cpu version of tank controller script

I am wanting to add bots to my tank battle game, how hard would it be to convert my player tank controller into an cpu tank controller that drives around on it's own?

 private var controller: CharacterController;
  var speed: float = 6.0;
  var turnSpeed: float = 90;
  function Start(){
  
      controller = GetComponent(CharacterController);
  }
  
  function Update(){
  
      var movDir: Vector3;
  
      transform.Rotate(0,Input.GetAxis("Horizontal1")*turnSpeed*Time.deltaTime,0);
      movDir = transform.forward*Input.GetAxis("Vertical1")*speed;
      // moves the character in horizontal direction
      controller.Move(movDir*Time.deltaTime-Vector3.up*0.1);    
  }