Code/net/minecraft/world/level/block/DoublePlantBlock.java

package net.minecraft.world.level.block;

import com.mojang.serialization.MapCodec;
import javax.annotation.Nullable;
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;
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;

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 p_52861_) {
        super(p_52861_);
        this.registerDefaultState(this.stateDefinition.any().setValue(HALF, DoubleBlockHalf.LOWER));
    }

    @Override
    protected BlockState updateShape(
        BlockState p_52894_,
        LevelReader p_365947_,
        ScheduledTickAccess p_362394_,
        BlockPos p_52898_,
        Direction p_52895_,
        BlockPos p_52899_,
        BlockState p_52896_,
        RandomSource p_360763_
    ) {
        DoubleBlockHalf doubleblockhalf = p_52894_.getValue(HALF);
        if (p_52895_.getAxis() != Direction.Axis.Y
            || doubleblockhalf == DoubleBlockHalf.LOWER != (p_52895_ == Direction.UP)
            || p_52896_.is(this) && p_52896_.getValue(HALF) != doubleblockhalf) {
            return doubleblockhalf == DoubleBlockHalf.LOWER && p_52895_ == Direction.DOWN && !p_52894_.canSurvive(p_365947_, p_52898_)
                ? Blocks.AIR.defaultBlockState()
                : super.updateShape(p_52894_, p_365947_, p_362394_, p_52898_, p_52895_, p_52899_, p_52896_, p_360763_);
        } else {
            return Blocks.AIR.defaultBlockState();
        }
    }

    @Nullable
    @Override
    public BlockState getStateForPlacement(BlockPlaceContext p_52863_) {
        BlockPos blockpos = p_52863_.getClickedPos();
        Level level = p_52863_.getLevel();
        return blockpos.getY() < level.getMaxY() && level.getBlockState(blockpos.above()).canBeReplaced(p_52863_) ? super.getStateForPlacement(p_52863_) : null;
    }

    @Override
    public void setPlacedBy(Level p_52872_, BlockPos p_52873_, BlockState p_52874_, LivingEntity p_52875_, ItemStack p_52876_) {
        BlockPos blockpos = p_52873_.above();
        p_52872_.setBlock(blockpos, copyWaterloggedFrom(p_52872_, blockpos, this.defaultBlockState().setValue(HALF, DoubleBlockHalf.UPPER)), 3);
    }

    @Override
    protected boolean canSurvive(BlockState p_52887_, LevelReader p_52888_, BlockPos p_52889_) {
        if (p_52887_.getValue(HALF) != DoubleBlockHalf.UPPER) {
            return super.canSurvive(p_52887_, p_52888_, p_52889_);
        } else {
            BlockState blockstate = p_52888_.getBlockState(p_52889_.below());
            return blockstate.is(this) && blockstate.getValue(HALF) == DoubleBlockHalf.LOWER;
        }
    }

    public static void placeAt(LevelAccessor p_153174_, BlockState p_153175_, BlockPos p_153176_, int p_153177_) {
        BlockPos blockpos = p_153176_.above();
        p_153174_.setBlock(p_153176_, copyWaterloggedFrom(p_153174_, p_153176_, p_153175_.setValue(HALF, DoubleBlockHalf.LOWER)), p_153177_);
        p_153174_.setBlock(blockpos, copyWaterloggedFrom(p_153174_, blockpos, p_153175_.setValue(HALF, DoubleBlockHalf.UPPER)), p_153177_);
    }

    public static BlockState copyWaterloggedFrom(LevelReader p_182454_, BlockPos p_182455_, BlockState p_182456_) {
        return p_182456_.hasProperty(BlockStateProperties.WATERLOGGED) ? p_182456_.setValue(BlockStateProperties.WATERLOGGED, p_182454_.isWaterAt(p_182455_)) : p_182456_;
    }

    @Override
    public BlockState playerWillDestroy(Level p_52878_, BlockPos p_52879_, BlockState p_52880_, Player p_52881_) {
        if (!p_52878_.isClientSide) {
            if (p_52881_.preventsBlockDrops()) {
                preventDropFromBottomPart(p_52878_, p_52879_, p_52880_, p_52881_);
            } else {
                dropResources(p_52880_, p_52878_, p_52879_, null, p_52881_, p_52881_.getMainHandItem());
            }
        }

        return super.playerWillDestroy(p_52878_, p_52879_, p_52880_, p_52881_);
    }

    @Override
    public void playerDestroy(Level p_52865_, Player p_52866_, BlockPos p_52867_, BlockState p_52868_, @Nullable BlockEntity p_52869_, ItemStack p_52870_) {
        super.playerDestroy(p_52865_, p_52866_, p_52867_, Blocks.AIR.defaultBlockState(), p_52869_, p_52870_);
    }

    protected static void preventDropFromBottomPart(Level p_52904_, BlockPos p_52905_, BlockState p_52906_, Player p_52907_) {
        DoubleBlockHalf doubleblockhalf = p_52906_.getValue(HALF);
        if (doubleblockhalf == DoubleBlockHalf.UPPER) {
            BlockPos blockpos = p_52905_.below();
            BlockState blockstate = p_52904_.getBlockState(blockpos);
            if (blockstate.is(p_52906_.getBlock()) && blockstate.getValue(HALF) == DoubleBlockHalf.LOWER) {
                BlockState blockstate1 = blockstate.getFluidState().is(Fluids.WATER) ? Blocks.WATER.defaultBlockState() : Blocks.AIR.defaultBlockState();
                p_52904_.setBlock(blockpos, blockstate1, 35);
                p_52904_.levelEvent(p_52907_, 2001, blockpos, Block.getId(blockstate));
            }
        }
    }

    @Override
    protected void createBlockStateDefinition(StateDefinition.Builder<Block, BlockState> p_52901_) {
        p_52901_.add(HALF);
    }

    @Override
    protected long getSeed(BlockState p_52891_, BlockPos p_52892_) {
        return Mth.getSeed(
            p_52892_.getX(), p_52892_.below(p_52891_.getValue(HALF) == DoubleBlockHalf.LOWER ? 0 : 1).getY(), p_52892_.getZ()
        );
    }
}