Distance option to prevent new towns to block old towns expansion.

Towny/src/main/java/com/palmergames/bukkit/config/ConfigNodes.java

@@ -1122,6 +1122,15 @@ public enum ConfigNodes {
 			"# Put in other words: the buffer area around every claim that no other town can claim into.",
 			"# Does not affect towns which are in the same nation.",
 			"# This will prevent town encasement to a certain degree."),
+	CLAIMING_MIN_PLOT_DISTANCE_FROM_OLDER_TOWN_PLOT(
+			"claiming.distance_rules.min_plot_distance_from_older_town_plot",
+			"5",
+			"",
+			"# The minimum number of plots required between a town and older towns. Must be higher than min_plot_distance_from_town_plot.",
+			"# Does not affect towns which are in the same nation when min_distances_ignored_for_towns_in_same_nation is set to true.",
+			"# Does not affect towns which are in the allied when min_distances_ignored_for_towns_in_allied_nation is set to true.",
+			"# This works exactly as min_plot_distance_from_town_plot except that it only affects towns created newer than already-existing towns.",
+			"# This will prevent old towns from being unable to expand outwards towards newer towns, which might have tried to claim-block them."),
 	CLAIMING_MIN_DISTANCE_FROM_TOWN_HOMEBLOCK(
 			"claiming.distance_rules.min_distance_from_town_homeblock",
 			"5",

Towny/src/main/java/com/palmergames/bukkit/towny/TownySettings.java

@@ -2579,6 +2579,10 @@ public static int getMinDistanceFromTownPlotblocks() {
 		return getInt(ConfigNodes.CLAIMING_MIN_PLOT_DISTANCE_FROM_TOWN_PLOT);
 	}
 
+	public static int getMinDistanceFromOlderTownPlotblocks() {
+		return getInt(ConfigNodes.CLAIMING_MIN_PLOT_DISTANCE_FROM_OLDER_TOWN_PLOT);
+	}
+
 	public static int getMaxDistanceForTownMerge() {
 		return getInt(ConfigNodes.GTOWN_SETTINGS_MAX_DISTANCE_FOR_MERGE);
 	}

Towny/src/main/java/com/palmergames/bukkit/towny/object/TownyWorld.java

@@ -6,6 +6,7 @@
 import com.palmergames.bukkit.towny.exceptions.TownyException;
 import com.palmergames.bukkit.towny.object.TownyPermission.ActionType;
 import com.palmergames.bukkit.towny.object.metadata.CustomDataField;
+import com.palmergames.bukkit.towny.utils.CombatUtil;
 import com.palmergames.util.MathUtil;
 
 import com.palmergames.util.StringMgmt;
@@ -29,6 +30,7 @@
 import java.util.Objects;
 import java.util.Set;
 import java.util.UUID;
+import java.util.function.Predicate;
 
 public class TownyWorld extends TownyObject {
 	private UUID uuid;
@@ -878,18 +880,39 @@ public int getMinDistanceFromOtherTownsPlots(Coord key) {
 	 * @return the closest distance to another towns nearest plot.
 	 */
 	public int getMinDistanceFromOtherTownsPlots(Coord key, Town homeTown) {
+		return getMinDistanceFromOtherTownsPlots(key, homeTown, t -> false);
+	}
+
+	/**
+	 * Checks the distance from a another older town's plots.
+	 * It have the same behavior than {@link #getMinDistanceFromOtherTownsPlots(Coord, Town)}
+	 * but it will only consider towns that are older than the homeTown.
+	 * 
+	 * @param key - Coord to check from.
+	 * @param homeTown Players town
+	 * @return the closest distance to another older towns nearest plot.
+	 */
+	public int getMinDistanceFromOtherOlderTownsPlots(Coord key, Town homeTown) {
+		return getMinDistanceFromOtherTownsPlots(key, homeTown, t -> t.getRegistered() > homeTown.getRegistered());
+	}
+
+	/**
+	 * Checks the distance from a another town's plots.
+	 * 
+	 * @param key - Coord to check from.
+	 * @param homeTown Players town
+	 * @param isIgnorableTown Predicate to filter out towns that should not be considered.
+	 * @return the closest distance to another towns nearest plot.
+	 */
+	private int getMinDistanceFromOtherTownsPlots(Coord key, Town homeTown, @NotNull Predicate<Town> isIgnorableTown) {
 		final int keyX = key.getX();
 		final int keyZ = key.getZ();
 
