Rolling a cube

using System.Collections;
using UnityEngine;

public class PlayerController : MonoBehaviour {
    [SerializeField] private float _rollSpeed = 5;
    private bool _isMoving;

    private void Update() {
        if (_isMoving) return;

        if (Input.GetKey(KeyCode.A)) Assemble(Vector3.left);
        else if (Input.GetKey(KeyCode.D)) Assemble(Vector3.right);
        else if (Input.GetKey(KeyCode.W)) Assemble(Vector3.forward);
        else if (Input.GetKey(KeyCode.S)) Assemble(Vector3.back);

        void Assemble(Vector3 dir) {
            var anchor = transform.position + (Vector3.down + dir) * 0.5f;
            var axis = Vector3.Cross(Vector3.up, dir);
            StartCoroutine(Roll(anchor, axis));
        }
    }

    private IEnumerator Roll(Vector3 anchor, Vector3 axis) {
        _isMoving = true;
        for (var i = 0; i < 90 / _rollSpeed; i++) {
            transform.RotateAround(anchor, axis, _rollSpeed);
            yield return new WaitForSeconds(0.01f);
        }
        _isMoving = false;
    }
}