void Update(){
Vector3 difference = Camera.main.ScreenToWorldPoint(Input.mousePosition) - transform.position; // subtracting the position of the player from the mouse mous position
difference.Normalize(); // normalizing the vector. meaning that all the sum of the vector will be equal to 1
float rotZ = Mathf.Atan2(difference.y, difference.x) * Mathf.Rad2Deg; //find the angle in degrees
transform.rotation = Quaternion.Euler(0f, 0f, rotZ );

 }

void Update(){

   transform.Rotate(0, 0, -3.0f);

   }

private int direction = 1;

void Update(){
  if(transform.rotation.z == 0 || transform.rotation.z == 180){
    direction = -direction;
  }
  transform.Rotate(0,0,-3f*direction);
}

public class Turret {

[SerializeField] private float _minEulerRotation;
[SerializeField] private float _maxEulerRotation;

[SerializeField] private float _rotationAmount;

private CoolDown _coolDown;

void Start(){

    this._rotationAmount *= Time.fixedDeltaTime;

    this.StartCoroutine(this.RotationProcess());

}

private IEnumerator RotationProcess()
{
    while (true)
    {
        yield return this.StartCoroutine(this.RotateToMin());
        yield return this.StartCoroutine(this.RotateToMax());
    }
}

private IEnumerator RotateToMin()
{
    while(transform.rotation.eulerAngles."Axis you need" > this._minEulerRotation){

        transform.Rotate("Your vector3" * this._rotationAmount);

        if(this._coolDown.IsActive)
        {
            yield return this._coolDown.Delay;
        }

        yield return null;
    }

    transform.rotation = Quaternion.Euler("Your vector3" * this._minEulerRotation);
}

private IEnumerator RotateToMax()
{
    while(transform.rotation.eulerAngles."Axis you need" < this._maxEulerRotation){

        transform.Rotate("Your vector3" * this._rotationAmount);

        if(this._coolDown.IsActive)
        {
            yield return this._coolDown.Delay;
        }

        yield return null;
    }

    transform.rotation = Quaternion.Euler("Your vector3" * this._maxEulerRotation);
}

public void Shoot()
{
    ...... some cooldown stuff
    this._coolDown.StartCountdown();
}
}