Code/net/minecraft/world/level/block/ObserverBlock.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.server.level.ServerLevel;
import net.minecraft.util.RandomSource;
import net.minecraft.world.item.context.BlockPlaceContext;
import net.minecraft.world.level.BlockGetter;
import net.minecraft.world.level.Level;
import net.minecraft.world.level.LevelReader;
import net.minecraft.world.level.ScheduledTickAccess;
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.BooleanProperty;
import net.minecraft.world.level.redstone.ExperimentalRedstoneUtils;
import net.minecraft.world.level.redstone.Orientation;

public class ObserverBlock extends DirectionalBlock {
    public static final MapCodec<ObserverBlock> CODEC = simpleCodec(ObserverBlock::new);
    public static final BooleanProperty POWERED = BlockStateProperties.POWERED;

    @Override
    public MapCodec<ObserverBlock> codec() {
        return CODEC;
    }

    public ObserverBlock(BlockBehaviour.Properties p_55085_) {
        super(p_55085_);
        this.registerDefaultState(this.stateDefinition.any().setValue(FACING, Direction.SOUTH).setValue(POWERED, false));
    }

    @Override
    protected void createBlockStateDefinition(StateDefinition.Builder<Block, BlockState> p_55125_) {
        p_55125_.add(FACING, POWERED);
    }

    @Override
    protected BlockState rotate(BlockState p_55115_, Rotation p_55116_) {
        return p_55115_.setValue(FACING, p_55116_.rotate(p_55115_.getValue(FACING)));
    }

    @Override
    protected BlockState mirror(BlockState p_55112_, Mirror p_55113_) {
        return p_55112_.rotate(p_55113_.getRotation(p_55112_.getValue(FACING)));
    }

    @Override
    protected void tick(BlockState p_221840_, ServerLevel p_221841_, BlockPos p_221842_, RandomSource p_221843_) {
        if (p_221840_.getValue(POWERED)) {
            p_221841_.setBlock(p_221842_, p_221840_.setValue(POWERED, false), 2);
        } else {
            p_221841_.setBlock(p_221842_, p_221840_.setValue(POWERED, true), 2);
            p_221841_.scheduleTick(p_221842_, this, 2);
        }

        this.updateNeighborsInFront(p_221841_, p_221842_, p_221840_);
    }

    @Override
    protected BlockState updateShape(
        BlockState p_55118_,
        LevelReader p_362436_,
        ScheduledTickAccess p_366728_,
        BlockPos p_55122_,
        Direction p_55119_,
        BlockPos p_55123_,
        BlockState p_55120_,
        RandomSource p_368192_
    ) {
        if (p_55118_.getValue(FACING) == p_55119_ && !p_55118_.getValue(POWERED)) {
            this.startSignal(p_362436_, p_366728_, p_55122_);
        }

        return super.updateShape(p_55118_, p_362436_, p_366728_, p_55122_, p_55119_, p_55123_, p_55120_, p_368192_);
    }

    private void startSignal(LevelReader p_369671_, ScheduledTickAccess p_365436_, BlockPos p_55094_) {
        if (!p_369671_.isClientSide() && !p_365436_.getBlockTicks().hasScheduledTick(p_55094_, this)) {
            p_365436_.scheduleTick(p_55094_, this, 2);
        }
    }

    protected void updateNeighborsInFront(Level p_55089_, BlockPos p_55090_, BlockState p_55091_) {
        Direction direction = p_55091_.getValue(FACING);
        BlockPos blockpos = p_55090_.relative(direction.getOpposite());
        Orientation orientation = ExperimentalRedstoneUtils.initialOrientation(p_55089_, direction.getOpposite(), null);
        p_55089_.neighborChanged(blockpos, this, orientation);
        p_55089_.updateNeighborsAtExceptFromFacing(blockpos, this, direction, orientation);
    }

    @Override
    protected boolean isSignalSource(BlockState p_55138_) {
        return true;
    }

    @Override
    protected int getDirectSignal(BlockState p_55127_, BlockGetter p_55128_, BlockPos p_55129_, Direction p_55130_) {
        return p_55127_.getSignal(p_55128_, p_55129_, p_55130_);
    }

    @Override
    protected int getSignal(BlockState p_55101_, BlockGetter p_55102_, BlockPos p_55103_, Direction p_55104_) {
        return p_55101_.getValue(POWERED) && p_55101_.getValue(FACING) == p_55104_ ? 15 : 0;
    }

    @Override
    protected void onPlace(BlockState p_55132_, Level p_55133_, BlockPos p_55134_, BlockState p_55135_, boolean p_55136_) {
        if (!p_55132_.is(p_55135_.getBlock())) {
            if (!p_55133_.isClientSide() && p_55132_.getValue(POWERED) && !p_55133_.getBlockTicks().hasScheduledTick(p_55134_, this)) {
                BlockState blockstate = p_55132_.setValue(POWERED, false);
                p_55133_.setBlock(p_55134_, blockstate, 18);
                this.updateNeighborsInFront(p_55133_, p_55134_, blockstate);
            }
        }
    }

    @Override
    protected void affectNeighborsAfterRemoval(BlockState p_394748_, ServerLevel p_398030_, BlockPos p_392130_, boolean p_394233_) {
        if (p_394748_.getValue(POWERED) && p_398030_.getBlockTicks().hasScheduledTick(p_392130_, this)) {
            this.updateNeighborsInFront(p_398030_, p_392130_, p_394748_.setValue(POWERED, false));
        }
    }

    @Override
    public BlockState getStateForPlacement(BlockPlaceContext p_55087_) {
        return this.defaultBlockState().setValue(FACING, p_55087_.getNearestLookingDirection().getOpposite().getOpposite());
    }
}