minecraft-src/net/minecraft/world/level/block/BaseRailBlock.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.tags.BlockTags;
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.properties.BlockStateProperties;
import net.minecraft.world.level.block.state.properties.BooleanProperty;
import net.minecraft.world.level.block.state.properties.Property;
import net.minecraft.world.level.block.state.properties.RailShape;
import net.minecraft.world.level.material.FluidState;
import net.minecraft.world.level.material.Fluids;
import net.minecraft.world.level.redstone.Orientation;
import net.minecraft.world.phys.shapes.CollisionContext;
import net.minecraft.world.phys.shapes.VoxelShape;
import org.jetbrains.annotations.Nullable;

public abstract class BaseRailBlock extends Block implements SimpleWaterloggedBlock {
	public static final BooleanProperty WATERLOGGED = BlockStateProperties.WATERLOGGED;
	private static final VoxelShape SHAPE_FLAT = Block.column(16.0, 0.0, 2.0);
	private static final VoxelShape SHAPE_SLOPE = Block.column(16.0, 0.0, 8.0);
	private final boolean isStraight;

	public static boolean isRail(Level level, BlockPos pos) {
		return isRail(level.getBlockState(pos));
	}

	public static boolean isRail(BlockState state) {
		return state.is(BlockTags.RAILS) && state.getBlock() instanceof BaseRailBlock;
	}

	protected BaseRailBlock(boolean isStraight, BlockBehaviour.Properties properties) {
		super(properties);
		this.isStraight = isStraight;
	}

	@Override
	protected abstract MapCodec<? extends BaseRailBlock> codec();

	public boolean isStraight() {
		return this.isStraight;
	}

	@Override
	protected VoxelShape getShape(BlockState state, BlockGetter level, BlockPos pos, CollisionContext context) {
		return ((RailShape)state.getValue(this.getShapeProperty())).isSlope() ? SHAPE_SLOPE : SHAPE_FLAT;
	}

	@Override
	protected boolean canSurvive(BlockState state, LevelReader level, BlockPos pos) {
		return canSupportRigidBlock(level, pos.below());
	}

	@Override
	protected void onPlace(BlockState state, Level level, BlockPos pos, BlockState oldState, boolean movedByPiston) {
		if (!oldState.is(state.getBlock())) {
			this.updateState(state, level, pos, movedByPiston);
		}
	}

	protected BlockState updateState(BlockState state, Level level, BlockPos pos, boolean movedByPiston) {
		state = this.updateDir(level, pos, state, true);
		if (this.isStraight) {
			level.neighborChanged(state, pos, this, null, movedByPiston);
		}

		return state;
	}

	@Override
	protected void neighborChanged(BlockState state, Level level, BlockPos pos, Block neighborBlock, @Nullable Orientation orientation, boolean movedByPiston) {
		if (!level.isClientSide && level.getBlockState(pos).is(this)) {
			RailShape railShape = state.getValue(this.getShapeProperty());
			if (shouldBeRemoved(pos, level, railShape)) {
				dropResources(state, level, pos);
				level.removeBlock(pos, movedByPiston);
			} else {
				this.updateState(state, level, pos, neighborBlock);
			}
		}
	}

	private static boolean shouldBeRemoved(BlockPos pos, Level level, RailShape shape) {
		if (!canSupportRigidBlock(level, pos.below())) {
			return true;
		} else {
			switch (shape) {
				case ASCENDING_EAST:
					return !canSupportRigidBlock(level, pos.east());
				case ASCENDING_WEST:
					return !canSupportRigidBlock(level, pos.west());
				case ASCENDING_NORTH:
					return !canSupportRigidBlock(level, pos.north());
				case ASCENDING_SOUTH:
					return !canSupportRigidBlock(level, pos.south());
				default:
					return false;
			}
		}
	}

	protected void updateState(BlockState state, Level level, BlockPos pos, Block neighborBlock) {
	}

	protected BlockState updateDir(Level level, BlockPos pos, BlockState state, boolean alwaysPlace) {
		if (level.isClientSide) {
			return state;
		} else {
			RailShape railShape = state.getValue(this.getShapeProperty());
			return new RailState(level, pos, state).place(level.hasNeighborSignal(pos), alwaysPlace, railShape).getState();
		}
	}

	@Override
	protected void affectNeighborsAfterRemoval(BlockState state, ServerLevel level, BlockPos pos, boolean movedByPiston) {
		if (!movedByPiston) {
			if (((RailShape)state.getValue(this.getShapeProperty())).isSlope()) {
				level.updateNeighborsAt(pos.above(), this);
			}

			if (this.isStraight) {
				level.updateNeighborsAt(pos, this);
				level.updateNeighborsAt(pos.below(), this);
			}
		}
	}

	@Override
	public BlockState getStateForPlacement(BlockPlaceContext context) {
		FluidState fluidState = context.getLevel().getFluidState(context.getClickedPos());
		boolean bl = fluidState.getType() == Fluids.WATER;
		BlockState blockState = super.defaultBlockState();
		Direction direction = context.getHorizontalDirection();
		boolean bl2 = direction == Direction.EAST || direction == Direction.WEST;
		return blockState.setValue(this.getShapeProperty(), bl2 ? RailShape.EAST_WEST : RailShape.NORTH_SOUTH).setValue(WATERLOGGED, bl);
	}

	public abstract Property<RailShape> getShapeProperty();

	@Override
	protected BlockState updateShape(
		BlockState state,
		LevelReader level,
		ScheduledTickAccess scheduledTickAccess,
		BlockPos pos,
		Direction direction,
		BlockPos neighborPos,
		BlockState neighborState,
		RandomSource random
	) {
		if ((Boolean)state.getValue(WATERLOGGED)) {
			scheduledTickAccess.scheduleTick(pos, Fluids.WATER, Fluids.WATER.getTickDelay(level));
		}

		return super.updateShape(state, level, scheduledTickAccess, pos, direction, neighborPos, neighborState, random);
	}

	@Override
	protected FluidState getFluidState(BlockState state) {
		return state.getValue(WATERLOGGED) ? Fluids.WATER.getSource(false) : super.getFluidState(state);
	}
}