Code/net/minecraft/world/level/levelgen/structure/structures/MineshaftStructure.java

package net.minecraft.world.level.levelgen.structure.structures;

import com.mojang.datafixers.util.Either;
import com.mojang.serialization.Codec;
import com.mojang.serialization.MapCodec;
import com.mojang.serialization.codecs.RecordCodecBuilder;
import com.mojang.serialization.codecs.RecordCodecBuilder.Instance;
import java.util.Optional;
import java.util.function.IntFunction;
import net.minecraft.core.BlockPos;
import net.minecraft.util.ByIdMap;
import net.minecraft.util.Mth;
import net.minecraft.util.StringRepresentable;
import net.minecraft.world.level.ChunkPos;
import net.minecraft.world.level.block.Block;
import net.minecraft.world.level.block.Blocks;
import net.minecraft.world.level.block.state.BlockState;
import net.minecraft.world.level.chunk.ChunkGenerator;
import net.minecraft.world.level.levelgen.Heightmap;
import net.minecraft.world.level.levelgen.WorldgenRandom;
import net.minecraft.world.level.levelgen.structure.Structure;
import net.minecraft.world.level.levelgen.structure.StructureType;
import net.minecraft.world.level.levelgen.structure.pieces.StructurePiecesBuilder;

public class MineshaftStructure extends Structure {
    public static final MapCodec<MineshaftStructure> CODEC = RecordCodecBuilder.mapCodec(
        p_227971_ -> p_227971_.group(
                settingsCodec(p_227971_), MineshaftStructure.Type.CODEC.fieldOf("mineshaft_type").forGetter(p_227969_ -> p_227969_.type)
            )
            .apply(p_227971_, MineshaftStructure::new)
    );
    private final MineshaftStructure.Type type;

    public MineshaftStructure(Structure.StructureSettings p_227961_, MineshaftStructure.Type p_227962_) {
        super(p_227961_);
        this.type = p_227962_;
    }

    @Override
    public Optional<Structure.GenerationStub> findGenerationPoint(Structure.GenerationContext p_227964_) {
        p_227964_.random().nextDouble();
        ChunkPos chunkpos = p_227964_.chunkPos();
        BlockPos blockpos = new BlockPos(chunkpos.getMiddleBlockX(), 50, chunkpos.getMinBlockZ());
        StructurePiecesBuilder structurepiecesbuilder = new StructurePiecesBuilder();
        int i = this.generatePiecesAndAdjust(structurepiecesbuilder, p_227964_);
        return Optional.of(new Structure.GenerationStub(blockpos.offset(0, i, 0), Either.right(structurepiecesbuilder)));
    }

    private int generatePiecesAndAdjust(StructurePiecesBuilder p_227966_, Structure.GenerationContext p_227967_) {
        ChunkPos chunkpos = p_227967_.chunkPos();
        WorldgenRandom worldgenrandom = p_227967_.random();
        ChunkGenerator chunkgenerator = p_227967_.chunkGenerator();
        MineshaftPieces.MineShaftRoom mineshaftpieces$mineshaftroom = new MineshaftPieces.MineShaftRoom(
            0, worldgenrandom, chunkpos.getBlockX(2), chunkpos.getBlockZ(2), this.type
        );
        p_227966_.addPiece(mineshaftpieces$mineshaftroom);
        mineshaftpieces$mineshaftroom.addChildren(mineshaftpieces$mineshaftroom, p_227966_, worldgenrandom);
        int i = chunkgenerator.getSeaLevel();
        if (this.type == MineshaftStructure.Type.MESA) {
            BlockPos blockpos = p_227966_.getBoundingBox().getCenter();
            int j = chunkgenerator.getBaseHeight(
                blockpos.getX(), blockpos.getZ(), Heightmap.Types.WORLD_SURFACE_WG, p_227967_.heightAccessor(), p_227967_.randomState()
            );
            int k = j <= i ? i : Mth.randomBetweenInclusive(worldgenrandom, i, j);
            int l = k - blockpos.getY();
            p_227966_.offsetPiecesVertically(l);
            return l;
        } else {
            return p_227966_.moveBelowSeaLevel(i, chunkgenerator.getMinY(), worldgenrandom, 10);
        }
    }

    @Override
    public StructureType<?> type() {
        return StructureType.MINESHAFT;
    }

    public static enum Type implements StringRepresentable {
        NORMAL("normal", Blocks.OAK_LOG, Blocks.OAK_PLANKS, Blocks.OAK_FENCE),
        MESA("mesa", Blocks.DARK_OAK_LOG, Blocks.DARK_OAK_PLANKS, Blocks.DARK_OAK_FENCE);

        public static final Codec<MineshaftStructure.Type> CODEC = StringRepresentable.fromEnum(MineshaftStructure.Type::values);
        private static final IntFunction<MineshaftStructure.Type> BY_ID = ByIdMap.continuous(Enum::ordinal, values(), ByIdMap.OutOfBoundsStrategy.ZERO);
        private final String name;
        private final BlockState woodState;
        private final BlockState planksState;
        private final BlockState fenceState;

        private Type(final String p_227985_, final Block p_227986_, final Block p_227987_, final Block p_227988_) {
            this.name = p_227985_;
            this.woodState = p_227986_.defaultBlockState();
            this.planksState = p_227987_.defaultBlockState();
            this.fenceState = p_227988_.defaultBlockState();
        }

        public String getName() {
            return this.name;
        }

        public static MineshaftStructure.Type byId(int p_227991_) {
            return BY_ID.apply(p_227991_);
        }

        public BlockState getWoodState() {
            return this.woodState;
        }

        public BlockState getPlanksState() {
            return this.planksState;
        }

        public BlockState getFenceState() {
            return this.fenceState;
        }

        @Override
        public String getSerializedName() {
            return this.name;
        }
    }
}