Toolkit2/Framework/Avalonia/Navigation/NavigateHandler.cs

using Avalonia.Controls;
using Toolkit.Controls.Avalonia;
using Toolkit.Framework.Foundation;
using Microsoft.Extensions.Primitives;
using System.Diagnostics;

namespace Toolkit.Framework.Avalonia;

public class NavigateHandler : IRequestHandler<Navigate>
{
    private readonly INavigationRouteDescriptorCollection descriptors;
    private readonly IMediator mediator;
    private readonly INamedContentTemplateFactory namedContentTemplateFactory;
    private readonly INamedContentFactory namedContentFactory;
    private readonly IContentTemplateFactory contentTemplateFactory;
    private readonly ITypedContentFactory typedContentFactory;

    public NavigateHandler(IMediator mediator,
        IContentTemplateFactory contentTemplateFactory,
        INamedContentFactory namedContentFactory,
        INamedContentTemplateFactory namedContentTemplateFactory,
        ITypedContentFactory typedContentFactory,
        INavigationRouteDescriptorCollection descriptors)
    {
        this.mediator = mediator;
        this.contentTemplateFactory = contentTemplateFactory;
        this.namedContentFactory = namedContentFactory;
        this.namedContentTemplateFactory = namedContentTemplateFactory;
        this.typedContentFactory = typedContentFactory;
        this.descriptors = descriptors;
    }

    public ValueTask<Unit> Handle(Navigate request, CancellationToken cancellationToken)
    {
        foreach (NavigationSegment segment in NavigationSegment.FromPath(request.Path))
        {
            object? content = null;
            object? template = null;

            Dictionary<string, object> keyedParameters = new();
            List<object> parameters = new();

            foreach (object? parameter in request.Parameters)
            {
                if (parameter is not null)
                {
                    if (parameter is KeyValuePair<string, object> keyed)
                    {
                        keyedParameters.Add(keyed.Key, keyed.Value);
                    }
                    else
                    {
                        parameters.Add(parameter);
                    }
                }
            }

            if (segment.Name is { Length: > 0 } name)
            {
                content = namedContentFactory.Create(name, parameters.ToArray());
                template = namedContentTemplateFactory.Create(name);
            }

            if (template is not null)
            {
                object? target = null;
                if (descriptors.FirstOrDefault(x => segment.Target is string { } name && name == x.Name) is NavigationRouteDescriptor descriptor)
                {
                    target = descriptor.Route;
                }
                else
                {
                    target = template;
                }

                if (target is Frame frame)
                {
                    mediator.Send(new FrameNavigation(frame, content, template, keyedParameters));
                }
                else if (target is ContentDialog dialog)
                {
                    mediator.Send(new ContentDialogNavigation(dialog, content, template, keyedParameters));
                }
                else if (target is ContentControl contentControl)
                {
                    mediator.Send(new ContentControlNavigation(contentControl, content, template, keyedParameters));
                }
            }
            else
            {
                if (descriptors.FirstOrDefault(x => segment.Target is string { } name && name == x.Name) is NavigationRouteDescriptor descriptor)
                {
                    if (descriptor.Route is ContentControl contentControl)
                    {
                        contentControl.Content = null;
                    }
                }
            }
        }

        return default;
    }
}