namespace WpfApp1
{
    using System;
    using System.Collections.ObjectModel;
    using System.Windows.Controls;

    public class DialogService
    {
        private static readonly Lazy<DialogService> LazyInstance = new(() => new DialogService());
        private readonly ObservableCollection<UserControl> _dialogs = new();

        public DialogService()
        {
            Dialogs = new ReadOnlyObservableCollection<UserControl>(_dialogs);
        }

        public static DialogService Instance => LazyInstance.Value;

        public ReadOnlyObservableCollection<UserControl> Dialogs { get; }

        public void Add(UserControl userControl)
        {
            _dialogs.Add(userControl);
        }

        public void Remove(UserControl userControl)
        {
            _dialogs.Remove(userControl);
        }
    }
}