package net.minecraft.util.eventlog;

import com.mojang.logging.LogUtils;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.Reader;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileLock;
import java.nio.channels.ReadableByteChannel;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.LinkOption;
import java.nio.file.Path;
import java.nio.file.StandardOpenOption;
import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeParseException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Objects;
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;
import org.jspecify.annotations.Nullable;
import org.slf4j.Logger;

public class EventLogDirectory {
	private static final Logger LOGGER = LogUtils.getLogger();
	private static final int COMPRESS_BUFFER_SIZE = 4096;
	private static final String COMPRESSED_EXTENSION = ".gz";
	private final Path root;
	private final String extension;

	private EventLogDirectory(final Path root, final String extension) {
		this.root = root;
		this.extension = extension;
	}

	public static EventLogDirectory open(final Path root, final String extension) throws IOException {
		Files.createDirectories(root);
		return new EventLogDirectory(root, extension);
	}

	public EventLogDirectory.FileList listFiles() throws IOException {
		Stream<Path> list = Files.list(this.root);

		EventLogDirectory.FileList var2;
		try {
			var2 = new EventLogDirectory.FileList(list.filter(x$0 -> Files.isRegularFile(x$0, new LinkOption[0])).map(this::parseFile).filter(Objects::nonNull).toList());
		} catch (Throwable var5) {
			if (list != null) {
				try {
					list.close();
				} catch (Throwable var4) {
					var5.addSuppressed(var4);
				}
			}

			throw var5;
		}

		if (list != null) {
			list.close();
		}

		return var2;
	}

	@Nullable
	private EventLogDirectory.File parseFile(final Path path) {
		String fileName = path.getFileName().toString();
		int extensionIndex = fileName.indexOf(46);
		if (extensionIndex == -1) {
			return null;
		} else {
			EventLogDirectory.FileId id = EventLogDirectory.FileId.parse(fileName.substring(0, extensionIndex));
			if (id != null) {
				String extension = fileName.substring(extensionIndex);
				if (extension.equals(this.extension)) {
					return new EventLogDirectory.RawFile(path, id);
				}

				if (extension.equals(this.extension + ".gz")) {
					return new EventLogDirectory.CompressedFile(path, id);
				}
			}

			return null;
		}
	}

	private static void tryCompress(final Path raw, final Path compressed) throws IOException {
		if (Files.exists(compressed, new LinkOption[0])) {
			throw new IOException("Compressed target file already exists: " + compressed);
		} else {
			FileChannel channel = FileChannel.open(raw, StandardOpenOption.WRITE, StandardOpenOption.READ);

			try {
				FileLock lock = channel.tryLock();
				if (lock == null) {
					throw new IOException("Raw log file is already locked, cannot compress: " + raw);
				}

				writeCompressed(channel, compressed);
				channel.truncate(0L);
			} catch (Throwable var6) {
				if (channel != null) {
					try {
						channel.close();
					} catch (Throwable var5) {
						var6.addSuppressed(var5);
					}
				}

				throw var6;
			}

			if (channel != null) {
				channel.close();
			}

			Files.delete(raw);
		}
	}

	private static void writeCompressed(final ReadableByteChannel channel, final Path target) throws IOException {
		OutputStream output = new GZIPOutputStream(Files.newOutputStream(target));

		try {
			byte[] bytes = new byte[4096];
			ByteBuffer buffer = ByteBuffer.wrap(bytes);

			while (channel.read(buffer) >= 0) {
				buffer.flip();
				output.write(bytes, 0, buffer.limit());
				buffer.clear();
			}
		} catch (Throwable var6) {
			try {
				output.close();
			} catch (Throwable var5) {
				var6.addSuppressed(var5);
			}

			throw var6;
		}

		output.close();
	}

	public EventLogDirectory.RawFile createNewFile(final LocalDate date) throws IOException {
		int index = 1;
		Set<EventLogDirectory.FileId> files = this.listFiles().ids();

		EventLogDirectory.FileId id;
		do {
			id = new EventLogDirectory.FileId(date, index++);
		} while (files.contains(id));

