package net.minecraft.world.level.chunk.storage;

import it.unimi.dsi.fastutil.longs.Long2ObjectLinkedOpenHashMap;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.file.Path;
import net.minecraft.SharedConstants;
import net.minecraft.nbt.CompoundTag;
import net.minecraft.nbt.NbtAccounter;
import net.minecraft.nbt.NbtIo;
import net.minecraft.nbt.StreamTagVisitor;
import net.minecraft.util.ExceptionCollector;
import net.minecraft.util.FileUtil;
import net.minecraft.world.level.ChunkPos;
import org.jspecify.annotations.Nullable;

public final class RegionFileStorage implements AutoCloseable {
	public static final String ANVIL_EXTENSION = ".mca";
	private static final int MAX_CACHE_SIZE = 256;
	private final Long2ObjectLinkedOpenHashMap<RegionFile> regionCache = new Long2ObjectLinkedOpenHashMap<>();
	private final RegionStorageInfo info;
	private final Path folder;
	private final boolean sync;

	public RegionFileStorage(final RegionStorageInfo info, final Path folder, final boolean sync) {
		this.folder = folder;
		this.sync = sync;
		this.info = info;
	}

	private RegionFile getRegionFile(final ChunkPos pos) throws IOException {
		long key = ChunkPos.pack(pos.getRegionX(), pos.getRegionZ());
		RegionFile region = this.regionCache.getAndMoveToFirst(key);
		if (region != null) {
			return region;
		}

		if (this.regionCache.size() >= 256) {
			this.regionCache.removeLast().close();
		}

		FileUtil.createDirectoriesSafe(this.folder);
		Path file = this.folder.resolve("r." + pos.getRegionX() + "." + pos.getRegionZ() + ".mca");
		RegionFile newRegion = new RegionFile(this.info, file, this.folder, this.sync);
		this.regionCache.putAndMoveToFirst(key, newRegion);
		return newRegion;
	}

	public @Nullable CompoundTag read(final ChunkPos pos) throws IOException {
		RegionFile region = this.getRegionFile(pos);

		try (DataInputStream regionChunkInputStream = region.getChunkDataInputStream(pos)) {
			return regionChunkInputStream == null ? null : NbtIo.read(regionChunkInputStream);
		}
	}

	public void scanChunk(final ChunkPos pos, final StreamTagVisitor scanner) throws IOException {
		RegionFile region = this.getRegionFile(pos);

		try (DataInputStream regionChunkInputStream = region.getChunkDataInputStream(pos)) {
			if (regionChunkInputStream != null) {
				NbtIo.parse(regionChunkInputStream, scanner, NbtAccounter.unlimitedHeap());
			}
		}
	}

	public void write(final ChunkPos pos, final @Nullable CompoundTag value) throws IOException {
		if (!SharedConstants.DEBUG_DONT_SAVE_WORLD) {
			RegionFile region = this.getRegionFile(pos);
			if (value == null) {
				region.clear(pos);
			} else {
				try (DataOutputStream output = region.getChunkDataOutputStream(pos)) {
					NbtIo.write(value, output);
				}
			}
		}
	}

	@Override
	public void close() throws IOException {
		ExceptionCollector<IOException> exception = new ExceptionCollector<>();

		for (RegionFile regionFile : this.regionCache.values()) {
			try {
				regionFile.close();
			} catch (IOException e) {
				exception.add(e);
			}
		}

		exception.throwIfPresent();
	}

	public void flush() throws IOException {
		for (RegionFile regionFile : this.regionCache.values()) {
			regionFile.flush();
		}
	}

	public RegionStorageInfo info() {
		return this.info;
	}
}