break widget related stuff into its own project as the main HB project was just becoming too bloated

Hyperbar.Widget/WidgetHost.cs

@@ -0,0 +1,61 @@
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+
+namespace Hyperbar.Widget;
+
+public class WidgetHost :
+    INotificationHandler<Changed<WidgetAvailability>>,
+    IWidgetHost
+{
+    private readonly IConfigurationInitializer<WidgetConfiguration> configurationInitializer;
+    private readonly IHost host;
+    private readonly IEnumerable<IInitializer> initializers;
+    private readonly IMediator mediator;
+    private readonly IProxyService<IMediator> proxyMediator;
+
+    public WidgetHost(IHost host,
+        IMediator mediator,
+        IEnumerable<IInitializer> initializers,
+        IProxyService<IMediator> proxyMediator,
+        IConfigurationInitializer<WidgetConfiguration> configurationInitializer)
+    {
+        this.host = host;
+        this.mediator = mediator;
+        this.initializers = initializers;
+        this.proxyMediator = proxyMediator;
+        this.configurationInitializer = configurationInitializer;
+
+        mediator.Subscribe(this);
+    }
+
+    public WidgetConfiguration Configuration => host.Services.GetRequiredService<WidgetConfiguration>();
+   
+    public IServiceProvider Services => host.Services;
+
+    public async Task Handle(Changed<WidgetAvailability> notification,
+        CancellationToken cancellationToken)
+    {
+        if (notification.Value is WidgetAvailability widgetAvailability)
+        {
+            if (widgetAvailability.Value)
+            {
+                await StartAsync();
+            }
+        }
+    }
+
+    public async Task InitializeAsync() => await configurationInitializer.InitializeAsync();
+
+    private async Task StartAsync()
+    {
+        if (proxyMediator.Proxy is IMediator mediator)
+        {
+            await mediator.PublishAsync(new Started<IWidgetHost>(this));
+        }
+
+        foreach (IInitializer initializer in initializers)
+        {
+            await initializer.InitializeAsync();
+        }
+    }
+}