import { Buffer } from 'buffer';
import type * as fs from 'node:fs';
import { Errno, ErrnoError } from '../error.js';
import type { File } from '../file.js';
import { flagToMode, isAppendable, isExclusive, isReadable, isTruncating, isWriteable, parseFlag } from '../file.js';
import type { FileContents } from '../filesystem.js';
import { BigIntStats, type Stats } from '../stats.js';
import { decodeUTF8, normalizeMode, normalizeOptions, normalizePath, normalizeTime } from '../utils.js';
import * as constants from './constants.js';
import { Dir, Dirent } from './dir.js';
import { dirname, join, parse } from './path.js';
import { _statfs, fd2file, fdMap, file2fd, fixError, mounts, resolveMount, type InternalOptions, type ReaddirOptions } from './shared.js';
import { config } from './config.js';
import { emitChange } from './watchers.js';
import * as cache from './cache.js';

export function renameSync(oldPath: fs.PathLike, newPath: fs.PathLike): void {
	oldPath = normalizePath(oldPath);
	newPath = normalizePath(newPath);
	const oldMount = resolveMount(oldPath);
	const newMount = resolveMount(newPath);
	if (config.checkAccess && !statSync(dirname(oldPath)).hasAccess(constants.W_OK)) {
		throw ErrnoError.With('EACCES', oldPath, 'rename');
	}
	try {
		if (oldMount === newMount) {
			oldMount.fs.renameSync(oldMount.path, newMount.path);
			emitChange('rename', oldPath.toString());
			return;
		}

		writeFileSync(newPath, readFileSync(oldPath));
		unlinkSync(oldPath);
		emitChange('rename', oldPath.toString());
	} catch (e) {
		throw fixError(e as ErrnoError, { [oldMount.path]: oldPath, [newMount.path]: newPath });
	}
}
renameSync satisfies typeof fs.renameSync;

/**
 * Test whether or not `path` exists by checking with the file system.
 */
export function existsSync(path: fs.PathLike): boolean {
	path = normalizePath(path);
	try {
		const { fs, path: resolvedPath } = resolveMount(realpathSync(path));
		return fs.existsSync(resolvedPath);
	} catch (e) {
		if ((e as ErrnoError).errno == Errno.ENOENT) {
			return false;
		}

		throw e;
	}
}
existsSync satisfies typeof fs.existsSync;

export function statSync(path: fs.PathLike, options?: { bigint?: boolean }): Stats;
export function statSync(path: fs.PathLike, options: { bigint: true }): BigIntStats;
export function statSync(path: fs.PathLike, options?: fs.StatOptions): Stats | BigIntStats {
	path = normalizePath(path);
	const { fs, path: resolved } = resolveMount(realpathSync(path));
	try {
		const stats = fs.statSync(resolved);
		if (config.checkAccess && !stats.hasAccess(constants.R_OK)) {
			throw ErrnoError.With('EACCES', resolved, 'stat');
		}
		return options?.bigint ? new BigIntStats(stats) : stats;
	} catch (e) {
		throw fixError(e as ErrnoError, { [resolved]: path });
	}
}
statSync satisfies typeof fs.statSync;

/**
 * Synchronous `lstat`.
 * `lstat()` is identical to `stat()`, except that if path is a symbolic link,
 * then the link itself is stat-ed, not the file that it refers to.
 */
export function lstatSync(path: fs.PathLike, options?: { bigint?: boolean }): Stats;
export function lstatSync(path: fs.PathLike, options: { bigint: true }): BigIntStats;
export function lstatSync(path: fs.PathLike, options?: fs.StatOptions): Stats | BigIntStats {
	path = normalizePath(path);
	const { fs, path: resolved } = resolveMount(path);
	try {
		const stats = fs.statSync(resolved);
		return options?.bigint ? new BigIntStats(stats) : stats;
	} catch (e) {
		throw fixError(e as ErrnoError, { [resolved]: path });
	}
}
lstatSync satisfies typeof fs.lstatSync;

export function truncateSync(path: fs.PathLike, len: number | null = 0): void {
	using file = _openSync(path, 'r+');
	len ||= 0;
	if (len < 0) {
		throw new ErrnoError(Errno.EINVAL);
	}
	file.truncateSync(len);
}
truncateSync satisfies typeof fs.truncateSync;

