using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;
using System.Collections.Generic;

public class CustomRaycaster : MonoBehaviour
{
    [HideInInspector]
    public GameObject hovered = null;
    [HideInInspector]
    public GameObject hitObject;
    [HideInInspector]
    bool isHit;

    public enum HoverState
    {
        Hover, None
    };

    [HideInInspector]
    public HoverState hover_state = HoverState.None;
    [HideInInspector]
    PointerEventData pointerData;
    [HideInInspector]
    RaycastHit hitInfo;
    [HideInInspector]
    Ray ray;

    [HideInInspector]
    List<RaycastResult> results = new List<RaycastResult>();

    void Update ()
    {
        pointerData = new PointerEventData(EventSystem.current);
        pointerData.position = Input.mousePosition;

        results.Clear();
        EventSystem.current.RaycastAll(pointerData, results);

        if (results.Count > 0)
        {
            hitObject = results[0].gameObject;
//          Debug.Log(Input.mousePosition.x.ToString()+" "+Input.mousePosition.y.ToString()+" "+hitObject.name);
            isHit = true;
        }
        else
        {
            ray = Camera.main.ScreenPointToRay(Input.mousePosition);
            isHit = (Physics.Raycast(ray, out hitInfo));
            if (isHit)
            {
                hitObject = hitInfo.collider.gameObject;
            }
        }
        Hover(isHit);
    }

    protected void Hover(bool isHit)
    {
        if (isHit)
        {
            if (hover_state == HoverState.None)
            {
                IClickable click = WholeObject(hitObject);
                if (click != null) click.OnMouseEnterCustom();
                hovered = hitObject;
            }
            else
            {
                if (hovered != hitObject)
                {
                    IClickable click = WholeObject(hovered);
                    if (click != null) click.OnMouseExitCustom();
                    click = WholeObject(hitObject);
                    if (click != null) click.OnMouseEnterCustom();
                    hovered = hitObject;
                }
            }
            hover_state = HoverState.Hover;
        }
        else
        {
            if (hover_state == HoverState.Hover)
            {
                IClickable click = WholeObject(hovered);
                if (click != null) click.OnMouseExitCustom();
                hovered = null;
                hover_state = HoverState.None;
            }
        }
        if (hover_state == HoverState.Hover)
        {
            IClickable click = WholeObject(hovered);
            if (click != null) click.OnMouseOverCustom();
        }
    }

    public IClickable WholeObject(GameObject o) //search object and parent for being IClickables
    {
        IClickable click = o.GetComponent<IClickable>();
        if (click == null)
        {
            click = o.GetComponentInParent<IClickable>();
        }
        return click;
    }
}

public class RaycastFilter : MonoBehaviour, ICanvasRaycastFilter //partially invisible (think odd shaped buttons)
{
    Collider2D myCollider;
    RectTransform rectTransform;

    public void Initialization()
    {
        myCollider = GetComponent<Collider2D>();
        rectTransform = GetComponent<RectTransform>();
    }

    public bool IsRaycastLocationValid (Vector2 screenPos, Camera eventCamera)
    {
        Vector3 worldPoint = Vector3.zero;
        bool isInside = RectTransformUtility.ScreenPointToWorldPointInRectangle(
            rectTransform,
            screenPos,
            eventCamera,
            out worldPoint
            );
        if (isInside)
            isInside = myCollider.OverlapPoint(worldPoint);

        return isInside;
    }
}

public class RaycastInvisible : MonoBehaviour, ICanvasRaycastFilter //invisible to raycasts (think always invisible panels)
{
    public IRaycastHidable owner;

    public bool IsRaycastLocationValid(Vector2 screenPoint, Camera eventCamera)
    {
        return (!owner.raycastHidden);
    }
}

public interface IClickable //can interact with raycaster
{
    void OnMouseEnterCustom();

    void OnMouseExitCustom();

    void OnMouseOverCustom();
}

public interface IRaycastHidable
{
    bool raycastHidden { get; set; }
}