Improve handling of multiple seasons in one file

Fixed: Invalid scene numbering leading to manual import failing to load
Fixes #2255

src/NzbDrone.Core/MediaFiles/EpisodeImport/Manual/ManualImportService.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -205,10 +205,23 @@ namespace NzbDrone.Core.MediaFiles.EpisodeImport.Manual
                 item.Series = decision.LocalEpisode.Series;
             }
 
-            if (decision.LocalEpisode.Episodes.Any())
+            if (decision.LocalEpisode.Episodes.Any() && decision.LocalEpisode.Episodes.Select(c => c.SeasonNumber).Distinct().Count() == 1)
             {
-                item.SeasonNumber = decision.LocalEpisode.SeasonNumber;
-                item.Episodes = decision.LocalEpisode.Episodes;
+                var seasons = decision.LocalEpisode.Episodes.Select(c => c.SeasonNumber).Distinct().ToList();
+
+                if (seasons.Empty())
+                {
+                    _logger.Warn("Expected one season, but found none for: {0}", decision.LocalEpisode.Path);
+                }
+                else if (seasons.Count > 1)
+                {
+                    _logger.Warn("Expected one season, but found {0} ({1}) for: {2}", seasons.Count, string.Join(", ", seasons), decision.LocalEpisode.Path);
+                }
+                else
+                {
+                    item.SeasonNumber = decision.LocalEpisode.SeasonNumber;
+                    item.Episodes = decision.LocalEpisode.Episodes;
+                }
             }
 
             item.Quality = decision.LocalEpisode.Quality;

src/NzbDrone.Core/MediaFiles/EpisodeImport/Specifications/NotSampleSpecification.cs

@@ -1,6 +1,8 @@
-using NLog;
+using System;
+using NLog;
 using NzbDrone.Core.DecisionEngine;
 using NzbDrone.Core.Download;
+using NzbDrone.Core.Parser;
 using NzbDrone.Core.Parser.Model;
 
 namespace NzbDrone.Core.MediaFiles.EpisodeImport.Specifications
@@ -25,18 +27,23 @@ namespace NzbDrone.Core.MediaFiles.EpisodeImport.Specifications
                 return Decision.Accept();
             }
 
-            var sample = _detectSample.IsSample(localEpisode.Series,
-                                                localEpisode.Path,
-                                                localEpisode.IsSpecial);
-
-            if (sample == DetectSampleResult.Sample)
+            try
             {
-                return Decision.Reject("Sample");
-            }
+                var sample = _detectSample.IsSample(localEpisode.Series, localEpisode.Path, localEpisode.IsSpecial);
 
-            else if (sample == DetectSampleResult.Indeterminate)
+                if (sample == DetectSampleResult.Sample)
+                {
+                    return Decision.Reject("Sample");
+                }
+
+                else if (sample == DetectSampleResult.Indeterminate)
+                {
+                    return Decision.Reject("Unable to determine if file is a sample");
+                }
+            }
+            catch (InvalidSeasonException e)
             {
-                return Decision.Reject("Unable to determine if file is a sample");
+                _logger.Warn(e, "Invalid season detected during sample check");
             }
 
             return Decision.Accept();

src/NzbDrone.Core/NzbDrone.Core.csproj

@@ -936,6 +936,7 @@
     <Compile Include="Notifications\Twitter\Twitter.cs" />
     <Compile Include="Notifications\Twitter\TwitterService.cs" />
     <Compile Include="Notifications\Twitter\TwitterSettings.cs" />
+    <Compile Include="Parser\InvalidSeasonException.cs" />
     <Compile Include="Parser\IsoLanguage.cs" />
     <Compile Include="Parser\IsoLanguages.cs" />
     <Compile Include="Parser\LanguageParser.cs" />

src/NzbDrone.Core/Parser/InvalidSeasonException.cs

@@ -0,0 +1,15 @@
+using NzbDrone.Common.Exceptions;
+
+namespace NzbDrone.Core.Parser
+{
+    public class InvalidSeasonException : NzbDroneException
+    {
+        public InvalidSeasonException(string message, params object[] args) : base(message, args)
+        {
+        }
+
+        public InvalidSeasonException(string message) : base(message)
+        {
+        }
+    }
+}

src/NzbDrone.Core/Parser/Model/LocalEpisode.cs

@@ -1,5 +1,6 @@
 using System.Linq;
 using System.Collections.Generic;
+using NzbDrone.Common.Extensions;
 using NzbDrone.Core.Qualities;
 using NzbDrone.Core.Tv;
 using NzbDrone.Core.MediaFiles.MediaInfo;
@@ -26,7 +27,19 @@ namespace NzbDrone.Core.Parser.Model
         { 
             get
             {
-                return Episodes.Select(c => c.SeasonNumber).Distinct().Single();
+                var seasons = Episodes.Select(c => c.SeasonNumber).Distinct().ToList();
+
+                if (seasons.Empty())
+                {
+                    throw new InvalidSeasonException("Expected one season, but found none");
+                }
+
+                if (seasons.Count > 1)
+                {
+                    throw new InvalidSeasonException("Expected one season, but found {0} ({1})", seasons.Count, string.Join(", ", seasons));
+                }
+
+                return seasons.Single();
             } 
         }
 
@@ -37,4 +50,4 @@ namespace NzbDrone.Core.Parser.Model
             return Path;
         }
     }
-}
+}