 		double minSqr = -1;
 		for (Town town : getTowns().values()) {
-			if (homeTown != null)
-				// If the townblock either: the town is the same as homeTown OR 
-				// both towns are in the same nation (and this is set to ignore distance in the config,) skip over the proximity filter.
-				if (homeTown.getUUID().equals(town.getUUID())
-					|| (TownySettings.isMinDistanceIgnoringTownsInSameNation() && homeTown.hasNation() && town.hasNation() && town.getNationOrNull().equals(homeTown.getNationOrNull()))
-					|| (TownySettings.isMinDistanceIgnoringTownsInAlliedNation() && homeTown.isAlliedWith(town)))
-					continue;
+			if (homeTown != null && townSkippedByProximityFilter(town, homeTown, isIgnorableTown))
+				continue;
+
 			for (TownBlock b : town.getTownBlocks()) {
 				if (!b.getWorld().equals(this)) continue;
 
@@ -906,8 +929,58 @@ public int getMinDistanceFromOtherTownsPlots(Coord key, Town homeTown) {
 		}
 		return minSqr == -1 ? Integer.MAX_VALUE : (int) Math.ceil(Math.sqrt(minSqr));
 	}
-
-
+
+	public boolean worldCoordNotTooCloseToOtherTowns(Coord key, Town homeTown) {
+		final Map<Integer, Predicate<Town>> minDistances = new HashMap<>();
+		if(TownySettings.getMinDistanceFromTownPlotblocks() > 0){
+			minDistances.put(TownySettings.getMinDistanceFromTownPlotblocks(), t -> false);
+		}
+		if (TownySettings.getMinDistanceFromOlderTownPlotblocks() > TownySettings.getMinDistanceFromTownPlotblocks()){
+			minDistances.put(TownySettings.getMinDistanceFromOlderTownPlotblocks(), t -> t.getRegistered() > homeTown.getRegistered());
+		}
+		final int keyX = key.getX();
+		final int keyZ = key.getZ();
+
+		for(Town town : getTowns().values()){
+			if (homeTown != null && townSkippedByProximityFilter(town, homeTown, t -> false)) // No skip with the predicate here because it will be done later by the map.
+				continue;
+
+			for (TownBlock b : town.getTownBlocks()) {
+				if (!b.getWorld().equals(this)) continue;
+
+				final int tbX = b.getX();
+				final int tbZ = b.getZ();
+
+				if (keyX == tbX && keyZ == tbZ)
+					continue;
+
+				final double distSqr = MathUtil.distanceSquared((double) tbX - keyX, (double) tbZ - keyZ);
+				// If there is a town that is too close, return false.
+				if (minDistances.entrySet().stream().anyMatch(entry -> distSqr >= entry.getKey() && !entry.getValue().test(town)))
+					return false;
+			}
+		}
+		return true;
+	}
+
+	/** 
+	 * Skip over the proximity filter if the town is any one of the following: 
+	 * the same as homeTown OR is ignorable for a reason set in the Predicate<Town>
+	 * OR both towns are in the same nation OR both towns are in allied nations  
+	 * (and nation/alliednations are set to ignore distance in the config.)
+	 * 
+	 * @param town Town we are testing against.
+	 * @param homeTown the Town which is attempting to claim land.
+	 * @param isIgnorableTown Predicate<Town> which tests the town variable to see if it can be ignored by the proximity test.
+	 * @return true if town can claim near to homeTown.
+	 */
+	private boolean townSkippedByProximityFilter(Town town, Town homeTown, @NotNull Predicate<Town> isIgnorableTown) {
+		return homeTown.equals(town)
+			|| isIgnorableTown.test(town)
+			|| (TownySettings.isMinDistanceIgnoringTownsInSameNation() && CombatUtil.isSameNation(town, homeTown))
+			|| (TownySettings.isMinDistanceIgnoringTownsInAlliedNation() && homeTown.isAlliedWith(town));
+	}
+
 	/**
 	 * Returns the distance to the closest townblock 
 	 * from the given coord, for the give town. 

