Fix double-tagging when file already has a release prefix

Fansub descriptor brackets like [Multiple Subtitle] or [Dual Audio]
were being misread as release group names because their individual
words didn't match any known metadata pattern. This caused a bogus
tag to be stacked in front of files that already carried their own
[Group] prefix (e.g. Erai-raws releases).

- Recognize common multi-word fansub descriptors (Multi(ple) Sub(s),
  Dual/Multi Audio, Hard/Soft sub, Uncensored/Batch/Complete, etc.)
  as metadata via whole-phrase matching in IsMetadataBracket.
- Never prepend a derived release tag when the file's own filename
  already starts with a different bracket prefix, preventing any
  tag from being stacked on top of an existing one.

Futonizer.csproj

@@ -9,8 +9,8 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <AssemblyName>Futonizer</AssemblyName>
     <RootNamespace>Futonizer</RootNamespace>
-    <Version>1.0.8</Version>
-    <FileVersion>1.0.8.0</FileVersion>
+    <Version>1.0.10</Version>
+    <FileVersion>1.0.10.0</FileVersion>
     <ApplicationIcon>Assets\app.ico</ApplicationIcon>
   </PropertyGroup>
 

Services/FileNameHelper.cs

@@ -14,11 +14,21 @@ public static class FileNameHelper
     private static readonly Regex FolderSuffixTagRegex =
         new(@"-([A-Z][A-Z0-9]{1,7})$", RegexOptions.Compiled);
 
+    // Folder suffix bracket release tag:  "Show Name ... x264 [i_c]"  →  tag = "i_c"
+    // A bracketed tag at the very end of the folder name (as opposed to
+    // PrefixTagRegex, which matches one at the start).
+    private static readonly Regex FolderSuffixBracketTagRegex =
+        new(@"\[([^\[\]]+)\]$", RegexOptions.Compiled);
+
     // File suffix release tag:  "…HEVC-DemiHuman"  →  tag = "DemiHuman"
     // Mixed case, 3-21 chars (no dots/spaces), at end of filename stem.
-    // Min 3 chars avoids false-positives like "-v2" or "-HD".
+    // Min 3 chars avoids false-positives like "-v2" or "-HD". The word
+    // immediately preceding the dash must itself be recognisable quality/
+    // source/codec metadata (checked by the caller via IsMetadataToken), so
+    // an ordinary hyphenated title word (e.g. "Scary-oke") is never mistaken
+    // for a "-GroupName" suffix.
     private static readonly Regex FileSuffixTagRegex =
-        new(@"-([A-Za-z][A-Za-z0-9]{2,20})$", RegexOptions.Compiled);
+        new(@"(?:^|[\s.])([A-Za-z0-9]+)-([A-Za-z][A-Za-z0-9]{2,20})$", RegexOptions.Compiled);
 
     // Trailing parenthesised metadata block ending in the release group as its
     // last word, e.g. "... (1080p AMZN WEB-DL x265 Celdra)" → group="Celdra".
@@ -57,6 +67,19 @@ public static class FileNameHelper
         new(@"^(HDR|SDR|10bit|8bit|HDR10|DV|DoVi)$",                              RegexOptions.IgnoreCase | RegexOptions.Compiled), // HDR / bit-depth
     ];
 
+    // Whole-phrase fansub/release descriptor patterns, checked against an
+    // entire bracket's contents rather than word-by-word. Catches common
+    // multi-word descriptors (e.g. "Multiple Subtitle", "Dual Audio") whose
+    // individual words wouldn't otherwise match any MetadataPatterns entry,
+    // so they'd be mistaken for a release group name.
+    private static readonly Regex[] DescriptorPhrasePatterns =
+    [
+        new(@"^Multi(ple)?[\s-]?Sub(s|title|titles)?$", RegexOptions.IgnoreCase | RegexOptions.Compiled),
+        new(@"^(Dual|Multi)[\s-]?Audio$",                RegexOptions.IgnoreCase | RegexOptions.Compiled),
+        new(@"^(Hard|Soft)[\s-]?sub(s)?$",               RegexOptions.IgnoreCase | RegexOptions.Compiled),
+        new(@"^(Uncensored|Censored|Batch|Complete)$",   RegexOptions.IgnoreCase | RegexOptions.Compiled),
+    ];
+
     // -------------------------------------------------------------------------
 
     /// <summary>
@@ -85,14 +108,25 @@ public static class FileNameHelper
         string? folder     = Path.GetDirectoryName(sourceFilePath);
         string folderName  = string.IsNullOrEmpty(folder) ? "" : (Path.GetFileName(folder) ?? "");
 
