using GongSolutions.Wpf.DragDrop;
using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Linq;
using System.Windows;
using System.Windows.Controls;

namespace Dominion.NET_WPF.ViewModel
{
	internal class CardListViewModel : IDropTarget
	{
		public bool PreserveSourceOrdering { get; set; }
		public ObservableCollection<CardViewModel> Cards { get; set; }
		public void ShowCards(IEnumerable<DominionBase.Cards.Card> cards, DominionBase.Piles.Visibility visibility)
		{
			var index = 0;
			Cards = new ObservableCollection<CardViewModel>();
			var _visibility = visibility;
			foreach (var card in cards)
			{
				Cards.Add(new CardViewModel
				{
					CardName = card.Name,
					Card = card,
					Visibility = _visibility == DominionBase.Piles.Visibility.None ? DominionBase.Piles.Visibility.None : DominionBase.Piles.Visibility.All,
					OriginalIndex = index++
				});
				if (_visibility == DominionBase.Piles.Visibility.Top)
					_visibility = DominionBase.Piles.Visibility.None;
			}
		}

		public CardListViewModel()
		{
			Cards = new ObservableCollection<CardViewModel>();
		}

		void IDropTarget.DragOver(DropInfo dropInfo)
		{
			var targetItem = dropInfo.TargetItem as CardViewModel;
			if (dropInfo.Data is CardViewModel && (targetItem != null || dropInfo.TargetCollection != null))
			{
				dropInfo.Effects = DragDropEffects.Move;
				if (!PreserveSourceOrdering)
					dropInfo.DropTargetAdorner = DropTargetAdorners.Insert;
			}
		}

		void IDropTarget.Drop(DropInfo dropInfo)
		{
			if (dropInfo.DragInfo == null)
				return;

			var insertIndex = dropInfo.InsertIndex;
			IList<CardViewModel> sourceList = null;
			var destinationList = GetList(dropInfo.TargetCollection);
			var data = ExtractData(dropInfo.Data);

			if (dropInfo.DragInfo.VisualSource is ListBox lbSource && dropInfo.VisualTarget is ListBox lbTarget
					&& lbSource.DataContext.GetType() == lbTarget.DataContext.GetType())
				sourceList = GetList(dropInfo.DragInfo.SourceCollection);

			if (PreserveSourceOrdering)
			{
				foreach (var o in data)
				{
					sourceList.Remove(o);

					insertIndex = -1;
					if (destinationList.Any())
						insertIndex = destinationList.Max(cvm => cvm.OriginalIndex < o.OriginalIndex ? destinationList.IndexOf(cvm) : -1);
					if (insertIndex == -1)
						destinationList.Insert(0, o);
					else if (insertIndex == destinationList.Count - 1)
						destinationList.Add(o);
					else
						destinationList.Insert(insertIndex + 1, o);
				}
			}
			else
			{
				if (sourceList != null)
				{
					foreach (var o in data)
					{
						var index = sourceList.IndexOf(o);

						if (index != -1)
						{
							sourceList.RemoveAt(index);

							if (sourceList == destinationList && index < insertIndex)
								--insertIndex;
						}
					}
				}

				foreach (var o in data)
					destinationList.Insert(insertIndex++, o);
			}
		}

		protected static IEnumerable<CardViewModel> ExtractData(object data)
		{
			var models = data as IEnumerable<CardViewModel>;
			return models ?? Enumerable.Repeat((CardViewModel)data, 1);
		}

		protected static IList<CardViewModel> GetList(IEnumerable enumerable)
		{
			if (enumerable is ICollectionView view)
				return view.SourceCollection as IList<CardViewModel>;
			return enumerable as IList<CardViewModel>;
		}
	}
}