Unity Borders Watcher

using System.Collections;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;

public class BordersWatcher : MonoBehaviour {


    private int maxLastValidPositionsCount = 5;
    private float minDistanceBetweenPositions = 4.0f;


    private CharacterController charController;
    private bool isGrounded { get { return charController.isGrounded; } }
    private Vector3 spawnPos;
    private List<Vector3> lastValidPositions;
    private Vector3? _teleportedFrom;

    // Use this for initialization
    void Start () {
        spawnPos = transform.position;
        charController = GetComponent<CharacterController>();
        lastValidPositions = new List<Vector3>();
        InvokeRepeating("ValidateFloor", 5.0f, 1.0f);
    }

    // Update is called once per frame
    void Update () {
        if (isOutOfMap())
        {
            TeleportBack();
        }
    }

    bool isOutOfMap()
    {
        return transform.position.y < -50;
    }

    void ValidateFloor()
    {
        if (isGrounded)
        {
            while (lastValidPositions.Count >= maxLastValidPositionsCount)
                lastValidPositions.RemoveAt(0);

            if (lastValidPositions.Count > 0 || _teleportedFrom.HasValue)
            {
                Vector3 lastPos = _teleportedFrom ?? lastValidPositions.Last();
                if (Vector3.Distance(lastPos, transform.position) < minDistanceBetweenPositions)
                    return;
            }
            lastValidPositions.Add(transform.position);
            _teleportedFrom = null;
        }
    }

    void TeleportBack()
    {
        Vector3 targetPos = spawnPos;
        if (lastValidPositions.Count > 0)
        {
            targetPos = lastValidPositions.Last();
            lastValidPositions.Remove(targetPos);
        }
        transform.position = targetPos + new Vector3(0,0.01f);
        _teleportedFrom = targetPos;
    }

}