using System;
using CoreGraphics;
using Foundation;
using UIKit;

namespace Shared
{
    public class LongPressMoveVerticalScrolViewLayout:ViewGroup
    {
		/// <summary>
		/// 构造函数
		/// </summary>
		public LongPressMoveVerticalScrolViewLayout()
		{
			viewGroup = new MyLongPressMoveVerticalScrolViewLayout(this);
            realViewGroup = viewGroup;
            viewGroup.AddGestureRecognizer(new MyUILongPressGestureRecognizer(sender =>
            {
                (sender as MyUILongPressGestureRecognizer).longPressMoveVerticalScrolViewLayout?.uiViewLongPressed(sender);
            })
            { longPressMoveVerticalScrolViewLayout = this });
        }

        class MyUILongPressGestureRecognizer : UILongPressGestureRecognizer {
            [Weak] internal LongPressMoveVerticalScrolViewLayout longPressMoveVerticalScrolViewLayout;
            public MyUILongPressGestureRecognizer(Action<UILongPressGestureRecognizer> action):base(action) {
               
            }
        }

        public override void AddChidren(View view)
        {
            base.AddChidren(view);
            int maxHeight = 0;
            foreach (View tempView in viewList)
            {
                if (maxHeight < tempView.Bottom)
                {
                    maxHeight = tempView.Bottom;
                }
            }
            (realViewGroup as MyLongPressMoveVerticalScrolViewLayout).ContentSize = new CGSize(Width, maxHeight);
        }

		/// <summary>
		/// 根据点击位置找出点击到的视图
		/// </summary>
		/// <returns>The view of point.</returns>
		/// <param name="point">Point.</param>
		/// <param name="uiview">Uiview.</param>
		UIView replaceUIViewOfPoint(CGPoint point, UIView uiview)
		{
            //第一个是背景图
            for (int i = 1; i < realViewGroup.Subviews.Length; i++)
			{
                var tempUIView = realViewGroup.Subviews[i];
				if (tempUIView != uiview)
				{
					if (tempUIView.Frame.Contains(point))
					{
                        return tempUIView;
					}
				}
			}
            return null;
		}

		/// <summary>
        /// 对换位置的两个视图
        /// </summary>
        public Action<View,View> ReplaceChanged;

        /// <summary>
        /// 根据点击位置找出点击到的视图
        /// </summary>
        /// <returns>返回点击到的视图</returns>
        /// <param name="point">当前点击位置</param>
        UIView selectedUIViewOfPoint(CGPoint point)
        {
            foreach (UIView uiView in realViewGroup.Subviews)
            {
                if (uiView.GetType() != typeof(UIImageView) && uiView.Frame.Contains(point))
                {
                    return uiView;
                }
            }
            return null;
        }


		CGPoint originPoint;
		bool contain;
		UIView selectedUIView;
		void uiViewLongPressed(UILongPressGestureRecognizer sender)
		{
            //长按开始
            if (sender.State == UIGestureRecognizerState.Began)
            {
                //找出当前点击位置的视图
                selectedUIView = selectedUIViewOfPoint(sender.LocationInView(sender.View));
                if (selectedUIView == null)
                {
                    return;
                }
                originPoint = selectedUIView.Center;
                UIView.Animate(1.0f, () =>
                {
                    selectedUIView.Transform = CGAffineTransform.MakeScale(1.1f, 1.1f);
                    selectedUIView.Alpha = 0.7f;
                });
            }
            else if (sender.State == UIGestureRecognizerState.Changed)
            {
                if (selectedUIView == null)
                {
                    return;
                }
                //移动当前视图
                selectedUIView.Center = sender.LocationInView(sender.View);
                //获取当前视图进入了哪个视图的区域
                var replaceUIView = replaceUIViewOfPoint(selectedUIView.Center, selectedUIView);
                if (replaceUIView ==null)
                {
                    contain = false;
                }
                else
                {
                    //进入区域后切换位置
                    UIView.Animate(1.0f, () =>
                    {
                        var temp = replaceUIView.Center;
                        replaceUIView.Center = originPoint;
                        selectedUIView.Center = temp;
                        originPoint = selectedUIView.Center;
                        contain = true;
                    }, () =>
                    {
                        View selectedView = null;
                        foreach (View view in viewList)
                        {
                            if (view.RealView == selectedUIView)
                            {
                                selectedView = view;
                                break;
                            }
                        }
                        View replaceView = null;
                        foreach (View view in viewList)
                        {
                            if (view.RealView == replaceUIView)
                            {
                                replaceView = view;
                                break;
                            }
                        }
                        if(ReplaceChanged!=null){
                            ReplaceChanged(selectedView, replaceView);
                        }

