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public class ReassemblyUnitBlock extends Block {
    public static final EnumProperty<DoubleBlockHalf> HALF = BlockStateProperties.DOUBLE_BLOCK_HALF;
 
    private static final VoxelShape LOWER_SHAPE = Shapes.or(
            Block.box(2, 0, 2, 14, 14, 14),
            Block.box(0, 11, 0, 16, 16, 16)
    );
 
    private static final VoxelShape UPPER_SHAPE = Block.box(0, 0, 0, 16, 16, 16);
 
    public ReassemblyUnitBlock(Properties properties) {
        super(properties);
        registerDefaultState(this.stateDefinition.any().setValue(HALF, DoubleBlockHalf.LOWER));
    }
 
    @Override
    public VoxelShape getShape(BlockState state, BlockGetter arg2, BlockPos arg3, CollisionContext arg4) {
        return state.getValue(HALF) == DoubleBlockHalf.LOWER ? LOWER_SHAPE : UPPER_SHAPE;
    }
 
    @Override
    protected void createBlockStateDefinition(StateDefinition.Builder<Block, BlockState> builder) {
        builder.add(HALF);
    }
 
    @Override
    public BlockState updateShape(BlockState state, Direction direction, BlockState neighborState,
                                  LevelAccessor level, BlockPos currentPos, BlockPos neighborPos) {
        DoubleBlockHalf half = state.getValue(HALF);
        if (direction.getAxis() == Direction.Axis.Y &&
                ((half == DoubleBlockHalf.LOWER && direction == Direction.UP) ||
                        (half == DoubleBlockHalf.UPPER && direction == Direction.DOWN))) {
            if (neighborState.getBlock() != this || neighborState.getValue(HALF) == half) {
                return Blocks.AIR.defaultBlockState();
            }
        }
 
        return super.updateShape(state, direction, neighborState, level, currentPos, neighborPos);
    }
 
    @Override
    public BlockState playerWillDestroy(Level level, BlockPos pos, BlockState state, Player player) {
        if (!level.isClientSide) {
            DoubleBlockHalf half = state.getValue(HALF);
            BlockPos otherHalfPos = half == DoubleBlockHalf.LOWER ? pos.above() : pos.below();
            BlockState otherHalfState = level.getBlockState(otherHalfPos);
 
            if (otherHalfState.getBlock() == this && otherHalfState.getValue(HALF) != half) {
                // Check if player should get drops - only if using correct tool and not in creative
                boolean hasCorrectTool = !player.isCreative() &&
                        level.getBlockState(pos).canHarvestBlock(level, pos, player);
 
                // Remove the other half but with flag 35 which prevents drops when hasCorrectTool is false
                // 35 = Block.UPDATE_ALL | Block.UPDATE_SUPPRESS_DROPS
                int flags = hasCorrectTool ? 3 : 35;
                level.setBlock(otherHalfPos, Blocks.AIR.defaultBlockState(), flags);
                level.levelEvent(player, 2001, otherHalfPos, Block.getId(otherHalfState));
            }
        }
 
        return super.playerWillDestroy(level, pos, state, player);
    }
 
    @Override
    public void setPlacedBy(Level level, BlockPos pos, BlockState state, LivingEntity placer, ItemStack stack) {
        level.setBlock(pos.above(), state.setValue(HALF, DoubleBlockHalf.UPPER), 3);
    }
 
    @Nullable
    public BlockState getStateForPlacement(BlockPlaceContext context) {
        BlockPos pos = context.getClickedPos();
        Level level = context.getLevel();
 
        if (pos.getY() < level.getMaxBuildHeight() - 1 && level.getBlockState(pos.above()).canBeReplaced(context)) {
            return this.defaultBlockState().setValue(HALF, DoubleBlockHalf.LOWER);
        } else {
            return null;
        }
    }
 
    @Override
    public boolean canDropFromExplosion(BlockState state, BlockGetter level, BlockPos pos, Explosion explosion) {
        return state.getValue(HALF) == DoubleBlockHalf.LOWER;
    }
}