feature: Added External Athentication base

src/ASPBaseOIDC.Web.Core/Controllers/TokenAuthController.cs

@@ -2,8 +2,10 @@
 using Abp.Authorization.Users;
 using Abp.MultiTenancy;
 using Abp.Runtime.Security;
+using ASPBaseOIDC.Application.Authorization.ExternalAuth.Dto;
 using ASPBaseOIDC.Authentication.JwtBearer;
 using ASPBaseOIDC.Authorization;
+using ASPBaseOIDC.Authorization.ExternalAuth;
 using ASPBaseOIDC.Authorization.Users;
 using ASPBaseOIDC.Models.TokenAuth;
 using ASPBaseOIDC.MultiTenancy;
@@ -24,17 +26,20 @@ namespace ASPBaseOIDC.Controllers
         private readonly ITenantCache _tenantCache;
         private readonly AbpLoginResultTypeHelper _abpLoginResultTypeHelper;
         private readonly TokenAuthConfiguration _configuration;
+        private readonly ExternalAuthenticationManager _externalAuthManager;
 
         public TokenAuthController(
             LogInManager logInManager,
             ITenantCache tenantCache,
             AbpLoginResultTypeHelper abpLoginResultTypeHelper,
-            TokenAuthConfiguration configuration)
+            TokenAuthConfiguration configuration,
+            ExternalAuthenticationManager externalAuthManager)
         {
             _logInManager = logInManager;
             _tenantCache = tenantCache;
             _abpLoginResultTypeHelper = abpLoginResultTypeHelper;
             _configuration = configuration;
+            _externalAuthManager = externalAuthManager;
         }
 
         [HttpPost]
@@ -57,6 +62,31 @@ namespace ASPBaseOIDC.Controllers
             };
         }
 
+        /// <summary>
+        /// Authenticate with external OIDC/OAuth2 provider (Authentik, Keycloak, etc.)
+        /// Passthrough approach: validates external token and returns it as-is
+        /// </summary>
+        [HttpPost]
+        [AbpAllowAnonymous]
+        public async Task<AuthenticateResultModel> AuthenticateExternal([FromBody] ExternalAuthModel model)
+        {
+            // Authenticate with external provider (validates token, provisions user if needed)
+            var result = await _externalAuthManager.AuthenticateWithExternalTokenAsync(
+                model.ProviderName,
+                model.IdToken,
+                AbpSession.TenantId
+            );
+
+            // Return original external token (passthrough approach)
+            return new AuthenticateResultModel
+            {
+                AccessToken = result.AccessToken, // Passthrough external token
+                EncryptedAccessToken = GetEncryptedAccessToken(result.AccessToken),
+                ExpireInSeconds = result.ExpiresIn,
+                UserId = result.User.Id
+            };
+        }
+
         private string GetTenancyNameOrNull()
         {
             if (!AbpSession.TenantId.HasValue)