Support cases where filename is entirely in the nzb file subject.

Author: nzbdav-dev

backend/Extensions/NzbFileExtensions.cs

@@ -18,7 +18,8 @@ public static string GetSubjectFileName(this NzbFile file)
         return GetFirstValidNonEmptyFilename(
             () => TryParseFilename1(file),
             () => TryParseFilename2(file),
-            () => TryParseFilename3(file)
+            () => TryParseFilename3(file),
+            () => TryParseFilename4(file)
         );
     }
 
@@ -47,6 +48,13 @@ private static string TryParseFilename3(this NzbFile file)
         return match.Success ? match.Groups[1].Value : "";
     }
 
+    private static string TryParseFilename4(this NzbFile file)
+    {
+        // example: `file.mkv` — no spaces allowed
+        var match = Regex.Match(file.Subject, @"^[^\s]+\.\w{2,6}$");
+        return match.Success ? match.Value : "";
+    }
+
     private static string GetFirstValidNonEmptyFilename(params Func<string>[] funcs)
     {
         return funcs

backend/Services/FileProcessors/FileProcessor.cs

@@ -17,7 +17,7 @@ public static bool CanProcess(NzbFile file)
         var firstSegment = nzbFile.Segments[0].MessageId.Value;
         var header = await usenet.GetSegmentYencHeaderAsync(firstSegment, default);
         var subjectFilename = nzbFile.GetSubjectFileName();
-        var fileName = Path.GetFileName(subjectFilename != "" ? subjectFilename : header.FileName);
+        var fileName = GetFileName(subjectFilename, header.FileName);
 
         return new Result()
         {
@@ -27,6 +27,17 @@ public static bool CanProcess(NzbFile file)
         };
     }
 
+    private static string GetFileName(string subjectFilename, string headerFilename)
+    {
+        // prioritize the subject filename with fallback to header filename
+        // unless the header filename has an `.mkv` extension while the subject filename doesn't.
+        subjectFilename = Path.GetFileName(subjectFilename);
+        headerFilename = Path.GetFileName(headerFilename);
+        if (subjectFilename != "" && Path.GetExtension(subjectFilename) == ".mkv") return subjectFilename;
+        if (headerFilename != "" && Path.GetExtension(headerFilename) == ".mkv") return headerFilename;
+        return subjectFilename != "" ? subjectFilename : headerFilename;
+    }
+
     public new class Result : BaseProcessor.Result
     {
         public NzbFile NzbFile { get; init; } = null!;