Refactor DIExtensions and add exception handling middleware

- Improved documentation in DIExtensions.cs for clarity.
- Added project reference to DigitalData.Core.Exceptions.
- Updated solution file to include DigitalData.Core.Exceptions.
- Introduced ExceptionHandlingMiddleware for global exception handling.
- Added BadRequestException and NotFoundException classes.
- Created DigitalData.Core.Exceptions project with .NET 7.0, 8.0, and 9.0 support.

DigitalData.Core.API/DIExtensions.cs

@@ -1,53 +1,50 @@
-using Microsoft.AspNetCore.Builder;
+namespace DigitalData.Core.API;
-using System.Configuration;
 
-namespace DigitalData.Core.API
+/// <summary>
+/// Provides extension methods for adding middleware to the application's request pipeline.
+/// </summary>
+public static class DIExtensions
 {
     /// <summary>
-    /// Provides extension methods for adding middleware to the application's request pipeline.
+    /// Adds the <see cref="CSPMiddleware"/> to the application's request pipeline to include 
+    /// Content Security Policy (CSP) headers in the HTTP response.
     /// </summary>
-    public static class DIExtensions
+    /// <param name="app">The application builder.</param>
-    {
+    /// <param name="policy">
-        /// <summary>
+    /// The CSP policy string with placeholders. The first format parameter {0} will be replaced 
-        /// Adds the <see cref="CSPMiddleware"/> to the application's request pipeline to include 
+    /// by the nonce value.
-        /// Content Security Policy (CSP) headers in the HTTP response.
+    /// </param>
-        /// </summary>
+    /// <returns>The application builder with the CSP middleware added.</returns>
-        /// <param name="app">The application builder.</param>
+    public static IApplicationBuilder UseCSPMiddleware(this IApplicationBuilder app, string policy)
-        /// <param name="policy">
+        => app.UseMiddleware<CSPMiddleware>(policy);
-        /// The CSP policy string with placeholders. The first format parameter {0} will be replaced 
-        /// by the nonce value.
-        /// </param>
-        /// <returns>The application builder with the CSP middleware added.</returns>
-        public static IApplicationBuilder UseCSPMiddleware(this IApplicationBuilder app, string policy)
-            => app.UseMiddleware<CSPMiddleware>(policy);
 
-        /// <summary>
+    /// <summary>
-        /// Checks if the DiP (Development in Production) mode is enabled for the WebApplicationBuilder.
+    /// Checks if the DiP (Development in Production) mode is enabled for the WebApplicationBuilder.
-        /// </summary>
+    /// </summary>
-        /// <param name="builder">The WebApplicationBuilder instance.</param>
+    /// <param name="builder">The WebApplicationBuilder instance.</param>
-        /// <returns>True if DiP mode is enabled; otherwise, false.</returns>
+    /// <returns>True if DiP mode is enabled; otherwise, false.</returns>
-        public static bool IsDiP(this WebApplicationBuilder builder) => builder.Configuration.GetValue<bool>("DiPMode");
+    public static bool IsDiP(this WebApplicationBuilder builder) => builder.Configuration.GetValue<bool>("DiPMode");
 
-        /// <summary>
+    /// <summary>
-        /// Checks if the DiP (Development in Production) mode is enabled for the WebApplication.
+    /// Checks if the DiP (Development in Production) mode is enabled for the WebApplication.
-        /// </summary>
+    /// </summary>
-        /// <param name="app">The WebApplication instance.</param>
+    /// <param name="app">The WebApplication instance.</param>
-        /// <returns>True if DiP mode is enabled; otherwise, false.</returns>
+    /// <returns>True if DiP mode is enabled; otherwise, false.</returns>
-        public static bool IsDiP(this WebApplication app) => app.Configuration.GetValue<bool>("DiPMode");
+    public static bool IsDiP(this WebApplication app) => app.Configuration.GetValue<bool>("DiPMode");
 
