using UnityEngine;
using System.Collections;

public class GUIScript : MonoBehaviour
{

    public void OnGUI ()
    {
        // call the method to draw the FPS label
        XGUI.xLabelFPS (3);
    }

    public void FixedUpdate ()
    {
        // increment the time that has passed with the fixedDeltaTime
        XGUI.timePassed++;
    }

}

/// <summary>
/// Class for storing some stuffz we need
/// </summary>
public abstract class XGUIAbstract {


    private static float? _fixedDeltaTime;
        /// <summary>
    /// interval at which the FixedUpdate method is called
    /// </summary>
    protected static float fixedDeltaTime
    {
        get { if(!_fixedDeltaTime.HasValue) _fixedDeltaTime = Time.fixedDeltaTime;
            return (float)_fixedDeltaTime; }
    }



    private static float _timePassed = 0;
        /// <summary>
    /// How much time has passed since last FPS display
    /// </summary>
    public static float timePassed {
        get { return _timePassed; }
        set { _timePassed = value == 0 ? 0 : _timePassed+fixedDeltaTime; }
    }

    /// <summary>
    /// Store the FPS of last update
    /// </summary>
    protected static float framesPerSecond = 0;

    /// <summary>
    /// Store how many frames have passed since last FPS update
    /// </summary>
    protected static int framesPassed = 0;

}

public class XGUI : XGUIAbstract
{

    /// <summary>
    /// stores how many seconds needs to pass for FPS update
    /// </summary>
    private static float _interval;

    private XGUI() {

    }

    public static void xLabelFPS ()
    {
        xLabelFPS(1);
    }

    public static void xLabelFPS (float interval )
    {
        _interval = interval;
        string fps = XGUI.calculateFPS ();
        GUI.Label (new Rect (0, 0, 100, 50), fps);
    }

    /// <summary>
    /// Calculate the FPS
    /// </summary>
    /// <returns>String of FPS</returns>
    protected static string calculateFPS ()
    {
        if (timePassed >= _interval) {
            float FPS = (Time.frameCount - framesPassed) / timePassed;

            framesPassed = Time.frameCount;
            framesPerSecond = FPS;
            timePassed = 0;
        }
        return framesPerSecond.ToString ();
    }
}