From f0ec2a822f88da69fd1ff607a87713637c79d222 Mon Sep 17 00:00:00 2001
From: Maciej Aszyk <maciej@ravendb.net>
Date: Tue, 23 Apr 2024 13:22:10 +0200
Subject: [PATCH] RavenDB-22311 Alphanumerical sorter - index out of range
 exception fix

---
 .../AlphaNumericFieldComparator.cs            |  4 +--
 test/SlowTests/Issues/RavenDB-22311.cs        | 35 +++++++++++++++++++
 2 files changed, 37 insertions(+), 2 deletions(-)
 create mode 100644 test/SlowTests/Issues/RavenDB-22311.cs

diff --git a/src/Raven.Server/Documents/Queries/Sorting/AlphaNumeric/AlphaNumericFieldComparator.cs b/src/Raven.Server/Documents/Queries/Sorting/AlphaNumeric/AlphaNumericFieldComparator.cs
index 8adfc58afc8c..072a97784f29 100644
--- a/src/Raven.Server/Documents/Queries/Sorting/AlphaNumeric/AlphaNumericFieldComparator.cs
+++ b/src/Raven.Server/Documents/Queries/Sorting/AlphaNumeric/AlphaNumericFieldComparator.cs
@@ -150,7 +150,7 @@ private unsafe void ScanNextAlphabeticOrNumericSequence()
             {
                 CurrentSequenceStartPosition = GetStartPosition();
                 Span<char> characters = stackalloc char[4];
-                var (usedBytes, usedChars) = ReadCharacter(CurrentPositionInString, characters);
+                var (usedBytes, usedChars) = ReadCharacter(StringBufferOffset, characters);
                 _currentSequenceIsNumber =  usedChars == 1 && char.IsDigit(characters[0]);
                 NumberLength = 0;
 
@@ -180,7 +180,7 @@ private unsafe void ScanNextAlphabeticOrNumericSequence()
 
                     if (CurrentPositionInString < _stringLength)
                     {
-                        (usedBytes, usedChars) = ReadCharacter(CurrentPositionInString, characters);
+                        (usedBytes, usedChars) = ReadCharacter(StringBufferOffset, characters);
                         currentCharacterIsDigit = usedChars == 1 && char.IsDigit(characters[0]);
                     }
                     else
diff --git a/test/SlowTests/Issues/RavenDB-22311.cs b/test/SlowTests/Issues/RavenDB-22311.cs
new file mode 100644
index 000000000000..fe886ff73b0e
--- /dev/null
+++ b/test/SlowTests/Issues/RavenDB-22311.cs
@@ -0,0 +1,35 @@
+using System.Linq;
+using FastTests;
+using Raven.Client.Documents;
+using Raven.Client.Documents.Session;
+using Tests.Infrastructure;
+using Tests.Infrastructure.Entities;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace SlowTests.Issues;
+
+public class RavenDB_22311 : RavenTestBase
+{
+    public RavenDB_22311(ITestOutputHelper output) : base(output)
+    {
+    }
+
+    [RavenFact(RavenTestCategory.Lucene | RavenTestCategory.Querying)]
+    public void AlphanumericalWillShiftWithGoodOffsetSize()
+    {
+        using var store = GetDocumentStore(Options.ForSearchEngine(RavenSearchEngineMode.Lucene));
+        using var session = store.OpenSession();
+        session.Store(new Order(){Company = "🚀1t"});
+        session.Store(new Order(){Company = "🚀1"});
+        session.SaveChanges();
+
+        var result = session.Query<Order>()
+            .Customize(c => c.WaitForNonStaleResults())
+            .OrderBy(x => x.Company, OrderingType.AlphaNumeric)
+            .ToList();
+        
+        Assert.Equal("🚀1", result[0].Company);
+        Assert.Equal("🚀1t", result[1].Company);
+    }
+}