class FileSystem

class FileSystem implements FileSystemInterface {
    
    /**
     * Default mode for new directories. See self::chmod().
     */
    const CHMOD_DIRECTORY = 0775;
    
    /**
     * Default mode for new files. See self::chmod().
     */
    const CHMOD_FILE = 0664;
    
    /**
     * The site settings.
     *
     * @var \Drupal\Core\Site\Settings
     */
    protected $settings;
    
    /**
     * The file logger channel.
     *
     * @var \Psr\Log\LoggerInterface
     */
    protected $logger;
    
    /**
     * The stream wrapper manager.
     *
     * @var \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface
     */
    protected $streamWrapperManager;
    
    /**
     * Constructs a new FileSystem.
     *
     * @param \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface $stream_wrapper_manager
     *   The stream wrapper manager.
     * @param \Drupal\Core\Site\Settings $settings
     *   The site settings.
     * @param \Psr\Log\LoggerInterface $logger
     *   The file logger channel.
     */
    public function __construct(StreamWrapperManagerInterface $stream_wrapper_manager, Settings $settings, LoggerInterface $logger) {
        $this->streamWrapperManager = $stream_wrapper_manager;
        $this->settings = $settings;
        $this->logger = $logger;
    }
    
    /**
     * {@inheritdoc}
     */
    public function moveUploadedFile($filename, $uri) {
        $result = @move_uploaded_file($filename, $uri);
        // PHP's move_uploaded_file() does not properly support streams if
        // open_basedir is enabled so if the move failed, try finding a real path
        // and retry the move operation.
        if (!$result) {
            if ($realpath = $this->realpath($uri)) {
                $result = move_uploaded_file($filename, $realpath);
            }
            else {
                $result = move_uploaded_file($filename, $uri);
            }
        }
        return $result;
    }
    
    /**
     * {@inheritdoc}
     */
    public function chmod($uri, $mode = NULL) {
        if (!isset($mode)) {
            if (is_dir($uri)) {
                $mode = $this->settings
                    ->get('file_chmod_directory', static::CHMOD_DIRECTORY);
            }
            else {
                $mode = $this->settings
                    ->get('file_chmod_file', static::CHMOD_FILE);
            }
        }
        if (@chmod($uri, $mode)) {
            return TRUE;
        }
        $this->logger
            ->error('The file permissions could not be set on %uri.', [
            '%uri' => $uri,
        ]);
        return FALSE;
    }
    
    /**
     * {@inheritdoc}
     */
    public function unlink($uri, $context = NULL) {
        if (!$this->streamWrapperManager
            ->isValidUri($uri) && substr(PHP_OS, 0, 3) == 'WIN') {
            chmod($uri, 0600);
        }
        if ($context) {
            return unlink($uri, $context);
        }
        else {
            return unlink($uri);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function realpath($uri) {
        // If this URI is a stream, pass it off to the appropriate stream wrapper.
        // Otherwise, attempt PHP's realpath. This allows use of this method even
        // for unmanaged files outside of the stream wrapper interface.
        if ($wrapper = $this->streamWrapperManager
            ->getViaUri($uri)) {
            return $wrapper->realpath();
        }
        return realpath($uri);
    }
    
    /**
     * {@inheritdoc}
     */
    public function dirname($uri) {
        $scheme = StreamWrapperManager::getScheme($uri);
        if ($this->streamWrapperManager
            ->isValidScheme($scheme)) {
            return $this->streamWrapperManager
                ->getViaScheme($scheme)
                ->dirname($uri);
        }
        else {
            return dirname($uri);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function basename($uri, $suffix = NULL) {
        $separators = '/';
        if (DIRECTORY_SEPARATOR != '/') {
            // For Windows OS add special separator.
            $separators .= DIRECTORY_SEPARATOR;
        }
        // Remove right-most slashes when $uri points to directory.
        $uri = rtrim($uri, $separators);
        // Returns the trailing part of the $uri starting after one of the directory
        // separators.
        $filename = preg_match('@[^' . preg_quote($separators, '@') . ']+$@', $uri, $matches) ? $matches[0] : '';
        // Cuts off a suffix from the filename.
        if ($suffix) {
            $filename = preg_replace('@' . preg_quote($suffix, '@') . '$@', '', $filename);
        }
        return $filename;
    }
    
