Detect and correct some localization key hash collisions (#2493) #patch

Author: IhateTrains

ImperatorToCK3/CK3/CK3LocDB.cs

@@ -3,6 +3,7 @@
 using commonItems.Localization;
 using commonItems.Mods;
 using ImperatorToCK3.CK3.Localization;
+using Murmur;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -83,6 +84,15 @@ public CK3LocBlock GetOrCreateLocBlock(string id) {
 				return locBlock;
 			}
 
+			// Check for hash collision.
+			var murmur3A = MurmurHash.Create32();
+			var hashStr = GetHashStrForKey(murmur3A, id);
+			if (hashToKeyDict.TryGetValue(hashStr, out var existingKey)) {
+				Logger.Warn($"Hash collision detected for loc key: {id}. Existing key: {existingKey}");
+			} else {
+				hashToKeyDict[hashStr] = id;
+			}
+			
 			// Create new loc block.
 			locBlock = new CK3LocBlock(id, ConverterGlobals.PrimaryLanguage);
 			Add(locBlock);
@@ -144,4 +154,17 @@ public List<string> GetLocLinesToOutputForLanguage(string language) {
 
 		return locLinesToOutput;
 	}
+	
+	public bool KeyHasConflictingHash(string key) {
+		var murmur3A = MurmurHash.Create32();
+		return hashToKeyDict.ContainsKey(GetHashStrForKey(murmur3A, key));
+	}
+
+	private string GetHashStrForKey(Murmur32 murmur32, string key) {
+		var keyBytes = System.Text.Encoding.UTF8.GetBytes(key);
+		var hash = murmur32.ComputeHash(keyBytes);
+		return string.Join("", hash.Select(b => b.ToString("X2")));
+	}
+	
+	private readonly Dictionary<string, string> hashToKeyDict = new(); // stores MurmurHash3A hash to key mapping
 }

ImperatorToCK3/CK3/Dynasties/Dynasty.cs

@@ -39,7 +39,13 @@ public Dynasty(Family irFamily, CharacterCollection irCharacters, CulturesDB irC
 
 	public Dynasty(CK3.Characters.Character character, string irFamilyName, ImperatorCharacter[] irMembers, CulturesDB irCulturesDB, LocDB irLocDB, CK3LocDB ck3LocDB, Date date) {
 		FromImperator = true;
-		Id = $"dynn_irtock3_from_{character.Id}";
+
+		string id = $"dynn_irtock3_from_{character.Id}";
+		uint counter = 0;
+		while (ck3LocDB.KeyHasConflictingHash(id)) {
+			id = $"dynn_irtock3_from_{character.Id}_{counter++}";
+		}
+		Id = id;
 		Name = Id;
 
 		CultureId = character.GetCultureId(date) ?? character.Father?.GetCultureId(date);

ImperatorToCK3/ImperatorToCK3.csproj

@@ -42,6 +42,7 @@
             <PrivateAssets>all</PrivateAssets>
             <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
         </PackageReference>
+        <PackageReference Include="MurmurHash.NETStandard" Version="1.0.0" />
         <PackageReference Include="PGCG.commonItems" Version="15.1.6" />
         <PackageReference Include="PGCG.commonItems.SourceGenerators" Version="1.0.8"/>
         <PackageReference Include="Polly" Version="8.5.2" />