align parsing with upstream

Separate release group parsing logic into dedicated classes and update references throughout codebase.

(cherry picked from commit b00229e53c7a4bcb8684fd0aa4f66650c64a9a20)

Co-Authored-By: Mark McDowall <mark@mcdowall.ca>

src/NzbDrone.Core.Test/ParserTests/ReleaseGroupParserFixture.cs

@@ -58,7 +58,7 @@ public class ReleaseGroupParserFixture : CoreTest
         [TestCase("Movie Name (2017) (Showtime) (1080p.BD.DD5.1.x265-TheSickle[TAoE])", "TheSickle")]
         public void should_parse_release_group(string title, string expected)
         {
-            Parser.Parser.ParseReleaseGroup(title).Should().Be(expected);
+            Parser.ReleaseGroupParser.ParseReleaseGroup(title).Should().Be(expected);
         }
 
         [TestCase("Movie Name (2020) [2160p x265 10bit S82 Joy]", "Joy")]
@@ -128,13 +128,13 @@ public void should_parse_release_group(string title, string expected)
         [TestCase("Movie Title (2024) (1080p BluRay x265 SDR DDP 5.1 English -BEN THE MEN", "BEN THE MEN")]
         public void should_parse_exception_release_group(string title, string expected)
         {
-            Parser.Parser.ParseReleaseGroup(title).Should().Be(expected);
+            Parser.ReleaseGroupParser.ParseReleaseGroup(title).Should().Be(expected);
         }
 
         [TestCase(@"C:\Test\Doctor.Series.2005.s01e01.internal.bdrip.x264-archivist.mkv", "archivist")]
         public void should_not_include_extension_in_release_group(string title, string expected)
         {
-            Parser.Parser.ParseReleaseGroup(title).Should().Be(expected);
+            Parser.ReleaseGroupParser.ParseReleaseGroup(title).Should().Be(expected);
         }
 
         [TestCase("Some.Movie.S02E04.720p.WEBRip.x264-SKGTV English", "SKGTV")]
@@ -143,7 +143,7 @@ public void should_not_include_extension_in_release_group(string title, string e
 
         public void should_not_include_language_in_release_group(string title, string expected)
         {
-            Parser.Parser.ParseReleaseGroup(title).Should().Be(expected);
+            Parser.ReleaseGroupParser.ParseReleaseGroup(title).Should().Be(expected);
         }
 
         [TestCase("Some.Movie.2019.1080p.BDRip.X264.AC3-EVO-RP", "EVO")]
@@ -173,7 +173,7 @@ public void should_not_include_language_in_release_group(string title, string ex
 
         public void should_not_include_bad_suffix_in_release_group(string title, string expected)
         {
-            Parser.Parser.ParseReleaseGroup(title).Should().Be(expected);
+            Parser.ReleaseGroupParser.ParseReleaseGroup(title).Should().Be(expected);
         }
 
         [TestCase("[FFF] Invaders of the Movies!! - S01E11 - Someday, With Movies", "FFF")]
@@ -184,13 +184,13 @@ public void should_not_include_bad_suffix_in_release_group(string title, string
 
         public void should_parse_anime_release_groups(string title, string expected)
         {
-            Parser.Parser.ParseReleaseGroup(title).Should().Be(expected);
+            Parser.ReleaseGroupParser.ParseReleaseGroup(title).Should().Be(expected);
         }
 
         [TestCase("Terrible.Anime.Title.2020.DBOX.480p.x264-iKaos [v3] [6AFFEF6B]")]
         public void should_not_parse_anime_hash_as_release_group(string title)
         {
-            Parser.Parser.ParseReleaseGroup(title).Should().BeNull();
+            Parser.ReleaseGroupParser.ParseReleaseGroup(title).Should().BeNull();
         }
     }
 }

