function wc_create_new_customer_username( $email, $new_user_args = array(), $suffix = '' ) {
	$username_parts = array();

	if ( isset( $new_user_args['first_name'] ) ) {
		$username_parts[] = sanitize_user( $new_user_args['first_name'], true );
	}

	if ( isset( $new_user_args['last_name'] ) ) {
		$username_parts[] = sanitize_user( $new_user_args['last_name'], true );
	}

	// Remove empty parts.
	$username_parts = array_filter( $username_parts );

	// If there are no parts, e.g. name had unicode chars, or was not provided, fallback to email.
	if ( empty( $username_parts ) ) {
		$email_parts    = explode( '@', $email );
		$email_username = $email_parts[0];

		// Exclude common prefixes.
		if ( in_array(
			$email_username,
			array(
				'sales',
				'hello',
				'mail',
				'contact',
				'info',
			),
			true
		) ) {
			// Get the domain part.
			$email_username = $email_parts[1];
		}

		$username_parts[] = sanitize_user( $email_username, true );
	}

	$username = wc_strtolower( implode( '.', $username_parts ) );

	if ( $suffix ) {
		$username .= $suffix;
	}

	/**
	 * WordPress 4.4 - filters the list of blacklisted usernames.
	 *
	 * @since 3.7.0
	 * @param array $usernames Array of blacklisted usernames.
	 */
	$illegal_logins = (array) apply_filters( 'illegal_user_logins', array() );

	// Stop illegal logins and generate a new random username.
	if ( in_array( strtolower( $username ), array_map( 'strtolower', $illegal_logins ), true ) ) {
		$new_args = array();

		/**
		 * Filter generated customer username.
		 *
		 * @since 3.7.0
		 * @param string $username      Generated username.
		 * @param string $email         New customer email address.
		 * @param array  $new_user_args Array of new user args, maybe including first and last names.
		 * @param string $suffix        Append string to username to make it unique.
		 */
		$new_args['first_name'] = apply_filters(
			'woocommerce_generated_customer_username',
			'woo_user_' . zeroise( wp_rand( 0, 9999 ), 4 ),
			$email,
			$new_user_args,
			$suffix
		);

		return wc_create_new_customer_username( $email, $new_args, $suffix );
	}

	if ( username_exists( $username ) ) {
		// Generate something unique to append to the username in case of a conflict with another user.
		$suffix = '-' . zeroise( wp_rand( 0, 9999 ), 4 );
		return wc_create_new_customer_username( $email, $new_user_args, $suffix );
	}

	/**
	 * Filter new customer username.
	 *
	 * @since 3.7.0
	 * @param string $username      Customer username.
	 * @param string $email         New customer email address.
	 * @param array  $new_user_args Array of new user args, maybe including first and last names.
	 * @param string $suffix        Append string to username to make it unique.
	 */
	return apply_filters( 'woocommerce_new_customer_username', $username, $email, $new_user_args, $suffix );
}