WebApi + ClientApp, GraphQL, Reflection

Events-WebApi/Events.FilesAPI/Features/Certificates/Download/CertificateFileLocator.cs

@@ -0,0 +1,32 @@
+using System.Globalization;
+using Events.FilesAPI.Infrastructure.Files;
+using Events.FilesAPI.Infrastructure.Options;
+using Microsoft.Extensions.Options;
+
+namespace Events.FilesAPI.Features.Certificates.Download;
+
+public sealed class CertificateFileLocator(
+  IHostEnvironment hostEnvironment,
+  IOptions<GeneratedFilesOptions> generatedFilesOptions)
+{
+  public GeneratedFileReference? TryGet(int eventId, int personId)
+  {
+    string rootPath = Path.IsPathRooted(generatedFilesOptions.Value.OutputPath)
+      ? generatedFilesOptions.Value.OutputPath
+      : Path.GetFullPath(Path.Combine(hostEnvironment.ContentRootPath, generatedFilesOptions.Value.OutputPath));
+
+    string certificatePath = Path.Combine(
+      rootPath,
+      eventId.ToString(CultureInfo.InvariantCulture),
+      $"{eventId}-{personId}.pdf");
+
+    if (!File.Exists(certificatePath))
+      return null;
+
+    return new GeneratedFileReference
+    {
+      FileName = Path.GetFileName(certificatePath),
+      PhysicalPath = certificatePath
+    };
+  }
+}

Events-WebApi/Events.FilesAPI/Features/Certificates/Download/DownloadCertificateHandler.cs

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+using Events.FilesAPI.Infrastructure.Files;
+using Events.FilesAPI.Features.Certificates.Synchronize;
+using Events.WebAPI.Handlers.EF.Data.Postgres;
+using MediatR;
+using Microsoft.EntityFrameworkCore;
+
+namespace Events.FilesAPI.Features.Certificates.Download;
+
+public sealed class DownloadCertificateHandler(
+  EventsContext context,
+  CertificateFileGenerator generator,
+  CertificateFileLocator fileLocator) : IRequestHandler<DownloadCertificateQuery, DownloadCertificateResult>
+{
+  public async Task<DownloadCertificateResult> Handle(DownloadCertificateQuery request, CancellationToken cancellationToken)
+  {
+    var registration = await context.Registrations
+      .AsNoTracking()
+      .Where(r => r.Id == request.RegistrationId)
+      .Select(r => new { r.EventId, r.PersonId })
+      .SingleOrDefaultAsync(cancellationToken);
+
+    if (registration == null)
+      return new DownloadCertificateResult(false, null);
+
+    GeneratedFileReference? file = fileLocator.TryGet(registration.EventId, registration.PersonId);
+
+    if (file == null)
+    {
+      await generator.GenerateAsync(registration.EventId, registration.PersonId, cancellationToken);
+      file = fileLocator.TryGet(registration.EventId, registration.PersonId);
+    }
+
+    return new DownloadCertificateResult(true, file);
+  }
+}

Events-WebApi/Events.FilesAPI/Features/Certificates/Download/DownloadCertificateQuery.cs

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+using Events.FilesAPI.Infrastructure.Files;
+using MediatR;
+
+namespace Events.FilesAPI.Features.Certificates.Download;
+
+public sealed record DownloadCertificateQuery(int RegistrationId) : IRequest<DownloadCertificateResult>;
+
+public sealed record DownloadCertificateResult(bool RegistrationFound, GeneratedFileReference? File);