src/NzbDrone.Core.Test/ParserTests/UrlFixture.cs

@@ -38,7 +38,7 @@ public void should_not_parse_url_in_name(string postTitle, string title)
         [TestCase("Movie Title Future 2023 DVDRip XviD RUNNER[www.allstate.net]", null)]
         public void should_not_parse_url_in_group(string title, string expected)
         {
-            Parser.Parser.ParseReleaseGroup(title).Should().Be(expected);
+            Parser.ReleaseGroupParser.ParseReleaseGroup(title).Should().Be(expected);
         }
     }
 }

src/NzbDrone.Core/Datastore/Migration/199_mediainfo_to_ffmpeg.cs

@@ -12,6 +12,7 @@
 using NzbDrone.Common.Extensions;
 using NzbDrone.Common.Serializer;
 using NzbDrone.Core.Datastore.Migration.Framework;
+using NzbDrone.Core.MediaFiles;
 using NzbDrone.Core.MediaFiles.MediaInfo;
 
 namespace NzbDrone.Core.Datastore.Migration
@@ -809,7 +810,7 @@ private string MigrateTransferCharacteristics(string transferCharacteristics)
 
         private static string GetSceneNameMatch(string sceneName, params string[] tokens)
         {
-            sceneName = sceneName.IsNotNullOrWhiteSpace() ? Parser.Parser.RemoveFileExtension(sceneName) : string.Empty;
+            sceneName = sceneName.IsNotNullOrWhiteSpace() ? FileExtensions.RemoveFileExtension(sceneName) : string.Empty;
 
             foreach (var token in tokens)
             {

src/NzbDrone.Core/MediaFiles/FileExtensions.cs

@@ -1,11 +1,21 @@
 using System;
 using System.Collections.Generic;
+using System.Text.RegularExpressions;
 
 namespace NzbDrone.Core.MediaFiles
 {
-    internal static class FileExtensions
+    public static class FileExtensions
     {
-        private static List<string> _archiveExtensions = new List<string>
+        private static readonly Regex FileExtensionRegex = new (@"\.[a-z0-9]{2,4}$",
+            RegexOptions.IgnoreCase | RegexOptions.Compiled);
+
+        private static readonly HashSet<string> UsenetExtensions = new HashSet<string>()
+        {
+            ".par2",
+            ".nzb"
+        };
+
+        public static HashSet<string> ArchiveExtensions => new (StringComparer.OrdinalIgnoreCase)
         {
             ".7z",
             ".bz2",
@@ -20,8 +30,7 @@ internal static class FileExtensions
             ".tgz",
             ".zip"
         };
-
+        public static HashSet<string> DangerousExtensions => new (StringComparer.OrdinalIgnoreCase)
-        private static List<string> _dangerousExtensions = new List<string>
         {
             ".arj",
             ".lnk",
@@ -31,8 +40,7 @@ internal static class FileExtensions
             ".vbs",
             ".zipx"
         };
-
+        public static HashSet<string> ExecutableExtensions => new (StringComparer.OrdinalIgnoreCase)
-        private static List<string> _executableExtensions = new List<string>
         {
             ".bat",
             ".cmd",
@@ -40,8 +48,20 @@ internal static class FileExtensions
             ".sh"
         };
 
-        public static HashSet<string> ArchiveExtensions => new HashSet<string>(_archiveExtensions, StringComparer.OrdinalIgnoreCase);
+        public static string RemoveFileExtension(string title)
-        public static HashSet<string> DangerousExtensions => new HashSet<string>(_dangerousExtensions, StringComparer.OrdinalIgnoreCase);
+        {
-        public static HashSet<string> ExecutableExtensions => new HashSet<string>(_executableExtensions, StringComparer.OrdinalIgnoreCase);
+            title = FileExtensionRegex.Replace(title, m =>
+            {
+                var extension = m.Value.ToLower();
+                if (MediaFileExtensions.Extensions.Contains(extension) || UsenetExtensions.Contains(extension))
+                {
+                    return string.Empty;
+                }
+
+                return m.Value;
+            });
+
+            return title;
+        }
     }
 }

src/NzbDrone.Core/MediaFiles/MediaInfo/MediaInfoFormatter.cs

@@ -293,7 +293,7 @@ public static string FormatVideoCodec(MediaInfoModel mediaInfo, string sceneName
 