    /**
     * {@inheritdoc}
     */
    public function mkdir($uri, $mode = NULL, $recursive = FALSE, $context = NULL) {
        if (!isset($mode)) {
            $mode = $this->settings
                ->get('file_chmod_directory', static::CHMOD_DIRECTORY);
        }
        // If the URI has a scheme, don't override the umask - schemes can handle
        // this issue in their own implementation.
        if (StreamWrapperManager::getScheme($uri)) {
            return $this->mkdirCall($uri, $mode, $recursive, $context);
        }
        // If recursive, create each missing component of the parent directory
        // individually and set the mode explicitly to override the umask.
        if ($recursive) {
            // Ensure the path is using DIRECTORY_SEPARATOR, and trim off any trailing
            // slashes because they can throw off the loop when creating the parent
            // directories.
            $uri = rtrim(str_replace('/', DIRECTORY_SEPARATOR, $uri), DIRECTORY_SEPARATOR);
            // Determine the components of the path.
            $components = explode(DIRECTORY_SEPARATOR, $uri);
            // If the filepath is absolute the first component will be empty as there
            // will be nothing before the first slash.
            if ($components[0] == '') {
                $recursive_path = DIRECTORY_SEPARATOR;
                // Get rid of the empty first component.
                array_shift($components);
            }
            else {
                $recursive_path = '';
            }
            // Don't handle the top-level directory in this loop.
            array_pop($components);
            // Create each component if necessary.
            foreach ($components as $component) {
                $recursive_path .= $component;
                if (!file_exists($recursive_path)) {
                    $success = $this->mkdirCall($recursive_path, $mode, FALSE, $context);
                    // If the operation failed, check again if the directory was created
                    // by another process/server, only report a failure if not.
                    if (!$success && !file_exists($recursive_path)) {
                        return FALSE;
                    }
                    // Not necessary to use self::chmod() as there is no scheme.
                    if (!chmod($recursive_path, $mode)) {
                        return FALSE;
                    }
                }
                $recursive_path .= DIRECTORY_SEPARATOR;
            }
        }
        // Do not check if the top-level directory already exists, as this condition
        // must cause this function to fail.
        if (!$this->mkdirCall($uri, $mode, FALSE, $context)) {
            return FALSE;
        }
        // Not necessary to use self::chmod() as there is no scheme.
        return chmod($uri, $mode);
    }
    
    /**
     * Ensures we don't pass a NULL as a context resource to mkdir().
     *
     * @see self::mkdir()
     */
    protected function mkdirCall($uri, $mode, $recursive, $context) {
        if (is_null($context)) {
            return mkdir($uri, $mode, $recursive);
        }
        else {
            return mkdir($uri, $mode, $recursive, $context);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function rmdir($uri, $context = NULL) {
        if (!$this->streamWrapperManager
            ->isValidUri($uri) && substr(PHP_OS, 0, 3) == 'WIN') {
            chmod($uri, 0700);
        }
        if ($context) {
            return rmdir($uri, $context);
        }
        else {
            return rmdir($uri);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function tempnam($directory, $prefix) {
        $scheme = StreamWrapperManager::getScheme($directory);
        if ($this->streamWrapperManager
            ->isValidScheme($scheme)) {
            $wrapper = $this->streamWrapperManager
                ->getViaScheme($scheme);
            if ($filename = tempnam($wrapper->getDirectoryPath(), $prefix)) {
                return $scheme . '://' . static::basename($filename);
            }
            else {
                return FALSE;
            }
        }
        else {
            // Handle as a normal tempnam() call.
            return tempnam($directory, $prefix);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function copy($source, $destination, $replace = self::EXISTS_RENAME) {
        $this->prepareDestination($source, $destination, $replace);
        if (!@copy($source, $destination)) {
            // If the copy failed and realpaths exist, retry the operation using them
            // instead.
            $real_source = $this->realpath($source) ?: $source;
            $real_destination = $this->realpath($destination) ?: $destination;
            if ($real_source === FALSE || $real_destination === FALSE || !@copy($real_source, $real_destination)) {
                $this->logger
                    ->error("The specified file '%source' could not be copied to '%destination'.", [
                    '%source' => $source,
                    '%destination' => $destination,
                ]);
                throw new FileWriteException("The specified file '{$source}' could not be copied to '{$destination}'.");
            }
        }
        // Set the permissions on the new file.
        $this->chmod($destination);
        return $destination;
    }
    
