Improve the algorithm for removing Islam from the map (#1672)

ImperatorToCK3.UnitTests/CK3/Map/MapDataTests.cs

@@ -3,6 +3,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Linq;
 using Xunit;
 
 namespace ImperatorToCK3.UnitTests.CK3.Map;
@@ -15,8 +16,8 @@ public void NeighborsDictDefaultsToEmpty() {
 		const string ck3Root = "TestFiles/MapData/CK3_1_province_map/game";
 		var ck3ModFS = new ModFilesystem(ck3Root, new List<Mod>());
 		var data = new MapData(ck3ModFS);
-
-		Assert.Empty(data.NeighborsDict);
+		
+		new ulong[] { 0, 1, 2, 3 }.ToList().ForEach(id => Assert.Empty(data.GetNeighborProvinceIds(id)));
 	}
 
 	[Fact]
@@ -27,9 +28,8 @@ public void NeighborProvincesCanBeDetermined() {
 		var ck3ModFS = new ModFilesystem(ck3Root, new List<Mod>());
 		var data = new MapData(ck3ModFS);
 		Assert.True(data.ProvinceDefinitions.ProvinceToColorDict.ContainsKey(byzantionId));
-		Assert.True(data.NeighborsDict.ContainsKey(byzantionId));
 
-		var byzantionNeighborProvs = data.NeighborsDict[byzantionId];
+		var byzantionNeighborProvs = data.GetNeighborProvinceIds(byzantionId);
 		var expectedByzantionNeighborProvs = new HashSet<ulong> {
 			3761, // Selymbria
 			8668, // sea_bosporus

ImperatorToCK3/CK3/Map/MapData.cs

@@ -32,7 +32,7 @@ public override int GetHashCode() {
 		}
 	}
 
-	public SortedDictionary<ulong, HashSet<ulong>> NeighborsDict { get; } = new();
+	private SortedDictionary<ulong, HashSet<ulong>> NeighborsDict { get; } = [];
 	public ISet<ulong> ColorableImpassableProvinces { get; } = new HashSet<ulong>();
 	public IDictionary<ulong, ProvincePosition> ProvincePositions { get; } = new Dictionary<ulong, ProvincePosition>();
 	public ProvinceDefinitions ProvinceDefinitions { get; }
@@ -62,6 +62,25 @@ public MapData(ModFilesystem ck3ModFS) {
 		FindImpassables(ck3ModFS);
 		Logger.IncrementProgress();
 	}
+
+	public double GetDistanceBetweenProvinces(ulong province1, ulong province2) {
+		if (!ProvincePositions.TryGetValue(province1, out var province1Position)) {
+			Logger.Warn($"Province {province1} has no position defined!");
+			return 0;
+		}
+		if (!ProvincePositions.TryGetValue(province2, out var province2Position)) {
+			Logger.Warn($"Province {province2} has no position defined!");
+			return 0;
+		}
+
+		var xDiff = province1Position.X - province2Position.X;
+		var yDiff = province1Position.Y - province2Position.Y;
+		return Math.Sqrt(xDiff * xDiff + yDiff * yDiff);
+	}
+
+	public IReadOnlySet<ulong> GetNeighborProvinceIds(ulong provinceId) {
+		return NeighborsDict.TryGetValue(provinceId, out var neighbors) ? neighbors : [];
+	}
 
 	private void DetermineProvincePositions(ModFilesystem ck3ModFS) {
 		const string provincePositionsPath = "gfx/map/map_object_data/building_locators.txt";
@@ -206,7 +225,7 @@ private void AddNeighbor(ulong mainProvince, ulong neighborProvince) {
 		if (NeighborsDict.TryGetValue(mainProvince, out var neighbors)) {
 			neighbors.Add(neighborProvince);
 		} else {
-			NeighborsDict[mainProvince] = new HashSet<ulong> {neighborProvince};
+			NeighborsDict[mainProvince] = [neighborProvince];
 		}
 	}
 }

ImperatorToCK3/CK3/Provinces/ProvinceHistory.cs

@@ -17,6 +17,13 @@ public partial class Province {
 			_ => null
 		};
 	}
+
+	public void SetFaithIdAndOverrideExistingEntries(string faithId) {
+		var faithHistoryField = History.Fields["faith"];
+		faithHistoryField.RemoveAllEntries();
+		faithHistoryField.AddEntryToHistory(null, "faith", faithId);
+	}
+
 	public void SetFaithId(string faithId, Date? date) {
 		History.AddFieldValue(date, "faith", "faith", faithId);
 	}

