#nullable disable
using System;
using Foundation;
using Microsoft.Maui.Controls.Handlers.Items;
using Microsoft.Maui.Graphics;
using UIKit;
 
namespace Microsoft.Maui.Controls.Handlers.Items2
{
	public partial class CarouselViewHandler2
	{
 
		public CarouselViewHandler2() : base(Mapper)
		{
 
 
		}
		public CarouselViewHandler2(PropertyMapper mapper = null) : base(mapper ?? Mapper)
		{
 
		}
 
		public static PropertyMapper<CarouselView, CarouselViewHandler2> Mapper = new(ItemsViewMapper)
		{
 
			[Controls.CarouselView.IsSwipeEnabledProperty.PropertyName] = MapIsSwipeEnabled,
			[Controls.CarouselView.PeekAreaInsetsProperty.PropertyName] = MapPeekAreaInsets,
			[Controls.CarouselView.IsBounceEnabledProperty.PropertyName] = MapIsBounceEnabled,
			[Controls.CarouselView.PositionProperty.PropertyName] = MapPosition,
			[Controls.CarouselView.CurrentItemProperty.PropertyName] = MapCurrentItem
		};
	}
 
	public partial class CarouselViewHandler2 : ItemsViewHandler2<CarouselView>
	{
		protected override CarouselViewController2 CreateController(CarouselView newElement, UICollectionViewLayout layout)
				=> new(newElement, layout);
 
		protected override UICollectionViewLayout SelectLayout()
		{
			bool IsHorizontal = VirtualView.ItemsLayout.Orientation == ItemsLayoutOrientation.Horizontal;
			UICollectionViewScrollDirection scrollDirection = IsHorizontal ? UICollectionViewScrollDirection.Horizontal : UICollectionViewScrollDirection.Vertical;
 
			NSCollectionLayoutDimension itemWidth = NSCollectionLayoutDimension.CreateFractionalWidth(1);
			NSCollectionLayoutDimension itemHeight = NSCollectionLayoutDimension.CreateFractionalHeight(1);
			NSCollectionLayoutDimension groupWidth = NSCollectionLayoutDimension.CreateFractionalWidth(1);
			NSCollectionLayoutDimension groupHeight = NSCollectionLayoutDimension.CreateFractionalHeight(1);
			nfloat itemSpacing = 0;
 
			var layout = new UICollectionViewCompositionalLayout((sectionIndex, environment) =>
			{
				if (VirtualView is null)
				{
					return null;
				}
				double sectionMargin = 0.0;
				if (!IsHorizontal)
				{
					sectionMargin = VirtualView.PeekAreaInsets.VerticalThickness / 2;
					var newGroupHeight = environment.Container.ContentSize.Height - VirtualView.PeekAreaInsets.VerticalThickness;
					groupHeight = NSCollectionLayoutDimension.CreateAbsolute((nfloat)newGroupHeight);
					groupWidth = NSCollectionLayoutDimension.CreateFractionalWidth(1);
				}
				else
				{
					sectionMargin = VirtualView.PeekAreaInsets.HorizontalThickness / 2;
					var newGroupWidth = environment.Container.ContentSize.Width - VirtualView.PeekAreaInsets.HorizontalThickness;
					groupWidth = NSCollectionLayoutDimension.CreateAbsolute((nfloat)newGroupWidth);
					groupHeight = NSCollectionLayoutDimension.CreateFractionalHeight(1);
				}
 
				// Each item has a size
				var itemSize = NSCollectionLayoutSize.Create(itemWidth, itemHeight);
				// Create the item itself from the size
				var item = NSCollectionLayoutItem.Create(layoutSize: itemSize);
 
				//item.ContentInsets = new NSDirectionalEdgeInsets(0, itemInset, 0, 0);
 
				var groupSize = NSCollectionLayoutSize.Create(groupWidth, groupHeight);
 
				var group = IsHorizontal ? NSCollectionLayoutGroup.GetHorizontalGroup(groupSize, item, 1) :
										 NSCollectionLayoutGroup.GetVerticalGroup(groupSize, item, 1);
 
				// Create our section layout
				var section = NSCollectionLayoutSection.Create(group: group);
				section.InterGroupSpacing = itemSpacing;
				section.OrthogonalScrollingBehavior = UICollectionLayoutSectionOrthogonalScrollingBehavior.GroupPagingCentered;
				section.VisibleItemsInvalidationHandler = (items, offset, env) =>
				{
					//This will allow us to SetPosition when we are scrolling the items
					//based on the current page
					var page = (offset.X + sectionMargin) / env.Container.ContentSize.Width;
 