    /**
     * {@inheritdoc}
     */
    public function delete($path) {
        if (is_file($path)) {
            if (!$this->unlink($path)) {
                $this->logger
                    ->error("Failed to unlink file '%path'.", [
                    '%path' => $path,
                ]);
                throw new FileException("Failed to unlink file '{$path}'.");
            }
            return TRUE;
        }
        if (is_dir($path)) {
            $this->logger
                ->error("Cannot delete '%path' because it is a directory. Use deleteRecursive() instead.", [
                '%path' => $path,
            ]);
            throw new NotRegularFileException("Cannot delete '{$path}' because it is a directory. Use deleteRecursive() instead.");
        }
        // Return TRUE for non-existent file, but log that nothing was actually
        // deleted, as the current state is the intended result.
        if (!file_exists($path)) {
            $this->logger
                ->notice('The file %path was not deleted because it does not exist.', [
                '%path' => $path,
            ]);
            return TRUE;
        }
        // We cannot handle anything other than files and directories.
        // Throw an exception for everything else (sockets, symbolic links, etc).
        $this->logger
            ->error("The file '%path' is not of a recognized type so it was not deleted.", [
            '%path' => $path,
        ]);
        throw new NotRegularFileException("The file '{$path}' is not of a recognized type so it was not deleted.");
    }
    
    /**
     * {@inheritdoc}
     */
    public function deleteRecursive($path, callable $callback = NULL) {
        if ($callback) {
            call_user_func($callback, $path);
        }
        if (is_dir($path)) {
            $dir = dir($path);
            while (($entry = $dir->read()) !== FALSE) {
                if ($entry == '.' || $entry == '..') {
                    continue;
                }
                $entry_path = $path . '/' . $entry;
                $this->deleteRecursive($entry_path, $callback);
            }
            $dir->close();
            return $this->rmdir($path);
        }
        return $this->delete($path);
    }
    
    /**
     * {@inheritdoc}
     */
    public function move($source, $destination, $replace = self::EXISTS_RENAME) {
        $this->prepareDestination($source, $destination, $replace);
        // Ensure compatibility with Windows.
        // @see \Drupal\Core\File\FileSystemInterface::unlink().
        if (!$this->streamWrapperManager
            ->isValidUri($source) && substr(PHP_OS, 0, 3) == 'WIN') {
            chmod($source, 0600);
        }
        // Attempt to resolve the URIs. This is necessary in certain
        // configurations (see above) and can also permit fast moves across local
        // schemes.
        $real_source = $this->realpath($source) ?: $source;
        $real_destination = $this->realpath($destination) ?: $destination;
        // Perform the move operation.
        if (!@rename($real_source, $real_destination)) {
            // Fall back to slow copy and unlink procedure. This is necessary for
            // renames across schemes that are not local, or where rename() has not
            // been implemented. It's not necessary to use FileSystem::unlink() as the
            // Windows issue has already been resolved above.
            if (!@copy($real_source, $real_destination)) {
                $this->logger
                    ->error("The specified file '%source' could not be moved to '%destination'.", [
                    '%source' => $source,
                    '%destination' => $destination,
                ]);
                throw new FileWriteException("The specified file '{$source}' could not be moved to '{$destination}'.");
            }
            if (!@unlink($real_source)) {
                $this->logger
                    ->error("The source file '%source' could not be unlinked after copying to '%destination'.", [
                    '%source' => $source,
                    '%destination' => $destination,
                ]);
                throw new FileException("The source file '{$source}' could not be unlinked after copying to '{$destination}'.");
            }
        }
        // Set the permissions on the new file.
        $this->chmod($destination);
        return $destination;
    }
    
