Can use ProblemDetails with message handlers as well. Can use message…

… handlers as HTTP endpoints. Closes GH-1069

docs/guide/http/problemdetails.md

@@ -139,3 +139,13 @@ public static ProblemDetails Before(IShipOrder command, Order order)
 ```
 <sup><a href='https://github.com/JasperFx/wolverine/blob/main/src/Http/WolverineWebApi/Marten/Orders.cs#L87-L101' title='Snippet source file'>snippet source</a> | <a href='#snippet-sample_using_before_on_http_aggregate' title='Start of snippet'>anchor</a></sup>
 <!-- endSnippet -->
+
+## Within Message Handlers <Badge type="tip" text="3.0" />
+
+`ProblemDetails` can be used within message handlers as well with similar rules. See this example
+from the tests:
+
+snippet: sample_using_problem_details_in_message_handler
+
+This functionality was added so that some handlers could be both an endpoint and message handler
+without having to duplicate code or delegate to the handler through an endpoint. 

src/Http/Wolverine.Http.Tests/problem_details_usage_in_http_middleware.cs

@@ -4,6 +4,7 @@
 using Microsoft.AspNetCore.Routing;
 using Microsoft.Extensions.DependencyInjection;
 using Shouldly;
+using Wolverine.Tracking;
 using WolverineWebApi;
 
 namespace Wolverine.Http.Tests;
@@ -40,6 +41,30 @@ public async Task stop_with_problems_if_middleware_trips_off()
     }
 
     #endregion
+
+    [Fact]
+    public async Task continue_happy_path_as_handler_acting_as_endpoint()
+    {
+        // Should be good
+        await Scenario(x =>
+        {
+            x.Post.Json(new NumberMessage(3)).ToUrl("/problems2");
+            x.StatusCodeShouldBe(204);
+        });
+    }
+
+    [Fact]
+    public async Task stop_with_problems_if_middleware_trips_off_in_handler_acting_as_endpoint()
+    {
+        // This is the "sad path" that should spawn a ProblemDetails
+        // object
+        var result = await Scenario(x =>
+        {
+            x.Post.Json(new NumberMessage(10)).ToUrl("/problems2");
+            x.StatusCodeShouldBe(400);
+            x.ContentTypeShouldBe("application/problem+json");
+        });
+    }
 
     [Fact]
     public void adds_default_problem_details_to_open_api_metadata()
@@ -53,4 +78,28 @@ public void adds_default_problem_details_to_open_api_metadata()
         produces.StatusCode.ShouldBe(400);
         produces.ContentTypes.Single().ShouldBe("application/problem+json");
     }
+
+    [Fact]
+    public async Task problem_details_in_message_handlers_positive()
+    {
+        NumberMessageHandler.Handled = false;
+
+        var tracked = await Host.InvokeMessageAndWaitAsync(new NumberMessage(3));
+        tracked.Executed.SingleMessage<NumberMessage>()
+            .Number.ShouldBe(3);
+
+        NumberMessageHandler.Handled.ShouldBeTrue();
+    }
+
+    [Fact]
+    public async Task problem_details_in_message_handlers_negative()
+    {
+        NumberMessageHandler.Handled = false;
+
+        var tracked = await Host.InvokeMessageAndWaitAsync(new NumberMessage(10));
+        tracked.Executed.SingleMessage<NumberMessage>()
+            .Number.ShouldBe(10);
+
+        NumberMessageHandler.Handled.ShouldBeFalse();
+    }
 }

src/Http/Wolverine.Http/CodeGen/ProblemDetailsContinuationPolicy.cs

@@ -4,19 +4,36 @@
 using JasperFx.Core.Reflection;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.Extensions.Logging;
+using Newtonsoft.Json;
+using Wolverine.Configuration;
 using Wolverine.Middleware;
 
 namespace Wolverine.Http.CodeGen;
 
-internal class ProblemDetailsContinuationPolicy : IContinuationStrategy
+public class ProblemDetailsContinuationPolicy : IContinuationStrategy
 {
-    public bool TryFindContinuationHandler(MethodCall call, out Frame? frame)
+    public static void WriteProblems(ILogger logger, ProblemDetails details)
+    {
+        var json = JsonConvert.SerializeObject(details, Formatting.None);
+        logger.LogInformation("Found problems with this message: {Problems}", json);
+    }
+
+    public bool TryFindContinuationHandler(IChain chain, MethodCall call, out Frame? frame)
