Add support for email attachments in SendEmailCommand

Enhanced the email-sending workflow to support attachments:
- Updated `SendEmailCommand` with an `Attachments` property.
- Added `WithAttachments` method to handle attachment initialization.
- Modified `EmailsController` to accept file uploads via `IFormFileCollection`.
- Implemented `BuildAttachmentsAsync` to process uploaded files.
- Updated `EmailMappingProfile` to map `Attachments` to `EmailContext`.
- Adjusted `SendEmail` endpoint to consume `multipart/form-data`.
- Enhanced `SendEmail` response to include the queued event ID.
- Updated project file to include Swagger infrastructure folder.

These changes enable handling of email attachments and improve API functionality.

src/core/DigitalData.MessagingService.Application/Common/Mappings/EmailMappingProfile.cs

@@ -14,6 +14,7 @@ public class EmailMappingProfile : Profile
         // SendEmailCommand -> Email
         // Sender is resolved via MediatR in the handler and set separately after mapping.
         CreateMap<SendEmailCommand, EmailContext>()
-            .ForMember(dest => dest.Sender, opt => opt.Ignore());
+            .ForMember(dest => dest.Sender, opt => opt.Ignore())
+            .ForMember(dest => dest.Attachments, opt => opt.MapFrom(src => src.Attachments));
     }
 }

src/core/DigitalData.MessagingService.Application/EmailSending/Commands/SendEmailCommand.cs

@@ -3,6 +3,7 @@ using DigitalData.MessagingService.Application.EmailAccount.Queries;
 using DigitalData.MessagingService.Domain.Exceptions;
 using DigitalData.MessagingService.Abstraction;
 using MediatR;
+using System.Text.Json.Serialization;
 
 namespace DigitalData.MessagingService.Application.EmailSending.Commands;
 
@@ -32,6 +33,16 @@ public record SendEmailCommand : IRequest<Guid>
     /// Is HTML email (default: true)
     /// </summary>
     public bool IsHtml { get; init; } = true;
+
+    [JsonIgnore]
+    internal IEnumerable<EmailAttachmentContext> Attachments { get; private init; } = [];
+
+    /// <summary>
+    /// Returns a new command instance with the supplied attachments.
+    /// Called by the controller after resolving uploaded files.
+    /// </summary>
+    public SendEmailCommand WithAttachments(IEnumerable<EmailAttachmentContext> attachments)
+        => this with { Attachments = attachments };
 }
 
 /// <summary>

src/presentation/DigitalData.MessagingService.API/Controllers/EmailsController.cs

@@ -1,33 +1,64 @@
 using DigitalData.MessagingService.Application.EmailSending.Commands;
+using DigitalData.MessagingService.Abstraction;
 using MediatR;
 using Microsoft.AspNetCore.Mvc;
 
 namespace DigitalData.MessagingService.API.Controllers;
 
 /// <summary>
-/// Email sending API controller
-/// Enqueues outgoing emails to RabbitMQ for async processing
+/// Email sending API controller.
+/// Enqueues outgoing emails to RabbitMQ for async processing.
 /// </summary>
 [ApiController]
 [Route("api/[controller]")]
 public class EmailsController(IMediator mediator) : ControllerBase
 {
     /// <summary>
-    /// Send email (enqueue to RabbitMQ for background processing)
+    /// Send an email, optionally with file attachments.
+    /// Omit the <c>attachments</c> field for a plain send.
     /// </summary>
-    /// <param name="command">Send email command</param>
+    /// <param name="command">Email fields as form values</param>
+    /// <param name="attachments">Optional uploaded files</param>
     /// <param name="cancellationToken">Cancellation token</param>
-    /// <returns>HTTP 202 Accepted (queued for processing)</returns>
-    [HttpPost("send")]
+    /// <returns>HTTP 202 Accepted with the queued event ID</returns>
+    [HttpPost]
+    [Consumes("multipart/form-data")]
     [ProducesResponseType(StatusCodes.Status202Accepted)]
     [ProducesResponseType(StatusCodes.Status400BadRequest)]
-    public async Task<IActionResult> SendEmail([FromBody] SendEmailCommand command, CancellationToken cancellationToken)
+    public async Task<IActionResult> SendEmail(
+        [FromForm] SendEmailCommand command,
+        IFormFileCollection? attachments,
+        CancellationToken cancellationToken)
     {
-        var eventId = await mediator.Send(command, cancellationToken);
+        var commandWithAttachments = command.WithAttachments(
+            await BuildAttachmentsAsync(attachments, cancellationToken));
 
-        return Accepted(new
+        var eventId = await mediator.Send(commandWithAttachments, cancellationToken);
+        return Accepted(new { Id = eventId });
+    }
+
+    private static async Task<IEnumerable<EmailAttachmentContext>> BuildAttachmentsAsync(
+        IFormFileCollection? files,
+        CancellationToken cancellationToken)
+    {
+        if (files is null || files.Count == 0)
+            return [];
+
+        var result = new List<EmailAttachmentContext>(files.Count);
+
+        foreach (var file in files)
         {
-            Id = eventId
-        });
+            using var ms = new MemoryStream();
+            await file.CopyToAsync(ms, cancellationToken);
+
+            result.Add(new EmailAttachmentContext
+            {
+                FileName    = file.FileName,
+                Content     = ms.ToArray(),
+                ContentType = file.ContentType
+            });
+        }
+
+        return result;
     }
 }

src/presentation/DigitalData.MessagingService.API/DigitalData.MessagingService.API.csproj

@@ -36,4 +36,8 @@
     <ProjectReference Include="..\..\infrastructure\DigitalData.MessagingService.Infrastructure\DigitalData.MessagingService.Infrastructure.csproj" />
   </ItemGroup>
 
+  <ItemGroup>
+    <Folder Include="Infrastructure\Swagger\" />
+  </ItemGroup>
+
 </Project>