using UnityEngine;
using System.Collections;

public class AspectUtility : MonoBehaviour {
	
	public float _wantedAspectRatio = 1.777778f;
  public Color _backgroundColor = Color.black;
	static float wantedAspectRatio;
  static Color backgroundColor;
	static Camera cam;
	static Camera backgroundCam;

  static int myWidth;
  static int myHeight;
	
	void Awake () {
		cam = GetComponent<Camera>();
		if (!cam) {
			cam = Camera.main;
		}
		if (!cam) {
			Debug.LogError ("No camera available");
			return;
		}
		wantedAspectRatio = _wantedAspectRatio;
    backgroundColor = _backgroundColor;

    myWidth = myHeight = 0;

    StartCoroutine( checkCamera() );
	}

  void OnDestroy() {
    StopAllCoroutines();
  }
  
  IEnumerator checkCamera()
  {
    while( true )
    {
      if( myWidth != Screen.width || myHeight != Screen.height )
      {
        SetCamera();
      }
      
      yield return new WaitForSeconds( 0.33f );
    }
  }
	
	public static void SetCamera () {
    myWidth = Screen.width;
    myHeight = Screen.height;

		float currentAspectRatio = (float)Screen.width / Screen.height;
		// If the current aspect ratio is already approximately equal to the desired aspect ratio,
		// use a full-screen Rect (in case it was set to something else previously)
		if ((int)(currentAspectRatio * 100) / 100.0f == (int)(wantedAspectRatio * 100) / 100.0f) {
			cam.rect = new Rect(0.0f, 0.0f, 1.0f, 1.0f);
			if (backgroundCam) {
				Destroy(backgroundCam.gameObject);
			}
			return;
		}
		// Pillarbox
		if (currentAspectRatio > wantedAspectRatio) {
			float inset = 1.0f - wantedAspectRatio/currentAspectRatio;
			cam.rect = new Rect(inset/2, 0.0f, 1.0f-inset, 1.0f);
		}
		// Letterbox
		else {
			float inset = 1.0f - currentAspectRatio/wantedAspectRatio;
			cam.rect = new Rect(0.0f, inset/2, 1.0f, 1.0f-inset);
		}
		if (!backgroundCam) {
			// Make a new camera behind the normal camera which displays black; otherwise the unused space is undefined
			backgroundCam = new GameObject("BackgroundCam", typeof(Camera)).GetComponent<Camera>();
			backgroundCam.depth = int.MinValue;
			backgroundCam.clearFlags = CameraClearFlags.SolidColor;
      backgroundCam.backgroundColor = backgroundColor;
			backgroundCam.cullingMask = 0;
		}
	}
	
	public static int screenHeight {
		get {
			return (int)(Screen.height * cam.rect.height);
		}
	}
	
	public static int screenWidth {
		get {
			return (int)(Screen.width * cam.rect.width);
		}
	}
	
	public static int xOffset {
		get {
			return (int)(Screen.width * cam.rect.x);
		}
	}
	
	public static int yOffset {
		get {
			return (int)(Screen.height * cam.rect.y);
		}
	}
	
	public static Rect screenRect {
		get {
			return new Rect(cam.rect.x * Screen.width, cam.rect.y * Screen.height, cam.rect.width * Screen.width, cam.rect.height * Screen.height);
		}
	}
	
	public static Vector3 mousePosition {
		get {
			Vector3 mousePos = Input.mousePosition;
			mousePos.y -= (int)(cam.rect.y * Screen.height);
			mousePos.x -= (int)(cam.rect.x * Screen.width);
			return mousePos;
		}
	}
	
	public static Vector2 guiMousePosition {
		get {
			Vector2 mousePos = Event.current.mousePosition;
			mousePos.y = Mathf.Clamp(mousePos.y, cam.rect.y * Screen.height, cam.rect.y * Screen.height + cam.rect.height * Screen.height);
			mousePos.x = Mathf.Clamp(mousePos.x, cam.rect.x * Screen.width, cam.rect.x * Screen.width + cam.rect.width * Screen.width);
			return mousePos;
		}
	}
}