Orbit camera for VR Cardboard

I'm trying to make a 3rd person camera controller for using Google VR sdk, but i face a problem when moving camera to keep it looking at Player object

My scene structure like this:

--- Player

--- CameraContainer

------ MainCamera

How can i calculate the position of CameraContainer base on Rotation of MainCamera to keep Player object always between the center of camera

The problem same with bellow question but i need move CameraContainer base on rotation of MainCamera

https://forum.unity.com/threads/rotate-the-camera-around-the-object.47353/

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Update:

I'm using this script to move camera positon but it works with Mouse Input, any idea to convert it using MainCamera rotation?

 public class CameraFollow : MonoBehaviour {
 
     public Transform target;
     float distance = 10f;
     int cameraSpeed = 5;
     float xSpeed = 175f;
     float ySpeed = 75f;
     int yMinLimit = 20;
     int yMaxLimit = 80;
 
     int minDistance = 5;
     int maxDistance = 20;
 
     float x = 0f;
     float y = 0f;
 
 
 
     // Use this for initialization
     void Start () {
         var angles = transform.eulerAngles;
         x = angles.y;
         y = angles.x;
 
         // Make the rigid body not change rotation
         var rigidbody = GetComponent<Rigidbody>();
         if (rigidbody)
             rigidbody.freezeRotation = true;
     }
     
     // Update is called once per frame
     void LateUpdate () {
         
 
         //Zooming with mouse
         distance += Input.GetAxis("Mouse ScrollWheel") * distance;
         distance = Mathf.Clamp(distance, minDistance, maxDistance);
 
         //Detect mouse drag;
         if (Input.GetMouseButton(0))
         {
 
             x += Input.GetAxis("Mouse X") * xSpeed * 0.02f;
             y -= Input.GetAxis("Mouse Y") * ySpeed * 0.02f;
         }
         y = ClampAngle(y, yMinLimit, yMaxLimit);
 
         var rotation = Quaternion.Euler(y, x, 0);
         var position = rotation * new Vector3(0.0f, 0.0f, -distance) + target.position;
 
         transform.position = Vector3.Lerp(transform.position, position, cameraSpeed * Time.deltaTime);
         transform.rotation = rotation;
     }
 
     float ClampAngle(float angle, float min, float max)
     {
         if (angle < -360)
             angle += 360;
         if (angle > 360)
             angle -= 360;
         return Mathf.Clamp(angle, min, max);
     }
 }