feat: add i18n helpers

README.md

@@ -197,6 +197,31 @@ Blazor login page example:
 }
 ```
 
+# I18n helpers
+
+Helpers to make it trivial to implement a client that pulls the language and culture info from the server.
+
+```csharp
+host.UseRequestLocalization(o => {
+   var cultures = ...;
+   o.AddSupportedCultures(cultures)
+    .AddSupportedUICultures(cultures)
+    .SetDefaultCulture(cultures[0]);
+   //insert before the final default provider (the AcceptLanguageHeaderRequestCultureProvider)
+   o.RequestCultureProviders.Insert(o.RequestCultureProviders.Count - 1, new OidcClaimsCultureProvider {Options = o});
+});
+```
+
+Notice, this requires the server sets the culture info in the claims.
+See below for example, or see `OidcClaimsCultureProviderHelper.AddClaims` for details.
+
+You also need to copy it from the server given claims to the local claims. E.g. if using `StoreRemoteAuthInSchemeAsync`:
+
+```csharp
+yourContext.StoreRemoteAuthInSchemeAsync(..., (identity, remote)=>OidcClaimsCultureProviderHelper.CopyClaims(identity, remote))))
+```
+
+
 ## Http helpers
 
 ### HttpClient for authentication code flow
@@ -400,3 +425,18 @@ services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme)
       o.ReturnStatusCodesOnAuthFailuresForApiCalls();
    });
 ```
+
+### I18n helper
+
+Add OIDC standard claims for culture (`locale`) and the non-standard `ui-locales` for the ui-culture.
+
+```csharp
+public abstract class ApplyCultureToClaims(...) : OidcAccessGranterBase(...)
+{
+   protected override Task<ImmutableArray<string>> SetClaimsAndGetScopes(...)
+   {
+      OidcClaimsCultureProviderHelper.AddClaimsFromCurrentCulture(identity);
+      return base.SetClaimsAndGetScopes(...);
+   }
+}
+```

src/Catglobe.Openiddict.Contrib.Client/I18nHelpers/OidcClaimsCultureProvider.cs

@@ -0,0 +1,70 @@
+#if NET
+using Microsoft.AspNetCore.Localization;
+using System.Security.Claims;
+
+namespace Openiddict.Contrib.Client.I18nHelpers;
+
+/// <summary>
+/// Pull the <see cref="OpenIddictConstants.Claims.Locale"/> claim from the user and use that as the culture.
+/// Also respects the non-standard "ui-locales" claim if present, in which case <see cref="OpenIddictConstants.Claims.Locale"/> is interpreted as the culture for formatting numbers, dates etc.
+/// <example><code>
+/// host.UseRequestLocalization(o =&gt; {
+///   var cultures = ...;
+///   o.AddSupportedCultures(cultures)
+///   .AddSupportedUICultures(cultures)
+///   .SetDefaultCulture(cultures[0]);
+/// //insert before the final default provider (the AcceptLanguageHeaderRequestCultureProvider)
+/// o.RequestCultureProviders.Insert(o.RequestCultureProviders.Count - 1, new OidcClaimsCultureProvider {Options = o});
+/// });
+/// </code></example>
+/// </summary>
+public class OidcClaimsCultureProvider : RequestCultureProvider
+{
+   ///<inheritdoc/>
+   public override Task<ProviderCultureResult?> DetermineProviderCultureResult(HttpContext httpContext) => Task.FromResult(GetCultureFromClaims(httpContext));
+
+   private static ProviderCultureResult? GetCultureFromClaims(HttpContext ctx)
+   {
+      var userCulture   = ctx.User.GetClaim(OpenIddictConstants.Claims.Locale);
+      var userUiCulture = ctx.User.GetClaim(OpenIddictConstants.Parameters.UiLocales) ?? userCulture;
+      if (userUiCulture == null) goto noneFound;
+
+      return new(userCulture ?? userUiCulture, userUiCulture);
+      noneFound:
+      return null;
+   }
+
+   /// <summary>
+   /// Add appropriate claims for the given culture to the identity.
+   /// You probably want to use <see cref="CopyClaims"/> during login callback instead.
+   /// </summary>
+   /// <param name="identity">Identity to populate</param>
+   /// <param name="culture">Culture to use in BCP47 [RFC5646] format.</param>
+   public static void AddClaims(ClaimsIdentity identity, string? culture)
+   {
+      if (culture != null) identity.AddClaim(new Claim(OpenIddictConstants.Claims.Locale, culture.Replace('_', '-')));
+   }
+
+   /// <summary>
+   /// Add standard claims for the given culture to the identity, plus the custom "ui-locales".
+   /// You would usually use this if you are loading the culture info from db or similar.
+   /// You probably want to use <see cref="CopyClaims"/> during login callback instead.
+   /// </summary>
+   /// <param name="identity">Identity to populate</param>
+   /// <param name="culture">Culture to use in BCP47 [RFC5646] format.</param>
+   /// <param name="uiCulture">UI Culture to use in BCP47 [RFC5646] format. Ignored if same as culture.</param>
+   public static void AddClaims(ClaimsIdentity identity, string? culture, string? uiCulture)
+   {
+      AddClaims(identity, culture);
+      if (uiCulture != null && uiCulture != culture) identity.AddClaim(new(OpenIddictConstants.Parameters.UiLocales, uiCulture));
+   }
+
+   /// <summary>
+   /// Copy appropriate claims for the given culture to the identity from remote.
+   /// </summary>
+   /// <param name="identity">Identity to populate.</param>
+   /// <param name="remote">Remote claims.</param>
+   public static void CopyClaims(ClaimsIdentity identity, ClaimsPrincipal remote) => AddClaims(identity, remote.GetClaim(OpenIddictConstants.Claims.Locale), remote.GetClaim(OpenIddictConstants.Parameters.UiLocales));
+
+}
+#endif

