/**
 * This code is part of the Fungus library (http://fungusgames.com) maintained by Chris Gregan (http://twitter.com/gofungus).
 * It is released for free under the MIT open source license (https://github.com/snozbot/fungus/blob/master/LICENSE)
 */

using UnityEngine;
using UnityEngine.EventSystems;

namespace Fungus
{
	/**
	 * Detects mouse clicks and touches on a Game Object, and sends an event to all Flowchart event handlers in the scene.
	 * The Game Object must have a Collider or Collider2D component attached.
	 * Use in conjunction with the ObjectClicked Flowchart event handler.
	 */
	public class Clickable2D : MonoBehaviour, IPointerClickHandler, IPointerEnterHandler, IPointerExitHandler
	{
		[Tooltip("Is object clicking enabled")]
		public bool clickEnabled = true;

		[Tooltip("Mouse texture to use when hovering mouse over object")]
		public Texture2D hoverCursor;

		[Tooltip("Use the UI Event System to check for clicks. Clicks that hit an overlapping UI object will be ignored. Camera must have a PhysicsRaycaster component, or a Physics2DRaycaster for 2D colliders.")]
		public bool useEventSystem;

		#region Legacy OnMouseX methods
		protected virtual void OnMouseDown()
		{
			if (!useEventSystem)
			{
				DoPointerClick();
			}
		}

		protected virtual void OnMouseEnter()
		{
			if (!useEventSystem)
			{
				DoPointerEnter();
			}
		}

		protected virtual void OnMouseExit()
		{
			if (!useEventSystem)
			{
				DoPointerExit();
			}
		}
		#endregion

        #region IPointerXHandler implementations
        public void OnPointerClick(PointerEventData eventData)
        {
			if (useEventSystem)
			{
				DoPointerClick();
			}
        }

		public void OnPointerEnter(PointerEventData eventData)
		{
			if (useEventSystem)
			{
				DoPointerEnter();
			}
		}

		public void OnPointerExit(PointerEventData eventData)
		{
			if (useEventSystem)
			{
				DoPointerExit();
			}
		}

		protected virtual void DoPointerClick()
		{
			if (!clickEnabled)
			{
				return;
			}
			
			// TODO: Cache these objects for faster lookup
			ObjectClicked[] handlers = GameObject.FindObjectsOfType<ObjectClicked>();
			foreach (ObjectClicked handler in handlers)
			{
				handler.OnObjectClicked(this);
			}
		}

		protected virtual void DoPointerEnter()
		{
			ChangeCursor(hoverCursor);
		}

		protected virtual void DoPointerExit()
		{
			// Always reset the mouse cursor to be on the safe side
			SetMouseCursor.ResetMouseCursor();
		}
		#endregion

		protected virtual void ChangeCursor(Texture2D cursorTexture)
		{
			if (!clickEnabled)
			{
				return;
			}
			
			Cursor.SetCursor(cursorTexture, Vector2.zero, CursorMode.Auto);
		}
	}
}