[oAuth2][Desktop!][Server] Implement interactive oAuth2 flow to external API

[DevTKSS]

What is needed:

Implement oAuth2 Interactive Authentication from Client -> Ext. API or Client -> WebAPI (Server Backend) -> Ext. API - especially Interactive Parts are not working

• Client Auth Provider for oAuth: https://github.com/DevTKSS/DevTKSS.MyManufacturerERP/blob/e292bf00bbb533861ddb35412ae1f1bcf743504e/src/Extensions/OAuth.UI/OAuthProvider.cs needs to get refactored (e.g. SoC) but should already hold most of the relevant flow. Implement and Call Service providing the UI
• System Browser Integration for Implementing IWebAuthenticationBrokerProvider on Desktop uses Callbackhandler from PR: feat(AuthCallbackHandler): Add a OAuthCallback Handler instance that can be used already build in carldebilly/Yllibed.HttpServer#12
• Use the Server Backend WebAPI Project
  • using the dev package created from Add Etsy OAuth provider aspnet-contrib/AspNet.Security.OAuth.Providers#1126
  • missing knowledge on how to integrate Client to the WebAPI project still.
• Use OpenIDDict if you find time to check / fix started PR: feat(etsy): Add Etsy Web Provider openiddict/openiddict-core#2398
• Use WebView2 in Page / Window / ContentDialog on Desktop using Uno.Extensions.Navigation INavigator
  • https://github.com/DevTKSS/DevTKSS.MyManufacturerERP/blob/d4e86ee3cf725fae74c86c7038210040fe05769e/src/Extensions/OAuth.UI.WebView2/Views/WebView2AuthenticationModel.cs
  • https://github.com/DevTKSS/DevTKSS.MyManufacturerERP/blob/9fdf5ce426ae24312a4a01dd493978b9af3b35b3/src/Extensions/OAuth.UI/Navigation/OAuthNavigationService.cs
• https://github.com/AzureAD/microsoft-authentication-library-for-dotnet/blob/main/src/client/Microsoft.Identity.Client.Desktop.WinUI3/WebView2WebUi/WinUI3WindowWithWebView2.cs (Uno hat leider vieeele der hier genutzten Eigenschaften und Funktionen nicht implementiert, aber etwa dieses Prinzip, wäre der Grundgedanke für die WebView2 Möglichkeit, bloß mit MVVM / MVUX sauberer Trennung vom UI und Logik. Uno Apps haben standardmäßg einen DI IDispatcher verfügbar, entsprechend würde man ggf. WebView2 + IDispatcher verwenden können

API's

• https://developers.etsy.com/documentation/essentials/authentication
• Due Date before 31.03.2026!!! https://api.sevdesk.de/#section/Authentication-and-Authorization - "regular" API Token

Issues blocking using Uno out-of-the-box implementations

• PR to "just" allow the Interface in Uno source of WebAuthenticationProvider as DI Parameter
  • Nobody from the Uno reviewed and potentially merged this by now (would possibly be the easiest way to fix this 🙄 ) feat(WebAuthenticationProvider): Allow providing IWebAuthenticationBrokerProvider via DI parameters unoplatform/uno.extensions#2890
  • Attempted to use the SystemBrowserProvider which build on suggestion from: [Auth][Desktop/Skia] Add support for WebAuthenticationBroker for OIDC/MSAL unoplatform/uno.extensions#2640 but blocked by ApiExtensionAttribute allowing no SoC / configuration / non-defaults for CallbackUrl
• Process.Start and Launcher does nothing e.g. open the browser and not supports response
  • would possibly require HttpListener for https - Production?! support

Referenzen:

• https://github.com/DuendeSoftware/foss/blob/main/identity-model-oidc-client/samples/WpfWebView2/WpfWebView2/WpfEmbeddedBrowser.cs
• https://github.com/AzureAD/microsoft-authentication-library-for-dotnet/blob/main/src/client/Microsoft.Identity.Client/Utils/UriBuilderExtensions.cs