         private static string GetSceneNameMatch(string sceneName, params string[] tokens)
         {
-            sceneName = sceneName.IsNotNullOrWhiteSpace() ? Parser.Parser.RemoveFileExtension(sceneName) : string.Empty;
+            sceneName = sceneName.IsNotNullOrWhiteSpace() ? FileExtensions.RemoveFileExtension(sceneName) : string.Empty;
 
             foreach (var token in tokens)
             {

src/NzbDrone.Core/MediaFiles/MovieImport/Manual/ManualImportService.cs

@@ -144,7 +144,7 @@ public ManualImportItem ReprocessItem(string path, string downloadId, int movieI
 
             var downloadClientItem = GetTrackedDownload(downloadId)?.DownloadItem;
             var finalReleaseGroup = releaseGroup.IsNullOrWhiteSpace()
-                ? Parser.Parser.ParseReleaseGroup(path)
+                ? ReleaseGroupParser.ParseReleaseGroup(path)
                 : releaseGroup;
             var finalQuality = (quality?.Quality ?? Quality.Unknown) == Quality.Unknown ? QualityParser.ParseQuality(path) : quality;
             var finalLanguages =
@@ -282,7 +282,7 @@ private ManualImportItem ProcessFile(string rootFolder, string baseFolder, strin
                 {
                     var localMovie = new LocalMovie();
                     localMovie.Path = file;
-                    localMovie.ReleaseGroup = Parser.Parser.ParseReleaseGroup(file);
+                    localMovie.ReleaseGroup = ReleaseGroupParser.ParseReleaseGroup(file);
                     localMovie.Quality = QualityParser.ParseQuality(file);
                     localMovie.Languages = LanguageParser.ParseLanguages(file);
                     localMovie.Size = _diskProvider.GetFileSize(file);
@@ -327,7 +327,7 @@ private List<ManualImportItem> ProcessDownloadDirectory(string rootFolder, List<
                 localMovie.Path = file;
                 localMovie.Quality = new QualityModel(Quality.Unknown);
                 localMovie.Languages = new List<Language> { Language.Unknown };
-                localMovie.ReleaseGroup = Parser.Parser.ParseReleaseGroup(file);
+                localMovie.ReleaseGroup = ReleaseGroupParser.ParseReleaseGroup(file);
                 localMovie.Size = _diskProvider.GetFileSize(file);
 
                 items.Add(MapItem(new ImportDecision(localMovie), rootFolder, null, null));

src/NzbDrone.Core/MediaFiles/MovieImport/SceneNameCalculator.cs

@@ -14,7 +14,7 @@ public static string GetSceneName(LocalMovie localMovie)
 
             if (!otherVideoFiles && downloadClientInfo != null)
             {
-                return Parser.Parser.RemoveFileExtension(downloadClientInfo.ReleaseTitle);
+                return FileExtensions.RemoveFileExtension(downloadClientInfo.ReleaseTitle);
             }
 
             var fileName = Path.GetFileNameWithoutExtension(localMovie.Path.CleanFilePath());

src/NzbDrone.Core/Parser/Parser.cs

@@ -6,6 +6,7 @@
 using NLog;
 using NzbDrone.Common.Extensions;
 using NzbDrone.Common.Instrumentation;
+using NzbDrone.Core.MediaFiles;
 using NzbDrone.Core.Parser.Model;
 
 namespace NzbDrone.Core.Parser
@@ -21,8 +22,6 @@ public static class Parser
         private static readonly Regex HardcodedSubsRegex = new Regex(@"\b((?<hcsub>(\w+(?<!SOFT|MULTI|HORRIBLE)SUBS?))|(?<hc>(HC|SUBBED)))\b",
                                                         RegexOptions.Compiled | RegexOptions.IgnoreCase | RegexOptions.IgnorePatternWhitespace);
 
