SecretRoomStructure

public class SecretRoomStructure extends Structure<NoFeatureConfig> {
    public SecretRoomStructure(Codec<NoFeatureConfig> codec) {
        super(codec);
    }

    @Override
    public  IStartFactory<NoFeatureConfig> getStartFactory()
    {
        return SecretRoomStructure.Start::new;
    }

    @Override
    public GenerationStage.Decoration step()
    {
        return GenerationStage.Decoration.UNDERGROUND_STRUCTURES;
    }

    @Override
    protected boolean isFeatureChunk(ChunkGenerator chunkGenerator, BiomeProvider biomeSource, long seed, SharedSeedRandom chunkRandom, int chunkX, int chunkZ, Biome biome, ChunkPos chunkPos, NoFeatureConfig featureConfig)
    {
        BlockPos centerOfChunk = new BlockPos(chunkX * 16, 0, chunkZ * 16);

        int landHeight = chunkGenerator.getFirstOccupiedHeight(centerOfChunk.getX(), centerOfChunk.getZ(), Heightmap.Type.WORLD_SURFACE_WG);
        IBlockReader columnOfBlocks = chunkGenerator.getBaseColumn(centerOfChunk.getX(), centerOfChunk.getZ());

        BlockState topBlock = columnOfBlocks.getBlockState(centerOfChunk.above(landHeight));

        return topBlock.getFluidState().isEmpty(); //landHeight > 100;
    }

    /**
     * Handles calling up the structure's pieces class and height that structure will spawn at.
     */
    public static class Start extends StructureStart<NoFeatureConfig>  {
        public Start(Structure<NoFeatureConfig> structureIn, int chunkX, int chunkZ, MutableBoundingBox mutableBoundingBox, int referenceIn, long seedIn) {
            super(structureIn, chunkX, chunkZ, mutableBoundingBox, referenceIn, seedIn);
        }

        @Override
        public void generatePieces(DynamicRegistries dynamicRegistryManager, ChunkGenerator chunkGenerator, TemplateManager templateManagerIn, int chunkX, int chunkZ, Biome biomeIn, NoFeatureConfig config) {

            int x = chunkX * 16;
            int z = chunkZ * 16;

            BlockPos centerPos = new BlockPos(x,0, z);
            int j = 20 + random.nextInt(20);

            Rotation rotation = Rotation.getRandom(this.random);
            SecretRoomPiece.start(templateManagerIn, centerPos, rotation, this.pieces, random);

            Vector3i structureCenter = this.pieces.get(0).getBoundingBox().getCenter();
            int xOffset = centerPos.getX() - structureCenter.getX();
            int zOffset = centerPos.getZ() - structureCenter.getZ();
            for(StructurePiece structurePiece : this.pieces)
            {
                structurePiece.move(xOffset, +j, zOffset);
            }

            this.calculateBoundingBox();

            Necromod.LOGGER.log(Level.DEBUG, "Secret room at " +
                            this.pieces.get(0).getBoundingBox().x0 + " " +
                            this.pieces.get(0).getBoundingBox().y0 + " " +
                            this.pieces.get(0).getBoundingBox().z0);
        }

    }
}