Towny/src/main/java/com/palmergames/bukkit/towny/utils/AreaSelectionUtil.java

@@ -9,6 +9,7 @@
 import com.palmergames.bukkit.towny.object.TownBlock;
 import com.palmergames.bukkit.towny.object.TownBlockOwner;
 import com.palmergames.bukkit.towny.object.TownBlockType;
+import com.palmergames.bukkit.towny.object.TownyWorld;
 import com.palmergames.bukkit.towny.object.Translatable;
 import com.palmergames.bukkit.towny.object.WorldCoord;
 import com.palmergames.bukkit.util.BiomeUtil;
@@ -334,13 +335,19 @@ public static List<WorldCoord> filterInvalidProximityTownBlocks(List<WorldCoord>
 
 		List<WorldCoord> out = new ArrayList<>();
 		for (WorldCoord worldCoord : selection)
-			if (worldCoord.getTownyWorld().getMinDistanceFromOtherTownsPlots(worldCoord, town) >= TownySettings.getMinDistanceFromTownPlotblocks()) {
+			if (worldCoordNotTooCloseToOtherTowns(town, worldCoord)) {
 				out.add(worldCoord);
 			} else {
 				TownyMessaging.sendDebugMsg("AreaSelectionUtil:filterInvalidProximity - Coord: " + worldCoord + " too close to another town." );
 			}
 		return out;
 	}
+
+	private static boolean worldCoordNotTooCloseToOtherTowns(Town town, WorldCoord worldCoord) {
+		TownyWorld townyWorld = worldCoord.getTownyWorld();
+		return townyWorld != null 
+				&& townyWorld.worldCoordNotTooCloseToOtherTowns(worldCoord, town);
+	}
 
 	/**
 	 * Returns a list containing only townblocks that can be claimed.

Towny/src/main/java/com/palmergames/bukkit/towny/utils/OutpostUtil.java

@@ -73,6 +73,11 @@ public static boolean OutpostTests(Town town, Resident resident, TownyWorld worl
 			minDistance < TownySettings.getMinDistanceForOutpostsFromPlot())
 			throw new TownyException(Translatable.of("msg_too_close2", Translatable.of("townblock")));
 
+		// Newer towns can be prevented from claiming near to older towns.
+		if (!isPlotSetOutpost &&
+			world.getMinDistanceFromOtherOlderTownsPlots(key, town) < TownySettings.getMinDistanceFromOlderTownPlotblocks())
+				throw new TownyException(Translatable.of("msg_too_close3", Translatable.of("townblock")));
+
 		return true;		
 	}
 

Towny/src/main/java/com/palmergames/bukkit/towny/utils/ProximityUtil.java

@@ -31,11 +31,13 @@ public static void allowTownHomeBlockOrThrow(TownyWorld world, Coord key, @Nulla
 			return;
 
 		if (newTown) { // Tests run only when there is a new town involved.
-			if (TownySettings.getMinDistanceFromTownPlotblocks() > 0 || TownySettings.getNewTownMinDistanceFromTownPlots() > 0) {
+			if (TownySettings.getMinDistanceFromTownPlotblocks() > 0 ||
+				TownySettings.getMinDistanceFromOlderTownPlotblocks() > 0 ||
+				TownySettings.getNewTownMinDistanceFromTownPlots() > 0) {
 				// Sometimes new towns have special min. distances from other towns.
 				int minDistance = TownySettings.getNewTownMinDistanceFromTownPlots();
 				if (minDistance <= 0)
-					minDistance = TownySettings.getMinDistanceFromTownPlotblocks();
+					minDistance = Math.max(TownySettings.getMinDistanceFromTownPlotblocks(), TownySettings.getMinDistanceFromOlderTownPlotblocks());
 
 				// throws when a new town is being made to close to another town's land.
 				if (world.getMinDistanceFromOtherTownsPlots(key) < minDistance)
@@ -86,6 +88,10 @@ public static void allowTownClaimOrThrow(TownyWorld world, WorldCoord townBlockT
 		if (world.getMinDistanceFromOtherTownsPlots(townBlockToClaim, town) < TownySettings.getMinDistanceFromTownPlotblocks())
 			throw new TownyException(Translatable.of("msg_too_close2", Translatable.of("townblock")));
 
+		// Check distance to other older townblocks.
+		if (world.getMinDistanceFromOtherOlderTownsPlots(townBlockToClaim, town) < TownySettings.getMinDistanceFromOlderTownPlotblocks())
+			throw new TownyException(Translatable.of("msg_too_close3", Translatable.of("townblock")));
+
 		// Check adjacent claims rules.
 		testAdjacentClaimsRulesOrThrow(townBlockToClaim, town, outpost);
 

