Waypoint system: loop and back-forth operations

Well, i am still improving my waypoint system, now i made a script to hold all waypoints as a Vector3 array, and a script in the object that i want to follow the path. All is working fine when i make my object loop trough the waypoints, like this:

 0 -> 1 -> 2
 0 <------ 2

But now i want to the object to follow the waypoint path backwards, then forward again (patrol style), like this:

 0 -> 1 -> 2
 0 <- 1 <- 2

Here's my waypoint script, wich is attached to a gameobject. This script is used to obtain the waypoints and display some graphical stuff in the editor:

     Waypoint.js
 
 @script ExecuteInEditMode()
 #if (UNITY_EDITOR)
 var waypoints : Vector3[];
 @HideInInspector
 var length : int;
 function OnDrawGizmos () {
     for (a = 0; a <= waypoints.length-1; a++) {
         if (a == waypoints.length-1) {
             Gizmos.color = Color.red;
             Gizmos.DrawLine(transform.position + waypoints[a],transform.position + waypoints[0]);
         }else{
             Gizmos.color = Color.yellow;
             Gizmos.DrawLine(transform.position + waypoints[a],transform.position + waypoints[a+1]);
         }
         Gizmos.color = Color.blue;
         Gizmos.DrawSphere(transform.position + waypoints[a], 0.2);
     }
 }
 #endif
 function GetWaypoint(w : int) : Vector3{
     return transform.position + waypoints[w];
 }
 function Update() {
     length = waypoints.Length;
 }

And this is my navigation script, wich handles the position of the object wich it is attached:

     AnimatePosition.js
 var waypoints : Waypoint;
 var speed : float;
 var loop : boolean = false;
 private var direction : boolean = false;
 private var time : float;
 private var state : int = 0;
 function Start () {
     time = Time.time;
 }
 function Update () {
     if (state == waypoints.length) {
         if (loop == true) {
             state = 0;
         }else{
             direction = true;
         }
     }
     if (state == 0 && direction == true) {
         direction = false;
     }
     Debug.Log(direction);
     transform.position = Vector3.Lerp(transform.position, waypoints.GetWaypoint(state), (Time.time - time)*speed);
     if (Mathf.Round(transform.position.x * 100) / 100 == Mathf.Round(waypoints.GetWaypoint(state).x * 100) / 100 && Mathf.Round(transform.position.y * 100) / 100 == Mathf.Round(waypoints.GetWaypoint(state).y * 100) / 100 && Mathf.Round(transform.position.z * 100) / 100 == Mathf.Round(waypoints.GetWaypoint(state).z * 100) / 100) {
         if (direction == false) {
             state++;
         }else if (direction == true){
             state = state-1;
         }
         time = Time.time;
         Debug.Log(state);
     }
 }

This code works fine with the "Loop" option selected (`private var loop : boolean`), but when i deselect it (to the back-and-forth operation) it starts erroring out about the array index being out of range. Probably, like my other questions, it will be a stupidly trivial error i can't notice.