Correction du flux d'inscription Keycloak

ChessCubing.App/Pages/Authentication.razor

@@ -1,13 +1,59 @@
 @page "/authentication/{action}"
+@inject NavigationManager Navigation
 
 <main class="rules-shell">
     <section class="panel panel-wide cta-panel" style="margin-top: 2rem;">
         <p class="eyebrow">Authentification</p>
-        <RemoteAuthenticatorView Action="@Action" />
+        @if (IsRegisterAction)
+        {
+            <div>
+                <strong>Redirection vers la creation de compte...</strong>
+                <p>L'inscription se poursuit dans Keycloak, puis vous reviendrez automatiquement dans l'application.</p>
+            </div>
+        }
+        else
+        {
+            <RemoteAuthenticatorView Action="@Action" />
+        }
     </section>
 </main>
 
 @code {
     [Parameter]
     public string? Action { get; set; }
+
+    [SupplyParameterFromQuery(Name = "returnUrl")]
+    public string? ReturnUrl { get; set; }
+
+    private bool IsRegisterAction
+        => string.Equals(Action, RemoteAuthenticationActions.Register, StringComparison.OrdinalIgnoreCase);
+
+    protected override void OnParametersSet()
+    {
+        if (!IsRegisterAction)
+        {
+            return;
+        }
+
+        var request = new InteractiveRequestOptions
+        {
+            Interaction = InteractionType.SignIn,
+            ReturnUrl = NormalizeReturnUrl(ReturnUrl)
+        };
+
+        request.TryAddAdditionalParameter("prompt", "create");
+        Navigation.NavigateToLogin("authentication/login", request);
+    }
+
+    private static string NormalizeReturnUrl(string? returnUrl)
+    {
+        if (string.IsNullOrWhiteSpace(returnUrl))
+        {
+            return "/";
+        }
+
+        return returnUrl.StartsWith("/", StringComparison.Ordinal)
+            ? returnUrl
+            : $"/{returnUrl}";
+    }
 }