-        private static readonly RegexReplace[] PreSubstitutionRegex = Array.Empty<RegexReplace>();
-
         private static readonly Regex[] ReportMovieTitleRegex = new[]
         {
             // Anime [Subgroup] and Year
@@ -110,9 +109,6 @@ public static class Parser
         private static readonly Regex NormalizeRegex = new Regex(@"((?:\b|_)(?<!^|[^a-zA-Z0-9_']\w[^a-zA-Z0-9_'])([aà](?!$|[^a-zA-Z0-9_']\w[^a-zA-Z0-9_'])|an|the|and|or|of)(?!$)(?:\b|_))|\W|_",
                                                                 RegexOptions.IgnoreCase | RegexOptions.Compiled);
 
-        private static readonly Regex FileExtensionRegex = new Regex(@"\.[a-z0-9]{2,4}$",
-                                                                RegexOptions.IgnoreCase | RegexOptions.Compiled);
-
         private static readonly Regex ReportImdbId = new Regex(@"(?<imdbid>tt\d{7,8})", RegexOptions.IgnoreCase | RegexOptions.Compiled);
         private static readonly Regex ReportTmdbId = new Regex(@"tmdb(id)?-(?<tmdbid>\d+)", RegexOptions.IgnoreCase | RegexOptions.Compiled);
 
@@ -123,44 +119,13 @@ public static class Parser
         private static readonly Regex SimpleReleaseTitleRegex = new Regex(@"\s*(?:[<>?*|])", RegexOptions.Compiled | RegexOptions.IgnoreCase);
 
         // Valid TLDs http://data.iana.org/TLD/tlds-alpha-by-domain.txt
-        private static readonly RegexReplace WebsitePrefixRegex = new RegexReplace(@"^(?:(?:\[|\()\s*)?(?:www\.)?[-a-z0-9-]{1,256}\.(?<!Naruto-Kun\.)(?:[a-z]{2,6}\.[a-z]{2,6}|xn--[a-z0-9-]{4,}|[a-z]{2,})\b(?:\s*(?:\]|\))|[ -]{2,})[ -]*",
-                                                                string.Empty,
-                                                                RegexOptions.IgnoreCase | RegexOptions.Compiled);
-
-        private static readonly RegexReplace WebsitePostfixRegex = new RegexReplace(@"(?:\[\s*)?(?:www\.)?[-a-z0-9-]{1,256}\.(?:xn--[a-z0-9-]{4,}|[a-z]{2,6})\b(?:\s*\])$",
-                                                        string.Empty,
-                                                        RegexOptions.IgnoreCase | RegexOptions.Compiled);
-
-        private static readonly RegexReplace CleanReleaseGroupRegex = new RegexReplace(@"(-(RP|1|NZBGeek|Obfuscated|Obfuscation|Scrambled|sample|Pre|postbot|xpost|Rakuv[a-z0-9]*|WhiteRev|BUYMORE|AsRequested|AlternativeToRequested|GEROV|Z0iDS3N|Chamele0n|4P|4Planet|AlteZachen|RePACKPOST))+$",
-                                                                string.Empty,
-                                                                RegexOptions.IgnoreCase | RegexOptions.Compiled);
-
-        private static readonly RegexReplace CleanTorrentSuffixRegex = new RegexReplace(@"\[(?:ettv|rartv|rarbg|cttv|publichd)\]$",
-                                                                string.Empty,
-                                                                RegexOptions.IgnoreCase | RegexOptions.Compiled);
 
         private static readonly Regex CleanQualityBracketsRegex = new Regex(@"\[[a-z0-9 ._-]+\]$",
                                                                    RegexOptions.IgnoreCase | RegexOptions.Compiled);
 
