WidgetInputRouterRegistry.cs

using Gondwana.Rendering;
 
namespace Gondwana.Widgets;
 
internal static class WidgetInputRouterRegistry
{
    private static readonly object _syncRoot = new();
 
    private static readonly Dictionary<RenderSurfaceHostBase, WidgetInputRouter> _routers = new(ReferenceEqualityComparer.Instance);
 
    internal static void Attach(RenderSurfaceHostBase renderSurfaceHost, WidgetInputRouter router)
    {
        ArgumentNullException.ThrowIfNull(renderSurfaceHost);
        ArgumentNullException.ThrowIfNull(router);
 
        lock (_syncRoot)
        {
            if (_routers.TryGetValue(renderSurfaceHost, out WidgetInputRouter? existing) &&
                !ReferenceEquals(existing, router))
            {
                throw new InvalidOperationException("A widget input router is already attached to this render surface host.");
            }
 
            _routers[renderSurfaceHost] = router;
        }
    }
 
    internal static void Detach(RenderSurfaceHostBase renderSurfaceHost, WidgetInputRouter router)
    {
        lock (_syncRoot)
        {
            if (_routers.TryGetValue(renderSurfaceHost, out WidgetInputRouter? existing) &&
                ReferenceEquals(existing, router))
            {
                _routers.Remove(renderSurfaceHost);
            }
        }
    }
 
    internal static bool TryRegister(WidgetBase widget)
    {
        ArgumentNullException.ThrowIfNull(widget);
 
        WidgetInputRouter? router = GetRouter(widget);
 
        if (router is null)
            return false;
 
        router.Register(widget);
        return true;
    }
 
    internal static bool TryBringToFront(WidgetBase widget)
    {
        ArgumentNullException.ThrowIfNull(widget);
 
        WidgetInputRouter? router = GetRouter(widget);
 
        if (router is null)
            return false;
 
        router.Register(widget);
        router.BringToFront(widget);
 
        return true;
    }
 
    internal static bool TryFocus(WidgetBase widget)
    {
        ArgumentNullException.ThrowIfNull(widget);
 
        WidgetInputRouter? router = GetRouter(widget);
 
        if (router is null)
            return false;
 
        router.Focus(widget);
        return true;
    }
 
    internal static void NotifyHidden(WidgetBase widget)
    {
        GetRouter(widget)?.NotifyWidgetHidden(widget);
    }
 
    internal static void NotifyInputDisabled(WidgetBase widget)
    {
        GetRouter(widget)?.NotifyWidgetInputDisabled(widget);
    }
 
    internal static void NotifyPointerInputDisabled(WidgetBase widget)
    {
        GetRouter(widget)?.NotifyWidgetPointerInputDisabled(widget);
    }
 
    internal static void NotifyKeyboardFocusDisabled(WidgetBase widget)
    {
        GetRouter(widget)?.NotifyWidgetKeyboardFocusDisabled(widget);
    }
 
    internal static WidgetBase? GetFocusedWidget(WidgetBase widget) => GetRouter(widget)?.FocusedWidget;
 
    internal static void RestoreFocus(WidgetBase widget, WidgetBase? previous)
    {
        var router = GetRouter(widget);
        router?.ClearFocus();
        router?.Focus(previous);
    }
 
    private static WidgetInputRouter? GetRouter(WidgetBase widget)
    {
        ArgumentNullException.ThrowIfNull(widget);
 
        lock (_syncRoot)
        {
            _routers.TryGetValue(widget.RenderSurfaceHost, out WidgetInputRouter? router);
            return router;
        }
    }
}