public function import() {
		// Displaying this page triggers Ajax action to run the import with a valid nonce,
		// therefore this page needs to be nonce protected as well.
		check_admin_referer( 'woocommerce-csv-importer' );

		if ( ! self::is_file_valid_csv( $this->file ) ) {
			$this->add_error( __( 'Invalid file type. The importer supports CSV and TXT file formats.', 'woocommerce' ) );
			$this->output_errors();
			return;
		}

		if ( ! is_file( $this->file ) ) {
			$this->add_error( __( 'The file does not exist, please try again.', 'woocommerce' ) );
			$this->output_errors();
			return;
		}

		if ( ! empty( $_POST['map_from'] ) && ! empty( $_POST['map_to'] ) ) {
			$mapping_from = wc_clean( wp_unslash( $_POST['map_from'] ) );
			$mapping_to   = wc_clean( wp_unslash( $_POST['map_to'] ) );

			// Save mapping preferences for future imports.
			update_user_option( get_current_user_id(), 'woocommerce_product_import_mapping', $mapping_to );
		} else {
			wp_redirect( esc_url_raw( $this->get_next_step_link( 'upload' ) ) );
			exit;
		}

		wp_localize_script(
			'wc-product-import',
			'wc_product_import_params',
			array(
				'import_nonce'    => wp_create_nonce( 'wc-product-import' ),
				'mapping'         => array(
					'from' => $mapping_from,
					'to'   => $mapping_to,
				),
				'file'            => $this->file,
				'update_existing' => $this->update_existing,
				'delimiter'       => $this->delimiter,
			)
		);
		wp_enqueue_script( 'wc-product-import' );

		include_once dirname( __FILE__ ) . '/views/html-csv-import-progress.php';
	}