* @since 3.37.15 "Sanitize" submitted filename.
	 *
	 * @param array  $args     Arguments to pass get_results().
	 * @param string $filename Filename of the existing file, if omitted creates a new file, if passed, will continue adding to existing file.
	 * @param string $type     Export file type for forward compatibility. Currently only accepts 'csv'.
	 * @return WP_Error|array
	 */
	public function generate_export_file( $args = array(), $filename = null, $type = 'csv' ) {

		// We only support CSVs and don't allow fakers.
		if ( ! empty( $filename ) && pathinfo( $filename, PATHINFO_EXTENSION ) !== $type ) {
			return false;
		}

		// Always force page 1 regardless of what is requested. Pagination is handled below.
		$args['page'] = 1;

		/**
		 * Customize the number of records per page when generating an export file.
		 *
		 * @since 3.28.0
		 *
		 * @param int $per_page Number of records per page.
		 */
		$args['per_page'] = apply_filters( 'llms_table_generate_export_file_per_page_boost', 250 );

		$filename    = $filename ? $filename : $this->get_export_file_name() . '.' . $type;
		$file_path   = LLMS_TMP_DIR . $filename;
		$option_name = 'llms_gen_export_' . basename( $filename, '.' . $type );
		$args        = get_option( $option_name, $args );

		$handle = @fopen( $file_path, 'a+' ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- Yea but we handle the error alright I think.
		if ( ! $handle ) {
			return new WP_Error( 'file_error', __( 'Unable to generate export file, could not open file for writing.', 'lifterlms' ) );
		}

		/**
		 * Customize the delimiter used when generating CSV export files.
		 *
		 * @since 3.28.0
		 *
		 * @param int                                  $delim Delimiter.
		 * @param LLMS_Abstract_Exportable_Admin_Table $table Instance of the table.
		 * @param array                                $args  Array of arguments.
		 */
		$delim = apply_filters( 'llms_table_generate_export_file_delimiter', ',', $this, $args );

		foreach ( $this->get_export( $args ) as $row ) {
			fputcsv( $handle, $row, $delim );
		}

		if ( ! $this->is_last_page() ) {

			$args['page'] = $this->get_current_page() + 1;
			update_option( $option_name, $args );
			$progress = round( ( $this->get_current_page() / $this->get_max_pages() ) * 100, 2 );

		} else {

			delete_option( $option_name );
			$progress = 100;

		}