From 03b25793ab3a0d6023cab98b23aa1a7f2a6c4c18 Mon Sep 17 00:00:00 2001
From: kcsombrio <kcsombrio@hotmail.com>
Date: Wed, 5 Jan 2022 15:39:40 -0300
Subject: [PATCH] Fix issue #2129 - reload 'last' index node in case the
 IndexPage has gone through a defrag

---
 LiteDB.Tests/Issues/Issue2129_Tests.cs | 49 ++++++++++++++++++++++++++
 LiteDB/Engine/Services/IndexService.cs |  2 ++
 2 files changed, 51 insertions(+)
 create mode 100644 LiteDB.Tests/Issues/Issue2129_Tests.cs

diff --git a/LiteDB.Tests/Issues/Issue2129_Tests.cs b/LiteDB.Tests/Issues/Issue2129_Tests.cs
new file mode 100644
index 000000000..1dce48cd1
--- /dev/null
+++ b/LiteDB.Tests/Issues/Issue2129_Tests.cs
@@ -0,0 +1,49 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Xunit;
+
+namespace LiteDB.Tests.Issues
+{
+    public class Issue2129_Tests
+    {
+        [Fact]
+        public void TestInsertAfterDeleteAll()
+        {
+            var db = new LiteDatabase(":memory:");
+            var col = db.GetCollection<SwapChance>(nameof(SwapChance));
+            col.EnsureIndex(x => x.Accounts1to2);
+            col.EnsureIndex(x => x.Accounts2to1);
+
+            col.InsertBulk(this.GenerateItems());
+            col.DeleteAll();
+            col.InsertBulk(this.GenerateItems());
+        }
+
+        private IEnumerable<SwapChance> GenerateItems()
+        {
+            var r = new Random();
+            int seq = 1;
+            return Enumerable.Range(0, 150).Select(x => new SwapChance
+            {
+                Rarity = "Uncommon",
+                Template1Id = r.Next(15023),
+                Template2Id = r.Next(142, 188645),
+                Accounts1to2 = Enumerable.Range(0, 8).Select(a => Guid.NewGuid().ToString().Substring(0, 10) + ".wam").ToList(),
+                Accounts2to1 = Enumerable.Range(0, 6).Select(a => Guid.NewGuid().ToString().Substring(0, 10) + ".wam").ToList(),
+                Sequence = seq++
+            });
+        }
+    }
+
+    public class SwapChance
+    {
+        public ObjectId Id { get; set; }
+        public int Sequence { get; set; } = 0;
+        public string Rarity { get; set; } = string.Empty;
+        public int Template1Id { get; set; }
+        public int Template2Id { get; set; }
+        public List<string> Accounts1to2 { get; set; } = new List<string>();
+        public List<string> Accounts2to1 { get; set; } = new List<string>();
+    }
+}
diff --git a/LiteDB/Engine/Services/IndexService.cs b/LiteDB/Engine/Services/IndexService.cs
index 9249284aa..46fc800e9 100644
--- a/LiteDB/Engine/Services/IndexService.cs
+++ b/LiteDB/Engine/Services/IndexService.cs
@@ -149,6 +149,8 @@ private IndexNode AddNode(CollectionIndex index, BsonValue key, PageAddress data
             {
                 ENSURE(last.NextNode == PageAddress.Empty, "last index node must point to null");
 
+                // reload 'last' index node in case the IndexPage has gone through a defrag
+                last = this.GetNode(last.Position);
                 last.SetNextNode(node.Position);
             }