    /**
     * Prepares the destination for a file copy or move operation.
     *
     * - Checks if $source and $destination are valid and readable/writable.
     * - Checks that $source is not equal to $destination; if they are an error
     *   is reported.
     * - If file already exists in $destination either the call will error out,
     *   replace the file or rename the file based on the $replace parameter.
     *
     * @param string $source
     *   A string specifying the filepath or URI of the source file.
     * @param string|null $destination
     *   A URI containing the destination that $source should be moved/copied to.
     *   The URI may be a bare filepath (without a scheme) and in that case the
     *   default scheme (file://) will be used.
     * @param int $replace
     *   Replace behavior when the destination file already exists:
     *   - FileSystemInterface::EXISTS_REPLACE - Replace the existing file.
     *   - FileSystemInterface::EXISTS_RENAME - Append _{incrementing number}
     *     until the filename is unique.
     *   - FileSystemInterface::EXISTS_ERROR - Do nothing and return FALSE.
     *
     * @see \Drupal\Core\File\FileSystemInterface::copy()
     * @see \Drupal\Core\File\FileSystemInterface::move()
     */
    protected function prepareDestination($source, &$destination, $replace) {
        $original_source = $source;
        if (!file_exists($source)) {
            if (($realpath = $this->realpath($original_source)) !== FALSE) {
                $this->logger
                    ->error("File '%original_source' ('%realpath') could not be copied because it does not exist.", [
                    '%original_source' => $original_source,
                    '%realpath' => $realpath,
                ]);
                throw new FileNotExistsException("File '{$original_source}' ('{$realpath}') could not be copied because it does not exist.");
            }
            else {
                $this->logger
                    ->error("File '%original_source' could not be copied because it does not exist.", [
                    '%original_source' => $original_source,
                ]);
                throw new FileNotExistsException("File '{$original_source}' could not be copied because it does not exist.");
            }
        }
        // Prepare the destination directory.
        if ($this->prepareDirectory($destination)) {
            // The destination is already a directory, so append the source basename.
            $destination = $this->streamWrapperManager
                ->normalizeUri($destination . '/' . $this->basename($source));
        }
        else {
            // Perhaps $destination is a dir/file?
            $dirname = $this->dirname($destination);
            if (!$this->prepareDirectory($dirname)) {
                $this->logger
                    ->error("The specified file '%original_source' could not be copied because the destination directory '%destination_directory' is not properly configured. This may be caused by a problem with file or directory permissions.", [
                    '%original_source' => $original_source,
                    '%destination_directory' => $dirname,
                ]);
                throw new DirectoryNotReadyException("The specified file '{$original_source}' could not be copied because the destination directory '{$dirname}' is not properly configured. This may be caused by a problem with file or directory permissions.");
            }
        }
        // Determine whether we can perform this operation based on overwrite rules.
        $destination = $this->getDestinationFilename($destination, $replace);
        if ($destination === FALSE) {
            $this->logger
                ->error("File '%original_source' could not be copied because a file by that name already exists in the destination directory ('%destination').", [
                '%original_source' => $original_source,
                '%destination' => $destination,
            ]);
            throw new FileExistsException("File '{$original_source}' could not be copied because a file by that name already exists in the destination directory ('{$destination}').");
        }
        // Assert that the source and destination filenames are not the same.
        $real_source = $this->realpath($source);
        $real_destination = $this->realpath($destination);
        if ($source == $destination || $real_source !== FALSE && $real_source == $real_destination) {
            $this->logger
                ->error("File '%source' could not be copied because it would overwrite itself.", [
                '%source' => $source,
            ]);
            throw new FileException("File '{$source}' could not be copied because it would overwrite itself.");
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function saveData($data, $destination, $replace = self::EXISTS_RENAME) {
        // Write the data to a temporary file.
        $temp_name = $this->tempnam('temporary://', 'file');
        if (file_put_contents($temp_name, $data) === FALSE) {
            $this->logger
                ->error("Temporary file '%temp_name' could not be created.", [
                '%temp_name' => $temp_name,
            ]);
            throw new FileWriteException("Temporary file '{$temp_name}' could not be created.");
        }
        // Move the file to its final destination.
        return $this->move($temp_name, $destination, $replace);
    }
    
