From 0700241ed05deb44e030dc91e25e0e47b56e65f5 Mon Sep 17 00:00:00 2001
From: Enzo Thomazi Lucas <enzotlucas31@gmail.com>
Date: Fri, 1 Dec 2023 00:46:08 -0300
Subject: [PATCH] feat: Implementing error handling middleware

---
 .../ApplicationBuilderExtensions.cs           |  5 +-
 .../Middlewares/ErrorHandlingMiddleware.cs    | 87 +++++++++++++++++--
 2 files changed, 85 insertions(+), 7 deletions(-)

diff --git a/src/shared/Example.EventDriven.DependencyInjection/ApplicationBuilderExtensions.cs b/src/shared/Example.EventDriven.DependencyInjection/ApplicationBuilderExtensions.cs
index a147747..33eab96 100644
--- a/src/shared/Example.EventDriven.DependencyInjection/ApplicationBuilderExtensions.cs
+++ b/src/shared/Example.EventDriven.DependencyInjection/ApplicationBuilderExtensions.cs
@@ -1,4 +1,5 @@
-using Example.EventDriven.DependencyInjection.Swagger;
+using Example.EventDriven.DependencyInjection.Middlewares;
+using Example.EventDriven.DependencyInjection.Swagger;
 using Microsoft.AspNetCore.Builder;
 using System.Diagnostics.CodeAnalysis;
 
@@ -17,6 +18,8 @@ public static IApplicationBuilder UseApiDependencyInjection(this IApplicationBui
 
             app.UseSwaggerConfiguration();
 
+            app.UseMiddleware<ErrorHandlingMiddleware>();
+
             return app;
         }
 
diff --git a/src/shared/Example.EventDriven.DependencyInjection/Middlewares/ErrorHandlingMiddleware.cs b/src/shared/Example.EventDriven.DependencyInjection/Middlewares/ErrorHandlingMiddleware.cs
index a7c7562..394c06b 100644
--- a/src/shared/Example.EventDriven.DependencyInjection/Middlewares/ErrorHandlingMiddleware.cs
+++ b/src/shared/Example.EventDriven.DependencyInjection/Middlewares/ErrorHandlingMiddleware.cs
@@ -1,13 +1,88 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
+using Example.EventDriven.Domain.Exceptions;
+using Example.EventDriven.Domain.Gateways.Logger;
+using FluentValidation;
+using Microsoft.AspNetCore.Http;
+using Newtonsoft.Json;
+using System.Net;
 
 namespace Example.EventDriven.DependencyInjection.Middlewares
 {
-    public class ErrorHandlingMiddleware
+    public sealed class ErrorHandlingMiddleware
     {
+        private readonly ILoggerManager _logger;
+        private readonly RequestDelegate _next;
 
+        public ErrorHandlingMiddleware(ILoggerManager logger, RequestDelegate next)
+        {
+            _logger = logger;
+            _next = next;
+        }
+
+        public async Task InvokeAsync(HttpContext context)
+        {
+            try
+            {
+                await _next(context);
+            }
+            catch (BusinessException ex)
+            {
+                _logger.Log("Business error caught by middleware", LoggerManagerSeverity.WARNING, ("exception", ex));
+
+                await HandleExceptionAsync(context, ex);
+            }
+            catch (ValidationException ex)
+            {
+                _logger.Log("Validation error caught by middleware", LoggerManagerSeverity.WARNING, ("exception", ex));
+
+                await HandleExceptionAsync(context, ex);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogException("Unexpected error caught by middleware", LoggerManagerSeverity.ERROR, ex);
+
+                await HandleExceptionAsync(context);
+            }
+        }
+
+        private static Task HandleExceptionAsync(HttpContext context, BusinessException exception)
+        {
+            var code = HttpStatusCode.BadRequest;
+
+            var result = JsonConvert.SerializeObject(new { Errors = new string[1] { exception.Message } });
+
+            return ErrorResponse(context, result, code);
+        }
+
+        private static Task HandleExceptionAsync(HttpContext context, ValidationException exception)
+        {
+            var code = HttpStatusCode.BadRequest;
+
+            var result = JsonConvert.SerializeObject(new { Errors = exception.Errors.Select(e => e.ErrorMessage).ToArray() });
+
+            return ErrorResponse(context, result, code);
+        }
+
+        private static Task HandleExceptionAsync(HttpContext context)
+        {
+            var code = HttpStatusCode.InternalServerError;
+
+            return ErrorResponse(context, code);
+        }
+
+        private static Task ErrorResponse(HttpContext context, HttpStatusCode code)
+        {
+            var result = JsonConvert.SerializeObject(new { Errors = new string[1] { "UnexpectedError" } });
+
+            return ErrorResponse(context, result, code);
+        }
+
+        private static Task ErrorResponse(HttpContext context, string result, HttpStatusCode code)
+        {
+            context.Response.ContentType = "application/json";
+
+            context.Response.StatusCode = (int)code;
+
+            return context.Response.WriteAsync(result);
+        }
     }
 }