Minestom/src/main/java/net/minestom/server/registry/Registry.java

package net.minestom.server.registry;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import net.minestom.server.item.Material;
import net.minestom.server.utils.NamespaceID;
import org.jetbrains.annotations.ApiStatus;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.io.InputStreamReader;
import java.util.function.Supplier;

@ApiStatus.Internal
public class Registry {
    private static final Gson GSON = new GsonBuilder().setPrettyPrinting().disableHtmlEscaping().create();

    public static BlockEntry block(@NotNull JsonObject jsonObject, JsonObject override) {
        return new BlockEntry(jsonObject, override);
    }

    public static JsonObject load(Resource resource) {
        final String path = String.format("/%s.json", resource.name);
        final var resourceStream = Registry.class.getResourceAsStream(path);
        return GSON.fromJson(new InputStreamReader(resourceStream), JsonObject.class);
    }

    public enum Resource {
        BLOCK("blocks");

        private final String name;

        Resource(String name) {
            this.name = name;
        }
    }

    public static class BlockEntry extends Entry {
        private final NamespaceID namespace;
        private final int id;
        private final int stateId;
        private final double hardness;
        private final double explosionResistance;
        private final double friction;
        private final double speedFactor;
        private final double jumpFactor;
        private final boolean air;
        private final boolean solid;
        private final boolean liquid;
        private final String blockEntity;
        private final Supplier<Material> materialSupplier;

        private BlockEntry(JsonObject main, JsonObject override) {
            super(main, override);
            this.namespace = NamespaceID.from(getString("namespaceId"));
            this.id = getInt("id");
            this.stateId = getInt("stateId");
            this.hardness = getDouble("hardness");
            this.explosionResistance = getDouble("explosionResistance");
            this.friction = getDouble("friction");
            this.speedFactor = getDouble("speedFactor", 1);
            this.jumpFactor = getDouble("jumpFactor", 1);
            this.air = getBoolean("air", false);
            this.solid = getBoolean("solid");
            this.liquid = getBoolean("liquid", false);
            this.blockEntity = getString("blockEntity", null);
            {
                final String materialNamespace = getString("correspondingItem", null);
                this.materialSupplier = materialNamespace != null ? () -> Registries.getMaterial(materialNamespace) : () -> null;
            }
        }

        public @NotNull NamespaceID namespace() {
            return namespace;
        }

        public int id() {
            return id;
        }

        public int stateId() {
            return stateId;
        }

        public double hardness() {
            return hardness;
        }

        public double explosionResistance() {
            return explosionResistance;
        }

        public double friction() {
            return friction;
        }

        public double speedFactor() {
            return speedFactor;
        }

        public double jumpFactor() {
            return jumpFactor;
        }

        public boolean isAir() {
            return air;
        }

        public boolean isSolid() {
            return solid;
        }

        public boolean isLiquid() {
            return liquid;
        }

        public boolean isBlockEntity() {
            return blockEntity != null;
        }

        public @Nullable String blockEntity() {
            return blockEntity;
        }

        public @Nullable Material material() {
            return materialSupplier.get();
        }
    }

    public static class Entry {
        private final JsonObject main, override;

        private Entry(JsonObject main, JsonObject override) {
            this.main = main;
            this.override = override;
        }

        public String getString(String name, String defaultValue) {
            var element = element(name);
            return element != null ? element.getAsString() : defaultValue;
        }

        public String getString(String name) {
            return element(name).getAsString();
        }

        public double getDouble(String name, double defaultValue) {
            var element = element(name);
            return element != null ? element.getAsDouble() : defaultValue;
        }

        public double getDouble(String name) {
            return element(name).getAsDouble();
        }

        public int getInt(String name, int defaultValue) {
            var element = element(name);
            return element != null ? element.getAsInt() : defaultValue;
        }

        public int getInt(String name) {
            return element(name).getAsInt();
        }

        public boolean getBoolean(String name, boolean defaultValue) {
            var element = element(name);
            return element != null ? element.getAsBoolean() : defaultValue;
        }

        public boolean getBoolean(String name) {
            return element(name).getAsBoolean();
        }

        protected JsonElement element(String name) {
            if (override.has(name)) {
                return override.get(name);
            }
            return main.get(name);
        }
    }
}