance3D, shape_name: String) -> int:
	if mesh == null or mesh.mesh == null:
		return -1
	for i: int in range(mesh.mesh.get_blend_shape_count()):
		if mesh.mesh.get_blend_shape_name(i) == shape_name:
			return i
	return -1


static func find_bone_case_insensitive(skeleton: Skeleton3D, bone_name: String) -> int:
	var idx := skeleton.find_bone(bone_name)
	if idx == -1:
		idx = skeleton.find_bone(bone_name.to_lower())
	if idx == -1:
		idx = skeleton.find_bone(bone_name.to_upper())
	return idx


static func read_vrm_morph_names(vrm_path: String) -> PackedStringArray:
	## Reads original morph target names from a .vrm (GLB) file's JSON chunk.
	## VRM4Godot renames blendshapes to morph_N during import, but the
	## original names (e.g. Japanese MMD names) are preserved in
	## mesh.primitives[].extras.targetNames inside the GLB JSON.
	var f := FileAccess.open(vrm_path, FileAccess.READ)
	if f == null:
		return PackedStringArray()

	# GLB header: magic(4) + version(4) + length(4)
	f.get_32()
	f.get_32()
	f.get_32()

	# First chunk: length(4) + type(4) + JSON data
	var chunk_length := f.get_32()
	f.get_32()
	var json_bytes := f.get_buffer(chunk_length)
	f.close()

	var json := JSON.new()
	if json.parse(json_bytes.get_string_from_utf8()) != OK:
		return PackedStringArray()

	var data: Dictionary = json.data
	var meshes: Array = data.get("meshes", [])
	for mesh_data: Variant in meshes:
		var primitives: Array = mesh_data.get("primitives", [])
		for prim: Variant in primitives:
			var extras: Dictionary = prim.get("extras", {})
			var target_names: Array = extras.get("targetNames", [])
			if target_names.size() > 0:
				var result := PackedStringArray()
				for n: Variant in target_names:
					result.append(str(n))
				return result

	return PackedStringArray()