     {
         var details = call.Creates.FirstOrDefault(x => x.VariableType == typeof(ProblemDetails));
 
         if (details != null)
         {
-            frame = new MaybeEndWithProblemDetailsFrame(details);
+            if (chain is HttpChain)
+            {
+                frame = new MaybeEndWithProblemDetailsFrame(details);
+            }
+            else
+            {
+                frame = new MaybeEndHandlerWithProblemDetailsFrame(details);
+            }
+
             return true;
         }
 
@@ -39,13 +56,13 @@ public MaybeEndWithProblemDetailsFrame(Variable details)
         uses.Add(details);
         _details = details;
     }
-
+    
     public override IEnumerable<Variable> FindVariables(IMethodVariables chain)
     {
         _context = chain.FindVariable(typeof(HttpContext));
         yield return _context;
     }
-
+    
     public override void GenerateCode(GeneratedMethod method, ISourceWriter writer)
     {
         writer.WriteComment("Evaluate whether the processing should stop if there are any problems");
@@ -55,6 +72,40 @@ public override void GenerateCode(GeneratedMethod method, ISourceWriter writer)
         writer.FinishBlock();
         writer.BlankLine();
 
+        Next?.GenerateCode(method, writer);
+    }
+}
+
+/// <summary>
+/// Used to potentially stop the execution of an Http request
+/// based on whether the IResult is a WolverineContinue or something else
+/// </summary>
+public class MaybeEndHandlerWithProblemDetailsFrame : AsyncFrame
+{
+    private readonly Variable _details;
+    private Variable? _logger;
+
+    public MaybeEndHandlerWithProblemDetailsFrame(Variable details)
+    {
+        uses.Add(details);
+        _details = details;
+    }
+
+    public override IEnumerable<Variable> FindVariables(IMethodVariables chain)
+    {
+        _logger = chain.FindVariable(typeof(ILogger));
+        yield return _logger;
+    }
+
+    public override void GenerateCode(GeneratedMethod method, ISourceWriter writer)
+    {
+        writer.WriteComment("Evaluate whether the processing should stop if there are any problems");
+        writer.Write($"BLOCK:if (!(ReferenceEquals({_details.Usage}, {typeof(WolverineContinue).FullNameInCode()}.{nameof(WolverineContinue.NoProblems)})))");
+        writer.Write($"{typeof(ProblemDetailsContinuationPolicy).FullNameInCode()}.{nameof(ProblemDetailsContinuationPolicy.WriteProblems)}({_logger.Usage}, {_details.Usage});");
+        writer.Write("return;");
+        writer.FinishBlock();
+        writer.BlankLine();
+
         Next?.GenerateCode(method, writer);
     }
 }

src/Http/Wolverine.Http/CodeGen/ResultContinuationPolicy.cs

@@ -3,13 +3,14 @@
 using JasperFx.CodeGeneration.Model;
 using JasperFx.Core.Reflection;
 using Microsoft.AspNetCore.Http;
+using Wolverine.Configuration;
 using Wolverine.Middleware;
 
 namespace Wolverine.Http.CodeGen;
 
 internal class ResultContinuationPolicy : IContinuationStrategy
 {
-    public bool TryFindContinuationHandler(MethodCall call, out Frame? frame)
+    public bool TryFindContinuationHandler(IChain chain, MethodCall call, out Frame? frame)
     {
         var result = call.Creates.FirstOrDefault(x => x.VariableType.CanBeCastTo<IResult>());
 

src/Http/WolverineWebApi/ProblemDetailsUsage.cs

@@ -1,3 +1,4 @@
+using System.Diagnostics;
 using Microsoft.AspNetCore.Mvc;
 using Wolverine.Http;
 
@@ -31,4 +32,36 @@ public static string Post(NumberMessage message)
 
 public record NumberMessage(int Number);
 
-#endregion
+#endregion
+
+public static class NumberMessageHandler
+{
+    #region sample_using_problem_details_in_message_handler
+
+    public static ProblemDetails Validate(NumberMessage message)
+    {
+        if (message.Number > 5)
+        {
+            return new ProblemDetails
+            {
+                Detail = "Number is bigger than 5",
+                Status = 400
+            };
+        }
+
+        // All good, keep on going!
