using UnityEngine;
using System.Collections;
using System;

public class ServerTime : MonoBehaviour
{
	#region Unity Singleton
	private static ServerTime _instance;

	public static ServerTime Instance
	{
		get
		{
			if (_instance == null)
			{
				_instance = FindObjectOfType(typeof(ServerTime)) as ServerTime;
				if (_instance == null)
				{
					AVDebug.LogError(string.Format("No gameObject with {0} component exists. Make sure to create a gameObject with {0} component", new System.Diagnostics.StackFrame().GetMethod().DeclaringType));
				}
			}

			return _instance;
		}
	}

	void Awake()
	{
		if (_instance != null && _instance != this)
		{
			AVDebug.LogWarning(string.Format("{0} Instance already exists on another gameObject. Destroying this gameObject {1}", this.GetType().Name, gameObject.name));
			Destroy(gameObject);
			return;
		}

		_instance = this;
		DontDestroyOnLoad(gameObject);
	}
	#endregion

	/// <summary>
	/// Returns the server time as a Unix Time Stamp, i.e. current time in the number of seconds since the Unix Epoch (January 1 1970 00:00:00 GMT),
	/// through the onComplete action.
	/// If there was an error, -1 is returned through the onComplete action
	/// </summary>
	public void RetrieveServerTime(Action<long> onComplete)
	{
		AVDebug.Assert(onComplete != null, "onComplete must not be null when requesting server time");
		StartCoroutine(RetrieveServerTimeCoroutine(onComplete));
	}

	IEnumerator RetrieveServerTimeCoroutine(Action<long> onComplete)
	{
		WWW www = new WWW(GameConstants.SERVER_BASE_URL + "serverTime.php");
		yield return www;

		if (www.error != null)
		{
			onComplete(-1);
		} else
		{
			long serverTime;
			if (long.TryParse(www.text, out serverTime))
			{
				onComplete(serverTime);
			} else
			{
				onComplete(-1); //parse error
			}
		}
	}
}