EnvelopeGenerator/EnvelopeGenerator.API/Controllers/DocumentController.cs

using DigitalData.Core.Exceptions;
using EnvelopeGenerator.Application.Common.Extensions;
using EnvelopeGenerator.Application.EnvelopeReceivers.Queries;
using EnvelopeGenerator.Domain.Constants;
using MediatR;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;

namespace EnvelopeGenerator.API.Controllers;

/// <summary>
/// Provides access to envelope documents for authenticated receivers.
/// </summary>
/// <remarks>
/// Initializes a new instance of the <see cref="DocumentController"/> class.
/// </remarks>
[Authorize(Roles = ReceiverRole.FullyAuth)]
[ApiController]
[Route("api/[controller]")]
public class DocumentController(IMediator mediator, ILogger<DocumentController> logger) : ControllerBase
{
    /// <summary>
    /// Returns the document bytes for the specified envelope receiver key.
    /// </summary>
    /// <param name="query">Encoded envelope key.</param>
    /// <param name="cancel">Cancellation token.</param>
    [HttpGet]
    public async Task<IActionResult> GetDocument(ReadEnvelopeReceiverQuery query, CancellationToken cancel)
    {
        var envRcv = await mediator.Send(query, cancel).FirstAsync(Exceptions.NotFound);

        var byteData = envRcv.Envelope?.Documents?.FirstOrDefault()?.ByteData;

        if (byteData is null || byteData.Length == 0)
        {
            logger.LogError("Document byte data is null or empty for envelope-receiver entity:\n{envelopeKey}.",
                envRcv.ToJson(Format.Json.ForDiagnostics));
            throw new NotFoundException("Document is empty.");
        }

        return File(byteData, "application/octet-stream");
    }
}