-        private static readonly Regex ReleaseGroupRegex = new Regex(@"-(?<releasegroup>[a-z0-9]+(?<part2>-[a-z0-9]+)?(?!.+?(?:480p|576p|720p|1080p|2160p)))(?<!(?:WEB-(DL|Rip)|Blu-Ray|480p|576p|720p|1080p|2160p|DTS-HD|DTS-X|DTS-MA|DTS-ES|-ES|-EN|-CAT|-ENG|-JAP|-GER|-FRA|-FRE|-ITA|-HDRip|\d{1,2}-bit|[ ._]\d{4}-\d{2}|-\d{2}|tmdb(id)?-(?<tmdbid>\d+)|(?<imdbid>tt\d{7,8}))(?:\k<part2>)?)(?:\b|[-._ ]|$)|[-._ ]\[(?<releasegroup>[a-z0-9]+)\]$",
-                                                                RegexOptions.IgnoreCase | RegexOptions.Compiled);
-
-        private static readonly Regex InvalidReleaseGroupRegex = new Regex(@"^([se]\d+|[0-9a-f]{8})$", RegexOptions.IgnoreCase | RegexOptions.Compiled);
-
-        private static readonly Regex AnimeReleaseGroupRegex = new Regex(@"^(?:\[(?<subgroup>(?!\s).+?(?<!\s))\](?:_|-|\s|\.)?)",
-                                                                RegexOptions.IgnoreCase | RegexOptions.Compiled);
-
         private static readonly Regex YearInTitleRegex = new Regex(@"^(?<title>.+?)(?:\W|_.)?[\(\[]?(?<year>\d{4})[\]\)]?",
                                                                 RegexOptions.IgnoreCase | RegexOptions.Compiled);
 
-        // Handle Exception Release Groups that don't follow -RlsGrp; Manual List
-        // groups whose releases end with RlsGroup) or RlsGroup]
-        private static readonly Regex ExceptionReleaseGroupRegex = new Regex(@"(?<=[._ \[])(?<releasegroup>(Silence|afm72|Panda|Ghost|MONOLITH|Tigole|Joy|ImE|UTR|t3nzin|Anime Time|Project Angel|Hakata Ramen|HONE|Vyndros|SEV|Garshasp|Kappa|Natty|RCVR|SAMPA|YOGI|r00t|EDGE2020|RZeroX|FreetheFish|Anna|Bandi|Qman|theincognito|HDO|DusIctv|DHD|CtrlHD|-ZR-|ADC|XZVN|RH|Kametsu|Garshasp)(?=\]|\)))", RegexOptions.IgnoreCase | RegexOptions.Compiled);
-
-        // Handle Exception Release Groups that don't follow -RlsGrp; Manual List
-        // name only...BE VERY CAREFUL WITH THIS, HIGH CHANCE OF FALSE POSITIVES
-        private static readonly Regex ExceptionReleaseGroupRegexExact = new Regex(@"\b(?<releasegroup>KRaLiMaRKo|E\.N\.D|D\-Z0N3|Koten_Gars|BluDragon|ZØNEHD|Tigole|HQMUX|VARYG|YIFY|YTS(.(MX|LT|AG))?|TMd|Eml HDTeam|LMain|DarQ|BEN THE MEN)\b", RegexOptions.IgnoreCase | RegexOptions.Compiled);
-
         private static readonly Regex SpecialCharRegex = new Regex(@"(\&|\:|\\|\/)+", RegexOptions.Compiled);
         private static readonly Regex PunctuationRegex = new Regex(@"[^\w\s]", RegexOptions.Compiled);
         private static readonly Regex ArticleWordRegex = new Regex(@"^(a|an|the)\s", RegexOptions.IgnoreCase | RegexOptions.Compiled);
@@ -215,7 +180,7 @@ public static ParsedMovieInfo ParseMovieTitle(string title, bool isDir = false)
 
                 if (ReversedTitleRegex.IsMatch(title))
                 {
-                    var titleWithoutExtension = RemoveFileExtension(title).ToCharArray();
+                    var titleWithoutExtension = FileExtensions.RemoveFileExtension(title).ToCharArray();
                     Array.Reverse(titleWithoutExtension);
 
                     title = $"{titleWithoutExtension}{title.Substring(titleWithoutExtension.Length)}";
@@ -223,14 +188,14 @@ public static ParsedMovieInfo ParseMovieTitle(string title, bool isDir = false)
                     Logger.Debug("Reversed name detected. Converted to '{0}'", title);
                 }
 