export function unlinkSync(path: fs.PathLike): void {
	path = normalizePath(path);
	const { fs, path: resolved } = resolveMount(path);
	try {
		if (config.checkAccess && !(cache.getStats(path) || fs.statSync(resolved)).hasAccess(constants.W_OK)) {
			throw ErrnoError.With('EACCES', resolved, 'unlink');
		}
		fs.unlinkSync(resolved);
		emitChange('rename', path.toString());
	} catch (e) {
		throw fixError(e as ErrnoError, { [resolved]: path });
	}
}
unlinkSync satisfies typeof fs.unlinkSync;

function _openSync(path: fs.PathLike, _flag: fs.OpenMode, _mode?: fs.Mode | null, resolveSymlinks: boolean = true): File {
	path = normalizePath(path);
	const mode = normalizeMode(_mode, 0o644),
		flag = parseFlag(_flag);

	path = resolveSymlinks ? realpathSync(path) : path;
	const { fs, path: resolved } = resolveMount(path);

	let stats: Stats | undefined;
	try {
		stats = fs.statSync(resolved);
	} catch {
		// nothing
	}

	if (!stats) {
		if ((!isWriteable(flag) && !isAppendable(flag)) || flag == 'r+') {
			throw ErrnoError.With('ENOENT', path, '_open');
		}
		// Create the file
		const parentStats: Stats = fs.statSync(dirname(resolved));
		if (config.checkAccess && !parentStats.hasAccess(constants.W_OK)) {
			throw ErrnoError.With('EACCES', dirname(path), '_open');
		}
		if (!parentStats.isDirectory()) {
			throw ErrnoError.With('ENOTDIR', dirname(path), '_open');
		}
		return fs.createFileSync(resolved, flag, mode);
	}

	if (config.checkAccess && (!stats.hasAccess(mode) || !stats.hasAccess(flagToMode(flag)))) {
		throw ErrnoError.With('EACCES', path, '_open');
	}

	if (isExclusive(flag)) {
		throw ErrnoError.With('EEXIST', path, '_open');
	}

	const file = fs.openFileSync(resolved, flag);

	if (isTruncating(flag)) {
		file.truncateSync(0);
		file.syncSync();
	}

	return file;
}

/**
 * Synchronous file open.
 * @see http://www.manpagez.com/man/2/open/
 */
export function openSync(path: fs.PathLike, flag: fs.OpenMode, mode: fs.Mode | null = constants.F_OK): number {
	return file2fd(_openSync(path, flag, mode, true));
}
openSync satisfies typeof fs.openSync;

/**
 * Opens a file or symlink
 * @internal
 */
export function lopenSync(path: fs.PathLike, flag: string, mode?: fs.Mode | null): number {
	return file2fd(_openSync(path, flag, mode, false));
}

function _readFileSync(fname: string, flag: string, resolveSymlinks: boolean): Uint8Array {
	// Get file.
	using file = _openSync(fname, flag, 0o644, resolveSymlinks);
	const stat = file.statSync();
	// Allocate buffer.
	const data = new Uint8Array(stat.size);
	file.readSync(data, 0, stat.size, 0);
	return data;
}

/**
 * Synchronously reads the entire contents of a file.
 * @option encoding The string encoding for the file contents. Defaults to `null`.
 * @option flag Defaults to `'r'`.
 * @returns file contents
 */
export function readFileSync(path: fs.PathOrFileDescriptor, options?: { flag?: string } | null): Buffer;
export function readFileSync(path: fs.PathOrFileDescriptor, options?: (fs.EncodingOption & { flag?: string }) | BufferEncoding | null): string;
export function readFileSync(path: fs.PathOrFileDescriptor, _options: fs.WriteFileOptions | null = {}): FileContents {
	const options = normalizeOptions(_options, null, 'r', 0o644);
	const flag = parseFlag(options.flag);
	if (!isReadable(flag)) {
		throw new ErrnoError(Errno.EINVAL, 'Flag passed to readFile must allow for reading.');
	}
	const data: Buffer = Buffer.from(_readFileSync(typeof path == 'number' ? fd2file(path).path : path.toString(), options.flag, true));
	return options.encoding ? data.toString(options.encoding) : data;
}
readFileSync satisfies typeof fs.readFileSync;

