minecraft-src/net/minecraft/world/level/block/DoublePlantBlock.java

package net.minecraft.world.level.block;

import com.mojang.serialization.MapCodec;
import net.minecraft.core.BlockPos;
import net.minecraft.core.Direction;
import net.minecraft.util.Mth;
import net.minecraft.util.RandomSource;
import net.minecraft.world.entity.LivingEntity;
import net.minecraft.world.entity.player.Player;
import net.minecraft.world.item.ItemStack;
import net.minecraft.world.item.context.BlockPlaceContext;
import net.minecraft.world.level.Level;
import net.minecraft.world.level.LevelAccessor;
import net.minecraft.world.level.LevelReader;
import net.minecraft.world.level.ScheduledTickAccess;
import net.minecraft.world.level.block.entity.BlockEntity;
import net.minecraft.world.level.block.state.BlockBehaviour;
import net.minecraft.world.level.block.state.BlockState;
import net.minecraft.world.level.block.state.StateDefinition.Builder;
import net.minecraft.world.level.block.state.properties.BlockStateProperties;
import net.minecraft.world.level.block.state.properties.DoubleBlockHalf;
import net.minecraft.world.level.block.state.properties.EnumProperty;
import net.minecraft.world.level.material.Fluids;
import org.jetbrains.annotations.Nullable;

public class DoublePlantBlock extends VegetationBlock {
	public static final MapCodec<DoublePlantBlock> CODEC = simpleCodec(DoublePlantBlock::new);
	public static final EnumProperty<DoubleBlockHalf> HALF = BlockStateProperties.DOUBLE_BLOCK_HALF;

	@Override
	public MapCodec<? extends DoublePlantBlock> codec() {
		return CODEC;
	}

	public DoublePlantBlock(BlockBehaviour.Properties properties) {
		super(properties);
		this.registerDefaultState(this.stateDefinition.any().setValue(HALF, DoubleBlockHalf.LOWER));
	}

	@Override
	protected BlockState updateShape(
		BlockState state,
		LevelReader level,
		ScheduledTickAccess scheduledTickAccess,
		BlockPos pos,
		Direction direction,
		BlockPos neighborPos,
		BlockState neighborState,
		RandomSource random
	) {
		DoubleBlockHalf doubleBlockHalf = state.getValue(HALF);
		if (direction.getAxis() != Direction.Axis.Y
			|| doubleBlockHalf == DoubleBlockHalf.LOWER != (direction == Direction.UP)
			|| neighborState.is(this) && neighborState.getValue(HALF) != doubleBlockHalf) {
			return doubleBlockHalf == DoubleBlockHalf.LOWER && direction == Direction.DOWN && !state.canSurvive(level, pos)
				? Blocks.AIR.defaultBlockState()
				: super.updateShape(state, level, scheduledTickAccess, pos, direction, neighborPos, neighborState, random);
		} else {
			return Blocks.AIR.defaultBlockState();
		}
	}

	@Nullable
	@Override
	public BlockState getStateForPlacement(BlockPlaceContext context) {
		BlockPos blockPos = context.getClickedPos();
		Level level = context.getLevel();
		return blockPos.getY() < level.getMaxY() && level.getBlockState(blockPos.above()).canBeReplaced(context) ? super.getStateForPlacement(context) : null;
	}

	@Override
	public void setPlacedBy(Level level, BlockPos pos, BlockState state, LivingEntity placer, ItemStack stack) {
		BlockPos blockPos = pos.above();
		level.setBlock(blockPos, copyWaterloggedFrom(level, blockPos, this.defaultBlockState().setValue(HALF, DoubleBlockHalf.UPPER)), 3);
	}

	@Override
	protected boolean canSurvive(BlockState state, LevelReader level, BlockPos pos) {
		if (state.getValue(HALF) != DoubleBlockHalf.UPPER) {
			return super.canSurvive(state, level, pos);
		} else {
			BlockState blockState = level.getBlockState(pos.below());
			return blockState.is(this) && blockState.getValue(HALF) == DoubleBlockHalf.LOWER;
		}
	}

	public static void placeAt(LevelAccessor level, BlockState state, BlockPos pos, int flags) {
		BlockPos blockPos = pos.above();
		level.setBlock(pos, copyWaterloggedFrom(level, pos, state.setValue(HALF, DoubleBlockHalf.LOWER)), flags);
		level.setBlock(blockPos, copyWaterloggedFrom(level, blockPos, state.setValue(HALF, DoubleBlockHalf.UPPER)), flags);
	}

	public static BlockState copyWaterloggedFrom(LevelReader level, BlockPos pos, BlockState state) {
		return state.hasProperty(BlockStateProperties.WATERLOGGED) ? state.setValue(BlockStateProperties.WATERLOGGED, level.isWaterAt(pos)) : state;
	}

	@Override
	public BlockState playerWillDestroy(Level level, BlockPos pos, BlockState state, Player player) {
		if (!level.isClientSide) {
			if (player.preventsBlockDrops()) {
				preventDropFromBottomPart(level, pos, state, player);
			} else {
				dropResources(state, level, pos, null, player, player.getMainHandItem());
			}
		}

		return super.playerWillDestroy(level, pos, state, player);
	}

	@Override
	public void playerDestroy(Level level, Player player, BlockPos pos, BlockState state, @Nullable BlockEntity blockEntity, ItemStack tool) {
		super.playerDestroy(level, player, pos, Blocks.AIR.defaultBlockState(), blockEntity, tool);
	}

	protected static void preventDropFromBottomPart(Level level, BlockPos pos, BlockState state, Player player) {
		DoubleBlockHalf doubleBlockHalf = state.getValue(HALF);
		if (doubleBlockHalf == DoubleBlockHalf.UPPER) {
			BlockPos blockPos = pos.below();
			BlockState blockState = level.getBlockState(blockPos);
			if (blockState.is(state.getBlock()) && blockState.getValue(HALF) == DoubleBlockHalf.LOWER) {
				BlockState blockState2 = blockState.getFluidState().is(Fluids.WATER) ? Blocks.WATER.defaultBlockState() : Blocks.AIR.defaultBlockState();
				level.setBlock(blockPos, blockState2, 35);
				level.levelEvent(player, 2001, blockPos, Block.getId(blockState));
			}
		}
	}

	@Override
	protected void createBlockStateDefinition(Builder<Block, BlockState> builder) {
		builder.add(HALF);
	}

	@Override
	protected long getSeed(BlockState state, BlockPos pos) {
		return Mth.getSeed(pos.getX(), pos.below(state.getValue(HALF) == DoubleBlockHalf.LOWER ? 0 : 1).getY(), pos.getZ());
	}
}