-                var releaseTitle = RemoveFileExtension(title);
+                var releaseTitle = FileExtensions.RemoveFileExtension(title);
 
                 // Trim dashes from end
                 releaseTitle = releaseTitle.Trim('-', '_');
 
                 releaseTitle = releaseTitle.Replace("【", "[").Replace("】", "]");
 
-                foreach (var replace in PreSubstitutionRegex)
+                foreach (var replace in ParserCommon.PreSubstitutionRegex)
                 {
                     if (replace.TryReplace(ref releaseTitle))
                     {
@@ -242,10 +207,10 @@ public static ParsedMovieInfo ParseMovieTitle(string title, bool isDir = false)
                 var simpleTitle = SimpleTitleRegex.Replace(releaseTitle);
 
                 // TODO: Quick fix stripping [url] - prefixes.
-                simpleTitle = WebsitePrefixRegex.Replace(simpleTitle);
+                simpleTitle = ParserCommon.WebsitePrefixRegex.Replace(simpleTitle);
-                simpleTitle = WebsitePostfixRegex.Replace(simpleTitle);
+                simpleTitle = ParserCommon.WebsitePostfixRegex.Replace(simpleTitle);
 
-                simpleTitle = CleanTorrentSuffixRegex.Replace(simpleTitle);
+                simpleTitle = ParserCommon.CleanTorrentSuffixRegex.Replace(simpleTitle);
 
                 simpleTitle = CleanQualityBracketsRegex.Replace(simpleTitle, m =>
                 {
@@ -295,7 +260,7 @@ public static ParsedMovieInfo ParseMovieTitle(string title, bool isDir = false)
                                     }
                                 }
 
-                                result.ReleaseGroup = ParseReleaseGroup(simpleReleaseTitle);
+                                result.ReleaseGroup = ReleaseGroupParser.ParseReleaseGroup(simpleReleaseTitle);
 
                                 var subGroup = GetSubGroup(match);
                                 if (!subGroup.IsNullOrWhiteSpace())
@@ -521,74 +486,6 @@ public static string ParseHardcodeSubs(string title)
             return null;
         }
 
-        public static string ParseReleaseGroup(string title)
-        {
-            title = title.Trim();
-            title = RemoveFileExtension(title);
-            title = WebsitePrefixRegex.Replace(title);
-            title = CleanTorrentSuffixRegex.Replace(title);
-
-            var animeMatch = AnimeReleaseGroupRegex.Match(title);
-
-            if (animeMatch.Success)
-            {
-                return animeMatch.Groups["subgroup"].Value;
-            }
-
-            title = CleanReleaseGroupRegex.Replace(title);
-
-            var exceptionReleaseGroupRegex = ExceptionReleaseGroupRegex.Matches(title);
-
-            if (exceptionReleaseGroupRegex.Count != 0)
-            {
-                return exceptionReleaseGroupRegex.OfType<Match>().Last().Groups["releasegroup"].Value;
-            }
-
-            var exceptionExactMatch = ExceptionReleaseGroupRegexExact.Matches(title);
-
-            if (exceptionExactMatch.Count != 0)
-            {
-                return exceptionExactMatch.OfType<Match>().Last().Groups["releasegroup"].Value;
-            }
-
-            var matches = ReleaseGroupRegex.Matches(title);
-
-            if (matches.Count != 0)
-            {
-                var group = matches.OfType<Match>().Last().Groups["releasegroup"].Value;
-
-                if (int.TryParse(group, out _))
-                {
-                    return null;
-                }
-
-                if (InvalidReleaseGroupRegex.IsMatch(group))
-                {
-                    return null;
-                }
-
-                return group;
-            }
-
-            return null;
-        }
-
-        public static string RemoveFileExtension(string title)
-        {
-            title = FileExtensionRegex.Replace(title, m =>
-            {
-                var extension = m.Value.ToLower();
-                if (MediaFiles.MediaFileExtensions.Extensions.Contains(extension) || new[] { ".par2", ".nzb" }.Contains(extension))
-                {
-                    return string.Empty;
-                }
-
-                return m.Value;
-            });
-
-            return title;
-        }
-
         public static bool HasMultipleLanguages(string title)
         {
             return MultiRegex.IsMatch(title);
@@ -697,7 +594,7 @@ private static bool ValidateBeforeParsing(string title)
                 return false;
             }
 
