New: Add tag support to indexers

Closes #487

src/NzbDrone.Core/DecisionEngine/Specifications/RssSync/IndexerTagSpecification.cs

@@ -0,0 +1,39 @@
+using System.Linq;
+using NLog;
+using NzbDrone.Common.Extensions;
+using NzbDrone.Core.Indexers;
+using NzbDrone.Core.IndexerSearch.Definitions;
+using NzbDrone.Core.Parser.Model;
+
+namespace NzbDrone.Core.DecisionEngine.Specifications.RssSync
+{
+    public class IndexerTagSpecification : IDecisionEngineSpecification
+    {
+        private readonly Logger _logger;
+        private readonly IIndexerRepository _indexerRepository;
+
+        public IndexerTagSpecification(Logger logger, IIndexerRepository indexerRepository)
+        {
+            _logger = logger;
+            _indexerRepository = indexerRepository;
+        }
+
+        public SpecificationPriority Priority => SpecificationPriority.Default;
+        public RejectionType Type => RejectionType.Permanent;
+
+        public virtual Decision IsSatisfiedBy(RemoteEpisode subject, SearchCriteriaBase searchCriteria)
+        {
+            // If indexer has tags, check that at least one of them is present on the series
+            var indexerTags = _indexerRepository.Get(subject.Release.IndexerId).Tags;
+
+            if (indexerTags.Any() && indexerTags.Intersect(subject.Series.Tags).Empty())
+            {
+                _logger.Debug("Indexer {0} has tags. None of these are present on series {1}. Rejecting", subject.Release.Indexer, subject.Series);
+
+                return Decision.Reject("Series tags do not match any of the indexer tags");
+            }
+
+            return Decision.Accept();
+        }
+    }
+}