package net.minecraft.world.level.levelgen.structure.templatesystem.loader;

import com.mojang.brigadier.exceptions.CommandSyntaxException;
import com.mojang.datafixers.DataFixer;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.nio.charset.StandardCharsets;
import java.util.Optional;
import java.util.function.Consumer;
import java.util.stream.Stream;
import net.minecraft.core.HolderGetter;
import net.minecraft.nbt.CompoundTag;
import net.minecraft.nbt.NbtAccounter;
import net.minecraft.nbt.NbtIo;
import net.minecraft.nbt.NbtUtils;
import net.minecraft.resources.Identifier;
import net.minecraft.server.packs.resources.IoSupplier;
import net.minecraft.util.FastBufferedInputStream;
import net.minecraft.util.datafix.DataFixTypes;
import net.minecraft.world.level.block.Block;
import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplate;

public abstract class TemplateSource {
	private final DataFixer fixerUpper;
	private final HolderGetter<Block> blockLookup;

	protected TemplateSource(final DataFixer fixerUpper, final HolderGetter<Block> blockLookup) {
		this.fixerUpper = fixerUpper;
		this.blockLookup = blockLookup;
	}

	public abstract Optional<StructureTemplate> load(Identifier id);

	public abstract Stream<Identifier> list();

	protected Optional<StructureTemplate> load(final IoSupplier<InputStream> opener, final boolean asText, final Consumer<Throwable> onError) {
		try (
			InputStream rawInput = opener.get();
			InputStream input = new FastBufferedInputStream(rawInput);
		) {
			CompoundTag structureTag;
			if (asText) {
				structureTag = readTextStructure(input);
			} else {
				structureTag = readStructure(input);
			}

			return Optional.of(this.readStructure(structureTag));
		} catch (FileNotFoundException e) {
			return Optional.empty();
		} catch (Throwable e) {
			onError.accept(e);
			return Optional.empty();
		}
	}

	private static CompoundTag readStructure(final InputStream input) throws IOException {
		return NbtIo.readCompressed(input, NbtAccounter.unlimitedHeap());
	}

	private static CompoundTag readTextStructure(final InputStream input) throws IOException, CommandSyntaxException {
		try (Reader reader = new InputStreamReader(input, StandardCharsets.UTF_8)) {
			String contents = reader.readAllAsString();
			return NbtUtils.snbtToStructure(contents);
		}
	}

	private StructureTemplate readStructure(final CompoundTag tag) {
		StructureTemplate structureTemplate = new StructureTemplate();
		int version = NbtUtils.getDataVersion(tag, 500);
		structureTemplate.load(this.blockLookup, DataFixTypes.STRUCTURE.updateToCurrentVersion(this.fixerUpper, tag, version));
		return structureTemplate;
	}
}