initial concept for parsing subtitle titles

src/NzbDrone.Core/Extras/Subtitles/ExistingSubtitleImporter.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -71,14 +72,29 @@ namespace NzbDrone.Core.Extras.Subtitles
                         continue;
                     }
 
+                    var firstEpisode = localEpisode.Episodes.First();
+
+                    List<string> languageTags = null;
+                    string title = null;
+
+                    try
+                    {
+                        (languageTags, title) = LanguageParser.ParseLanguageTagsAndTitle(possibleSubtitleFile, firstEpisode);
+                    }
+                    catch (Exception ex)
+                    {
+                        _logger.Debug(ex, "Failed parsing language tags with title from subtitle file: {0}", possibleSubtitleFile);
+                    }
+
                     var subtitleFile = new SubtitleFile
                                        {
                                            SeriesId = series.Id,
                                            SeasonNumber = localEpisode.SeasonNumber,
-                                           EpisodeFileId = localEpisode.Episodes.First().EpisodeFileId,
+                                           EpisodeFileId = firstEpisode.EpisodeFileId,
                                            RelativePath = series.Path.GetRelativePath(possibleSubtitleFile),
                                            Language = LanguageParser.ParseSubtitleLanguage(possibleSubtitleFile),
-                                           LanguageTags = LanguageParser.ParseLanguageTags(possibleSubtitleFile),
+                                           LanguageTags = languageTags ?? LanguageParser.ParseLanguageTags(possibleSubtitleFile),
+                                           Title = title,
                                            Extension = extension
                                        };
 

src/NzbDrone.Core/Extras/Subtitles/SubtitleFile.cs

@@ -13,15 +13,17 @@ namespace NzbDrone.Core.Extras.Subtitles
 
         public Language Language { get; set; }
 
-        public string AggregateString => Language + LanguageTagsAsString + Extension;
+        public string AggregateString => Language + Title + LanguageTagsAsString + Extension;
 
         public List<string> LanguageTags { get; set; }
 
+        public string Title { get; set; }
+
         private string LanguageTagsAsString => string.Join(".", LanguageTags);
 
         public override string ToString()
         {
-            return $"[{Id}] {RelativePath} ({Language}{(LanguageTags.Count > 0 ? "." : "")}{LanguageTagsAsString}{Extension})";
+            return $"[{Id}] {RelativePath} ({Language}{(Title is not null ? "." : "")}{Title ?? ""}{(LanguageTags.Count > 0 ? "." : "")}{LanguageTagsAsString}{Extension})";
         }
     }
 }

src/NzbDrone.Core/Extras/Subtitles/SubtitleService.cs

@@ -81,7 +81,7 @@ namespace NzbDrone.Core.Extras.Subtitles
 
                     foreach (var subtitleFile in group)
                     {
-                        var suffix = GetSuffix(subtitleFile.Language, copy, subtitleFile.LanguageTags, groupCount > 1);
+                        var suffix = GetSuffix(subtitleFile.Language, copy, subtitleFile.LanguageTags, groupCount > 1, subtitleFile.Title);
 
                         movedFiles.AddIfNotNull(MoveFile(series, episodeFile, subtitleFile, suffix));
 
@@ -229,11 +229,23 @@ namespace NzbDrone.Core.Extras.Subtitles
             return importedFiles;
         }
 
-        private string GetSuffix(Language language, int copy, List<string> languageTags, bool multipleCopies = false)
+        private string GetSuffix(Language language, int copy, List<string> languageTags, bool multipleCopies = false, string title = null)
         {
             var suffixBuilder = new StringBuilder();
 
-            if (multipleCopies)
+            if (title is not null)
+            {
+                suffixBuilder.Append('.');
+                suffixBuilder.Append(title);
+
+                if (multipleCopies)
+                {
+                    suffixBuilder.Append(" - ");
+                    suffixBuilder.Append(copy);
+                }
+
+            }
+            else if (multipleCopies)
             {
                 suffixBuilder.Append('.');
                 suffixBuilder.Append(copy);

src/NzbDrone.Core/Parser/LanguageParser.cs

@@ -7,6 +7,7 @@ using NLog;
 using NzbDrone.Common.Extensions;
 using NzbDrone.Common.Instrumentation;
 using NzbDrone.Core.Languages;
+using NzbDrone.Core.Tv;
 
 namespace NzbDrone.Core.Parser
 {
@@ -28,7 +29,9 @@ namespace NzbDrone.Core.Parser
         private static readonly Regex GermanDualLanguageRegex = new (@"(?<!WEB[-_. ]?)\bDL\b", RegexOptions.Compiled | RegexOptions.IgnoreCase);
         private static readonly Regex GermanMultiLanguageRegex = new (@"\bML\b", RegexOptions.Compiled | RegexOptions.IgnoreCase);
 
-        private static readonly Regex SubtitleLanguageRegex = new Regex(".+?[-_. ](?<iso_code>[a-z]{2,3})([-_. ](?<tags>full|forced|foreign|default|cc|psdh|sdh))*$", RegexOptions.Compiled | RegexOptions.IgnoreCase);
+        private static readonly Regex SubtitleLanguageRegex = new Regex(".+?([-_. ]((?<iso_code>[a-z]{2,3})|(?<tags>full|forced|foreign|default|cc|psdh|sdh)))*$", RegexOptions.Compiled | RegexOptions.IgnoreCase);
+
+        private static readonly Regex SubtitleLanguageTitleRegex = new Regex(".+?(\\.((?<iso_code>[a-z]{2,3})|(?<tags1>full|forced|foreign|default|cc|psdh|sdh)))*(\\.(?<title>[^.]*))??(\\.((?<iso_code>[a-z]{2,3})|(?<tags2>full|forced|foreign|default|cc|psdh|sdh)))*$", RegexOptions.Compiled | RegexOptions.IgnoreCase);
 
         public static List<Language> ParseLanguages(string title)
         {
@@ -249,6 +252,31 @@ namespace NzbDrone.Core.Parser
             return Language.Unknown;
         }
 
+        public static (List<string> languageTags, string title) ParseLanguageTagsAndTitle(string fileName, Episode episode)
+        {
+            var simpleFilename = Path.GetFileNameWithoutExtension(fileName);
+            var matchTitle = SubtitleLanguageTitleRegex.Match(simpleFilename);
+            var languageTags = matchTitle.Groups["tags1"].Captures
+                .Union(matchTitle.Groups["tags2"].Captures)
+                .Cast<Capture>()
+                .Where(tag => !tag.Value.Empty())
+                .Select(tag => tag.Value.ToLower());
+            var title = matchTitle.Groups["title"].Captures.Cast<Capture>().First().ToString();
+
+            if (matchTitle.Groups["tags1"].Captures.Empty())
+            {
+                var episodeFile = episode.EpisodeFile.Value;
+                var episodeFileTitle = Path.GetFileNameWithoutExtension(episodeFile.RelativePath);
+
+                if (episodeFileTitle.Contains(title, StringComparison.OrdinalIgnoreCase))
+                {
+                    throw new ArgumentException("Subtitle file title probably parsed incorrectly, not using.");
+                }
+            }
+
+            return (languageTags.ToList(), title);
+        }
+
         public static List<string> ParseLanguageTags(string fileName)
         {
             try