/**
 * Synchronously writes data to a file, replacing the file if it already exists.
 *
 * The encoding option is ignored if data is a buffer.
 * @option encoding Defaults to `'utf8'`.
 * @option mode Defaults to `0644`.
 * @option flag Defaults to `'w'`.
 */
export function writeFileSync(path: fs.PathOrFileDescriptor, data: FileContents, options?: fs.WriteFileOptions): void;
export function writeFileSync(path: fs.PathOrFileDescriptor, data: FileContents, encoding?: BufferEncoding): void;
export function writeFileSync(path: fs.PathOrFileDescriptor, data: FileContents, _options: fs.WriteFileOptions | BufferEncoding = {}): void {
	const options = normalizeOptions(_options, 'utf8', 'w+', 0o644);
	const flag = parseFlag(options.flag);
	if (!isWriteable(flag)) {
		throw new ErrnoError(Errno.EINVAL, 'Flag passed to writeFile must allow for writing.');
	}
	if (typeof data != 'string' && !options.encoding) {
		throw new ErrnoError(Errno.EINVAL, 'Encoding not specified');
	}
	const encodedData = typeof data == 'string' ? Buffer.from(data, options.encoding!) : new Uint8Array(data.buffer, data.byteOffset, data.byteLength);
	if (!encodedData) {
		throw new ErrnoError(Errno.EINVAL, 'Data not specified');
	}
	using file = _openSync(typeof path == 'number' ? fd2file(path).path : path.toString(), flag, options.mode, true);
	file.writeSync(encodedData, 0, encodedData.byteLength, 0);
	emitChange('change', path.toString());
}
writeFileSync satisfies typeof fs.writeFileSync;

/**
 * Asynchronously append data to a file, creating the file if it not yet exists.
 * @option encoding Defaults to `'utf8'`.
 * @option mode Defaults to `0644`.
 * @option flag Defaults to `'a'`.
 */
export function appendFileSync(filename: fs.PathOrFileDescriptor, data: FileContents, _options: fs.WriteFileOptions = {}): void {
	const options = normalizeOptions(_options, 'utf8', 'a', 0o644);
	const flag = parseFlag(options.flag);
	if (!isAppendable(flag)) {
		throw new ErrnoError(Errno.EINVAL, 'Flag passed to appendFile must allow for appending.');
	}
	if (typeof data != 'string' && !options.encoding) {
		throw new ErrnoError(Errno.EINVAL, 'Encoding not specified');
	}
	const encodedData = typeof data == 'string' ? Buffer.from(data, options.encoding!) : new Uint8Array(data.buffer, data.byteOffset, data.byteLength);
	using file = _openSync(typeof filename == 'number' ? fd2file(filename).path : filename.toString(), flag, options.mode, true);
	file.writeSync(encodedData, 0, encodedData.byteLength);
}
appendFileSync satisfies typeof fs.appendFileSync;

/**
 * Synchronous `fstat`.
 * `fstat()` is identical to `stat()`, except that the file to be stat-ed is
 * specified by the file descriptor `fd`.
 */
export function fstatSync(fd: number, options?: { bigint?: boolean }): Stats;
export function fstatSync(fd: number, options: { bigint: true }): BigIntStats;
export function fstatSync(fd: number, options?: fs.StatOptions): Stats | BigIntStats {
	const stats: Stats = fd2file(fd).statSync();
	return options?.bigint ? new BigIntStats(stats) : stats;
}
fstatSync satisfies typeof fs.fstatSync;

export function closeSync(fd: number): void {
	fd2file(fd).closeSync();
	fdMap.delete(fd);
}
closeSync satisfies typeof fs.closeSync;

export function ftruncateSync(fd: number, len: number | null = 0): void {
	len ||= 0;
	if (len < 0) {
		throw new ErrnoError(Errno.EINVAL);
	}
	fd2file(fd).truncateSync(len);
}
ftruncateSync satisfies typeof fs.ftruncateSync;

export function fsyncSync(fd: number): void {
	fd2file(fd).syncSync();
}
fsyncSync satisfies typeof fs.fsyncSync;

export function fdatasyncSync(fd: number): void {
	fd2file(fd).datasyncSync();
}
fdatasyncSync satisfies typeof fs.fdatasyncSync;

/**
 * Write buffer to the file specified by `fd`.
 * @param data Uint8Array containing the data to write to the file.
 * @param offset Offset in the buffer to start reading data from.
 * @param length The amount of bytes to write to the file.
 * @param position Offset from the beginning of the file where this data should be written.
 * If position is null, the data will be written at the current position.
 */
export function writeSync(fd: number, data: ArrayBufferView, offset?: number | null, length?: number | null, position?: number | null): number;
export function writeSync(fd: number, data: string, position?: number | null, encoding?: BufferEncoding | null): number;
export function writeSync(fd: number, data: FileContents, posOrOff?: number | null, lenOrEnc?: BufferEncoding | number | null, pos?: number | null): number {
	let buffer: Uint8Array, offset: number | undefined, length: number, position: number | null;
	if (typeof data === 'string') {
		// Signature 1: (fd, string, [position?, [encoding?]])
		position = typeof posOrOff === 'number' ? posOrOff : null;
		const encoding = typeof lenOrEnc === 'string' ? lenOrEnc : ('utf8' as BufferEncoding);
		offset = 0;
		buffer = Buffer.from(data, encoding);
		length = buffer.byteLength;
	} else {
		// Signature 2: (fd, buffer, offset, length, position?)
		buffer = new Uint8Array(data.buffer, data.byteOffset, data.byteLength);
		offset = posOrOff!;
		length = lenOrEnc as number;
		position = typeof pos === 'number' ? pos : null;
	}