+        // Capture the file's own pre-existing bracket prefix (if any) before any
+        // transformation below, so we never stack a second/different tag on top
+        // of a file that already carries its own release-group prefix.
+        var originalPrefixMatch = PrefixTagRegex.Match(stemNoExt);
+        string? originalPrefixTag = originalPrefixMatch.Success ? originalPrefixMatch.Groups[1].Value : null;
+
         // 1. Extract in-filename suffix tag and remove it from the stem.
-        //    e.g. "...HEVC-DemiHuman" → tag="DemiHuman", stem="...HEVC"
+        //    e.g. "...x264-DemiHuman" → tag="DemiHuman", stem="...x264"
+        //    Only fires when the word right before the dash is itself a
+        //    recognised metadata token (codec/source/etc.), so ordinary
+        //    hyphenated title words are left alone.
         string? fileTag = null;
         var fileSuffixMatch = FileSuffixTagRegex.Match(stemNoExt);
-        if (fileSuffixMatch.Success)
+        if (fileSuffixMatch.Success
+            && IsMetadataToken(fileSuffixMatch.Groups[1].Value)
+            && !IsMetadataToken(fileSuffixMatch.Groups[2].Value))
         {
-            fileTag  = fileSuffixMatch.Groups[1].Value;
-            stemNoExt = stemNoExt[..fileSuffixMatch.Index];
+            fileTag  = fileSuffixMatch.Groups[2].Value;
+            stemNoExt = stemNoExt[..(fileSuffixMatch.Groups[2].Index - 1)];
             fileName  = stemNoExt + ext;
         }
         else
@@ -157,29 +191,44 @@ public static class FileNameHelper
             }
         }
 
-        // 4. Prepend release tag if not already present.
+        // 4. Prepend release tag if not already present. Skip when the file
+        //    already carries its own (different) bracket prefix — never stack
+        //    a second tag on top of an existing one.
         if (!string.IsNullOrEmpty(tag))
+        {
+            bool differsFromOriginalTag = originalPrefixTag != null
+                && !string.Equals(originalPrefixTag, tag, StringComparison.OrdinalIgnoreCase);
+
+            if (!differsFromOriginalTag)
             {
                 string tagPrefix = $"[{tag}]";
                 if (!fileName.StartsWith(tagPrefix, StringComparison.OrdinalIgnoreCase))
                     fileName = tagPrefix + " " + fileName;
             }
+        }
 
         return fileName;
     }
 
     /// <summary>
-    /// Extracts the release tag string (without brackets) from a folder name.
-    /// Suffix pattern (<c>-TAG</c>) takes priority over prefix pattern
-    /// (<c>[TAG]</c>).  Returns <c>null</c> when neither is present.
+    /// Extracts the release tag string (without brackets) from a folder name,
+    /// checking (in priority order): a dash suffix (<c>-TAG</c>), a bracketed
+    /// suffix (<c>[tag]</c> at the end), then a bracketed prefix (<c>[tag]</c>
+    /// at the start). Returns <c>null</c> when none are present.
     /// </summary>
     public static string? ExtractReleaseTag(string folderName)
     {
         var suffixMatch = FolderSuffixTagRegex.Match(folderName);
-        if (suffixMatch.Success) return suffixMatch.Groups[1].Value;
+        if (suffixMatch.Success && !IsMetadataToken(suffixMatch.Groups[1].Value))
+            return suffixMatch.Groups[1].Value;
+
+        var bracketSuffixMatch = FolderSuffixBracketTagRegex.Match(folderName);
+        if (bracketSuffixMatch.Success && !IsMetadataBracket(bracketSuffixMatch.Groups[1].Value))
+            return bracketSuffixMatch.Groups[1].Value;
 
         var prefixMatch = PrefixTagRegex.Match(folderName);
-        if (prefixMatch.Success) return prefixMatch.Groups[1].Value;
+        if (prefixMatch.Success && !IsMetadataBracket(prefixMatch.Groups[1].Value))
+            return prefixMatch.Groups[1].Value;
 
         return null;
     }
@@ -198,6 +247,7 @@ public static class FileNameHelper
     {
         // Strip release tags first.
         string name = FolderSuffixTagRegex.Replace(folderName, "").Trim();
+        name = FolderSuffixBracketTagRegex.Replace(name, "").Trim();
         name = PrefixTagRegex.Replace(name, "").Trim();
 
         // Nothing left, or what remains immediately starts with a bracket — no show name.
@@ -226,4 +276,19 @@ public static class FileNameHelper
             if (pattern.IsMatch(token)) return true;
         return false;
     }
+
+    /// <summary>
+    /// True when every word inside a bracketed block is recognisable quality/
+    /// source/codec metadata (e.g. "[HEVC]", "[1080p-FLAC]"), meaning it's
+    /// just another metadata tag rather than an actual release group name
+    /// (e.g. "[i_c]").
+    /// </summary>
+    private static bool IsMetadataBracket(string content)
+    {
+        string trimmed = content.Trim();
+        if (DescriptorPhrasePatterns.Any(p => p.IsMatch(trimmed))) return true;
+
+        var parts = trimmed.Split(new[] { ' ', '-' }, StringSplitOptions.RemoveEmptyEntries);
+        return parts.Length > 0 && parts.All(IsMetadataToken);
+    }
 }