Refactor Diagnostics Index to use MediatR query pattern

SecurityService.BusinessLogic/Oidc/OidcCommands.cs

@@ -14,4 +14,5 @@ public sealed record VerifyGetQuery(HttpContext HttpContext) : IRequest<Result<V
     public sealed record VerifyPostCommand(HttpContext HttpContext, string Action, string UserCode) : IRequest<Result<VerifyPostCommandResult>>;
     public sealed record ConsentGetQuery(HttpContext HttpContext, string ReturnUrl) : IRequest<Result<ConsentGetQueryResult>>;
     public sealed record ConsentPostCommand(string ReturnUrl, string Button, IReadOnlyCollection<string> SelectedScopes) : IRequest<Result<ConsentPostCommandResult>>;
+    public sealed record DiagnosticsQuery(HttpContext HttpContext) : IRequest<Result<DiagnosticsQueryResult>>;
 }

SecurityService.BusinessLogic/Oidc/OidcResults.cs

@@ -84,3 +84,17 @@ public abstract record ConsentPostCommandResult;
 public sealed record ConsentPostRedirectResult(string Url) : ConsentPostCommandResult;
 
 public sealed record ConsentPostPageResult(string ModelError) : ConsentPostCommandResult;
+
+// ---- Diagnostics endpoint ----
+
+public abstract record DiagnosticsQueryResult;
+
+public sealed record DiagnosticsPageResult(
+    IReadOnlyCollection<DiagnosticItem> Claims,
+    IReadOnlyCollection<DiagnosticItem> Properties) : DiagnosticsQueryResult;
+
+public sealed record DiagnosticsNotFoundResult : DiagnosticsQueryResult;
+
+public sealed record DiagnosticsChallengeResult(string AuthenticationScheme) : DiagnosticsQueryResult;
+
+public sealed record DiagnosticItem(string Type, string Value);

SecurityService.BusinessLogic/RequestHandlers/DiagnosticsRequestHandler.cs

@@ -0,0 +1,41 @@
+using System.Net;
+using MediatR;
+using Microsoft.AspNetCore.Authentication;
+using Microsoft.AspNetCore.Identity;
+using SecurityService.BusinessLogic.Oidc;
+using SimpleResults;
+
+namespace SecurityService.BusinessLogic.RequestHandlers;
+
+public sealed class DiagnosticsRequestHandler :
+    IRequestHandler<OidcCommands.DiagnosticsQuery, Result<DiagnosticsQueryResult>>
+{
+    public async Task<Result<DiagnosticsQueryResult>> Handle(OidcCommands.DiagnosticsQuery query, CancellationToken cancellationToken)
+    {
+        var context = query.HttpContext;
+
+        if (context.Connection.RemoteIpAddress is { } remoteIpAddress &&
+            IPAddress.IsLoopback(remoteIpAddress) == false)
+        {
+            return Result.Success<DiagnosticsQueryResult>(new DiagnosticsNotFoundResult());
+        }
+
+        var result = await context.AuthenticateAsync(IdentityConstants.ApplicationScheme);
+        if (result.Succeeded == false || result.Principal is null)
+        {
+            return Result.Success<DiagnosticsQueryResult>(new DiagnosticsChallengeResult(IdentityConstants.ApplicationScheme));
+        }
+
+        var claims = result.Principal.Claims
+            .Select(claim => new DiagnosticItem(claim.Type, claim.Value))
+            .OrderBy(item => item.Type, StringComparer.OrdinalIgnoreCase)
+            .ToArray();
+
+        var properties = result.Properties?.Items
+            .OrderBy(item => item.Key, StringComparer.OrdinalIgnoreCase)
+            .Select(item => new DiagnosticItem(item.Key, item.Value ?? string.Empty))
+            .ToArray() ?? Array.Empty<DiagnosticItem>();
+
+        return Result.Success<DiagnosticsQueryResult>(new DiagnosticsPageResult(claims, properties));
+    }
+}

SecurityService/Pages/Diagnostics/Index.cshtml.cs

@@ -1,43 +1,41 @@
-using System.Net;
-using Microsoft.AspNetCore.Authentication;
-using Microsoft.AspNetCore.Identity;
+using MediatR;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.AspNetCore.Mvc.RazorPages;
+using SecurityService.BusinessLogic.Oidc;
 
 namespace SecurityService.Pages.Diagnostics;
 
 public sealed class IndexModel : PageModel
 {
+    private readonly IMediator _mediator;
+
+    public IndexModel(IMediator mediator)
+    {
+        this._mediator = mediator;
+    }
+
     public IReadOnlyCollection<DiagnosticItem> Claims { get; private set; } = Array.Empty<DiagnosticItem>();
 
     public IReadOnlyCollection<DiagnosticItem> Properties { get; private set; } = Array.Empty<DiagnosticItem>();
 
-    public async Task<IActionResult> OnGetAsync()
+    public async Task<IActionResult> OnGetAsync(CancellationToken cancellationToken)
     {
-        if (this.Request.HttpContext.Connection.RemoteIpAddress is { } remoteIpAddress &&
-            IPAddress.IsLoopback(remoteIpAddress) == false)
-        {
-            return this.NotFound();
-        }
+        var result = await this._mediator.Send(new OidcCommands.DiagnosticsQuery(this.HttpContext), cancellationToken);
 
-        var result = await this.HttpContext.AuthenticateAsync(IdentityConstants.ApplicationScheme);
-        if (result.Succeeded == false || result.Principal is null)
+        return result.Data switch
         {
-            return this.Challenge(IdentityConstants.ApplicationScheme);
-        }
-
-        this.Claims = result.Principal.Claims
-            .Select(claim => new DiagnosticItem(claim.Type, claim.Value))
-            .OrderBy(item => item.Type, StringComparer.OrdinalIgnoreCase)
-            .ToArray();
-
-        this.Properties = result.Properties?.Items
-            .OrderBy(item => item.Key, StringComparer.OrdinalIgnoreCase)
-            .Select(item => new DiagnosticItem(item.Key, item.Value ?? string.Empty))
-            .ToArray() ?? Array.Empty<DiagnosticItem>();
+            DiagnosticsNotFoundResult => this.NotFound(),
+            DiagnosticsChallengeResult challenge => this.Challenge(challenge.AuthenticationScheme),
+            DiagnosticsPageResult page => this.ApplyPageResult(page),
+            _ => this.Page()
+        };
+    }
 
+    private IActionResult ApplyPageResult(DiagnosticsPageResult page)
+    {
+        this.Claims = page.Claims;
+        this.Properties = page.Properties;
         return this.Page();
     }
 }
 
-public sealed record DiagnosticItem(string Type, string Value);