    /**
     * {@inheritdoc}
     */
    public function prepareDirectory(&$directory, $options = self::MODIFY_PERMISSIONS) {
        if (!$this->streamWrapperManager
            ->isValidUri($directory)) {
            // Only trim if we're not dealing with a stream.
            $directory = rtrim($directory, '/\\');
        }
        if (!is_dir($directory)) {
            if (!($options & static::CREATE_DIRECTORY)) {
                return FALSE;
            }
            // Let mkdir() recursively create directories and use the default
            // directory permissions.
            $success = @$this->mkdir($directory, NULL, TRUE);
            if ($success) {
                return TRUE;
            }
            // If the operation failed, check again if the directory was created
            // by another process/server, only report a failure if not. In this case
            // we still need to ensure the directory is writable.
            if (!is_dir($directory)) {
                return FALSE;
            }
        }
        $writable = is_writable($directory);
        if (!$writable && $options & static::MODIFY_PERMISSIONS) {
            return $this->chmod($directory);
        }
        return $writable;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getDestinationFilename($destination, $replace) {
        $basename = $this->basename($destination);
        if (!Unicode::validateUtf8($basename)) {
            throw new FileException(sprintf("Invalid filename '%s'", $basename));
        }
        if (file_exists($destination)) {
            switch ($replace) {
                case FileSystemInterface::EXISTS_REPLACE:
                    // Do nothing here, we want to overwrite the existing file.
                    break;
                case FileSystemInterface::EXISTS_RENAME:
                    $directory = $this->dirname($destination);
                    $destination = $this->createFilename($basename, $directory);
                    break;
                case FileSystemInterface::EXISTS_ERROR:
                    // Error reporting handled by calling function.
                    return FALSE;
            }
        }
        return $destination;
    }
    
    /**
     * {@inheritdoc}
     */
    public function createFilename($basename, $directory) {
        $original = $basename;
        // Strip control characters (ASCII value < 32). Though these are allowed in
        // some filesystems, not many applications handle them well.
        $basename = preg_replace('/[\\x00-\\x1F]/u', '_', $basename);
        if (preg_last_error() !== PREG_NO_ERROR) {
            throw new FileException(sprintf("Invalid filename '%s'", $original));
        }
        if (substr(PHP_OS, 0, 3) == 'WIN') {
            // These characters are not allowed in Windows filenames.
            $basename = str_replace([
                ':',
                '*',
                '?',
                '"',
                '<',
                '>',
                '|',
            ], '_', $basename);
        }
        // A URI or path may already have a trailing slash or look like "public://".
        if (substr($directory, -1) == '/') {
            $separator = '';
        }
        else {
            $separator = '/';
        }
        $destination = $directory . $separator . $basename;
        if (file_exists($destination)) {
            // Destination file already exists, generate an alternative.
            $pos = strrpos($basename, '.');
            if ($pos !== FALSE) {
                $name = substr($basename, 0, $pos);
                $ext = substr($basename, $pos);
            }
            else {
                $name = $basename;
                $ext = '';
            }
            $counter = 0;
            do {
                $destination = $directory . $separator . $name . '_' . $counter++ . $ext;
            } while (file_exists($destination));
        }
        return $destination;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getTempDirectory() {
        // Use settings.
        $temporary_directory = $this->settings
            ->get('file_temp_path');
        if (!empty($temporary_directory)) {
            return $temporary_directory;
        }
        // Fallback to OS default.
        $temporary_directory = FileSystemComponent::getOsTemporaryDirectory();
        if (empty($temporary_directory)) {
            // If no directory has been found default to 'files/tmp'.
            $temporary_directory = PublicStream::basePath() . '/tmp';
            // Windows accepts paths with either slash (/) or backslash (\), but
            // will not accept a path which contains both a slash and a backslash.
            // Since the 'file_public_path' variable may have either format, we
            // sanitize everything to use slash which is supported on all platforms.
            $temporary_directory = str_replace('\\', '/', $temporary_directory);
        }
        return $temporary_directory;
    }
    