-        /// <summary>
+    /// <summary>
-        /// Checks if the environment is Development or DiP (Development in Production) mode is enabled for the WebApplicationBuilder.
+    /// Checks if the environment is Development or DiP (Development in Production) mode is enabled for the WebApplicationBuilder.
-        /// </summary>
+    /// </summary>
-        /// <param name="builder">The WebApplicationBuilder instance.</param>
+    /// <param name="builder">The WebApplicationBuilder instance.</param>
-        /// <returns>True if the environment is Development or DiP mode is enabled; otherwise, false.</returns>
+    /// <returns>True if the environment is Development or DiP mode is enabled; otherwise, false.</returns>
-        public static bool IsDevOrDiP(this WebApplicationBuilder builder) => builder.Environment.IsDevelopment() || builder.IsDiP();
+    public static bool IsDevOrDiP(this WebApplicationBuilder builder) => builder.Environment.IsDevelopment() || builder.IsDiP();
 
-        /// <summary>
+    /// <summary>
-        /// Checks if the environment is Development or DiP (Development in Production) mode is enabled for the WebApplication.
+    /// Checks if the environment is Development or DiP (Development in Production) mode is enabled for the WebApplication.
-        /// </summary>
+    /// </summary>
-        /// <param name="app">The WebApplication instance.</param>
+    /// <param name="app">The WebApplication instance.</param>
-        /// <returns>True if the environment is Development or DiP mode is enabled; otherwise, false.</returns>
+    /// <returns>True if the environment is Development or DiP mode is enabled; otherwise, false.</returns>
-        public static bool IsDevOrDiP(this WebApplication app) => app.Environment.IsDevelopment() || app.IsDiP();
+    public static bool IsDevOrDiP(this WebApplication app) => app.Environment.IsDevelopment() || app.IsDiP();
 
 		/// <summary>
 		/// Configures the services with options from the specified section of the appsettings.json file.
@@ -66,4 +63,3 @@ namespace DigitalData.Core.API
 			return builder;
 		}
 	}
-}

DigitalData.Core.API/DigitalData.Core.API.csproj

@@ -33,6 +33,7 @@
 
   <ItemGroup>
     <ProjectReference Include="..\DigitalData.Core.Application\DigitalData.Core.Application.csproj" />
+    <ProjectReference Include="..\DigitalData.Core.Exceptions\DigitalData.Core.Exceptions.csproj" />
   </ItemGroup>
 
   <ItemGroup>

DigitalData.Core.API/ExceptionHandlingMiddleware.cs

@@ -0,0 +1,84 @@
+namespace DigitalData.Core.API;
+
+using DigitalData.Core.Exceptions;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Logging;
+using System.Net;
+using System.Text.Json;
+
+/// <summary>
+/// Middleware for handling exceptions globally in the application.
+/// Captures exceptions thrown during the request pipeline execution,
+/// logs them, and returns an appropriate HTTP response with a JSON error message.
+/// </summary>
+public class ExceptionHandlingMiddleware
+{
+    private readonly RequestDelegate _next;
+    private readonly ILogger<ExceptionHandlingMiddleware> _logger;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ExceptionHandlingMiddleware"/> class.
+    /// </summary>
+    /// <param name="next">The next middleware in the request pipeline.</param>
+    /// <param name="logger">The logger instance for logging exceptions.</param>
+    public ExceptionHandlingMiddleware(RequestDelegate next, ILogger<ExceptionHandlingMiddleware> logger)
+    {
+        _next = next;
+        _logger = logger;
+    }
+
+    /// <summary>
+    /// Invokes the middleware to handle the HTTP request.
+    /// </summary>
+    /// <param name="context">The HTTP context of the current request.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
+    public async Task InvokeAsync(HttpContext context)
+    {
+        try
+        {
+            await _next(context); // Continue down the pipeline
+        }
+        catch (Exception ex)
+        {
+            await HandleExceptionAsync(context, ex, _logger);
+        }
+    }
+
+    /// <summary>
+    /// Handles exceptions by logging them and writing an appropriate JSON response.
+    /// </summary>
+    /// <param name="context">The HTTP context of the current request.</param>
+    /// <param name="exception">The exception that occurred.</param>
+    /// <param name="logger">The logger instance for logging the exception.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
+    private static async Task HandleExceptionAsync(HttpContext context, Exception exception, ILogger logger)
+    {
+        context.Response.ContentType = "application/json";
+
+        string message;
+
+        switch (exception)
+        {
+            case BadRequestException badRequestEx:
+                context.Response.StatusCode = (int)HttpStatusCode.BadRequest;
+                message = badRequestEx.Message;
+                break;
+
+            case NotFoundException notFoundEx:
+                context.Response.StatusCode = (int)HttpStatusCode.NotFound;
+                message = notFoundEx.Message;
+                break;
+
+            default:
+                logger.LogError(exception, "Unhandled exception occurred.");
+                context.Response.StatusCode = (int)HttpStatusCode.InternalServerError;
+                message = "An unexpected error occurred.";
+                break;
+        }
+
+        await context.Response.WriteAsync(JsonSerializer.Serialize(new
+        {
+            message
+        }));
+    }
+}