                    });
                }
            }
			else if (sender.State == UIGestureRecognizerState.Ended)
			{
				if (selectedUIView == null)
				{
					return;
				}
				UIView.Animate(1.0f, () =>
				   {
					   selectedUIView.Transform = CGAffineTransform.MakeIdentity();
					   selectedUIView.Alpha = 1.0f;
					   //如果不需要移动位置
					   if (!contain)
					   {
						   selectedUIView.Center = originPoint;
					   }
				   });
			}
		}

		/// <summary>
		/// 是否允许滑动
		/// </summary>
		/// <value><c>true</c> if scroll enabled; otherwise, <c>false</c>.</value>
		public bool ScrollEnabled
		{
			get
			{
				return (viewGroup as MyLongPressMoveVerticalScrolViewLayout).ScrollEnabled;
			}
			set
			{
				(viewGroup as MyLongPressMoveVerticalScrolViewLayout).ScrollEnabled = value;
			}
		}

		/// <summary>
		/// 是否正在滑动
		/// </summary>
		/// <value><c>true</c> if decelerating; otherwise, <c>false</c>.</value>
		public bool Decelerating
		{
			get
			{
				return (viewGroup as MyLongPressMoveVerticalScrolViewLayout).Decelerating;
			}
		}

		/// <summary>
		/// 滑动事件
		/// </summary>
		public  EventHandler<MouseEventArgs> ScrolledEventHandler;

        /// <summary>
        /// 垂直方向滚动视图
        /// </summary>
        class MyLongPressMoveVerticalScrolViewLayout : UIScrollView
        {
            [Weak] LongPressMoveVerticalScrolViewLayout  view;
            public MyLongPressMoveVerticalScrolViewLayout(LongPressMoveVerticalScrolViewLayout view)
            {
                this.view = view;
               
                Scrolled += (sender, e) =>
                {
                   this.view?.ScrolledEventHandler?.Invoke(this, new MouseEventArgs { X = (float)(sender as MyLongPressMoveVerticalScrolViewLayout).ContentOffset.X, Y = (float)(sender as MyLongPressMoveVerticalScrolViewLayout).ContentOffset.Y });
                };
            }
            /// <summary>
            /// 点击开始
            /// </summary>
            /// <param name="touches">Touches.</param>
            /// <param name="evt">Evt.</param>
            public override void TouchesBegan(NSSet touches, UIEvent evt)
            {
                view?.TouchEvent(EventActions.Down, (touches.AnyObject as UITouch).LocationInView(this));
            }
            /// <summary>
            ///  移动
            /// </summary>
            /// <param name="touches">Touches.</param>
            /// <param name="evt">Evt.</param>
            public override void TouchesMoved(NSSet touches, UIEvent evt)
            {
                view?.TouchEvent(EventActions.Move, (touches.AnyObject as UITouch).LocationInView(this));
            }

            /// <summary>
            /// 点击弹起
            /// </summary>
            /// <param name="touches">Touches.</param>
            /// <param name="evt">Evt.</param>
            public override void TouchesEnded(NSSet touches, UIEvent evt)
            {
                view?.TouchEvent(EventActions.Up, (touches.AnyObject as UITouch).LocationInView(this));
            }

            public override void TouchesCancelled(NSSet touches, UIEvent evt)
            {
                view?.TouchEvent(EventActions.Cancel, (touches.AnyObject as UITouch).LocationInView(this));
            }
            /// <summary>
            /// 框架默认加了两个UIImageView ，这样可以去掉默认添加
            /// </summary>
            /// <param name="view">View.</param>
            public override void AddSubview(UIView view)
            {
                if (view.GetType() == typeof(UIImageView) && view.Tag != int.MinValue)
                {
                    return;
                }
                base.AddSubview(view);
            }
        }
    }
}