#nullable enable

using System.Collections.Generic;

using System.Collections.ObjectModel;

namespace SharpGen.Platform;

public sealed class ObservableSet<T> : ObservableCollection<T>

{

private readonly HashSet<T> set;

public ObservableSet(IEqualityComparer<T> equalityComparer) => set = new HashSet<T>(equalityComparer);

public void AddRange(IEnumerable<T> items)

{

foreach (var item in items)

Add(item);

}

protected override void InsertItem(int index, T item)

{

if (!set.Add(item))

return;

base.InsertItem(index, item);

}

protected override void ClearItems()

{

base.ClearItems();

set.Clear();

}

protected override void RemoveItem(int index)

{

var item = this[index];

set.Remove(item);

base.RemoveItem(index);

}

protected override void SetItem(int index, T item)

{

if (!set.Add(item))

return;

var oldItem = this[index];

set.Remove(oldItem);

base.SetItem(index, item);

}

}