package net.minecraft.server.packs;

import com.google.common.collect.Lists;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import net.minecraft.resources.Identifier;
import net.minecraft.server.packs.metadata.MetadataSectionType;
import net.minecraft.server.packs.resources.IoSupplier;
import org.jspecify.annotations.Nullable;

public class CompositePackResources implements PackResources {
	private final PackResources primaryPackResources;
	private final List<PackResources> packResourcesStack;

	public CompositePackResources(final PackResources primaryPackResources, final List<PackResources> overlayPackResources) {
		this.primaryPackResources = primaryPackResources;
		List<PackResources> stack = new ArrayList(overlayPackResources.size() + 1);
		stack.addAll(Lists.reverse(overlayPackResources));
		stack.add(primaryPackResources);
		this.packResourcesStack = List.copyOf(stack);
	}

	@Nullable
	@Override
	public IoSupplier<InputStream> getRootResource(final String... path) {
		return this.primaryPackResources.getRootResource(path);
	}

	@Nullable
	@Override
	public IoSupplier<InputStream> getResource(final PackType type, final Identifier location) {
		for (PackResources packResources : this.packResourcesStack) {
			IoSupplier<InputStream> resource = packResources.getResource(type, location);
			if (resource != null) {
				return resource;
			}
		}

		return null;
	}

	@Override
	public void listResources(final PackType type, final String namespace, final String directory, final PackResources.ResourceOutput output) {
		Map<Identifier, IoSupplier<InputStream>> result = new HashMap();

		for (PackResources packResources : this.packResourcesStack) {
			packResources.listResources(type, namespace, directory, result::putIfAbsent);
		}

		result.forEach(output);
	}

	@Override
	public Set<String> getNamespaces(final PackType type) {
		Set<String> result = new HashSet();

		for (PackResources overlayPackResource : this.packResourcesStack) {
			result.addAll(overlayPackResource.getNamespaces(type));
		}

		return result;
	}

	@Nullable
	@Override
	public <T> T getMetadataSection(final MetadataSectionType<T> metadataSerializer) throws IOException {
		return this.primaryPackResources.getMetadataSection(metadataSerializer);
	}

	@Override
	public PackLocationInfo location() {
		return this.primaryPackResources.location();
	}

	@Override
	public void close() {
		this.packResourcesStack.forEach(PackResources::close);
	}
}