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

NzbDrone.Core/DecisionEngine/Specifications/UpgradeDiskSpecification.cs

@@ -0,0 +1,46 @@
+using System;
+using System.Linq;
+using NLog;
+using NzbDrone.Core.Model;
+using NzbDrone.Core.Tv;
+
+namespace NzbDrone.Core.DecisionEngine.Specifications
+{
+    public class UpgradeDiskSpecification : IFetchableSpecification
+    {
+        private readonly QualityUpgradableSpecification _qualityUpgradableSpecification;
+        private readonly Logger _logger;
+
+        public UpgradeDiskSpecification(QualityUpgradableSpecification qualityUpgradableSpecification, Logger logger)
+        {
+            _qualityUpgradableSpecification = qualityUpgradableSpecification;
+            _logger = logger;
+        }
+
+        public string RejectionReason
+        {
+            get
+            {
+                return "Higher quality exists on disk";
+            }
+        }
+
+        public virtual bool IsSatisfiedBy(EpisodeParseResult subject)
+        {
+            foreach (var file in subject.Episodes.Select(c => c.EpisodeFile).Where(c => c != null))
+            {
+                _logger.Trace("Comparing file quality with report. Existing file is {0} proper:{1}", file.Quality, file.Proper);
+                if (!_qualityUpgradableSpecification.IsUpgradable(subject.Series.QualityProfile, new QualityModel { Quality = file.Quality, Proper = file.Proper }, subject.Quality))
+                    return false;
+
+                if (subject.Quality.Proper && file.DateAdded < DateTime.Today.AddDays(-7))
+                {
+                    _logger.Trace("Proper for old file, skipping: {0}", subject);
+                    return false;
+                }
+            }
+
+            return true;
+        }
+    }
+}