Towny/src/main/resources/lang/en-US.yml

@@ -1226,6 +1226,7 @@ msg_save_success: 'Database saved.'
 msg_load_success: 'Database loaded.'
 msg_err_cannot_afford_to_set_outpost: 'Your town does not have enough funds to set this townblock to an outpost.'
 msg_too_close2: 'This area is too close to another town''s %s.'
+msg_too_close3: 'This area is too close to %s claimed by a town older than yours.'
 homeblock: 'homeblock'
 townblock: 'townblock'
 outpost: 'outpost'

Towny/src/test/java/com/palmergames/bukkit/towny/object/TownyWorldTest.java

@@ -0,0 +1,65 @@
+package com.palmergames.bukkit.towny.object;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import java.util.UUID;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+import com.palmergames.bukkit.config.ConfigNodes;
+import com.palmergames.bukkit.towny.TownySettings;
+import be.seeseemelk.mockbukkit.MockBukkit;
+
+class TownyWorldTest {
+
+	@BeforeAll
+	static void init() {
+		MockBukkit.getOrCreateMock();
+		TownySettings.loadDefaultConfig();
+		// new Towny();
+	}
+
+	@Test
+	void testTownCreationWithNoOtherTown() {
+		TownyWorld world = new TownyWorld("world");
+		Town town = new Town("testTown");
+		town.setWorld(world);
+
+		assertTrue(world.hasTowns());
+		assertTrue(world.worldCoordNotTooCloseToOtherTowns(new Coord(0, 0), town));
+	}
+
+	@ParameterizedTest
+	@CsvSource({"0,0, 0,0,0,false", "0,1, 0,0,0,true", "0,1, 1,0,0,false", "0,1, 0,1,0,false", "0,1, 0,0,1,false", "0,2, 1,0,0,true",
+			"0,2, 0,1,0,true", "0,2, 0,0,1,true"})
+	void testTownCreationWithOneOtherTown(int x, int z, int minDistanceBetweenHomeblocks, int minPlotDistanceFromTownPlot,
+			int minPlotDistanceFromOlderTownPlot, boolean expected) {
+		TownySettings.getConfig().set(ConfigNodes.CLAIMING_MIN_DISTANCE_BETWEEN_HOMEBLOCKS.getRoot(), minDistanceBetweenHomeblocks);
+		TownySettings.getConfig().set(ConfigNodes.CLAIMING_MIN_PLOT_DISTANCE_FROM_TOWN_PLOT.getRoot(), minPlotDistanceFromTownPlot);
+		TownySettings.getConfig().set(ConfigNodes.CLAIMING_MIN_PLOT_DISTANCE_FROM_OLDER_TOWN_PLOT.getRoot(),
+				minPlotDistanceFromOlderTownPlot);
+		TownyWorld world = new TownyWorld("world");
+		Town oldTown = new Town("oldTown");
+		oldTown.setUUID(UUID.randomUUID());
+		oldTown.setWorld(world);
+		TownBlock townBlock = new TownBlock(0, 0, world);
+		// townBlock.setTown(oldTown);
+		// Upper line throws:
+		// java.lang.IllegalStateException: Attempted to use getPlugin() while the plugin is null, are you shading Towny? If you do not
+		// understand this message, join the Towny discord using https://discord.com/invite/gnpVs5m and ask for support.
+		// at com.palmergames.bukkit.towny.Towny.getPlugin(Towny.java:764)
+		// at com.palmergames.bukkit.towny.TownyUniverse.(TownyUniverse.java:100)
+		// at com.palmergames.bukkit.towny.TownyUniverse.getInstance(TownyUniverse.java:106)
+		// at com.palmergames.bukkit.towny.object.TownBlock.setTown(TownBlock.java:79)
+		// at com.palmergames.bukkit.towny.object.TownBlock.setTown(TownBlock.java:68)
+
+		Town newTown = new Town("newTown");
+		newTown.setUUID(UUID.randomUUID());
+		newTown.setWorld(world);
+
+
+		assertEquals(expected, world.worldCoordNotTooCloseToOtherTowns(new Coord(x, z), newTown));
+	}
+
+}