-            var titleWithoutExtension = RemoveFileExtension(title);
+            var titleWithoutExtension = FileExtensions.RemoveFileExtension(title);
 
             if (RejectHashedReleasesRegex.Any(v => v.IsMatch(titleWithoutExtension)))
             {

src/NzbDrone.Core/Parser/ParserCommon.cs

@@ -0,0 +1,23 @@
+using System.Text.RegularExpressions;
+
+namespace NzbDrone.Core.Parser;
+
+// These are functions shared between different parser functions
+// they are not intended to be used outside of them parsing.
+internal static class ParserCommon
+{
+    internal static readonly RegexReplace[] PreSubstitutionRegex = System.Array.Empty<RegexReplace>();
+
+    // Valid TLDs http://data.iana.org/TLD/tlds-alpha-by-domain.txt
+    internal static readonly RegexReplace WebsitePrefixRegex = new (@"^(?:(?:\[|\()\s*)?(?:www\.)?[-a-z0-9-]{1,256}\.(?<!Naruto-Kun\.)(?:[a-z]{2,6}\.[a-z]{2,6}|xn--[a-z0-9-]{4,}|[a-z]{2,})\b(?:\s*(?:\]|\))|[ -]{2,})[ -]*",
+        string.Empty,
+        RegexOptions.IgnoreCase | RegexOptions.Compiled);
+
+    internal static readonly RegexReplace WebsitePostfixRegex = new (@"(?:\[\s*)?(?:www\.)?[-a-z0-9-]{1,256}\.(?:xn--[a-z0-9-]{4,}|[a-z]{2,6})\b(?:\s*\])$",
+        string.Empty,
+        RegexOptions.IgnoreCase | RegexOptions.Compiled);
+
+    internal static readonly RegexReplace CleanTorrentSuffixRegex = new (@"\[(?:ettv|rartv|rarbg|cttv|publichd)\]$",
+        string.Empty,
+        RegexOptions.IgnoreCase | RegexOptions.Compiled);
+}

