Fixed: Size on disk calculation including multi-episode files multiple times

Closes #5296

src/NzbDrone.Core.Test/SeriesStatsTests/SeriesStatisticsFixture.cs

@@ -4,6 +4,7 @@ using System.Linq;
 using FizzWare.NBuilder;
 using FluentAssertions;
 using NUnit.Framework;
+using NzbDrone.Common.Extensions;
 using NzbDrone.Core.Languages;
 using NzbDrone.Core.MediaFiles;
 using NzbDrone.Core.Qualities;
@@ -180,5 +181,25 @@ namespace NzbDrone.Core.Test.SeriesStatsTests
             stats.Should().HaveCount(1);
             stats.First().SizeOnDisk.Should().Be(_episodeFile.Size);
         }
+
+        [Test]
+        public void should_not_duplicate_size_for_multi_episode_files()
+        {
+            GivenEpisodeWithFile();
+            GivenEpisode();
+            GivenEpisodeFile();
+
+            var episode2 = _episode.JsonClone();
+
+            episode2.Id = 0;
+            episode2.EpisodeNumber += 1;
+
+            Db.Insert(episode2);
+
+            var stats = Subject.SeriesStatistics();
+
+            stats.Should().HaveCount(1);
+            stats.First().SizeOnDisk.Should().Be(_episodeFile.Size);
+        }
     }
 }

src/NzbDrone.Core/SeriesStats/SeriesStatisticsRepository.cs

@@ -55,7 +55,7 @@ namespace NzbDrone.Core.SeriesStats
             return new SqlBuilder()
             .Select(@"Episodes.SeriesId AS SeriesId,
                              Episodes.SeasonNumber,
-                             SUM(COALESCE(EpisodeFiles.Size, 0)) AS SizeOnDisk,
+                             SUM(COALESCE(EpisodeFiles.Size, 0)) * COUNT(DISTINCT EpisodeFiles.Id) / COUNT(EpisodeFiles.Id) AS SizeOnDisk,
                              GROUP_CONCAT(EpisodeFiles.ReleaseGroup, '|') AS ReleaseGroupsString,
                              COUNT(*) AS TotalEpisodeCount,
                              SUM(CASE WHEN AirdateUtc <= @currentDate OR EpisodeFileId > 0 THEN 1 ELSE 0 END) AS AvailableEpisodeCount,