Submission_Export_Handler::handle_export_action()

	public function handle_export_action() {
		if ( ! isset( $_REQUEST['_wpnonce'] ) ) {
			wp_die( __( 'Missing nonce.', 'torro-forms' ) );
		}

		if ( ! wp_verify_nonce( $_REQUEST['_wpnonce'], $this->nonce_action ) ) {
			wp_die( __( 'Invalid nonce.', 'torro-forms' ) );
		}

		if ( ! isset( $_REQUEST['form_id'] ) ) {
			wp_die( __( 'Missing form ID.', 'torro-forms' ) );
		}

		$capabilities = $this->submission_manager->capabilities();
		if ( ! $capabilities || ! $capabilities->user_can_read() ) {
			wp_die( __( 'Insufficient permissions.', 'torro-forms' ) );
		}

		$form = $this->submission_manager->get_parent_manager( 'forms' )->get( (int) $_REQUEST['form_id'] );
		if ( ! $form ) {
			wp_die( __( 'Invalid form ID.', 'torro-forms' ) );
		}

		if ( ! isset( $_REQUEST['mode'] ) ) {
			wp_die( __( 'Missing submission export handler.', 'torro-forms' ) );
		}

		$args = array();
		if ( isset( $_REQUEST['orderby'] ) && isset( $_REQUEST['order'] ) ) {
			$orderby = in_array( $_REQUEST['orderby'], array( 'id', 'timestamp' ), true ) ? $_REQUEST['orderby'] : 'id';
			$order   = in_array( $_REQUEST['order'], array( 'ASC', 'DESC' ), true ) ? $_REQUEST['order'] : 'ASC';

			$args['orderby'] = array( $orderby => $order );
		} else {
			$args['orderby'] = array( 'id' => 'ASC' );
		}

		$this->export_submissions( wp_unslash( $_REQUEST['mode'] ), $form, $args );
	}