From b1e92e7f73f695a886a59afe020f3d26d62e1929 Mon Sep 17 00:00:00 2001
From: ta264 <ta264@users.noreply.github.com>
Date: Sun, 25 Jul 2021 21:39:59 +0100
Subject: [PATCH] Fixed: Computing most common author now we have multiple
 authors

---
 .../Identification/CandidateService.cs        |  8 ++++++-
 .../Identification/DistanceCalculator.cs      | 21 ++++++++++---------
 2 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/src/NzbDrone.Core/MediaFiles/BookImport/Identification/CandidateService.cs b/src/NzbDrone.Core/MediaFiles/BookImport/Identification/CandidateService.cs
index 71cd7004c..f7d8acc78 100644
--- a/src/NzbDrone.Core/MediaFiles/BookImport/Identification/CandidateService.cs
+++ b/src/NzbDrone.Core/MediaFiles/BookImport/Identification/CandidateService.cs
@@ -285,7 +285,13 @@ public IEnumerable<CandidateEdition> GetRemoteCandidates(LocalEdition localEditi
             }
             else
             {
-                authorTags.AddRange(localEdition.LocalBooks.MostCommon(x => x.FileTrackInfo.Authors));
+                // the most common list of authors reported by a file
+                var authors = localEdition.LocalBooks.Select(x => x.FileTrackInfo.Authors.Where(a => a.IsNotNullOrWhiteSpace()).ToList())
+                    .GroupBy(x => x.ConcatToString())
+                    .OrderByDescending(x => x.Count())
+                    .First()
+                    .First();
+                authorTags.AddRange(authors);
             }
 
             var bookTag = localEdition.LocalBooks.MostCommon(x => x.FileTrackInfo.BookTitle) ?? "";
diff --git a/src/NzbDrone.Core/MediaFiles/BookImport/Identification/DistanceCalculator.cs b/src/NzbDrone.Core/MediaFiles/BookImport/Identification/DistanceCalculator.cs
index 1e9ce5e23..292c0d9fa 100644
--- a/src/NzbDrone.Core/MediaFiles/BookImport/Identification/DistanceCalculator.cs
+++ b/src/NzbDrone.Core/MediaFiles/BookImport/Identification/DistanceCalculator.cs
@@ -23,19 +23,20 @@ public static Distance BookDistance(List<LocalBook> localTracks, Edition edition
         {
             var dist = new Distance();
 
-            var authors = new List<string>();
+            // the most common list of authors reported by a file
+            var fileAuthors = localTracks.Select(x => x.FileTrackInfo.Authors.Where(a => a.IsNotNullOrWhiteSpace()).ToList())
+                .GroupBy(x => x.ConcatToString())
+                .OrderByDescending(x => x.Count())
+                .First()
+                .First();
 
-            var fileAuthors = localTracks.MostCommon(x => x.FileTrackInfo.Authors);
-            if (fileAuthors?.Any() ?? false)
+            var authors = new List<string>(fileAuthors);
+
+            foreach (var author in fileAuthors)
             {
-                authors.AddRange(fileAuthors);
-
-                foreach (var author in fileAuthors)
+                if (author.Contains(','))
                 {
-                    if (author.Contains(','))
-                    {
-                        authors.Add(authors[0].Split(',', 2).Select(x => x.Trim()).Reverse().ConcatToString(" "));
-                    }
+                    authors.Add(authors[0].Split(',', 2).Select(x => x.Trim()).Reverse().ConcatToString(" "));
                 }
             }