using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Windows;
using System.Windows.Threading;

namespace JD.Guinness.WPF.Module
{
    public sealed class DispatcherObservableCollection<T> : ObservableCollection<T>
    {
        private readonly Dispatcher _dispatcher;

        public DispatcherObservableCollection(IEnumerable<T> items)
            : base(items)
        {
            _dispatcher = Application.Current.Dispatcher;
        }

        public DispatcherObservableCollection()
            : this(Enumerable.Empty<T>())
        { }

        protected override void InsertItem(int index, T item)
        {
            if (!_dispatcher.CheckAccess())
            {
                _dispatcher.Invoke(() => base.InsertItem(index, item));
            }
            else
            {
                base.InsertItem(index, item);
            }
        }

        protected override void RemoveItem(int index)
        {
            if (!_dispatcher.CheckAccess())
            {
                _dispatcher.Invoke(() => base.RemoveItem(index));
            }
            else
            {
                base.RemoveItem(index);
            }
        }

        protected override void MoveItem(int oldIndex, int newIndex)
        {
            if (!_dispatcher.CheckAccess())
            {
                _dispatcher.Invoke(() => base.MoveItem(oldIndex, newIndex));
            }
            else
            {
                base.MoveItem(oldIndex, newIndex);
            }
        }

        protected override void SetItem(int index, T item)
        {
            if (!_dispatcher.CheckAccess())
            {
                _dispatcher.Invoke(() => base.SetItem(index, item));
            }
            else
            {
                base.SetItem(index, item);
            }
        }

        protected override void ClearItems()
        {
            if (!_dispatcher.CheckAccess())
            {
                _dispatcher.Invoke(ClearItems);
            }
            else
            {
                while (Count > 0)
                {
                    base.RemoveItem(0);
                }
            }
        }
    }
}