/// <summary>
/// Provides a game object that automatically self terminates.
/// </summary>
[ExecuteInEditMode]
public class SelfTerminatingObject : MonoBehaviour
{
    /// <summary>
    /// Holds a reference to a callback that will be called just before termination.
    /// </summary>
    public Action Callback;

    /// <summary>
    /// Holds the time delay in seconds before object self terminates.
    /// </summary>
    public float Delay;

    /// <summary>
    /// Holds a time value used to determine whether it's time to self terminate.
    /// </summary>
    private DateTime lastTime;

    /// <summary>
    /// Called by Unity to update the object.
    /// </summary>
    public void Update()
    {
        this.PerformCheck();
    }

    /// <summary>
    /// Called by Unity to draw the object's GUI.
    /// </summary>
    public void OnGui()
    {
        this.PerformCheck();
    }

    /// <summary>
    /// Determines whether it's time to terminate.
    /// </summary>
    private void PerformCheck()
    {
        // check if specified time span has elapsed
        if (DateTime.Now > this.lastTime + TimeSpan.FromSeconds(this.Delay))
        {
            // run callback is specified
            if (this.Callback != null)
            {
                this.Callback();
            }

            // destroy object
#if UNITY_EDITOR
        DestroyImmediate(this.gameObject, true);
#else
            Destroy(this.gameObject);
#endif
        }
    }

    /// <summary>
    /// Creates a self terminating game object.
    /// </summary>
    /// <param name="callback">The method to be called before the object terminates.</param>
    /// <returns>Returns a reference to the game object that will self terminate.</returns>
    public static GameObject CreateUpdateCallback(Action callback)
    {
        return CreateUpdateCallback(callback, 0);
    }

    /// <summary>
    /// Creates a self terminating game object.
    /// </summary>
    /// <param name="callback">The method to be called before the object terminates.</param>
    /// <param name="delay">Specifies a delay value in seconds before the object will self terminate.</param>
    /// <returns>Returns a reference to the game object that will self terminate.</returns>
    public static GameObject CreateUpdateCallback(Action callback, float delay)
    {
        var obj = new GameObject();
        var com = obj.AddComponent<SelfTerminatingObject>();
        com.lastTime = DateTime.Now;
        com.Delay = delay;
        com.Callback = callback;

        return obj;
    }
}