//
//  VROPhysicsMotionState.h
//  ViroRenderer
//
//  Copyright © 2017 Viro Media. All rights reserved.
//

#ifndef VROPhysicsMotionState_h
#define VROPhysicsMotionState_h

#include <btBulletDynamicsCommon.h>

/*
 VROPhysicsMotionState, when attached to a Bullet body, notifies or grabs
 transformation updates to/from a weakly referenced VROPhysicsBody.
 */
class VROPhysicsMotionState : public btMotionState {
public:
    std::weak_ptr<VROPhysicsBody> _w_physicsBody;
    VROPhysicsMotionState(std::shared_ptr<VROPhysicsBody> body, btTransform transformOffset) {
        _w_physicsBody = body;
        _physicsTransformOffset = transformOffset;
    }

    virtual ~VROPhysicsMotionState(){}

    void getWorldTransform(btTransform& centerOfMassWorldTrans) const {
        std::shared_ptr<VROPhysicsBody> body = _w_physicsBody.lock();
        if (!body) {
            return;
        }

        body->getWorldTransform(centerOfMassWorldTrans);
    }

    void setWorldTransform(const btTransform& centerOfMassWorldTrans) {
        std::shared_ptr<VROPhysicsBody> body = _w_physicsBody.lock();
        if (!body) {
            return;
        }

        body->setWorldTransform(centerOfMassWorldTrans);
    }

    btTransform getPhysicsTransformOffset(){
        return _physicsTransformOffset;
    }

private:
    /*
     The offset from Viro's geometric transform to Bullet's physicsBody transform (center of mass).
     */
    btTransform _physicsTransformOffset;
};
#endif