/* Use of  Delegate for multiple buttons. Different functions are assigned to delegate that perform the required functionality. The basic color change and animation that are common to all buttons are given here. */

// Apply this Script on every button in your game.

using UnityEngine;
using System.Collections;

public class GeneralButton : MonoBehaviour
{
    /*initialize this delegate "OnButtonHandler()" with different button functions in which ever class  needed. Example-  playButton.onButtonHandler = OnPlay; -> OnPlay() */


    public delegate void OnButtonHandler();

    public OnButtonHandler onButtonHandler;
    public BoxCollider2D collider;    // button collider

    public SpriteRenderer buttonBackSprite;
    public Color selectedColor = Color.blue;

    private static GameObject selectedObject = null;  //null game object

   

   void Start ()
    {
              //initialize any here animation if needed
    }
    
    
    void Update ()     
    {

             OnTouch();
    }

    public void OnTouch()
    {
        
        Ray ray;
        RaycastHit2D[] hit;   //returns information about the object detected by the ray cast in 2D physics.
        
        Vector3 pos = Input.mousePosition;
            
        ray = camera.ScreenPointToRay(pos);
        
        hit = Physics2D.RaycastAll(ray.origin, Vector2.zero);  //origin and direction of the ray
        

        // On Button Click


        if (Input.GetMouseButtonDown(0))
        {
            if (hit == null) return;  // no ray detected

            foreach (RaycastHit2D elem in hit)
            {
                if (elem != null && elem.collider == collider)
                {
                    this.buttonBackSprite.color = selectedColor;  // color of the button changed
                    selectedObject = this.gameObject;
                   
                    break;
                }
            }
            return;
        }

        else if (Input.GetMouseButtonUp(0) && selectedObject == this.gameObject)
        {
            this.buttonBackSprite.color = new Color(1.0f, 1.0f, 1.0f);

            if (hit == null) return;

            foreach (RaycastHit2D elem in hit)
            {
                if (elem != null && elem.collider == collider)
                {
                    if (onButtonHandler != null)
                    {
                        onButtonHandler();  // calling required function through delegate
                    }
                    break;
                }
            }
            selectedObject = null;
        }       
    }

  }