+        return WolverineContinue.NoProblems;
+    }
+
+    // Look at this! You can use this as an HTTP endpoint too!
+    [WolverinePost("/problems2")]
+    public static void Handle(NumberMessage message)
+    {
+        Debug.WriteLine("Handled " + message);
+        Handled = true;
+    }
+
+    #endregion
+
+    public static bool Handled { get; set; }
+}

src/Http/WolverineWebApi/Validation/ValidatedEndpoint.cs

@@ -1,3 +1,4 @@
+using System.Diagnostics;
 using FluentValidation;
 using Wolverine.Http;
 

src/Samples/Diagnostics/DiagnosticsApp/Invoices.cs

@@ -1,5 +1,6 @@
 using Wolverine;
 using Wolverine.Attributes;
+using Wolverine.Configuration;
 using Wolverine.ErrorHandling;
 using Wolverine.Runtime.Handlers;
 

src/Wolverine/Configuration/Chain.cs

@@ -238,7 +238,7 @@ protected void applyImpliedMiddlewareFromHandlers(GenerationRules generationRule
                 Middleware.Add(frame);
 
                 // Potentially add handling for IResult or HandlerContinuation
-                if (generationRules.TryFindContinuationHandler(frame, out var continuation))
+                if (generationRules.TryFindContinuationHandler(this, frame, out var continuation))
                 {
                     Middleware.Add(continuation!);
                 }

src/Wolverine/Middleware/ContinuationHandling.cs

@@ -1,5 +1,6 @@
 using JasperFx.CodeGeneration;
 using JasperFx.CodeGeneration.Frames;
+using Wolverine.Configuration;
 
 namespace Wolverine.Middleware;
 
@@ -41,11 +42,12 @@ public static List<IContinuationStrategy> ContinuationStrategies(this Generation
         }
     }
 
-    public static bool TryFindContinuationHandler(this GenerationRules rules, MethodCall call, out Frame? frame)
+    public static bool TryFindContinuationHandler(this GenerationRules rules, IChain chain, MethodCall call,
+        out Frame? frame)
     {
         var strategies = rules.ContinuationStrategies();
         foreach (var strategy in strategies)
-            if (strategy.TryFindContinuationHandler(call, out frame))
+            if (strategy.TryFindContinuationHandler(chain, call, out frame))
             {
                 return true;
             }
@@ -57,12 +59,12 @@ public static bool TryFindContinuationHandler(this GenerationRules rules, Method
 
 public interface IContinuationStrategy
 {
-    bool TryFindContinuationHandler(MethodCall call, out Frame? frame);
+    bool TryFindContinuationHandler(IChain chain, MethodCall call, out Frame? frame);
 }
 
 internal class HandlerContinuationPolicy : IContinuationStrategy
 {
-    public bool TryFindContinuationHandler(MethodCall call, out Frame? frame)
+    public bool TryFindContinuationHandler(IChain chain, MethodCall call, out Frame? frame)
     {
         if (call.CreatesNewOf<HandlerContinuation>())
         {

src/Wolverine/Middleware/MiddlewarePolicy.cs

@@ -143,19 +143,19 @@ public IEnumerable<Frame> BuildBeforeCalls(IChain chain, GenerationRules rules)
             foreach (var frame in frames) yield return frame;
         }
 
-        private IEnumerable<Frame> wrapBeforeFrame(MethodCall call, GenerationRules rules)
+        private IEnumerable<Frame> wrapBeforeFrame(IChain chain, MethodCall call, GenerationRules rules)
         {
             if (_finals.Length == 0)
             {
                 yield return call;
-                if (rules.TryFindContinuationHandler(call, out var frame))
+                if (rules.TryFindContinuationHandler(chain, call, out var frame))
                 {
                     yield return frame!;
                 }
             }
             else
             {
-                if (rules.TryFindContinuationHandler(call, out var frame))
+                if (rules.TryFindContinuationHandler(chain, call, out var frame))
                 {
                     call.Next = frame;
                 }
@@ -209,7 +209,7 @@ private IEnumerable<Frame> buildBefores(IChain chain, GenerationRules rules)
                 {
                     AssertMethodDoesNotHaveDuplicateReturnValues(call);
 
-                    foreach (var frame in wrapBeforeFrame(call, rules)) yield return frame;
+                    foreach (var frame in wrapBeforeFrame(chain, call, rules)) yield return frame;
                 }
             }
         }