	const file = fd2file(fd);
	position ??= file.position;
	const bytesWritten = file.writeSync(buffer, offset, length, position);
	emitChange('change', file.path);
	return bytesWritten;
}
writeSync satisfies typeof fs.writeSync;

export function readSync(fd: number, buffer: ArrayBufferView, options?: fs.ReadSyncOptions): number;
export function readSync(fd: number, buffer: ArrayBufferView, offset: number, length: number, position?: fs.ReadPosition | null): number;
/**
 * Read data from the file specified by `fd`.
 * @param buffer The buffer that the data will be written to.
 * @param offset The offset within the buffer where writing will start.
 * @param length An integer specifying the number of bytes to read.
 * @param position An integer specifying where to begin reading from in the file.
 * If position is null, data will be read from the current file position.
 */
export function readSync(fd: number, buffer: ArrayBufferView, options?: fs.ReadSyncOptions | number, length?: number, position?: fs.ReadPosition | null): number {
	const file = fd2file(fd);
	const offset = typeof options == 'object' ? options.offset : options;
	if (typeof options == 'object') {
		length = options.length;
		position = options.position;
	}

	position = Number(position);
	if (isNaN(position)) {
		position = file.position!;
	}

	return file.readSync(buffer, offset, length, position);
}
readSync satisfies typeof fs.readSync;

export function fchownSync(fd: number, uid: number, gid: number): void {
	fd2file(fd).chownSync(uid, gid);
}
fchownSync satisfies typeof fs.fchownSync;

export function fchmodSync(fd: number, mode: number | string): void {
	const numMode = normalizeMode(mode, -1);
	if (numMode < 0) {
		throw new ErrnoError(Errno.EINVAL, `Invalid mode.`);
	}
	fd2file(fd).chmodSync(numMode);
}
fchmodSync satisfies typeof fs.fchmodSync;

/**
 * Change the file timestamps of a file referenced by the supplied file descriptor.
 */
export function futimesSync(fd: number, atime: string | number | Date, mtime: string | number | Date): void {
	fd2file(fd).utimesSync(normalizeTime(atime), normalizeTime(mtime));
}
futimesSync satisfies typeof fs.futimesSync;

export function rmdirSync(path: fs.PathLike): void {
	path = normalizePath(path);
	const { fs, path: resolved } = resolveMount(realpathSync(path));
	try {
		const stats = cache.getStats(path) || fs.statSync(resolved);
		if (!stats.isDirectory()) {
			throw ErrnoError.With('ENOTDIR', resolved, 'rmdir');
		}
		if (config.checkAccess && !stats.hasAccess(constants.W_OK)) {
			throw ErrnoError.With('EACCES', resolved, 'rmdir');
		}
		fs.rmdirSync(resolved);
		emitChange('rename', path.toString());
	} catch (e) {
		throw fixError(e as ErrnoError, { [resolved]: path });
	}
}
rmdirSync satisfies typeof fs.rmdirSync;

/**
 * Synchronous `mkdir`. Mode defaults to `o777`.
 */
export function mkdirSync(path: fs.PathLike, options: fs.MakeDirectoryOptions & { recursive: true }): string | undefined;
export function mkdirSync(path: fs.PathLike, options?: fs.Mode | (fs.MakeDirectoryOptions & { recursive?: false }) | null): void;
export function mkdirSync(path: fs.PathLike, options?: fs.Mode | fs.MakeDirectoryOptions | null): string | undefined;
export function mkdirSync(path: fs.PathLike, options?: fs.Mode | fs.MakeDirectoryOptions | null): string | undefined | void {
	options = typeof options === 'object' ? options : { mode: options };
	const mode = normalizeMode(options?.mode, 0o777);

	path = realpathSync(path);
	const { fs, path: resolved } = resolveMount(path);
	const errorPaths: Record<string, string> = { [resolved]: path };

	try {
		if (!options?.recursive) {
			if (config.checkAccess && !fs.statSync(dirname(resolved)).hasAccess(constants.W_OK)) {
				throw ErrnoError.With('EACCES', dirname(resolved), 'mkdir');
			}
			return fs.mkdirSync(resolved, mode);
		}

