^^&&^^

Edit File: ReportExporter.php

<?php
/**
 * Handles reports CSV export.
 */

namespace Automattic\Kkart\Admin;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

use \Automattic\Kkart\Admin\Schedulers\SchedulerTraits;

/**
 * ReportExporter Class.
 */
class ReportExporter {
	/**
	 * Slug to identify the scheduler.
	 *
	 * @var string
	 */
	public static $name = 'report_exporter';

/**
	 * Scheduler traits.
	 */
	use SchedulerTraits {
		init as scheduler_init;
	}

/**
	 * Export status option name.
	 */
	const EXPORT_STATUS_OPTION = 'kkart_admin_report_export_status';

/**
	 * Export file download action.
	 */
	const DOWNLOAD_EXPORT_ACTION = 'kkart_admin_download_report_csv';

/**
	 * Get all available scheduling actions.
	 * Used to determine action hook names and clear events.
	 *
	 * @return array
	 */
	public static function get_scheduler_actions() {
		return array(
			'export_report'              => 'kkart_admin_report_export',
			'email_report_download_link' => 'kkart_admin_email_report_download_link',
		);
	}

/**
	 * Add action dependencies.
	 *
	 * @return array
	 */
	public static function get_dependencies() {
		return array(
			'email_report_download_link' => self::get_action( 'export_report' ),
		);
	}

/**
	 * Hook in action methods.
	 */
	public static function init() {
		// Initialize scheduled action handlers.
		self::scheduler_init();

// Report download handler.
		add_action( 'admin_init', array( __CLASS__, 'download_export_file' ) );
	}

/**
	 * Queue up actions for a full report export.
	 *
	 * @param string $export_id Unique ID for report (timestamp expected).
	 * @param string $report_type Report type. E.g. 'customers'.
	 * @param array  $report_args Report parameters, passed to data query.
	 * @param bool   $send_email Optional. Send an email when the export is complete.
	 * @return int Number of items to export.
	 */
	public static function queue_report_export( $export_id, $report_type, $report_args = array(), $send_email = false ) {
		$exporter = new ReportCSVExporter( $report_type, $report_args );
		$exporter->prepare_data_to_export();

$total_rows  = $exporter->get_total_rows();
		$batch_size  = $exporter->get_limit();
		$num_batches = (int) ceil( $total_rows / $batch_size );

// Create batches, like initial import.
		$report_batch_args = array( $export_id, $report_type, $report_args );

if ( 0 < $num_batches ) {
			self::queue_batches( 1, $num_batches, 'export_report', $report_batch_args );

if ( $send_email ) {
				$email_action_args = array( get_current_user_id(), $export_id, $report_type );
				self::schedule_action( 'email_report_download_link', $email_action_args );
			}
		}

return $total_rows;
	}

/**
	 * Process a report export action.
	 *
	 * @param int    $page_number Page number for this action.
	 * @param string $export_id Unique ID for report (timestamp expected).
	 * @param string $report_type Report type. E.g. 'customers'.
	 * @param array  $report_args Report parameters, passed to data query.
	 * @return void
	 */
	public static function export_report( $page_number, $export_id, $report_type, $report_args ) {
		$report_args['page'] = $page_number;

$exporter = new ReportCSVExporter( $report_type, $report_args );
		$exporter->set_filename( "kkart-{$report_type}-report-export-{$export_id}" );
		$exporter->generate_file();

self::update_export_percentage_complete( $report_type, $export_id, $exporter->get_percent_complete() );
	}

/**
	 * Generate a key to reference an export status.
	 *
	 * @param string $report_type Report type. E.g. 'customers'.
	 * @param string $export_id Unique ID for report (timestamp expected).
	 * @return string Status key.
	 */
	protected static function get_status_key( $report_type, $export_id ) {
		return $report_type . ':' . $export_id;
	}

/**
	 * Update the completion percentage of a report export.
	 *
	 * @param string $report_type Report type. E.g. 'customers'.
	 * @param string $export_id Unique ID for report (timestamp expected).
	 * @param int    $percentage Completion percentage.
	 * @return void
	 */
	public static function update_export_percentage_complete( $report_type, $export_id, $percentage ) {
		$exports_status = get_option( self::EXPORT_STATUS_OPTION, array() );
		$status_key     = self::get_status_key( $report_type, $export_id );

$exports_status[ $status_key ] = $percentage;

update_option( self::EXPORT_STATUS_OPTION, $exports_status );
	}

/**
	 * Get the completion percentage of a report export.
	 *
	 * @param string $report_type Report type. E.g. 'customers'.
	 * @param string $export_id Unique ID for report (timestamp expected).
	 * @return bool|int Completion percentage, or false if export not found.
	 */
	public static function get_export_percentage_complete( $report_type, $export_id ) {
		$exports_status = get_option( self::EXPORT_STATUS_OPTION, array() );
		$status_key     = self::get_status_key( $report_type, $export_id );

if ( isset( $exports_status[ $status_key ] ) ) {
			return $exports_status[ $status_key ];
		}

return false;
	}

/**
	 * Serve the export file.
	 */
	public static function download_export_file() {
		// @todo - add nonce? (nonces are good for 24 hours)
		if (
			isset( $_GET['action'] ) &&
			! empty( $_GET['filename'] ) &&
			self::DOWNLOAD_EXPORT_ACTION === wp_unslash( $_GET['action'] ) && // WPCS: input var ok, sanitization ok.
			current_user_can( 'view_kkart_reports' )
		) {
			$exporter = new ReportCSVExporter();
			$exporter->set_filename( wp_unslash( $_GET['filename'] ) ); // WPCS: input var ok, sanitization ok.
			$exporter->export();
		}
	}

/**
	 * Process a report export email action.
	 *
	 * @param int    $user_id User ID that requested the email.
	 * @param string $export_id Unique ID for report (timestamp expected).
	 * @param string $report_type Report type. E.g. 'customers'.
	 * @return void
	 */
	public static function email_report_download_link( $user_id, $export_id, $report_type ) {
		$percent_complete = self::get_export_percentage_complete( $report_type, $export_id );

if ( 100 === $percent_complete ) {
			$query_args   = array(
				'action'   => self::DOWNLOAD_EXPORT_ACTION,
				'filename' => "kkart-{$report_type}-report-export-{$export_id}",
			);
			$download_url = add_query_arg( $query_args, admin_url() );

\KKART_Emails::instance();
			$email = new ReportCSVEmail();
			$email->trigger( $user_id, $report_type, $download_url );
		}
	}
}