Add upper-road stairwell generation

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

@@ -0,0 +1,97 @@
+/*
+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;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public final class AvenueStairwayLayout {
+  private AvenueStairwayLayout() {}
+
+  public static List<Step> centeredEastAvenue(
+      Cuboid plot, int roadWidth, int stairWidth, int lowerY, int rise) {
+    int plotLength = plot.maxZ - plot.minZ + 1;
+    if (roadWidth < 1
+        || stairWidth < 1
+        || stairWidth >= roadWidth
+        || rise < 1
+        || rise + 2 > plotLength) {
+      return List.of();
+    }
+
+    int firstX = plot.maxX + 1 + (roadWidth - stairWidth) / 2;
+    int firstZ = plot.minZ + (plotLength - rise) / 2 + 1;
+    List<Step> steps = new ArrayList<>(stairWidth * rise);
+    for (int riseIndex = 0; riseIndex < rise; riseIndex++) {
+      for (int widthIndex = 0; widthIndex < stairWidth; widthIndex++) {
+        steps.add(new Step(firstX + widthIndex, lowerY + riseIndex + 1, firstZ + riseIndex));
+      }
+    }
+    return List.copyOf(steps);
+  }
+
+  public static List<Step> upperRoadOpening(
+      Cuboid plot, int roadWidth, int stairWidth, int lowerY, int rise, int openingLength) {
+    List<Step> stairs = centeredEastAvenue(plot, roadWidth, stairWidth, lowerY, rise);
+    if (stairs.isEmpty() || openingLength < 1) {
+      return List.of();
+    }
+
+    Step topStair = stairs.get(stairs.size() - 1);
+    int firstX = stairs.getFirst().x();
+    int upperRoadY = lowerY + rise;
+    List<Step> opening = new ArrayList<>(stairWidth * openingLength);
+    for (int widthIndex = 0; widthIndex < stairWidth; widthIndex++) {
+      for (int lengthIndex = openingLength; lengthIndex > 0; lengthIndex--) {
+        opening.add(new Step(firstX + widthIndex, upperRoadY, topStair.z() - lengthIndex));
+      }
+    }
+    return List.copyOf(opening);
+  }
+
+  public static Flight forUpperRoad(
+      Cuboid plot, int roadWidth, int stairWidth, int lowerY, int rise, int openingLength) {
+    List<Step> stairs = centeredEastAvenue(plot, roadWidth, stairWidth, lowerY, rise);
+    if (stairs.isEmpty()) {
+      return new Flight(List.of(), List.of(), List.of());
+    }
+
+    List<Step> invertedBackings = new ArrayList<>();
+    for (Step stair : stairs) {
+      if (stair.y() > lowerY + 1) {
+        invertedBackings.add(new Step(stair.x(), stair.y() - 1, stair.z()));
+      }
+    }
+
+    return new Flight(
+        stairs,
+        invertedBackings,
+        upperRoadOpening(plot, roadWidth, stairWidth, lowerY, rise, openingLength));
+  }
+
+  public record Step(int x, int y, int z) {}
+
+  public record Flight(
+      List<Step> stairBlocks, List<Step> invertedBackingBlocks, List<Step> roadOpenings) {
+    public Flight {
+      stairBlocks = List.copyOf(stairBlocks);
+      invertedBackingBlocks = List.copyOf(invertedBackingBlocks);
+      roadOpenings = List.copyOf(roadOpenings);
+    }
+  }
+}