src/game/java/net/minecraft/util/datafix/fixes/BlendingDataFix.java

package net.minecraft.util.datafix.fixes;

import com.mojang.datafixers.DSL;
import com.mojang.datafixers.DataFix;
import com.mojang.datafixers.TypeRewriteRule;
import com.mojang.datafixers.Typed;
import com.mojang.datafixers.schemas.Schema;
import com.mojang.datafixers.types.Type;
import com.mojang.serialization.Dynamic;
import com.mojang.serialization.OptionalDynamic;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import net.minecraft.core.SectionPos;
import net.minecraft.util.datafix.schemas.NamespacedSchema;

public class BlendingDataFix extends DataFix {
    private final String name;
    private static final Set<String> STATUSES_TO_SKIP_BLENDING = Set.of("minecraft:empty", "minecraft:structure_starts", "minecraft:structure_references", "minecraft:biomes");

    public BlendingDataFix(Schema p_216561_) {
        super(p_216561_, false);
        this.name = "Blending Data Fix v" + p_216561_.getVersionKey();
    }

    @Override
    protected TypeRewriteRule makeRule() {
        Type<?> type = this.getOutputSchema().getType(References.CHUNK);
        return this.fixTypeEverywhereTyped(
            this.name, type, p_216563_ -> p_216563_.update(DSL.remainderFinder(), p_240248_ -> updateChunkTag(p_240248_, p_240248_.get("__context")))
        );
    }

    private static Dynamic<?> updateChunkTag(Dynamic<?> p_240279_, OptionalDynamic<?> p_240280_) {
        p_240279_ = p_240279_.remove("blending_data");
        boolean flag = "minecraft:overworld".equals(p_240280_.get("dimension").asString().result().orElse(""));
        Optional<? extends Dynamic<?>> optional = p_240279_.get("Status").result();
        if (flag && optional.isPresent()) {
            String s = NamespacedSchema.ensureNamespaced(optional.get().asString("empty"));
            Optional<? extends Dynamic<?>> optional1 = p_240279_.get("below_zero_retrogen").result();
            if (!STATUSES_TO_SKIP_BLENDING.contains(s)) {
                p_240279_ = updateBlendingData(p_240279_, 384, -64);
            } else if (optional1.isPresent()) {
                Dynamic<?> dynamic = (Dynamic<?>)optional1.get();
                String s1 = NamespacedSchema.ensureNamespaced(dynamic.get("target_status").asString("empty"));
                if (!STATUSES_TO_SKIP_BLENDING.contains(s1)) {
                    p_240279_ = updateBlendingData(p_240279_, 256, 0);
                }
            }
        }

        return p_240279_;
    }

    private static Dynamic<?> updateBlendingData(Dynamic<?> p_216567_, int p_216568_, int p_216569_) {
        return p_216567_.set(
            "blending_data",
            p_216567_.createMap(
                Map.of(
                    p_216567_.createString("min_section"),
                    p_216567_.createInt(SectionPos.blockToSectionCoord(p_216569_)),
                    p_216567_.createString("max_section"),
                    p_216567_.createInt(SectionPos.blockToSectionCoord(p_216569_ + p_216568_))
                )
            )
        );
    }
}