    /**
     * {@inheritdoc}
     */
    public function scanDirectory($dir, $mask, array $options = []) {
        // Merge in defaults.
        $options += [
            'callback' => 0,
            'recurse' => TRUE,
            'key' => 'uri',
            'min_depth' => 0,
        ];
        $dir = $this->streamWrapperManager
            ->normalizeUri($dir);
        if (!is_dir($dir)) {
            throw new NotRegularDirectoryException("{$dir} is not a directory.");
        }
        // Allow directories specified in settings.php to be ignored. You can use
        // this to not check for files in common special-purpose directories. For
        // example, node_modules and bower_components. Ignoring irrelevant
        // directories is a performance boost.
        if (!isset($options['nomask'])) {
            $ignore_directories = $this->settings
                ->get('file_scan_ignore_directories', []);
            array_walk($ignore_directories, function (&$value) {
                $value = preg_quote($value, '/');
            });
            $options['nomask'] = '/^' . implode('|', $ignore_directories) . '$/';
        }
        $options['key'] = in_array($options['key'], [
            'uri',
            'filename',
            'name',
        ]) ? $options['key'] : 'uri';
        return $this->doScanDirectory($dir, $mask, $options);
    }
    
    /**
     * Internal function to handle directory scanning with recursion.
     *
     * @param string $dir
     *   The base directory or URI to scan, without trailing slash.
     * @param string $mask
     *   The preg_match() regular expression for files to be included.
     * @param array $options
     *   The options as per ::scanDirectory().
     * @param int $depth
     *   The current depth of recursion.
     *
     * @return array
     *   An associative array as per ::scanDirectory().
     *
     * @throws \Drupal\Core\File\Exception\NotRegularDirectoryException
     *   If the directory does not exist.
     *
     * @see \Drupal\Core\File\FileSystemInterface::scanDirectory()
     */
    protected function doScanDirectory($dir, $mask, array $options = [], $depth = 0) {
        $files = [];
        // Avoid warnings when opendir does not have the permissions to open a
        // directory.
        if ($handle = @opendir($dir)) {
            while (FALSE !== ($filename = readdir($handle))) {
                // Skip this file if it matches the nomask or starts with a dot.
                if ($filename[0] != '.' && !preg_match($options['nomask'], $filename)) {
                    if (substr($dir, -1) == '/') {
                        $uri = "{$dir}{$filename}";
                    }
                    else {
                        $uri = "{$dir}/{$filename}";
                    }
                    if ($options['recurse'] && is_dir($uri)) {
                        // Give priority to files in this folder by merging them in after
                        // any subdirectory files.
                        $files = array_merge($this->doScanDirectory($uri, $mask, $options, $depth + 1), $files);
                    }
                    elseif ($depth >= $options['min_depth'] && preg_match($mask, $filename)) {
                        // Always use this match over anything already set in $files with
                        // the same $options['key'].
                        $file = new \stdClass();
                        $file->uri = $uri;
                        $file->filename = $filename;
                        $file->name = pathinfo($filename, PATHINFO_FILENAME);
                        $key = $options['key'];
                        $files[$file->{$key}] = $file;
                        if ($options['callback']) {
                            $options['callback']($uri);
                        }
                    }
                }
            }
            closedir($handle);
        }
        else {
            $this->logger
                ->error('@dir can not be opened', [
                '@dir' => $dir,
            ]);
        }
        return $files;
    }

}