DigitalData.Core.Exceptions/BadRequestException.cs

@@ -0,0 +1,22 @@
+namespace DigitalData.Core.Exceptions;
+
+/// <summary>
+/// Represents an exception that is thrown when a bad request is encountered.
+/// </summary>
+public class BadRequestException : Exception
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="BadRequestException"/> class.
+    /// </summary>
+    public BadRequestException()
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="BadRequestException"/> class with a specified error message.
+    /// </summary>
+    /// <param name="message">The message that describes the error.</param>
+    public BadRequestException(string? message) : base(message)
+    {
+    }
+}

DigitalData.Core.Exceptions/DigitalData.Core.Exceptions.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFrameworks>net7.0;net8.0;net9.0</TargetFrameworks>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

DigitalData.Core.Exceptions/NotFoundException.cs

@@ -0,0 +1,22 @@
+namespace DigitalData.Core.Exceptions;
+
+/// <summary>
+/// Represents an exception that is thrown when a requested resource is not found.
+/// </summary>
+public class NotFoundException : Exception
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="NotFoundException"/> class.
+    /// </summary>
+    public NotFoundException()
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="NotFoundException"/> class with a specified error message.
+    /// </summary>
+    /// <param name="message">The message that describes the error.</param>
+    public NotFoundException(string? message) : base(message)
+    {
+    }
+}

DigitalData.Core.sln

@@ -39,6 +39,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "DigitalData.Core.Infrastruc
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Infrastructure", "Infrastructure", "{41795B74-A757-4E93-B907-83BFF04EEE5C}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "DigitalData.Core.Exceptions", "DigitalData.Core.Exceptions\DigitalData.Core.Exceptions.csproj", "{BAEF6CC9-4FE2-4E3F-9D32-911C9E8CCFB4}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -100,6 +102,10 @@ Global
 		{CE00E1F7-2771-4D9C-88FB-E564894E539E}.Debug|Any CPU.Build.0 = Release|Any CPU
 		{CE00E1F7-2771-4D9C-88FB-E564894E539E}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{CE00E1F7-2771-4D9C-88FB-E564894E539E}.Release|Any CPU.Build.0 = Release|Any CPU
+		{BAEF6CC9-4FE2-4E3F-9D32-911C9E8CCFB4}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{BAEF6CC9-4FE2-4E3F-9D32-911C9E8CCFB4}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{BAEF6CC9-4FE2-4E3F-9D32-911C9E8CCFB4}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{BAEF6CC9-4FE2-4E3F-9D32-911C9E8CCFB4}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -121,6 +127,7 @@ Global
 		{C9266749-9504-4EA9-938F-F083357B60B7} = {72CBAFBA-55CC-49C9-A484-F8F4550054CB}
 		{CE00E1F7-2771-4D9C-88FB-E564894E539E} = {41795B74-A757-4E93-B907-83BFF04EEE5C}
 		{41795B74-A757-4E93-B907-83BFF04EEE5C} = {02EA681E-C7D8-13C7-8484-4AC65E1B71E8}
+		{BAEF6CC9-4FE2-4E3F-9D32-911C9E8CCFB4} = {02EA681E-C7D8-13C7-8484-4AC65E1B71E8}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {8E2C3187-F848-493A-9E79-56D20DDCAC94}