		EventLogDirectory.RawFile file = new EventLogDirectory.RawFile(this.root.resolve(id.toFileName(this.extension)), id);
		Files.createFile(file.path());
		return file;
	}

	public record CompressedFile(Path path, EventLogDirectory.FileId id) implements EventLogDirectory.File {
		@Nullable
		@Override
		public Reader openReader() throws IOException {
			return !Files.exists(this.path, new LinkOption[0])
				? null
				: new BufferedReader(new InputStreamReader(new GZIPInputStream(Files.newInputStream(this.path)), StandardCharsets.UTF_8));
		}

		@Override
		public EventLogDirectory.CompressedFile compress() {
			return this;
		}
	}

	public interface File {
		Path path();

		EventLogDirectory.FileId id();

		@Nullable
		Reader openReader() throws IOException;

		EventLogDirectory.CompressedFile compress() throws IOException;
	}

	public record FileId(LocalDate date, int index) {
		private static final DateTimeFormatter DATE_FORMATTER = DateTimeFormatter.BASIC_ISO_DATE;

		@Nullable
		public static EventLogDirectory.FileId parse(final String name) {
			int separator = name.indexOf("-");
			if (separator == -1) {
				return null;
			} else {
				String date = name.substring(0, separator);
				String index = name.substring(separator + 1);

				try {
					return new EventLogDirectory.FileId(LocalDate.parse(date, DATE_FORMATTER), Integer.parseInt(index));
				} catch (DateTimeParseException | NumberFormatException var5) {
					return null;
				}
			}
		}

		public String toString() {
			return DATE_FORMATTER.format(this.date) + "-" + this.index;
		}

		public String toFileName(final String extension) {
			return this + extension;
		}
	}

	public static class FileList implements Iterable<EventLogDirectory.File> {
		private final List<EventLogDirectory.File> files;

		private FileList(final List<EventLogDirectory.File> files) {
			this.files = new ArrayList(files);
		}

		public EventLogDirectory.FileList prune(final LocalDate date, final int expiryDays) {
			this.files.removeIf(file -> {
				EventLogDirectory.FileId id = file.id();
				LocalDate expiresAt = id.date().plusDays(expiryDays);
				if (!date.isBefore(expiresAt)) {
					try {
						Files.delete(file.path());
						return true;
					} catch (IOException var6) {
						EventLogDirectory.LOGGER.warn("Failed to delete expired event log file: {}", file.path(), var6);
					}
				}

				return false;
			});
			return this;
		}

		public EventLogDirectory.FileList compressAll() {
			ListIterator<EventLogDirectory.File> iterator = this.files.listIterator();

			while (iterator.hasNext()) {
				EventLogDirectory.File file = (EventLogDirectory.File)iterator.next();

				try {
					iterator.set(file.compress());
				} catch (IOException var4) {
					EventLogDirectory.LOGGER.warn("Failed to compress event log file: {}", file.path(), var4);
				}
			}

			return this;
		}

		public Iterator<EventLogDirectory.File> iterator() {
			return this.files.iterator();
		}

		public Stream<EventLogDirectory.File> stream() {
			return this.files.stream();
		}

		public Set<EventLogDirectory.FileId> ids() {
			return (Set<EventLogDirectory.FileId>)this.files.stream().map(EventLogDirectory.File::id).collect(Collectors.toSet());
		}
	}

	public record RawFile(Path path, EventLogDirectory.FileId id) implements EventLogDirectory.File {
		public FileChannel openChannel() throws IOException {
			return FileChannel.open(this.path, StandardOpenOption.WRITE, StandardOpenOption.READ);
		}

		@Nullable
		@Override
		public Reader openReader() throws IOException {
			return Files.exists(this.path, new LinkOption[0]) ? Files.newBufferedReader(this.path) : null;
		}

		@Override
		public EventLogDirectory.CompressedFile compress() throws IOException {
			Path compressedPath = this.path.resolveSibling(this.path.getFileName().toString() + ".gz");
			EventLogDirectory.tryCompress(this.path, compressedPath);
			return new EventLogDirectory.CompressedFile(compressedPath, this.id);
		}
	}
}