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

NzbDrone.Core/DecisionEngine/Specifications/CustomStartDateSpecification.cs

@@ -0,0 +1,43 @@
+using System.Linq;
+using NLog;
+using NzbDrone.Core.Model;
+
+namespace NzbDrone.Core.DecisionEngine.Specifications
+{
+    public class CustomStartDateSpecification : IFetchableSpecification
+    {
+        private readonly Logger _logger;
+
+        public CustomStartDateSpecification(Logger logger)
+        {
+            _logger = logger;
+        }
+
+        public string RejectionReason
+        {
+            get
+            {
+                return "Aired before configured cut-off";
+            }
+        }
+
+
+        public virtual bool IsSatisfiedBy(EpisodeParseResult subject)
+        {
+            if (!subject.Series.CustomStartDate.HasValue)
+            {
+                _logger.Debug("{0} does not restrict downloads before date.", subject.Series.Title);
+                return true;
+            }
+
+            if (subject.Episodes.Any(episode => episode.AirDate >= subject.Series.CustomStartDate.Value))
+            {
+                _logger.Debug("One or more episodes aired after cutoff, downloading.");
+                return true;
+            }
+
+            _logger.Debug("Episodes aired before cutoff date: {0}", subject.Series.CustomStartDate);
+            return false;
+        }
+    }
+}