		const dirs: string[] = [];
		for (let dir = resolved, original = path; !fs.existsSync(dir); dir = dirname(dir), original = dirname(original)) {
			dirs.unshift(dir);
			errorPaths[dir] = original;
		}
		for (const dir of dirs) {
			if (config.checkAccess && !fs.statSync(dirname(dir)).hasAccess(constants.W_OK)) {
				throw ErrnoError.With('EACCES', dirname(dir), 'mkdir');
			}
			fs.mkdirSync(dir, mode);
			emitChange('rename', dir);
		}
		return dirs[0];
	} catch (e) {
		throw fixError(e as ErrnoError, errorPaths);
	}
}
mkdirSync satisfies typeof fs.mkdirSync;

export function readdirSync(path: fs.PathLike, options?: (fs.ObjectEncodingOptions & ReaddirOptions & { withFileTypes?: false }) | BufferEncoding | null): string[];
export function readdirSync(path: fs.PathLike, options: fs.BufferEncodingOption & ReaddirOptions & { withFileTypes?: false }): Buffer[];
export function readdirSync(path: fs.PathLike, options?: (fs.ObjectEncodingOptions & ReaddirOptions & { withFileTypes?: false }) | BufferEncoding | null): string[] | Buffer[];
export function readdirSync(path: fs.PathLike, options: fs.ObjectEncodingOptions & ReaddirOptions & { withFileTypes: true }): Dirent[];
export function readdirSync(
	path: fs.PathLike,
	options?: (ReaddirOptions & (fs.ObjectEncodingOptions | fs.BufferEncodingOption)) | BufferEncoding | null
): string[] | Dirent[] | Buffer[];
export function readdirSync(
	path: fs.PathLike,
	options?: (ReaddirOptions & (fs.ObjectEncodingOptions | fs.BufferEncodingOption)) | BufferEncoding | null
): string[] | Dirent[] | Buffer[] {
	options = typeof options === 'object' ? options : { encoding: options };
	path = normalizePath(path);
	const { fs, path: resolved } = resolveMount(realpathSync(path));
	let entries: string[];
	try {
		const stats = cache.getStats(path) || fs.statSync(resolved);
		cache.setStats(path, stats);
		if (config.checkAccess && !stats.hasAccess(constants.R_OK)) {
			throw ErrnoError.With('EACCES', resolved, 'readdir');
		}
		if (!stats.isDirectory()) {
			throw ErrnoError.With('ENOTDIR', resolved, 'readdir');
		}
		entries = fs.readdirSync(resolved);
	} catch (e) {
		throw fixError(e as ErrnoError, { [resolved]: path });
	}

	for (const mount of mounts.keys()) {
		if (!mount.startsWith(path)) {
			continue;
		}
		const entry = mount.slice(path.length);
		if (entry.includes('/') || entry.length == 0) {
			// ignore FSs mounted in subdirectories and any FS mounted to `path`.
			continue;
		}
		entries.push(entry);
	}

	// Iterate over entries and handle recursive case if needed
	const values: (string | Dirent | Buffer)[] = [];
	for (const entry of entries) {
		const entryStat = cache.getStats(join(path, entry)) || fs.statSync(join(resolved, entry));
		cache.setStats(join(path, entry), entryStat);

		if (options?.withFileTypes) {
			values.push(new Dirent(entry, entryStat));
		} else if (options?.encoding == 'buffer') {
			values.push(Buffer.from(entry));
		} else {
			values.push(entry);
		}
		if (!entryStat.isDirectory() || !options?.recursive) continue;

		for (const subEntry of readdirSync(join(path, entry), { ...options, _isIndirect: true })) {
			if (subEntry instanceof Dirent) {
				subEntry.path = join(entry, subEntry.path);
				values.push(subEntry);
			} else if (Buffer.isBuffer(subEntry)) {
				values.push(Buffer.from(join(entry, decodeUTF8(subEntry))));
			} else {
				values.push(join(entry, subEntry));
			}
		}
	}

	if (!options?._isIndirect) {
		cache.clearStats();
	}
	return values as string[] | Dirent[] | Buffer[];
}
readdirSync satisfies typeof fs.readdirSync;

