using UnityEngine;
using System.Collections;

public class LoadingScreen : MonoBehaviour {
	Texture2D emptyProgressBar,
		fullProgressBar; 
	float emptyLoadingBarWidth,
		emptyLoadingBarHeight;

	static string levelName; 

	float fullLoadingBarWidth,fullLoadingBarHeight,
		fullLoadingBarMarginMultiplier;
	float marginFromBottom,
		fullToEmptyMultiplier;

	AsyncOperation async;

	public static void StartLoading(string nextlevelName){
		Application.LoadLevel ("LoadingScreen");
		levelName = nextlevelName;
	}

	void Start(){
		//set default parameter variables
		fullProgressBar = Texture2D.whiteTexture;
		emptyProgressBar = Texture2D.blackTexture;

		emptyLoadingBarWidth = 300;
		emptyLoadingBarHeight = 40;

		marginFromBottom = 10;
		fullToEmptyMultiplier = .7f;

		//setup Full Loading Bar using the Empty Loading Bar
		fullLoadingBarWidth = emptyLoadingBarWidth * fullToEmptyMultiplier;
		fullLoadingBarHeight = emptyLoadingBarHeight * fullToEmptyMultiplier;
		fullLoadingBarMarginMultiplier = (1-fullToEmptyMultiplier)/2;

		//set up aSyncTask
		StartCoroutine ("load");
	}
	
	IEnumerator load() {
		Debug.LogWarning("ASYNC LOAD STARTED - " +
		                 "DO NOT EXIT PLAY MODE UNTIL SCENE LOADS... UNITY WILL CRASH");
		async = Application.LoadLevelAsync(levelName);
		async.allowSceneActivation = false;
		yield return async;
	}

	void OnGUI() {
		
		GUI.DrawTexture(new Rect(centerX(emptyLoadingBarWidth) , 
		                         bottomY (emptyLoadingBarHeight) , 
		                         emptyLoadingBarWidth, 
		                         emptyLoadingBarHeight), 
		                emptyProgressBar);

		if (async != null) {
			//Debug.Log("Loading Progress: "+async.progress);

			if(async.progress <.9f){//Due to some stupid Unity thing, .9 = completed
				drawLoadingBar(async.progress);
			}else{
				float continueBtnWidth = 75;
				float continueBtnHeight = 25;
				if(GUI.Button(new Rect(centerX(continueBtnWidth) , 
				                       bottomY (emptyLoadingBarHeight) - emptyLoadingBarHeight, 
				                       continueBtnWidth, 
				                       continueBtnHeight), 
						"Continue")){
					Debug.Log("Leaving Loading Screen");
					async.allowSceneActivation = true;
				}
				drawLoadingBar(1);
			}
		}
	}

	void drawLoadingBar(float currentProgress){
        //not displaying for some reason
		GUI.DrawTexture(new Rect(centerX(emptyLoadingBarWidth), 
		                         bottomY (emptyLoadingBarHeight), 
		                         emptyLoadingBarWidth * currentProgress, 
		                         emptyLoadingBarHeight), 
		                emptyProgressBar);	
        
		GUI.DrawTexture(new Rect(centerX(fullLoadingBarWidth), 
		                         bottomY (fullLoadingBarHeight) - fullLoadingBarMarginMultiplier * emptyLoadingBarHeight, 
		                         fullLoadingBarWidth * currentProgress, 
		                         fullLoadingBarHeight), 
		                fullProgressBar);	
	}
	
	float centerX(float item_width){
		return Screen.width / 2 - item_width / 2;
	}
	float bottomY(float item_height){
		return Screen.height - item_height - marginFromBottom;
	}
}