namespace System.Windows.Forms
{
    public partial class CheckedListBox
    {
        private class Item : INotifyPropertyChangedImpl, IComparable
        {
            private CheckedListBox owner { get; }

            public object Value { get; set; }

            private bool? isChecked;
            public bool? IsChecked
            {
                get => isChecked;
                set
                {
                    if (isChecked != value)
                    {
                        owner.OnItemCheck(new ItemCheckEventArgs(owner.Items.IndexOfItem(this), BoolToCheckState(value), BoolToCheckState(isChecked)));
                        RaiseAndSetIfChanged(ref isChecked, value);
                    }
                }
            }

            private bool? CheckStateToBool(CheckState check)
            {
                return check == CheckState.Unchecked ? false :
                    (check == CheckState.Checked ? true : null);
            }

            private CheckState BoolToCheckState(bool? check)
            {
                return check == false ? CheckState.Unchecked :
                    (check == true ? CheckState.Checked : CheckState.Indeterminate);
            }

            public void SetState(CheckState check)
            {
                IsChecked = CheckStateToBool(check);
            }

            public int CompareTo(object obj)
            {
                if (Value is IComparable val && obj is Item item)
                    return val.CompareTo(item.Value);
                return -1;
            }

            public Item(CheckedListBox owner, object value)
            {
                this.owner = owner;
                Value = value;
            }
        }
    }
}