enemy attacking

Unity Engine
1

I know this is probally simple, but how can I make the enemy AI stop x amount of distance in front of the player when attacking?

using UnityEngine;
using System.Collections;

public class ZombieAI : MonoBehaviour 
{	
	HealthBarGUI healthbargui;
	
	public Transform player;

	public float moveSpeed;
	private float damping = 6;

	//1 = 0 degrees
	//0 = 90 degrees
	//-1 = 180 degrees
	private float angle = 0;
	
	public float fov; //field of vision
	
	public float attackTime;
	public float coolDown;
	public float attackDistance = 10;
	
	void  Start()
	{
		attackTime = 0;
		coolDown = 1.0f;
	}
	
	void  Update ()
	{
		Vector3 direction = player.position - transform.position;
		
		//wander state
		if (direction.sqrMagnitude > fov  
			Vector3.Dot(direction.normalized, transform.forward) < angle)
		{
			Idle();
		}
		
		//attack state
		if(direction.sqrMagnitude < fov  
			Vector3.Dot(direction.normalized, transform.forward) > angle)
		{
			Attack();
		}	
		
		if(attackTime > 0)
			attackTime -= Time.deltaTime;
		if(attackTime < 0)
			attackTime = 0;
		if(attackTime == 0)
		{
			ApplyDamage();
			attackTime = coolDown;
		}	
	}
	
	void Idle()
	{
		renderer.material.color = Color.green;
	}
	
	void Alerted()
	{	
		renderer.material.color = Color.yellow;
	}
	
	void Attack()
	{
		Quaternion rotation = Quaternion.LookRotation(player.position - transform.position);
		transform.rotation = Quaternion.Slerp(transform.rotation, rotation, Time.deltaTime * damping);
		transform.Translate(Vector3.forward * moveSpeed * Time.deltaTime);
		renderer.material.color = Color.red;
	}
	
	void ApplyDamage()
	{
		float distance = Vector3.Distance(player.transform.position, transform.position);
		
		Vector3 dir = (player.transform.position - transform.position).normalized;
		float direction = Vector3.Dot(dir, transform.forward);
		
		if(distance < 2.5f)
		{
			if(direction > 0)
			{
				HealthBarGUI healthbar = (HealthBarGUI)player.GetComponent("HealthBarGUI");
				healthbar.updateHealth(-10);
			}
		}	
	}
}
2

Basically, you want to add a close condition to this condition:

        if(direction.sqrMagnitude < fov  direction.sqrMagnitude> closeDistance*closeDistance 

            Vector3.Dot(direction.normalized, transform.forward) > angle)

        {

            Attack();

        }