#include "Entity.h"

void Entity::_UpdateChildTransform() const {
	for(auto& child : _children) {
		child->_localToWorld = _localToWorld * child->_transform;
		child->_worldToLocal = glm::inverse(child->_transform);

		child->_UpdateChildTransform();
	}
}

Entity::Entity(Entity* parent) : _localToWorld(1.0f), _worldToLocal(1.0f)
{
	_parent = parent;
	_transform = glm::mat4(1.0f);

	if (parent == nullptr)
		return;

	parent->AddChild(this);
	_localToWorld = _parent->_localToWorld;
	_worldToLocal = glm::inverse(_localToWorld);
}

Entity::~Entity() {
	_parent->RemoveChild(this);
}

void Entity::AddChild(Entity* entity) {
	_children.insert(entity);
}

void Entity::RemoveChild(Entity* entity) {
	_children.erase(entity);
}

void Entity::Transform(const glm::mat4& transform) {
	glm::mat4 transformLocalBasis = _worldToLocal * transform;
	
	_transform = transformLocalBasis * _transform;

	if (_parent == nullptr) {
		_localToWorld = _transform;
	}
	else {
		_localToWorld = _parent->LocalToWorld() * _transform;
	}

	_worldToLocal = glm::inverse(_localToWorld);
	_UpdateChildTransform();
}

void Entity::TransformLocal(const glm::mat4& transform)
{
	_transform = transform * _transform;

	if (_parent == nullptr) {
		_localToWorld = _transform;
	}
	else {
		_localToWorld = _parent->LocalToWorld() * _transform;
	}

	_worldToLocal = glm::inverse(_localToWorld);
	_UpdateChildTransform();
}

void Entity::SetTransform(const glm::mat4& transform) {
	_transform = transform;

	if (_parent != nullptr) {
		_localToWorld = transform * _parent->_localToWorld;
		_worldToLocal = glm::inverse(transform) * _parent->_worldToLocal;
	}
	else {
		_localToWorld = transform;
		_worldToLocal = glm::inverse(transform);
	}

	_UpdateChildTransform();
}