Add configurable spawn dimensions

src/main/java/com/majinnaibu/bukkitplugins/metropolis/SpawnLayout.java

@@ -0,0 +1,51 @@
+/*
+This file is part of Metropolis.
+
+Metropolis is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+Metropolis is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with Metropolis. If not, see <https://www.gnu.org/licenses/agpl-3.0.txt>.
+*/
+
+package com.majinnaibu.bukkitplugins.metropolis;
+
+public final class SpawnLayout {
+  private SpawnLayout() {}
+
+  public static Cuboid bounds(
+      int sizeX,
+      int sizeY,
+      int sizeZ,
+      int plotSizeX,
+      int plotSizeY,
+      int plotSizeZ,
+      int roadWidth,
+      int roadLevel) {
+    if (sizeX < 1 || sizeY < 1 || sizeZ < 1 || roadWidth < 0) {
+      throw new IllegalArgumentException(
+          "Spawn multipliers must be positive and road width nonnegative");
+    }
+
+    int gridSizeX = Math.addExact(plotSizeX, roadWidth);
+    int gridSizeZ = Math.addExact(plotSizeZ, roadWidth);
+    int inset = roadWidth / 2;
+    int maxInset = roadWidth - inset;
+    int maxX = Math.subtractExact(Math.multiplyExact(sizeX, gridSizeX) - 1, maxInset);
+    int maxY = Math.addExact(roadLevel, Math.multiplyExact(sizeY, plotSizeY) - 1);
+    int maxZ = Math.subtractExact(Math.multiplyExact(sizeZ, gridSizeZ) - 1, maxInset);
+
+    return new Cuboid(inset, roadLevel, inset, maxX, maxY, maxZ);
+  }
+
+  public static boolean withinBuildHeight(Cuboid cuboid, int minHeight, int maxHeight) {
+    return cuboid.minY >= minHeight && cuboid.maxY < maxHeight;
+  }
+}