From 11577b6db90f2c0eb1406b23e6c6e703e0edb8a4 Mon Sep 17 00:00:00 2001
From: ta264 <ta264@users.noreply.github.com>
Date: Fri, 7 May 2021 18:54:33 +0100
Subject: [PATCH] Fixed: Identification failing if book metadata has no authors

---
 .../Identification/DistanceFixture.cs         | 32 +++++++++++++++++++
 .../BookImport/Identification/Distance.cs     | 18 +++++++++--
 2 files changed, 48 insertions(+), 2 deletions(-)

diff --git a/src/NzbDrone.Core.Test/MediaFiles/TrackImport/Identification/DistanceFixture.cs b/src/NzbDrone.Core.Test/MediaFiles/TrackImport/Identification/DistanceFixture.cs
index b1b78d0a4..f1e98bf8e 100644
--- a/src/NzbDrone.Core.Test/MediaFiles/TrackImport/Identification/DistanceFixture.cs
+++ b/src/NzbDrone.Core.Test/MediaFiles/TrackImport/Identification/DistanceFixture.cs
@@ -131,6 +131,38 @@ namespace NzbDrone.Core.Test.MediaFiles.BookImport.Identification
             dist.Penalties.Should().BeEquivalentTo(new Dictionary<string, List<double>> { { "string", new List<double> { 0.0 } } });
         }
 
+        [Test]
+        public void test_add_string_empty_values_valid_target()
+        {
+            var dist = new Distance();
+            dist.AddString("string", new List<string>(), "target");
+            dist.Penalties.Should().BeEquivalentTo(new Dictionary<string, List<double>> { { "string", new List<double> { 1.0 } } });
+        }
+
+        [Test]
+        public void test_add_string_empty_values_empty_target()
+        {
+            var dist = new Distance();
+            dist.AddString("string", new List<string>(), string.Empty);
+            dist.Penalties.Should().BeEquivalentTo(new Dictionary<string, List<double>> { { "string", new List<double> { 0.0 } } });
+        }
+
+        [Test]
+        public void test_add_string_empty_options_valid_value()
+        {
+            var dist = new Distance();
+            dist.AddString("string", "value", new List<string>());
+            dist.Penalties.Should().BeEquivalentTo(new Dictionary<string, List<double>> { { "string", new List<double> { 1.0 } } });
+        }
+
+        [Test]
+        public void test_add_string_empty_options_empty_value()
+        {
+            var dist = new Distance();
+            dist.AddString("string", string.Empty, new List<string>());
+            dist.Penalties.Should().BeEquivalentTo(new Dictionary<string, List<double>> { { "string", new List<double> { 0.0 } } });
+        }
+
         [Test]
         public void test_distance()
         {
diff --git a/src/NzbDrone.Core/MediaFiles/BookImport/Identification/Distance.cs b/src/NzbDrone.Core/MediaFiles/BookImport/Identification/Distance.cs
index b2a13b6da..e40d84b90 100644
--- a/src/NzbDrone.Core/MediaFiles/BookImport/Identification/Distance.cs
+++ b/src/NzbDrone.Core/MediaFiles/BookImport/Identification/Distance.cs
@@ -151,12 +151,26 @@ namespace NzbDrone.Core.MediaFiles.BookImport.Identification
 
         public void AddString(string key, string value, List<string> options)
         {
-            Add(key, options.Min(x => StringScore(value, x)));
+            if (!options.Any())
+            {
+                Add(key, StringScore(value, string.Empty));
+            }
+            else
+            {
+                Add(key, options.Min(x => StringScore(value, x)));
+            }
         }
 
         public void AddString(string key, List<string> values, string target)
         {
-            Add(key, values.Min(v => StringScore(v, target)));
+            if (!values.Any())
+            {
+                Add(key, StringScore(string.Empty, target));
+            }
+            else
+            {
+                Add(key, values.Min(v => StringScore(v, target)));
+            }
         }
 
         public void AddBool(string key, bool expr)