// SYMLINK METHODS

export function linkSync(targetPath: fs.PathLike, linkPath: fs.PathLike): void {
	targetPath = normalizePath(targetPath);
	if (config.checkAccess && !statSync(dirname(targetPath)).hasAccess(constants.R_OK)) {
		throw ErrnoError.With('EACCES', dirname(targetPath), 'link');
	}
	linkPath = normalizePath(linkPath);
	if (config.checkAccess && !statSync(dirname(linkPath)).hasAccess(constants.W_OK)) {
		throw ErrnoError.With('EACCES', dirname(linkPath), 'link');
	}

	const { fs, path } = resolveMount(targetPath);
	const link = resolveMount(linkPath);
	if (fs != link.fs) {
		throw ErrnoError.With('EXDEV', linkPath, 'link');
	}
	try {
		if (config.checkAccess && !fs.statSync(path).hasAccess(constants.W_OK)) {
			throw ErrnoError.With('EACCES', path, 'link');
		}
		return fs.linkSync(path, linkPath);
	} catch (e) {
		throw fixError(e as ErrnoError, { [path]: targetPath, [link.path]: linkPath });
	}
}
linkSync satisfies typeof fs.linkSync;

/**
 * Synchronous `symlink`.
 * @param target target path
 * @param path link path
 * @param type can be either `'dir'` or `'file'` (default is `'file'`)
 */
export function symlinkSync(target: fs.PathLike, path: fs.PathLike, type: fs.symlink.Type | null = 'file'): void {
	if (!['file', 'dir', 'junction'].includes(type!)) {
		throw new ErrnoError(Errno.EINVAL, 'Invalid type: ' + type);
	}
	if (existsSync(path)) {
		throw ErrnoError.With('EEXIST', path.toString(), 'symlink');
	}

	writeFileSync(path, target.toString());
	const file = _openSync(path, 'r+', 0o644, false);
	file._setTypeSync(constants.S_IFLNK);
}
symlinkSync satisfies typeof fs.symlinkSync;

export function readlinkSync(path: fs.PathLike, options?: fs.BufferEncodingOption): Buffer;
export function readlinkSync(path: fs.PathLike, options: fs.EncodingOption | BufferEncoding): string;
export function readlinkSync(path: fs.PathLike, options?: fs.EncodingOption | BufferEncoding | fs.BufferEncodingOption): Buffer | string;
export function readlinkSync(path: fs.PathLike, options?: fs.EncodingOption | BufferEncoding | fs.BufferEncodingOption): Buffer | string {
	const value: Buffer = Buffer.from(_readFileSync(path.toString(), 'r', false));
	const encoding = typeof options == 'object' ? options?.encoding : options;
	if (encoding == 'buffer') {
		return value;
	}
	return value.toString(encoding!);
}
readlinkSync satisfies typeof fs.readlinkSync;

// PROPERTY OPERATIONS

export function chownSync(path: fs.PathLike, uid: number, gid: number): void {
	const fd = openSync(path, 'r+');
	fchownSync(fd, uid, gid);
	closeSync(fd);
}
chownSync satisfies typeof fs.chownSync;

export function lchownSync(path: fs.PathLike, uid: number, gid: number): void {
	const fd = lopenSync(path, 'r+');
	fchownSync(fd, uid, gid);
	closeSync(fd);
}
lchownSync satisfies typeof fs.lchownSync;

export function chmodSync(path: fs.PathLike, mode: fs.Mode): void {
	const fd = openSync(path, 'r+');
	fchmodSync(fd, mode);
	closeSync(fd);
}
chmodSync satisfies typeof fs.chmodSync;

export function lchmodSync(path: fs.PathLike, mode: number | string): void {
	const fd = lopenSync(path, 'r+');
	fchmodSync(fd, mode);
	closeSync(fd);
}
lchmodSync satisfies typeof fs.lchmodSync;

/**
 * Change file timestamps of the file referenced by the supplied path.
 */
export function utimesSync(path: fs.PathLike, atime: string | number | Date, mtime: string | number | Date): void {
	const fd = openSync(path, 'r+');
	futimesSync(fd, atime, mtime);
	closeSync(fd);
}
utimesSync satisfies typeof fs.utimesSync;

