[ADD] Added endpoint for providing files

Manager.App/Services/LibraryService.cs

@@ -1,3 +1,4 @@
+using System.Net.Mime;
 using DotBased.Monads;
 using Manager.App.Constants;
 using Manager.App.Models.Library;
@@ -51,7 +52,7 @@ public class LibraryService : ILibraryService
         }
         catch (Exception e)
         {
-            return ResultError.Error(e);
+            return HandleException(e);
         }
         
         return Result.Success();
@@ -134,7 +135,27 @@ public class LibraryService : ILibraryService
         }
         catch (Exception e)
         {
-            return ResultError.Error(e);
+            return HandleException(e);
+        }
+    }
+
+    public async Task<Result<LibraryFile>> GetFileByIdAsync(Guid id, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            await using var context = await _dbContextFactory.CreateDbContextAsync(cancellationToken);
+            var file = context.Files.FirstOrDefault(f => f.Id == id);
+            if (file == null)
+            {
+                return ResultError.Fail($"File with id {id} not found.");
+            }
+            
+            var fs = new FileStream(Path.Combine(_libraryDirectory.FullName, file.RelativePath), FileMode.Open, FileAccess.Read, FileShare.Read);
+            return new LibraryFile { DataStream = fs, SizeBytes = file.SizeBytes, FileName = file.OriginalFileName ?? file.Id.ToString(), MimeType = file.MimeType ?? MediaTypeNames.Application.Octet };
+        }
+        catch (Exception e)
+        {
+            return HandleException(e);
         }
     }
 
@@ -285,7 +306,7 @@ public class LibraryService : ILibraryService
         }
         catch (Exception e)
         {
-            return ResultError.Error(e);
+            return HandleException(e);
         }
     }
 
@@ -344,7 +365,7 @@ public class LibraryService : ILibraryService
             return ResultError.Fail("Library service operation cancelled");
         }
 
-        _logger.LogError(exception, "Failed to get library information");
+        _logger.LogError(exception, "Service error");
         return ResultError.Fail("Failed to get library information");
     }
 }