using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;

namespace ytLive.Helpers;

/// <summary>Gives a ComboBox's CLOSED box a different template from its drop-down
/// rows (TASK 63).
///
/// <para>WPF asks an <see cref="ItemTemplateSelector"/> with the ContentPresenter's
/// templated parent: the <see cref="ComboBox"/> itself when it renders the closed
/// selection box, the <see cref="ComboBoxItem"/> when it renders a row. That is the
/// only way to tell the two apart — <c>ComboBox.SelectionBoxItemTemplate</c> is
/// read-only, and WPF copies <c>ItemTemplate</c> into it, so a ComboBox otherwise
/// cannot show one thing when shut and another when open.</para>
///
/// <para>Verified against WPF on .NET 8 (2026-10-21): with the rows' presenter the
/// templated parent is the ComboBoxItem, with the closed box's it is the ComboBox.</para>
/// </summary>
public sealed class ClosedBoxTemplateSelector : DataTemplateSelector
{
    /// <summary>The template for the closed box — what the creator reads while the
    /// drop-down is shut.</summary>
    public DataTemplate? ClosedTemplate { get; set; }

    /// <summary>The template for the drop-down rows.</summary>
    public DataTemplate? RowTemplate { get; set; }

    public override DataTemplate? SelectTemplate(object item, DependencyObject container)
        => container is FrameworkElement { TemplatedParent: ComboBox }
            ? ClosedTemplate
            : RowTemplate;
}