using UnityEngine;
using System.Collections;
using System.IO;

using UnityEngine.UI;
using UnityEngine.EventSystems;
using UnityEngine.Events;

public class UICreator : MonoBehaviour 
{
	
	private const int LayerUI = 5;
	
	void Start () 
	{
		CreateUI();
	}
	
	void Update () 
	{
	}
	
	
	private void CreateUI() 
	{
		
		GameObject canvas = CreateCanvas(this.transform);
		
		CreateEventSystem(canvas.transform);
		
		GameObject panel = CreatePanel(canvas.transform);
		
		CreateText(panel.transform, 0, 100, 160, 50, "Message", 32);
		CreateText(panel.transform, 0, 0, 160, 50, "Are you sure, you want to exit?", 24);
		
		CreateButton(panel.transform, -100, -100, 160, 50, "Yes", delegate {OnExit();});
		CreateButton(panel.transform, 100, -100, 160, 50, "No", delegate {OnCancel();});
	}
	
	private GameObject CreateCanvas(Transform parent) 
	{
		// create the canvas
		GameObject canvasObject = new GameObject("Canvas");
		canvasObject.layer = LayerUI;
		
		/*RectTransform canvasTrans = */canvasObject.AddComponent<RectTransform>();
		
		Canvas canvas = canvasObject.AddComponent<Canvas>();
		canvas.renderMode = RenderMode.ScreenSpaceOverlay;
		canvas.pixelPerfect = true;
		
		CanvasScaler canvasScal = canvasObject.AddComponent<CanvasScaler>();
		canvasScal.uiScaleMode = CanvasScaler.ScaleMode.ScaleWithScreenSize;
		canvasScal.referenceResolution = new Vector2(800, 600);
		
		/*GraphicRaycaster canvasRayc = */canvasObject.AddComponent<GraphicRaycaster>();
		
		canvasObject.transform.SetParent(parent);
		
		return canvasObject;
	}
	
	private GameObject CreateEventSystem(Transform parent) 
	{
		GameObject esObject = new GameObject("EventSystem");
		
		EventSystem esClass = esObject.AddComponent<EventSystem>();
		esClass.sendNavigationEvents = true;
		esClass.pixelDragThreshold = 5;
		
		StandaloneInputModule stdInput = esObject.AddComponent<StandaloneInputModule>();
		stdInput.horizontalAxis = "Horizontal";
		stdInput.verticalAxis = "Vertical";
		
		/*TouchInputModule touchInput = */esObject.AddComponent<TouchInputModule>();
		
		esObject.transform.SetParent(parent);
		
		return esObject;
	}
	
	private GameObject CreatePanel(Transform parent) 
	{
		GameObject panelObject = new GameObject("Panel");
		panelObject.transform.SetParent(parent);
		
		panelObject.layer = LayerUI;
		
		RectTransform trans = panelObject.AddComponent<RectTransform>();
		trans.anchorMin = new Vector2(0, 0);
		trans.anchorMax = new Vector2(1, 1);
		trans.anchoredPosition3D = new Vector3(0, 0, 0);
		trans.anchoredPosition = new Vector2(0, 0);
		trans.offsetMin = new Vector2(0, 0);
		trans.offsetMax = new Vector2(0, 0);
		trans.localPosition = new Vector3(0, 0, 0);
		trans.sizeDelta = new Vector2(0, 0);
		trans.localScale = new Vector3(0.8f, 0.8f, 1.0f);
		
		/*CanvasRenderer renderer = */panelObject.AddComponent<CanvasRenderer>();

#if USE_IMAGE
		Image image = panelObject.AddComponent<Image>();
		Texture2D tex = Resources.Load<Texture2D>("panel_bkg");
		image.sprite = Sprite.Create(tex, new Rect(0, 0, tex.width, tex.height), 
        										new Vector2(0.5f, 0.5f));
#else
		panelObject.AddComponent<Image>();
#endif
		return panelObject;
	}
	
	private GameObject CreateText(Transform parent, float x, float y,
	                              float w, float h, string message, int fontSize) 
	{
		GameObject textObject = new GameObject("Text");
		textObject.transform.SetParent(parent);
		
		textObject.layer = LayerUI;
		
		RectTransform trans = textObject.AddComponent<RectTransform>();
		trans.sizeDelta.Set(w, h);
		trans.anchoredPosition3D = new Vector3(0, 0, 0);
		trans.anchoredPosition = new Vector2(x, y);
		trans.localScale = new Vector3(1.0f, 1.0f, 1.0f);
		trans.localPosition.Set(0, 0, 0);
		
		/*CanvasRenderer renderer =*/textObject.AddComponent<CanvasRenderer>();
		
		Text text = textObject.AddComponent<Text>();
		text.supportRichText = true;
		text.text = message;
		text.fontSize = fontSize;
		text.font = Resources.GetBuiltinResource(typeof(Font), "Arial.ttf") as Font;
		text.alignment = TextAnchor.MiddleCenter;
		text.horizontalOverflow = HorizontalWrapMode.Overflow;
		text.color = new Color(0, 0, 1);
		
		return textObject;
	}
	
	private GameObject CreateButton(Transform parent, float x, float y,
	                                float w, float h, string message,
	                                UnityAction eventListner) 
	{
		GameObject buttonObject = new GameObject("Button");
		buttonObject.transform.SetParent(parent);
		
		buttonObject.layer = LayerUI;
		
		RectTransform trans = buttonObject.AddComponent<RectTransform>();
		SetSize(trans, new Vector2(w, h));
		trans.anchoredPosition3D = new Vector3(0, 0, 0);
		trans.anchoredPosition = new Vector2(x, y);
		trans.localScale = new Vector3(1.0f, 1.0f, 1.0f);
		trans.localPosition.Set(0, 0, 0);
		
		/*CanvasRenderer renderer = */buttonObject.AddComponent<CanvasRenderer>();
		
		Image image = buttonObject.AddComponent<Image>();
#if USE_IMAGE		
		Texture2D tex = Resources.Load<Texture2D>("button_bkg");
		image.sprite = Sprite.Create(tex, new Rect(0, 0, tex.width, tex.height),
		                             new Vector2(0.5f, 0.5f));
#else
		image.color = new Color(.3f, .3f, .1f, .5f);
#endif		
		Button button = buttonObject.AddComponent<Button>();
		button.interactable = true;
		button.onClick.AddListener(eventListner);
		
		/*GameObject textObject = */CreateText(buttonObject.transform, 0, 0, 0, 0, message, 24);
		
		return buttonObject;
	}
	
	private static void SetSize(RectTransform trans, Vector2 size) 
	{
		Vector2 currSize = trans.rect.size;
		Vector2 sizeDiff = size - currSize;
		trans.offsetMin = trans.offsetMin -
			new Vector2(sizeDiff.x * trans.pivot.x,
			            sizeDiff.y * trans.pivot.y);
		trans.offsetMax = trans.offsetMax + 
			new Vector2(sizeDiff.x * (1.0f - trans.pivot.x),
			            sizeDiff.y * (1.0f - trans.pivot.y));
	}
	
	private void OnExit()
	{
		Debug.Log("OnExit");
	}
	
	private void OnCancel()
	{
		Debug.Log("OnCancel");
	}
}