using System;

namespace AcDream.App.UI;

/// <summary>
/// Lifecycle contract for a controller attached to a retained retail window.
/// Implementations own panel-specific subscriptions and reactions; the window
/// manager owns visibility, focus, capture, geometry, and teardown ordering.
/// </summary>
public interface IRetainedPanelController : IDisposable
{
    /// <summary>Called once for each hidden-to-shown transition.</summary>
    void OnShown() { }

    /// <summary>Called once for each shown-to-hidden transition.</summary>
    void OnHidden() { }

    /// <summary>
    /// Called when keyboard focus enters, leaves, or moves within this window.
    /// <paramref name="focusedDescendant"/> is null when focus left the window.
    /// Controllers that do not react to focus may use this default no-op.
    /// </summary>
    void OnDescendantFocusChanged(UiElement? focusedDescendant) { }
}