some preliminary work to move decision engine to use the visitor pattern.

NzbDrone.Core/DecisionEngine/Specifications/MonitoredEpisodeSpecification.cs

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+using System.Linq;
+using NLog;
+using NzbDrone.Core.Model;
+using NzbDrone.Core.Tv;
+
+namespace NzbDrone.Core.DecisionEngine.Specifications
+{
+    public class MonitoredEpisodeSpecification : IFetchableSpecification
+    {
+        private readonly IEpisodeService _episodeService;
+        private readonly ISeriesRepository _seriesRepository;
+        private readonly Logger _logger;
+
+        public MonitoredEpisodeSpecification(IEpisodeService episodeService, ISeriesRepository seriesRepository, Logger logger)
+        {
+            _episodeService = episodeService;
+            _seriesRepository = seriesRepository;
+            _logger = logger;
+        }
+
+        public string RejectionReason
+        {
+            get
+            {
+                return "Series is not monitored";
+            }
+        }
+
+        public virtual bool IsSatisfiedBy(EpisodeParseResult subject)
+        {
+            var series = _seriesRepository.GetByTitle(subject.CleanTitle);
+
+            if (series == null)
+            {
+                _logger.Trace("{0} is not mapped to any series in DB. skipping", subject.CleanTitle);
+                return false;
+            }
+
+            subject.Series = series;
+
+            if (!series.Monitored)
+            {
+                _logger.Debug("{0} is present in the DB but not tracked. skipping.", subject.CleanTitle);
+                return false;
+            }
+
+            var episodes = _episodeService.GetEpisodesByParseResult(subject);
+            subject.Episodes = episodes;
+
+            //return monitored if any of the episodes are monitored
+            if (episodes.Any(episode => !episode.Ignored))
+            {
+                return true;
+            }
+
+            _logger.Debug("All episodes are ignored. skipping.");
+            return false;
+        }
+    }
+}