ImperatorToCK3/CK3/World.cs

@@ -637,37 +637,97 @@ private void RemoveIslam(Configuration config) {
 			new("world_africa_west", "berber_pagan"),
 			new("world_africa_east", "waaqism_pagan"),
 			new("world_africa_sahara", "berber_pagan"),
-			new("world_africa", "berber_pagan"), // fallback
-			new("world_africa", "pagan"), // fallback
+			new("world_africa", "berber_pagan"),
 			// Rest of the world
-			new("world_europe", "arabic_pagan"),
-			new("world_asia_minor", "arabic_pagan"),
 			new("world_middle_east", "arabic_pagan"),
-			new("world_india", "arabic_pagan"),
-			new("world_steppe", "arabic_pagan"),
-			new("world_tibet", "arabic_pagan"),
-			new("world_burma", "arabic_pagan"),
 		}.Where(kvp => Religions.GetFaith(kvp.Value) is not null);
 
 		foreach (var (regionId, faithId) in regionToNewFaithMap) {
 			var regionProvinces = muslimProvinces
 				.Where(p => ck3RegionMapper.ProvinceIsInRegion(p.Id, regionId));
 			foreach (var province in regionProvinces) {
-				var faithHistoryField = province.History.Fields["faith"];
-				faithHistoryField.RemoveAllEntries();
-				faithHistoryField.AddEntryToHistory(null, "faith", faithId);
-
+				province.SetFaithIdAndOverrideExistingEntries(faithId);
 				muslimProvinces.Remove(province);
 			}
 		}
 
+		UseNeighborProvincesToRemoveIslam(muslimProvinces, date);
+		UseClosestProvincesToRemoveIslam(muslimProvinces, date);
+		UseFallbackNonMuslimFaithToRemoveIslam(muslimProvinces, muslimFaiths);
+
 		// Log warning if there are still muslim provinces left.
 		if (muslimProvinces.Count > 0) {
 			Logger.Warn($"{muslimProvinces.Count} muslim provinces left after removing Islam: " +
 			            $"{string.Join(", ", muslimProvinces.Select(p => p.Id))}");
 		}
 	}
 
+	private void UseFallbackNonMuslimFaithToRemoveIslam(HashSet<Province> muslimProvinces, IdObjectCollection<string, Faith> muslimFaiths) {
+		if (muslimProvinces.Count <= 0) {
+			return;
+		}
+
+		var fallbackFaith = Religions.Faiths.Except(muslimFaiths).FirstOrDefault();
+		if (fallbackFaith is not null) {
+			foreach (var province in muslimProvinces.ToList()) {
+				Logger.Debug($"Using fallback faith \"{fallbackFaith.Id}\" for province {province.Id}");
+				province.SetFaithIdAndOverrideExistingEntries(fallbackFaith.Id);
+				muslimProvinces.Remove(province);
+			}
+		}
+	}
+
+	private void UseClosestProvincesToRemoveIslam(HashSet<Province> muslimProvinces, Date date) {
+		if (muslimProvinces.Count <= 0) {
+			return;
+		}
+
+		var provincesWithValidFaith = Provinces
+			.Except(muslimProvinces)
+			.Where(p => p.GetFaithId(date) is not null)
+			.ToHashSet();
+		foreach (var province in muslimProvinces) {
+			var closestValidProvince = provincesWithValidFaith
+				.Except(muslimProvinces)
+				.Select(p => new {
+					Province = p, 
+					Distance = MapData.GetDistanceBetweenProvinces(province.Id, p.Id),
+				})
+				.Where(x => x.Distance > 0)
+				.MinBy(x => x.Distance)?.Province;
+			if (closestValidProvince is null) {
+				continue;
+			}
+
+			var faithId = closestValidProvince.GetFaithId(date)!;
+			Logger.Debug($"Using faith \"{faithId}\" of closest province for province {province.Id}");
+			province.SetFaithIdAndOverrideExistingEntries(faithId);
+			muslimProvinces.Remove(province);
+		}
+	}
+
+	private void UseNeighborProvincesToRemoveIslam(HashSet<Province> muslimProvinces, Date date) {
+		foreach (var province in muslimProvinces) {
+			var neighborIds = MapData.GetNeighborProvinceIds(province.Id);
+			if (neighborIds.Count == 0) {
+				continue;
+			}
+
+			var neighborFaithId = Provinces
+				.Except(muslimProvinces)
+				.Where(p => neighborIds.Contains(p.Id))
+				.Select(p => p.GetFaithId(date))
+				.FirstOrDefault(f => f is not null);
+			if (neighborFaithId is null) {
+				continue;
+			}
+
+			Logger.Debug($"Using neighbor's faith \"{neighborFaithId}\" for province {province.Id}.");
+			province.SetFaithIdAndOverrideExistingEntries(neighborFaithId);
+			muslimProvinces.Remove(province);
+		}
+	}
+
 	private void GenerateFillerHoldersForUnownedLands(CultureCollection cultures, Configuration config) {
 		Logger.Info("Generating filler holders for unowned lands...");
 		var date = config.CK3BookmarkDate;

ImperatorToCK3/Outputter/BookmarkOutputter.cs

@@ -214,11 +214,9 @@ private static void DrawBookmarkMap(Configuration config, List<Title> playerTitl
 			var provincesToColor = new HashSet<ulong>(heldProvinces);
 			var impassables = mapData.ColorableImpassableProvinces;
 			foreach (var impassableId in impassables) {
-				if (!mapData.NeighborsDict.TryGetValue(impassableId, out var neighborProvs)) {
-					continue;
-				}
-
-				var nonImpassableNeighborProvs = new HashSet<ulong>(neighborProvs.Except(impassables));
+				var nonImpassableNeighborProvs = mapData.GetNeighborProvinceIds(impassableId)
+					.Except(impassables)
+					.ToHashSet();
 				if (nonImpassableNeighborProvs.Count == 0) {
 					continue;
 				}