Fixed parsing of multiple languages from Newznab indexer releases

(cherry picked from commit 2a241294b5eeb9e95c46e030828191da09d05e88)

Closes #4114

src/NzbDrone.Core.Test/IndexerTests/NewznabTests/NewznabFixture.cs

@@ -9,6 +9,7 @@ using NUnit.Framework;
 using NzbDrone.Common.Http;
 using NzbDrone.Core.Indexers;
 using NzbDrone.Core.Indexers.Newznab;
+using NzbDrone.Core.Languages;
 using NzbDrone.Core.Test.Framework;
 using NzbDrone.Test.Common;
 
@@ -106,5 +107,23 @@ namespace NzbDrone.Core.Test.IndexerTests.NewznabTests
 
             ExceptionVerification.ExpectedWarns(1);
         }
+
+        [Test]
+        public async Task should_parse_languages()
+        {
+            var recentFeed = ReadAllText(@"Files/Indexers/Newznab/newznab_language.xml");
+
+            Mocker.GetMock<IHttpClient>()
+                .Setup(o => o.ExecuteAsync(It.Is<HttpRequest>(v => v.Method == HttpMethod.Get)))
+                .Returns<HttpRequest>(r => Task.FromResult(new HttpResponse(r, new HttpHeader(), recentFeed)));
+
+            var releases = await Subject.FetchRecent();
+
+            releases.Should().HaveCount(100);
+
+            releases[0].Languages.Should().BeEquivalentTo(new[] { Language.English, Language.Japanese });
+            releases[1].Languages.Should().BeEquivalentTo(new[] { Language.English, Language.Spanish });
+            releases[2].Languages.Should().BeEquivalentTo(new[] { Language.French });
+        }
     }
 }

src/NzbDrone.Core/Indexers/Newznab/NewznabRssParser.cs

@@ -105,22 +105,28 @@ namespace NzbDrone.Core.Indexers.Newznab
 
         protected override List<Language> GetLanguages(XElement item)
         {
-            var languages = TryGetMultipleNewznabAttributes(item, "language");
+            var languageElements = TryGetMultipleNewznabAttributes(item, "language");
             var results = new List<Language>();
 
             // Try to find <language> elements for some indexers that suck at following the rules.
-            if (languages.Count == 0)
+            if (languageElements.Count == 0)
             {
-                languages = item.Elements("language").Select(e => e.Value).ToList();
+                languageElements = item.Elements("language").Select(e => e.Value).ToList();
             }
 
-            foreach (var language in languages)
+            foreach (var languageElement in languageElements)
             {
-                var mappedLanguage = IsoLanguages.FindByName(language)?.Language ?? null;
+                var languages = languageElement.Split(',',
+                    StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
 
-                if (mappedLanguage != null)
+                foreach (var language in languages)
                 {
-                    results.Add(mappedLanguage);
+                    var mappedLanguage = IsoLanguages.FindByName(language)?.Language ?? null;
+
+                    if (mappedLanguage != null)
+                    {
+                        results.Add(mappedLanguage);
+                    }
                 }
             }