src/Catglobe.Openiddict.Contrib.Server/I18nHelpers/OidcClaimsCultureProvider.cs

@@ -0,0 +1,56 @@
+using System.Globalization;
+using System.Security.Claims;
+
+namespace Openiddict.Contrib.Server.I18nHelpers;
+
+/// <summary>
+/// Set the <see cref="OpenIddictConstants.Claims.Locale"/> claim from the user and use that as the culture.
+/// <example><code>
+/// host.UseRequestLocalization(o =&gt; {
+///   var cultures = ...;
+///   o.AddSupportedCultures(cultures)
+///   .AddSupportedUICultures(cultures)
+///   .SetDefaultCulture(cultures[0])
+///   .RequestCultureProviders = new List&lt;IRequestCultureProvider&gt; {
+///   new QueryStringRequestCultureProvider {Options          = o},
+///   new CookieRequestCultureProvider {Options               = o},
+///   new SoapClaimsCultureProvider {Options                  = o},
+///   new OidcClaimsCultureProvider {Options                  = o},
+///   new AcceptLanguageHeaderRequestCultureProvider {Options = o},
+///   };
+/// });
+/// </code></example>
+/// </summary>
+public class OidcClaimsCultureProviderHelper
+{
+   /// <summary>
+   /// Infer culture from current culture and add appropriate claims to the identity.
+   /// You would usually use this if you already have infrastructure in place to set the culture.
+   /// </summary>
+   /// <param name="identity">Identity to populate</param>
+   public static void AddClaimsFromCurrentCulture(ClaimsIdentity identity) => AddClaims(identity, CultureInfo.CurrentCulture.Name, CultureInfo.CurrentUICulture.Name);
+
+   /// <summary>
+   /// Add standard claims for the given culture to the identity.
+   /// You would usually use this if you are loading the culture info from db or similar.
+   /// </summary>
+   /// <param name="identity">Identity to populate</param>
+   /// <param name="culture">Culture to use in BCP47 [RFC5646] format.</param>
+   public static void AddClaims(ClaimsIdentity identity, string? culture)
+   {
+      if (culture != null) identity.AddClaim(new(OpenIddictConstants.Claims.Locale, culture));
+   }
+
+   /// <summary>
+   /// Add standard claims for the given culture to the identity, plus the custom "ui-locales".
+   /// You would usually use this if you are loading the culture info from db or similar.
+   /// </summary>
+   /// <param name="identity">Identity to populate</param>
+   /// <param name="culture">Culture to use in BCP47 [RFC5646] format.</param>
+   /// <param name="uiCulture">UI Culture to use in BCP47 [RFC5646] format. Ignored if same as culture.</param>
+   public static void AddClaims(ClaimsIdentity identity, string? culture, string? uiCulture)
+   {
+      AddClaims(identity, culture);
+      if (uiCulture != null && uiCulture != culture) identity.AddClaim(new(OpenIddictConstants.Parameters.UiLocales, uiCulture));
+   }
+}