From cc9d04acd7a1d091a7dbeaeafb2301d8c4a8e998 Mon Sep 17 00:00:00 2001
From: Ben <thatbenbierens@gmail.com>
Date: Wed, 14 Aug 2024 15:10:33 +0200
Subject: [PATCH] Adds normalized kademlia positions

---
 .../OverwatchSupport/CodexTranscriptWriter.cs |  3 +-
 .../KademliaPositionFinder.cs                 | 68 +++++++++++++++++++
 .../OverwatchSupport/ModelExtensions.cs       |  1 +
 3 files changed, 71 insertions(+), 1 deletion(-)
 create mode 100644 ProjectPlugins/CodexPlugin/OverwatchSupport/KademliaPositionFinder.cs

diff --git a/ProjectPlugins/CodexPlugin/OverwatchSupport/CodexTranscriptWriter.cs b/ProjectPlugins/CodexPlugin/OverwatchSupport/CodexTranscriptWriter.cs
index 8fe2549..f836fa3 100644
--- a/ProjectPlugins/CodexPlugin/OverwatchSupport/CodexTranscriptWriter.cs
+++ b/ProjectPlugins/CodexPlugin/OverwatchSupport/CodexTranscriptWriter.cs
@@ -13,6 +13,7 @@ namespace CodexPlugin.OverwatchSupport
         private readonly ITranscriptWriter writer;
         private readonly CodexLogConverter converter;
         private readonly IdentityMap identityMap = new IdentityMap();
+        private readonly KademliaPositionFinder positionFinder = new KademliaPositionFinder();
 
         public CodexTranscriptWriter(ILog log, ITranscriptWriter transcriptWriter)
         {
@@ -76,7 +77,7 @@ namespace CodexPlugin.OverwatchSupport
         {
             return new OverwatchCodexHeader
             {
-                Nodes = identityMap.Get()
+                Nodes = positionFinder.DeterminePositions(identityMap.Get())
             };
         }
 
diff --git a/ProjectPlugins/CodexPlugin/OverwatchSupport/KademliaPositionFinder.cs b/ProjectPlugins/CodexPlugin/OverwatchSupport/KademliaPositionFinder.cs
new file mode 100644
index 0000000..7e80341
--- /dev/null
+++ b/ProjectPlugins/CodexPlugin/OverwatchSupport/KademliaPositionFinder.cs
@@ -0,0 +1,68 @@
+using System.Numerics;
+using Utils;
+using YamlDotNet.Core.Tokens;
+
+namespace CodexPlugin.OverwatchSupport
+{
+    public class KademliaPositionFinder
+    {
+        public CodexNodeIdentity[] DeterminePositions(CodexNodeIdentity[] identities)
+        {
+            var zero = identities.First();
+            var distances = CalculateDistances(zero, identities);
+
+            var maxDistance = distances.Values.Max();
+            CalculateNormalizedPositions(distances, maxDistance);
+
+            return identities;
+        }
+
+        private Dictionary<CodexNodeIdentity, BigInteger>  CalculateDistances(CodexNodeIdentity zero, CodexNodeIdentity[] identities)
+        {
+            var result = new Dictionary<CodexNodeIdentity, BigInteger>();
+            foreach (var id in identities.Skip(1))
+            {
+                result.Add(id, GetDistance(zero.NodeId, id.NodeId));
+            }
+            return result;
+        }
+
+        private BigInteger GetDistance(string id1, string id2)
+        {
+            var one = BigInteger.Parse(id1, System.Globalization.NumberStyles.HexNumber).ToByteArray();
+            var two = BigInteger.Parse(id2, System.Globalization.NumberStyles.HexNumber).ToByteArray();
+
+            var x = Xor(one, two);
+            return new BigInteger(x, isUnsigned: true);
+        }
+
+        private byte[] Xor(byte[] one, byte[] two)
+        {
+            if (one.Length != two.Length) throw new Exception("Not equal length");
+
+            var result = new byte[one.Length];
+            for (int i = 0; i < one.Length; i++)
+            {
+                uint a = one[i];
+                uint b = two[i];
+                uint c = (a ^ b);
+                result[i] = (byte)c;
+            }
+            return result;
+        }
+
+        private void CalculateNormalizedPositions(Dictionary<CodexNodeIdentity, BigInteger> distances, BigInteger maxDistance)
+        {
+            foreach (var pair in distances)
+            {
+                pair.Key.KademliaNormalizedPosition = DeterminePosition(pair.Value, maxDistance);
+            }
+        }
+
+        private float DeterminePosition(BigInteger value, BigInteger maxDistance)
+        {
+            var f = (value * 10000) / maxDistance;
+            return ((float)f) / 10000.0f;
+        }
+    }
+}
diff --git a/ProjectPlugins/CodexPlugin/OverwatchSupport/ModelExtensions.cs b/ProjectPlugins/CodexPlugin/OverwatchSupport/ModelExtensions.cs
index 9503cb9..eba43e8 100644
--- a/ProjectPlugins/CodexPlugin/OverwatchSupport/ModelExtensions.cs
+++ b/ProjectPlugins/CodexPlugin/OverwatchSupport/ModelExtensions.cs
@@ -52,6 +52,7 @@ namespace CodexPlugin.OverwatchSupport
         public string Name { get; set; } = string.Empty;
         public string PeerId { get; set; } = string.Empty;
         public string NodeId { get; set; } = string.Empty;
+        public float KademliaNormalizedPosition { get; set; } = 0.0f;
     }
 
     #region Scenario Generated Events