src/NzbDrone.Core/Parser/ReleaseGroupParser.cs

@@ -0,0 +1,87 @@
+using System.Linq;
+using System.Text.RegularExpressions;
+using NzbDrone.Core.MediaFiles;
+
+namespace NzbDrone.Core.Parser;
+
+public static class ReleaseGroupParser
+{
+    private static readonly Regex ReleaseGroupRegex = new (@"-(?<releasegroup>[a-z0-9]+(?<part2>-[a-z0-9]+)?(?!.+?(?:480p|576p|720p|1080p|2160p)))(?<!(?:WEB-(DL|Rip)|Blu-Ray|480p|576p|720p|1080p|2160p|DTS-HD|DTS-X|DTS-MA|DTS-ES|-ES|-EN|-CAT|-ENG|-JAP|-GER|-FRA|-FRE|-ITA|-HDRip|\d{1,2}-bit|[ ._]\d{4}-\d{2}|-\d{2}|tmdb(id)?-(?<tmdbid>\d+)|(?<imdbid>tt\d{7,8}))(?:\k<part2>)?)(?:\b|[-._ ]|$)|[-._ ]\[(?<releasegroup>[a-z0-9]+)\]$",
+        RegexOptions.IgnoreCase | RegexOptions.Compiled);
+
+    private static readonly Regex InvalidReleaseGroupRegex = new (@"^([se]\d+|[0-9a-f]{8})$", RegexOptions.IgnoreCase | RegexOptions.Compiled);
+
+    private static readonly Regex AnimeReleaseGroupRegex = new (@"^(?:\[(?<subgroup>(?!\s).+?(?<!\s))\](?:_|-|\s|\.)?)",
+        RegexOptions.IgnoreCase | RegexOptions.Compiled);
+
+    // Handle Exception Release Groups that don't follow -RlsGrp; Manual List
+    // name only...be very careful with this last; high chance of false positives
+    private static readonly Regex ExceptionReleaseGroupRegexExact = new (@"\b(?<releasegroup>KRaLiMaRKo|E\.N\.D|D\-Z0N3|Koten_Gars|BluDragon|ZØNEHD|Tigole|HQMUX|VARYG|YIFY|YTS(.(MX|LT|AG))?|TMd|Eml HDTeam|LMain|DarQ|BEN THE MEN)\b", RegexOptions.IgnoreCase | RegexOptions.Compiled);
+
+    // groups whose releases end with RlsGroup) or RlsGroup]
+    private static readonly Regex ExceptionReleaseGroupRegex = new (@"(?<=[._ \[])(?<releasegroup>(Silence|afm72|Panda|Ghost|MONOLITH|Tigole|Joy|ImE|UTR|t3nzin|Anime Time|Project Angel|Hakata Ramen|HONE|Vyndros|SEV|Garshasp|Kappa|Natty|RCVR|SAMPA|YOGI|r00t|EDGE2020|RZeroX|FreetheFish|Anna|Bandi|Qman|theincognito|HDO|DusIctv|DHD|CtrlHD|-ZR-|ADC|XZVN|RH|Kametsu)(?=\]|\)))", RegexOptions.IgnoreCase | RegexOptions.Compiled);
+
+    private static readonly RegexReplace CleanReleaseGroupRegex = new (@"(-(RP|1|NZBGeek|Obfuscated|Obfuscation|Scrambled|sample|Pre|postbot|xpost|Rakuv[a-z0-9]*|WhiteRev|BUYMORE|AsRequested|AlternativeToRequested|GEROV|Z0iDS3N|Chamele0n|4P|4Planet|AlteZachen|RePACKPOST))+$",
+        string.Empty,
+        RegexOptions.IgnoreCase | RegexOptions.Compiled);
+
+    public static string ParseReleaseGroup(string title)
+    {
+        title = title.Trim();
+        title = FileExtensions.RemoveFileExtension(title);
+        foreach (var replace in ParserCommon.PreSubstitutionRegex)
+        {
+            if (replace.TryReplace(ref title))
+            {
+                break;
+            }
+        }
+
+        title = ParserCommon.WebsitePrefixRegex.Replace(title);
+        title = ParserCommon.CleanTorrentSuffixRegex.Replace(title);
+
+        var animeMatch = AnimeReleaseGroupRegex.Match(title);
+
+        if (animeMatch.Success)
+        {
+            return animeMatch.Groups["subgroup"].Value;
+        }
+
+        title = CleanReleaseGroupRegex.Replace(title);
+
+        var exceptionReleaseGroupRegex = ExceptionReleaseGroupRegex.Matches(title);
+
+        if (exceptionReleaseGroupRegex.Count != 0)
+        {
+            return exceptionReleaseGroupRegex.OfType<Match>().Last().Groups["releasegroup"].Value;
+        }
+
+        var exceptionExactMatch = ExceptionReleaseGroupRegexExact.Matches(title);
+
+        if (exceptionExactMatch.Count != 0)
+        {
+            return exceptionExactMatch.OfType<Match>().Last().Groups["releasegroup"].Value;
+        }
+
+        var matches = ReleaseGroupRegex.Matches(title);
+
+        if (matches.Count != 0)
+        {
+            var group = matches.OfType<Match>().Last().Groups["releasegroup"].Value;
+
+            if (int.TryParse(group, out _))
+            {
+                return null;
+            }
+
+            if (InvalidReleaseGroupRegex.IsMatch(group))
+            {
+                return null;
+            }
+
+            return group;
+        }
+
+        return null;
+    }
+}