/**
 * Change file timestamps of the file referenced by the supplied path.
 */
export function lutimesSync(path: fs.PathLike, atime: string | number | Date, mtime: string | number | Date): void {
	const fd = lopenSync(path, 'r+');
	futimesSync(fd, atime, mtime);
	closeSync(fd);
}
lutimesSync satisfies typeof fs.lutimesSync;

export function realpathSync(path: fs.PathLike, options: fs.BufferEncodingOption): Buffer;
export function realpathSync(path: fs.PathLike, options?: fs.EncodingOption): string;
export function realpathSync(path: fs.PathLike, options?: fs.EncodingOption | fs.BufferEncodingOption): string | Buffer {
	path = normalizePath(path);
	const { base, dir } = parse(path);
	const lpath = join(dir == '/' ? '/' : realpathSync(dir), base);
	const { fs, path: resolvedPath, mountPoint } = resolveMount(lpath);

	try {
		const stats = fs.statSync(resolvedPath);
		if (!stats.isSymbolicLink()) {
			return lpath;
		}

		return realpathSync(mountPoint + readlinkSync(lpath, options).toString());
	} catch (e) {
		if ((e as ErrnoError).code == 'ENOENT') {
			return path;
		}
		throw fixError(e as ErrnoError, { [resolvedPath]: lpath });
	}
}
realpathSync satisfies Omit<typeof fs.realpathSync, 'native'>;

export function accessSync(path: fs.PathLike, mode: number = 0o600): void {
	if (!config.checkAccess) return;
	if (!statSync(path).hasAccess(mode)) {
		throw new ErrnoError(Errno.EACCES);
	}
}
accessSync satisfies typeof fs.accessSync;

/**
 * Synchronous `rm`. Removes files or directories (recursively).
 * @param path The path to the file or directory to remove.
 */
export function rmSync(path: fs.PathLike, options?: fs.RmOptions & InternalOptions): void {
	path = normalizePath(path);

	let stats: Stats | undefined;
	try {
		stats = cache.getStats(path) || statSync(path);
	} catch (error) {
		if ((error as ErrnoError).code != 'ENOENT' || !options?.force) throw error;
	}

	if (!stats) {
		return;
	}

	cache.setStats(path, stats);

	switch (stats.mode & constants.S_IFMT) {
		case constants.S_IFDIR:
			if (options?.recursive) {
				for (const entry of readdirSync(path, { _isIndirect: true })) {
					rmSync(join(path, entry), { ...options, _isIndirect: true });
				}
			}

			rmdirSync(path);
			break;
		case constants.S_IFREG:
		case constants.S_IFLNK:
			unlinkSync(path);
			break;
		case constants.S_IFBLK:
		case constants.S_IFCHR:
		case constants.S_IFIFO:
		case constants.S_IFSOCK:
		default:
			cache.clearStats();
			throw new ErrnoError(Errno.EPERM, 'File type not supported', path, 'rm');
	}

	if (!options?._isIndirect) {
		cache.clearStats();
	}
}
rmSync satisfies typeof fs.rmSync;

/**
 * Synchronous `mkdtemp`. Creates a unique temporary directory.
 * @param prefix The directory prefix.
 * @param options The encoding (or an object including `encoding`).
 * @returns The path to the created temporary directory, encoded as a string or buffer.
 */
export function mkdtempSync(prefix: string, options: fs.BufferEncodingOption): Buffer;
export function mkdtempSync(prefix: string, options?: fs.EncodingOption): string;
export function mkdtempSync(prefix: string, options?: fs.EncodingOption | fs.BufferEncodingOption): string | Buffer {
	const encoding = typeof options === 'object' ? options?.encoding : options || 'utf8';
	const fsName = `${prefix}${Date.now()}-${Math.random().toString(36).slice(2)}`;
	const resolvedPath = '/tmp/' + fsName;

	mkdirSync(resolvedPath);

	return encoding == 'buffer' ? Buffer.from(resolvedPath) : resolvedPath;
}
mkdtempSync satisfies typeof fs.mkdtempSync;

/**
 * Synchronous `copyFile`. Copies a file.
 * @param flags Optional flags for the copy operation. Currently supports these flags:
 * - `fs.constants.COPYFILE_EXCL`: If the destination file already exists, the operation fails.
 */
export function copyFileSync(source: fs.PathLike, destination: fs.PathLike, flags?: number): void {
	source = normalizePath(source);
	destination = normalizePath(destination);

	if (flags && flags & constants.COPYFILE_EXCL && existsSync(destination)) {
		throw new ErrnoError(Errno.EEXIST, 'Destination file already exists.', destination, 'copyFile');
	}

	writeFileSync(destination, readFileSync(source));
	emitChange('rename', destination.toString());
}
copyFileSync satisfies typeof fs.copyFileSync;

/**
 * Synchronous `readv`. Reads from a file descriptor into multiple buffers.
 * @param fd The file descriptor.
 * @param buffers An array of Uint8Array buffers.
 * @param position The position in the file where to begin reading.
 * @returns The number of bytes read.
 */
export function readvSync(fd: number, buffers: readonly NodeJS.ArrayBufferView[], position?: number): number {
	const file = fd2file(fd);
	let bytesRead = 0;

	for (const buffer of buffers) {
		bytesRead += file.readSync(buffer, 0, buffer.byteLength, position! + bytesRead);
	}

	return bytesRead;
}
readvSync satisfies typeof fs.readvSync;