					// Check if we not are at the beginning or end of the page and if we have items
					if (Math.Abs(page % 1) > (double.Epsilon * 100) || Controller.ItemsSource.ItemCount <= 0)
					{
						return;
					}
 
					var pageIndex = (int)page;
					var carouselPosition = pageIndex;
 
					var cv2Controller = (CarouselViewController2)Controller;
 
					//If we are looping, we need to get the correct position
					if (ItemsView.Loop)
					{
						var maxIndex = (Controller.ItemsSource as ILoopItemsViewSource).LoopCount - 1;
 
						//To mimic looping, we needed to modify the ItemSource and inserted a new item at the beginning and at the end
						if (pageIndex == maxIndex)
						{
							//When at last item, we need to change to 2nd item, so we can scroll right or left
							pageIndex = 1;
						}
						else if (pageIndex == 0)
						{
							//When at first item, need to change to one before last, so we can scroll right or left
							pageIndex = maxIndex - 1;
						}
 
						//since we added one item at the beginning of our ItemSource, we need to subtract one
						carouselPosition = pageIndex - 1;
 
						if (ItemsView.Position != carouselPosition)
						{
							//If we are updating the ItemsSource, we don't want to scroll the CollectionView
							if (cv2Controller.IsUpdating())
							{
								return;
							}
 
							var goToIndexPath = cv2Controller.GetScrollToIndexPath(carouselPosition);
 
							//This will move the carousel to fake the loop
							Controller.CollectionView.ScrollToItem(NSIndexPath.FromItemSection(pageIndex, 0), UICollectionViewScrollPosition.Left, false);
 
						}
					}
 
					//Update the CarouselView position
					cv2Controller?.SetPosition(carouselPosition);
 
				};
				return section;
			});
 
			return layout;
		}
 
		protected override void ScrollToRequested(object sender, ScrollToRequestEventArgs args)
		{
			if (VirtualView?.Loop == true)
			{
				var goToIndexPath = (Controller as CarouselViewController2).GetScrollToIndexPath(args.Index);
 
				if (!IsIndexPathValid(goToIndexPath))
				{
					return;
				}
 
				bool IsHorizontal = VirtualView.ItemsLayout.Orientation == ItemsLayoutOrientation.Horizontal;
				UICollectionViewScrollDirection scrollDirection = IsHorizontal ? UICollectionViewScrollDirection.Horizontal : UICollectionViewScrollDirection.Vertical;
 
				Controller.CollectionView.ScrollToItem(goToIndexPath,
					args.ScrollToPosition.ToCollectionViewScrollPosition(scrollDirection), // TODO: Fix _layout.ScrollDirection),
					args.IsAnimated);
			}
			else
			{
				base.ScrollToRequested(sender, args);
			}
		}
 
		public static void MapIsSwipeEnabled(CarouselViewHandler2 handler, CarouselView carouselView)
		{
			handler.Controller.CollectionView.ScrollEnabled = carouselView.IsSwipeEnabled;
		}
 
		public static void MapIsBounceEnabled(CarouselViewHandler2 handler, CarouselView carouselView)
		{
			handler.Controller.CollectionView.Bounces = carouselView.IsBounceEnabled;
		}
 
		public static void MapPeekAreaInsets(CarouselViewHandler2 handler, CarouselView carouselView)
		{
			handler.UpdateLayout();
		}
 
		public static void MapCurrentItem(CarouselViewHandler2 handler, CarouselView carouselView)
		{
			(handler.Controller as CarouselViewController2)?.UpdateFromCurrentItem();
		}
 
		public static void MapPosition(CarouselViewHandler2 handler, CarouselView carouselView)
		{
			// If the initial position hasn't been set, we have a UpdateInitialPosition call on CarouselViewController2
			// that will handle this so we want to skip this mapper call. We need to wait for the CollectionView to be ready
			if (handler.Controller is CarouselViewController2 CarouselViewController2 && CarouselViewController2.InitialPositionSet)
			{
				CarouselViewController2.UpdateFromPosition();
			}
		}
 
		public static void MapLoop(CarouselViewHandler2 handler, CarouselView carouselView)
		{
			(handler.Controller as CarouselViewController2)?.UpdateLoop();
		}
 
	}
}