Louie AIBehaviour

using UnityEngine;
using System.Collections;

public class AIBehaviour : MonoBehaviour
{
    public enum AIState
    {
        Going, // going to nearest vacant building
        Waiting, // waiting for building to be vacant
        Inside, // inside building
        Exiting // finished occupying building and leaving
    };

    public AIState state;

    Transform buildingToGoTo;

    const float WAIT_DISTANCE = 1.0f;
    const float INSIDE_DISTANCE = 0.1f;

    const float WAIT_DURATION = 5;
    const float INSIDE_DURATION = 10;

    void Start()
    {
        SetState(AIState.Going);
    }

    void Update()
    {
        if (state == AIState.Going)
        {
            // go to building
            transform.position = Vector3.MoveTowards(transform.position, buildingToGoTo.position, 0.05f);

            float distanceToBuilding = Vector3.Distance(transform.position, buildingToGoTo.position);

            if (buildingToGoTo.tag == "OccupiedBuilding" && distanceToBuilding <= WAIT_DISTANCE)
            {
                // someone got there ahead of us
                SetState(AIState.Waiting);
            }
            // check if inside already
            else if (buildingToGoTo.tag == "VacantBuilding" && distanceToBuilding <= INSIDE_DISTANCE)
            {
                // mark it as occupied so others won't go here
                buildingToGoTo.tag = "OccupiedBuilding";

                SetState(AIState.Inside);
            }
        }
        else if (state == AIState.Exiting)
        {
            // add code to move to left side
            Destroy(gameObject);
        }
    }

    void SetState(AIState s)
    {
        if (s == AIState.Going)
        {
            buildingToGoTo = FindClosestBuilding().transform;
        }
        else if (s == AIState.Inside)
        {
            // call FinishedInside() after 10 secs
            Invoke("FinishedInside", INSIDE_DURATION);
        }
        else if (s == AIState.Waiting)
        {
            // call FinishedWaiting() after 5 secs
            Invoke("FinishedWaiting", WAIT_DURATION);
        }
        state = s;
    }

    void FinishedInside()
    {
        buildingToGoTo.tag = "VacantBuilding";
        SetState(AIState.Exiting);
    }

    void FinishedWaiting()
    {
        SetState(AIState.Going);
    }

    GameObject FindClosestBuilding()
    {
        GameObject[] gos;
        gos = GameObject.FindGameObjectsWithTag("VacantBuilding");
        GameObject closest = null;
        float distance = Mathf.Infinity;
        Vector3 position = transform.position;
        foreach (GameObject go in gos)
        {
            Vector3 diff = go.transform.position - position;
            float curDistance = diff.sqrMagnitude;
            if (curDistance < distance)
            {
                closest = go;
                distance = curDistance;
            }
        }
        return closest;
    }
}