Problems with enemy attack script!

I'm trying to make an enemy attack script but keep failing. No methods work, I've tried invokeRepeating, but that wont work properly because I need to be checked constantly, just normal Time.deltaTime doesnt work because it just subtracts 1 every whatever, and I've tried Corountine and waitForSeconds thing, still doesn't work, here is what I have, and the problem with this is that it subtracts all health in like 1 second, instead of subracting a certain amount of health every couple seconds. AND the OnTriggerStay doesnt work either, it suppose to do attack fun the player enters a range. #pragma strict

 var enemyDamage : int;
 var enemyAttackSpeed : float;
 var attackState : boolean = false;
 var Player : GameObject;
 
 function Start () {
 Player = GameObject.FindGameObjectWithTag("Player");
 StartCoroutine("DamagePlayer");
 
 }
 
 function Update () {
     if(attackState == true){
         DamagePlayer();
     }
 }
 
 function OnTrggerStay (other : Collider){
     if(other.gameObject.name == "Player"){
         attackState = true;
     }
 }
 
 function DamagePlayer () {
     do{
         Player.GetComponent(Stats).curHealth -= enemyDamage;
         yield WaitForSeconds(enemyAttackSpeed);
     }while (attackState == true);
 }