/**
 * Synchronous `writev`. Writes from multiple buffers into a file descriptor.
 * @param fd The file descriptor.
 * @param buffers An array of Uint8Array buffers.
 * @param position The position in the file where to begin writing.
 * @returns The number of bytes written.
 */
export function writevSync(fd: number, buffers: readonly ArrayBufferView[], position?: number): number {
	const file = fd2file(fd);
	let bytesWritten = 0;

	for (const buffer of buffers) {
		bytesWritten += file.writeSync(new Uint8Array(buffer.buffer), 0, buffer.byteLength, position! + bytesWritten);
	}

	return bytesWritten;
}
writevSync satisfies typeof fs.writevSync;

/**
 * Synchronous `opendir`. Opens a directory.
 * @param path The path to the directory.
 * @param options Options for opening the directory.
 * @returns A `Dir` object representing the opened directory.
 * @todo Handle options
 */
export function opendirSync(path: fs.PathLike, options?: fs.OpenDirOptions): Dir {
	path = normalizePath(path);
	return new Dir(path);
}
opendirSync satisfies typeof fs.opendirSync;

/**
 * Synchronous `cp`. Recursively copies a file or directory.
 * @param source The source file or directory.
 * @param destination The destination file or directory.
 * @param opts Options for the copy operation. Currently supports these options from Node.js 'fs.cpSync':
 * - `dereference`: Dereference symbolic links. *(unconfirmed)*
 * - `errorOnExist`: Throw an error if the destination file or directory already exists.
 * - `filter`: A function that takes a source and destination path and returns a boolean, indicating whether to copy `source` element.
 * - `force`: Overwrite the destination if it exists, and overwrite existing readonly destination files. *(unconfirmed)*
 * - `preserveTimestamps`: Preserve file timestamps.
 * - `recursive`: If `true`, copies directories recursively.
 */
export function cpSync(source: fs.PathLike, destination: fs.PathLike, opts?: fs.CopySyncOptions): void {
	source = normalizePath(source);
	destination = normalizePath(destination);

	const srcStats = lstatSync(source); // Use lstat to follow symlinks if not dereferencing

	if (opts?.errorOnExist && existsSync(destination)) {
		throw new ErrnoError(Errno.EEXIST, 'Destination file or directory already exists.', destination, 'cp');
	}

	switch (srcStats.mode & constants.S_IFMT) {
		case constants.S_IFDIR:
			if (!opts?.recursive) {
				throw new ErrnoError(Errno.EISDIR, source + ' is a directory (not copied)', source, 'cp');
			}
			mkdirSync(destination, { recursive: true }); // Ensure the destination directory exists
			for (const dirent of readdirSync(source, { withFileTypes: true })) {
				if (opts.filter && !opts.filter(join(source, dirent.name), join(destination, dirent.name))) {
					continue; // Skip if the filter returns false
				}
				cpSync(join(source, dirent.name), join(destination, dirent.name), opts);
			}
			break;
		case constants.S_IFREG:
		case constants.S_IFLNK:
			copyFileSync(source, destination);
			break;
		case constants.S_IFBLK:
		case constants.S_IFCHR:
		case constants.S_IFIFO:
		case constants.S_IFSOCK:
		default:
			throw new ErrnoError(Errno.EPERM, 'File type not supported', source, 'rm');
	}

	// Optionally preserve timestamps
	if (opts?.preserveTimestamps) {
		utimesSync(destination, srcStats.atime, srcStats.mtime);
	}
}
cpSync satisfies typeof fs.cpSync;

/**
 * Synchronous statfs(2). Returns information about the mounted file system which contains path.
 * In case of an error, the err.code will be one of Common System Errors.
 * @param path A path to an existing file or directory on the file system to be queried.
 */
export function statfsSync(path: fs.PathLike, options?: fs.StatFsOptions & { bigint?: false }): fs.StatsFs;
export function statfsSync(path: fs.PathLike, options: fs.StatFsOptions & { bigint: true }): fs.BigIntStatsFs;
export function statfsSync(path: fs.PathLike, options?: fs.StatFsOptions): fs.StatsFs | fs.BigIntStatsFs;
export function statfsSync(path: fs.PathLike, options?: fs.StatFsOptions): fs.StatsFs | fs.BigIntStatsFs {
	path = normalizePath(path);
	const { fs } = resolveMount(path);
	return _statfs(fs, options?.bigint);
}