CsTableViewSource

using System;
using System.Collections;
using System.Collections.Specialized;
using System.Linq;
using Cirrious.CrossCore.Core;
using Cirrious.CrossCore.WeakSubscription;
using Cirrious.MvvmCross.Binding.Attributes;
using Cirrious.MvvmCross.Binding.BindingContext;
using Cirrious.MvvmCross.Binding.ExtensionMethods;
using MonoMac.AppKit;
using MonoMac.Foundation;

namespace CentraStage.Mac
{
  public class CsTableViewSource : NSTableViewSource
	{
		IEnumerable itemsSource;
		IDisposable subscription;
		NSTableView tableView;

		public CsTableViewSource (NSTableView tableView): base()
		{
			this.tableView = tableView;
		}

		public override int GetRowCount (NSTableView tableView)
		{
			return ItemsSource.Count ();
		}

		[MvxSetToNullAfterBinding]
		public virtual IEnumerable ItemsSource
		{
			get { return itemsSource; }
			set
			{
				if (itemsSource == value)
					return;

				if (subscription != null)
				{
					subscription.Dispose();
					subscription = null;
				}

				itemsSource = value;

				var collectionChanged = itemsSource as INotifyCollectionChanged;
				if (collectionChanged != null)
				{
					subscription = collectionChanged.WeakSubscribe(CollectionChangedOnCollectionChanged);
				}

				ReloadTableData();
			}
		}

		void ReloadTableData ()
		{
			tableView.ReloadData ();
		}

		NSView GetOrCreateViewFor (NSTableView tableView, NSTableColumn tableColumn)
		{
			var view = tableView.MakeView (tableColumn.Identifier, this);
			var bindableColumn = tableColumn as CsTableColumn;
			if (bindableColumn != null){
				if (view == null)
					view = new CsTableCellView (bindableColumn.BindingText);
				else {
					IMvxBindingContextOwner bindableView = view as IMvxBindingContextOwner;
					bindableView.CreateBindingContext (bindableColumn.BindingText);
				}
			}
			return view;
		}

		public override NSView GetViewForItem (NSTableView tableView, NSTableColumn tableColumn, int row)
		{
			if (ItemsSource == null)
				return null;

			var item =  ItemsSource.ElementAt(row);
			var view = GetOrCreateViewFor (tableView, tableColumn);

			var bindable = view as IMvxDataConsumer;
			if (bindable != null)
				bindable.DataContext = item;

			return view;
		}

		protected virtual void CollectionChangedOnCollectionChanged(object sender, NotifyCollectionChangedEventArgs args)
		{
			TryDoAnimatedChange (args);
		}

		protected static NSIndexSet CreateNSIndexSet(int startingPosition, int count)
		{
			return NSIndexSet.FromArray (Enumerable.Range(startingPosition, count).ToArray());
		}

		protected bool TryDoAnimatedChange(NotifyCollectionChangedEventArgs args)
		{
			switch (args.Action)
			{
				case NotifyCollectionChangedAction.Add:
			{
				var newIndexSet = CreateNSIndexSet(args.NewStartingIndex, args.NewItems.Count);
				tableView.InsertRows (newIndexSet, NSTableViewAnimation.Fade);
				return true;
			}
				case NotifyCollectionChangedAction.Remove:
			{
				var newIndexSet = CreateNSIndexSet(args.OldStartingIndex, args.OldItems.Count);
				tableView.RemoveRows (newIndexSet, NSTableViewAnimation.Fade);
				return true;
			}
				case NotifyCollectionChangedAction.Move:
			{
				if (args.NewItems.Count != 1 && args.OldItems.Count != 1)
					return false;
				tableView.MoveRow (args.OldStartingIndex, args.NewStartingIndex);
				return true;
			}
				case NotifyCollectionChangedAction.Replace:
			{
//				if (args.NewItems.Count != args.OldItems.Count)
//					return false;
//
//				var indexPath = NSIndexPath.FromItemSection(args.NewStartingIndex, 0);
//				TableView.ReloadRows(new[]
//				                     {
//					indexPath
//				}, UITableViewRowAnimation.Fade);
				tableView.ReloadData ();
				return true;
			}
				default:
				return false;
			}
		}

//		protected static NSIndexPath[] CreateNSIndexPathArray(int startingPosition, int count)
//		{
//			var newIndexPaths = new NSIndexPath[count];
//			for (var i = 0; i < count; i++)
//			{
//				newIndexPaths[i] = NSIndexPath.FromItemSection(i + startingPosition, 0);
//			}
//			return newIndexPaths;
//		}


//		public override int RowsInSection(NSTableView tableview, int section)
//		{
//			if (ItemsSource == null)
//				return 0;
//
//			return ItemsSource.Count();
//		}
	}
}