using System;
using System.Collections.ObjectModel;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Linq;
using System.Linq.Expressions;
using System.Runtime.CompilerServices;

using Xamarin.Forms;
using System.Collections.Generic;

using Xamarin.Forms.CustomAttributes;
using Xamarin.Forms.Internals;

namespace Xamarin.Forms.Controls
{
	[Preserve (AllMembers=true)]
	[Issue (IssueTracker.Github, 1762, "Binding issue with SwitchCell - System.ArgumentException:'jobject' must not be IntPtr.Zero", PlatformAffected.Android)]
	public class Issue1762 : ContentPage
	{
		public static ObservableGroupMyObjCollection Objs = new ObservableGroupMyObjCollection ();

		public Issue1762 ()
		{
			StackLayout stack = new StackLayout
			{};
			stack.Children.Add (new ListView {
				ItemsSource = Objs,
				ItemTemplate = new DataTemplate (() => {
					SwitchCell cell = new SwitchCell ();
					cell.SetBinding<MyObj> (SwitchCell.TextProperty, m => m.DisplayText);
					cell.SetBinding<MyObj> (SwitchCell.OnProperty, m => m.IsSelected);
					return cell;
				}),
				IsGroupingEnabled = true,
				GroupDisplayBinding = new Binding ("Key")
			});
			Button b = new Button {
				Text = "add"
			};
			b.Clicked += (sender, e) => {
				Random r = new Random ();
				Objs.Add (new MyObj {
					DisplayText = r.Next ().ToString (),
					IsSelected = r.Next () % 2 == 0
				});
			};
			stack.Children.Add (b);

			Content = stack;
		}
	}

	public class Grouping<K, T> : ObservableCollection<T>, IGroupingCollection<K, T> where T : INotifyPropertyChanged
	{
		public K Key { get; private set; }

		public Grouping (K key, IEnumerable<T> items)
		{
			Key = key;
			foreach (var item in items)
				Items.Add (item);
		}

		public Grouping (K key, T item)
		{
			Key = key;
			Items.Add (item);
		}
	}

	public static class Extensions
	{
		public static IEnumerable<T> Enumerate<T> (this IEnumerable<IEnumerable<T>> listOfList)
		{
			foreach (var list in listOfList) {
				foreach (T item in list)
					yield return item;
			}
		}
	}

	public interface IGroupingCollection<K, T> : ICollection<T>, IGrouping<K, T> {}

	public interface ISortingKey<T>
	{
		T SortingKey { get; }
	}

	public class MyObj : ObservableObject, ISortingKey<bool>
	{
		public MyObj () {}

		string _displayText;

		public string DisplayText
		{
			get { return _displayText; }
			set { SetProperty (ref _displayText, value); }
		}

		bool _isSelected;

		public bool IsSelected
		{
			get { return _isSelected; }
			set
			{
				if (SetProperty (ref _isSelected, value))
					NotifyPropertyChanged (() => SortingKey);
			}
		}

		#region ISortingKey implementation
		public bool SortingKey
		{
			get { return IsSelected; }
		}
		#endregion
	}

	public abstract class ObservableGroupCollection<K, T> : ObservableCollection<IGroupingCollection<K, T>> where T : class, INotifyPropertyChanged, ISortingKey<K>
	{
		Func<K, K, bool> _equalityComparer;

		public ObservableGroupCollection (IEnumerable<IGroupingCollection<K, T>> items, Func<K, K, bool> equalityComparer)
			: base (items)
		{
			_equalityComparer = equalityComparer;
			if (items != null) {
				foreach (var propChangeItem in items.Enumerate ())
					SetupPropertyChanged (propChangeItem, equalityComparer);
			}
		}

