package org.bukkit.craftbukkit;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.function.BiFunction;
import java.util.stream.Stream;
import net.minecraft.core.IRegistry;
import net.minecraft.core.IRegistryCustom;
import org.bukkit.Keyed;
import org.bukkit.NamespacedKey;
import org.bukkit.Registry;
import org.bukkit.craftbukkit.generator.strucutre.CraftStructure;
import org.bukkit.craftbukkit.generator.strucutre.CraftStructureType;
import org.bukkit.craftbukkit.util.CraftNamespacedKey;
import org.bukkit.generator.structure.Structure;
import org.bukkit.generator.structure.StructureType;

public class CraftRegistry<B extends Keyed, M> implements Registry<B> {

    public static <B extends Keyed> Registry<?> createRegistry(Class<B> bukkitClass, IRegistryCustom registryHolder) {
        if (bukkitClass == Structure.class) {
            return new CraftRegistry<>(registryHolder.registryOrThrow(IRegistry.STRUCTURE_REGISTRY), CraftStructure::new);
        }
        if (bukkitClass == StructureType.class) {
            return new CraftRegistry<>(IRegistry.STRUCTURE_TYPES, CraftStructureType::new);
        }

        return null;
    }

    private final Map<NamespacedKey, B> cache = new HashMap<>();
    private final IRegistry<M> minecraftRegistry;
    private final BiFunction<NamespacedKey, M, B> minecraftToBukkit;

    public CraftRegistry(IRegistry<M> minecraftRegistry, BiFunction<NamespacedKey, M, B> minecraftToBukkit) {
        this.minecraftRegistry = minecraftRegistry;
        this.minecraftToBukkit = minecraftToBukkit;
    }

    @Override
    public B get(NamespacedKey namespacedKey) {
        B cached = cache.get(namespacedKey);
        if (cached != null) {
            return cached;
        }

        B bukkit = createBukkit(namespacedKey, minecraftRegistry.getOptional(CraftNamespacedKey.toMinecraft(namespacedKey)).orElse(null));
        if (bukkit == null) {
            return null;
        }

        cache.put(namespacedKey, bukkit);

        return bukkit;
    }

    @Override
    public Iterator<B> iterator() {
        return values().iterator();
    }

    public B createBukkit(NamespacedKey namespacedKey, M minecraft) {
        if (minecraft == null) {
            return null;
        }

        return minecraftToBukkit.apply(namespacedKey, minecraft);
    }

    public Stream<B> values() {
        return minecraftRegistry.keySet().stream().map(minecraftKey -> get(CraftNamespacedKey.fromMinecraft(minecraftKey)));
    }
}