how to make my ai have animations without a user input

im trying to make an ai play an animation when he walks in a certain direction. for example when he walks left he plays the walk animation. and when he stops he stays facing left. right now i can only seem to get it to work when i give the input like the ai is a player. here is my script as of right now

public class EnemyMovement : MonoBehaviour {

public Transform player;
public float speed;
public float maxDistance;
public float minDistance;
public Vector2 lastMove;
public string startPoint;
public float attackTime;
public bool canMove;

private float moveX;
private float moveY;
private bool attacking;
private Animator anim;
private bool enemyMoving;
private Rigidbody2D myRigidbody;
private static bool enemyExists;
private float currentMoveSpeed;
private float attackTimeCounter;
private Vector2 moveInput;

void Start()
    player = GameObject.FindGameObjectWithTag("Player").transform;
    anim = GetComponent<Animator>();
    myRigidbody = GetComponent<Rigidbody2D>();
    canMove = true;
    lastMove = new Vector2(0, -1f);

    if (!enemyExists)
        enemyExists = true;

void Update()

    if (Time.timeScale == 0f)
    enemyMoving = false;

    moveInput = new Vector2(Input.GetAxis("Horizontal"), Input.GetAxis("Vertical")).normalized;
    if (moveInput !=
        if ((Vector2.Distance(transform.position, player.position) < maxDistance)
&& (Vector2.Distance(transform.position, player.position) > minDistance))
            transform.position = Vector2.MoveTowards(transform.position, player.position, speed * Time.deltaTime);
        enemyMoving = true;
        lastMove = moveInput;

    anim.SetFloat("MoveX", Input.GetAxis("Horizontal"));
    anim.SetFloat("MoveY", Input.GetAxis("Vertical"));
    anim.SetBool("EnemyMoving", enemyMoving);
    anim.SetFloat("LastMoveX", lastMove.x);
    anim.SetFloat("LastMoveY", lastMove.y);


Rather that setting your animator variables (“MoveX” or “MoveY” etc) from player input, you can set them based on which direction the enemy is moving, and leave player input out of it.
What you will want to do, though, is to cause the enemy to move without player input as well, I assume. Then, you can use its movement values to set anim floats.

Check out the mecanim overview Unity - Manual: Mecanim Animation System
You may also want to learn more about moving objects with code. It can be very similar to what you have set up, but you need to decide how you want the enemy to move, then set up your own vectors to make it happen, instead of using player input.