		void SetupPropertyChanged (T propChangeItem, Func<K, K, bool> equalityComparer)
		{
			propChangeItem.PropertyChanged += (sender, e) => {
				if (e.PropertyName == "SortingKey") {
					//using (BlockReentrancy())
					{
						T changedItem = (T)sender;
						IGroupingCollection<K, T> oldGroup = null, newGroup = null;
						foreach (var group in Items) //go through all groups to find item
						{
							if (oldGroup == null /* || newGroup == null*/) {
								foreach (var item2 in group) {
									if (oldGroup == null && item2 == changedItem)
										oldGroup = group;
								}
							}
							if (newGroup == null && equalityComparer (group.Key, changedItem.SortingKey))
								newGroup = group;
						}
						if (oldGroup != null) {
							oldGroup.Remove (changedItem);
							if (oldGroup.Count == 0) {
								OnCollectionChanged (new NotifyCollectionChangedEventArgs (NotifyCollectionChangedAction.Remove, oldGroup));
								Items.Remove (oldGroup);
							}
						}
#if DEBUG
						else
							throw new Exception ("oldGroup == null");
#endif
						if (newGroup == null) {
							Items.Add (newGroup = new Grouping<K, T> (changedItem.SortingKey, changedItem));
							OnCollectionChanged (new NotifyCollectionChangedEventArgs (NotifyCollectionChangedAction.Add, newGroup));
						} else {
							foreach (var item in newGroup) {
								if (item == changedItem)
									return;
							}
							newGroup.Add (changedItem);
						}
					}
				}
			};
		}

		public ObservableGroupCollection (IGroupingCollection<K, T> item, Func<K, K, bool> equalityComparer)
		{
			_equalityComparer = equalityComparer;
			if (item != null) {
				foreach (T t in item)
					SetupPropertyChanged (t, equalityComparer);
			}
		}

		public void Add (T item)
		{
			SetupPropertyChanged (item, _equalityComparer);
			foreach (IGroupingCollection<K, T> group in Items) {
				if (_equalityComparer (group.Key, item.SortingKey)) {
					group.Add (item);
					return;
				}
			}
			Grouping<K, T> newGroup = new Grouping<K, T> (item.SortingKey, item);
			Items.Add (newGroup);
			OnCollectionChanged (new NotifyCollectionChangedEventArgs (NotifyCollectionChangedAction.Add, newGroup));
		}

		/*protected override void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
        {
            base.OnCollectionChanged(e);
        }*/
	}

	public class ObservableGroupMyObjCollection : ObservableGroupCollection<bool, MyObj>
	{
		public ObservableGroupMyObjCollection ()
			: base ((IGroupingCollection<bool, MyObj>)null, (k1, k2) => k1 == k2) {}
	}

	public abstract class ObservableObject : INotifyPropertyChanged
	{
		public event PropertyChangedEventHandler PropertyChanged;


		protected virtual void NotifyPropertyChanged ([CallerMemberName] string propertyName = null)
		{
			OnPropertyChanged (new PropertyChangedEventArgs (propertyName));
		}

		protected virtual void NotifyPropertyChanged<T> (Expression<Func<T>> propertyExpression)
		{
			string propertyName = GetPropertyName (propertyExpression);
			OnPropertyChanged (new PropertyChangedEventArgs (propertyName));
		}

		protected virtual void OnPropertyChanged (PropertyChangedEventArgs e)
		{
			var eventHandler = PropertyChanged;
			if (eventHandler != null) {
				try {
					eventHandler (this, e); //crashes here!
				} catch (Exception ex) {
					System.Diagnostics.Debug.WriteLine (ex);
				}
			}
		}


		protected bool SetProperty<T> (ref T storage, T value, Expression<Func<T>> propertyExpression)
		{
			var propertyName = GetPropertyName (propertyExpression);
			return SetProperty<T> (ref storage, value, propertyName);
		}


		protected bool SetProperty<T> (ref T storage, T value, [CallerMemberName] string propertyName = null)
		{
			if (EqualityComparer<T>.Default.Equals (storage, value))
				return false;

			storage = value;
			NotifyPropertyChanged (propertyName);
			return true;
		}

		string GetPropertyName<T> (Expression<Func<T>> propertyExpression)
		{
			if (propertyExpression == null)
				throw new ArgumentNullException ("propertyExpression");

			if (propertyExpression.Body.NodeType != ExpressionType.MemberAccess)
				throw new ArgumentException ("Should be a member access lambda expression", "propertyExpression");

			var memberExpression = (MemberExpression)propertyExpression.Body;
			return memberExpression.Member.Name;
		}
	}
}