Implemented missing file handling endpoints

Added contract update endpoint

PostFundManagement.Application/Services/Evidence/EvidenceService.cs

@@ -10,7 +10,7 @@ using PostFundManagement.Infrastructure.Database;
 namespace PostFundManagement.Application.Services.Evidence;
 
 public sealed class EvidenceService(IDbContextFactory<ApplicationDbContext> contextFactory, HashService hashService,
-    [FromKeyedServices(Constants.EvidenceBucketName)] IS3Service s3Service) : IEvidenceService
+    [FromKeyedServices(Constants.GeneralBucketName)] IS3Service s3Service) : IEvidenceService
 {
     public async ValueTask<Result> CreateEvidenceAsync(Guid userId, IFormCollection form, IFormFile file, CancellationToken cancellationToken = default) =>
         await Result.Try((Func<ValueTask<Result>>)(async () =>
@@ -22,13 +22,12 @@ public sealed class EvidenceService(IDbContextFactory<ApplicationDbContext> cont
 
             await using var stream = file.OpenReadStream();
 
-            var uploadResult = await s3Service.UploadFileAsync(file.FileName, stream, file.ContentType, cancellationToken);
+            var uploadResult = await s3Service.UploadFileAsync(file.FileName, "evidence", stream, 
+                file.ContentType, cancellationToken);
 
             if (uploadResult.IsFailed)
                 return Result.Fail(uploadResult.Errors);
 
-            var documentUrl = uploadResult.Value;
-
             await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);
 
             var evidence = new Domain.Entities.Evidence
@@ -41,7 +40,7 @@ public sealed class EvidenceService(IDbContextFactory<ApplicationDbContext> cont
                 CreatedAt = DateTime.UtcNow,
                 Version = 1,
                 Type = type,
-                DocumentUrl = documentUrl,
+                DocumentUrl = uploadResult.Value,
                 Status = ApprovalStatus.Pending
             };
 
@@ -238,4 +237,31 @@ public sealed class EvidenceService(IDbContextFactory<ApplicationDbContext> cont
 
             return Result.OkIf(changedTotal > 0, UpdateError.New);
         }));
+
+    public async ValueTask<Result<string>> GetEvidenceUrlAsync(string evidenceIdHash, CancellationToken cancellationToken = default) =>
+        await Result.Try((Func<ValueTask<Result<string>>>)(async () =>
+        {
+            var decodeResult = hashService.DecodeLongIdHash(evidenceIdHash);
+
+            if (decodeResult.IsFailed)
+                return Result.Fail(IdDecodeError.Create()
+                    .CausedBy(decodeResult.Errors));
+
+            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);
+
+            var evidence = await context.Evidences.AsNoTracking().FirstOrDefaultAsync(e => e.Id == decodeResult.Value, cancellationToken);
+
+            if (evidence is null)
+                return Result.Fail<string>(NotFoundError.New);
+
+            if (string.IsNullOrWhiteSpace(evidence.DocumentUrl))
+                return Result.Fail<string>(ValidationError.Create("Ecidence is invalid, has no saved documentUrl"));
+
+            var secureDownloadUrlResult = await s3Service.GeneratePresignedUrlAsync(evidence.DocumentUrl, 
+                TimeSpan.FromMinutes(15), null, cancellationToken);
+
+            return Result.OkIf(secureDownloadUrlResult.IsSuccess && !string.IsNullOrWhiteSpace(secureDownloadUrlResult.Value), 
+                NotFoundError.Create("Failed to generate secure file url"))
+                    .ToResult(secureDownloadUrlResult.Value);
+        }));
 }