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

namespace UIWidgets
{
	public abstract class DragSupport<T> : BaseDragSupport, IBeginDragHandler, IEndDragHandler, IDragHandler, IEventSystemHandler
	{
		[SerializeField]
		public Texture2D AllowDropCursor;

		[SerializeField]
		public Vector2 AllowDropCursorHotSpot = new Vector2(4f, 2f);

		[SerializeField]
		public Texture2D DeniedDropCursor;

		[SerializeField]
		public Vector2 DeniedDropCursorHotSpot = new Vector2(4f, 2f);

		[SerializeField]
		public Texture2D DefaultCursorTexture;

		[SerializeField]
		public Vector2 DefaultCursorHotSpot;

		protected bool IsDragged;

		protected IDropSupport<T> oldTarget;

		protected IDropSupport<T> currentTarget;

		private List<RaycastResult> raycastResults = new List<RaycastResult>();

		public T Data { get; protected set; }

		public virtual bool CanDrag(PointerEventData eventData)
		{
			return true;
		}

		protected abstract void InitDrag(PointerEventData eventData);

		public virtual void Dropped(bool success)
		{
			Data = default(T);
		}

		public virtual void OnBeginDrag(PointerEventData eventData)
		{
			if (CanDrag(eventData))
			{
				IsDragged = true;
				InitDrag(eventData);
			}
		}

		public virtual void OnDrag(PointerEventData eventData)
		{
			if (IsDragged)
			{
				oldTarget = currentTarget;
				currentTarget = FindTarget(eventData);
				if (oldTarget != null && currentTarget != oldTarget)
				{
					oldTarget.DropCanceled(Data, eventData);
				}
				if (currentTarget != null)
				{
					Cursor.SetCursor(AllowDropCursor, AllowDropCursorHotSpot, Utilites.GetCursorMode());
				}
				else
				{
					Cursor.SetCursor(DeniedDropCursor, DeniedDropCursorHotSpot, Utilites.GetCursorMode());
				}
				Vector2 localPoint;
				if (RectTransformUtility.ScreenPointToLocalPointInRectangle(base.CanvasTransform as RectTransform, Input.mousePosition, eventData.pressEventCamera, out localPoint))
				{
					base.DragPoint.localPosition = localPoint;
				}
			}
		}

		protected IDropSupport<T> FindTarget(PointerEventData eventData)
		{
			raycastResults.Clear();
			EventSystem.current.RaycastAll(eventData, raycastResults);
			foreach (RaycastResult raycastResult in raycastResults)
			{
				if (raycastResult.isValid)
				{
					IDropSupport<T> component = raycastResult.gameObject.GetComponent<IDropSupport<T>>();
					if (component != null)
					{
						return (!component.CanReceiveDrop(Data, eventData)) ? null : component;
					}
				}
			}
			return null;
		}

		public virtual void OnEndDrag(PointerEventData eventData)
		{
			if (IsDragged)
			{
				IDropSupport<T> dropSupport = FindTarget(eventData);
				if (dropSupport != null)
				{
					dropSupport.Drop(Data, eventData);
					Dropped(true);
				}
				else
				{
					Dropped(false);
				}
				IsDragged = false;
				Cursor.SetCursor(DefaultCursorTexture, DefaultCursorHotSpot, Utilites.GetCursorMode());
			}
		}

		protected virtual void OnDestroy()
		{
			if (BaseDragSupport.DragPoints != null && base.CanvasTransform != null && BaseDragSupport.DragPoints.ContainsKey(base.CanvasTransform))
			{
				BaseDragSupport.DragPoints.Remove(base.CanvasTransform);
			}
		}
	}
}