package net.minecraft.util.filefix.access;

import com.mojang.logging.LogUtils;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.stream.Stream;
import org.slf4j.Logger;

@FunctionalInterface
public interface FileRelation {
	Logger LOGGER = LogUtils.getLogger();
	FileRelation ORIGIN = List::of;
	FileRelation REGION = basePath -> List.of(basePath.resolve("region"));
	FileRelation DATA = basePath -> List.of(basePath.resolve("data"));
	FileRelation PLAYER_DATA = basePath -> List.of(basePath.resolve("players/data"));
	FileRelation DIMENSIONS = FileRelation::discoverDimensions;
	FileRelation DIMENSIONS_DATA = DIMENSIONS.resolve(DATA);
	FileRelation GENERATED_NAMESPACES = ORIGIN.resolve(basePath -> directoriesInPath(basePath.resolve("generated")));
	FileRelation OLD_OVERWORLD = ORIGIN;
	FileRelation OLD_NETHER = ORIGIN.resolve(basePath -> List.of(basePath.resolve("DIM-1")));
	FileRelation OLD_END = ORIGIN.resolve(basePath -> List.of(basePath.resolve("DIM1")));

	List<Path> getPaths(final Path basePath);

	static FileRelation forDataFileInDimension(final String dimension, final String fileName) {
		return basePath -> List.of(basePath.resolve("dimensions/minecraft/" + dimension + "/data/" + fileName));
	}

	default FileRelation forFile(final String fileName) {
		return this.resolve(basePath -> List.of(basePath.resolve(fileName)));
	}

	default FileRelation resolve(final FileRelation other) {
		return basePath -> this.getPaths(basePath).stream().flatMap(path -> other.getPaths(path).stream()).toList();
	}

	default FileRelation join(final FileRelation... relations) {
		return basePath -> {
			Set<Path> paths = new HashSet<>();

			for (FileRelation relation : relations) {
				paths.addAll(relation.getPaths(basePath));
			}

			return List.copyOf(paths);
		};
	}

	private static List<Path> discoverDimensions(final Path basePath) {
		Path dimensionsRoot = basePath.resolve("dimensions");
		if (!Files.exists(dimensionsRoot)) {
			return getDefaultDimensions(basePath);
		}

		try (Stream<Path> namespacePaths = Files.list(dimensionsRoot)) {
			List<Path> discoveredDimensions = namespacePaths.filter(x$0 -> Files.isDirectory(x$0)).flatMap(path -> directoriesInPath(path).stream()).toList();
			return discoveredDimensions.isEmpty() ? getDefaultDimensions(basePath) : discoveredDimensions;
		} catch (IOException e) {
			LOGGER.warn("Failed to discover dimensions, assuming default: {}", e.toString());
			return getDefaultDimensions(basePath);
		}
	}

	static List<Path> directoriesInPath(final Path path) {
		try (Stream<Path> dimensionPaths = Files.list(path)) {
			return dimensionPaths.filter(x$0 -> Files.isDirectory(x$0)).toList();
		} catch (IOException e) {
			return List.of();
		}
	}

	private static List<Path> getDefaultDimensions(final Path basePath) {
		return List.of(
			basePath.resolve("dimensions/minecraft/overworld"), basePath.resolve("dimensions/minecraft/the_nether"), basePath.resolve("dimensions/minecraft/the_end")
		);
	}
}