bbp_admin_repair_user_topic_subscriptions()

function bbp_admin_repair_user_topic_subscriptions() {
	global $wpdb;

	$statement = __( 'Removing trashed discussions from user subscriptions… %s', 'buddyboss' );
	$result    = __( 'Failed!', 'buddyboss' );
	$key       = $wpdb->prefix . '_bbp_subscriptions';
	$users     = $wpdb->get_results( "SELECT `user_id`, `meta_value` AS `subscriptions` FROM `{$wpdb->usermeta}` WHERE `meta_key` = '{$key}';" );

	if ( is_wp_error( $users ) )
		return array( 1, sprintf( $statement, $result ) );

	$topics = $wpdb->get_col( "SELECT `ID` FROM `{$wpdb->posts}` WHERE `post_type` = '" . bbp_get_topic_post_type() . "' AND `post_status` = '" . bbp_get_public_status_id() . "';" );
	if ( is_wp_error( $topics ) )
		return array( 2, sprintf( $statement, $result ) );

	$values = array();
	foreach ( $users as $user ) {
		if ( empty( $user->subscriptions ) || !is_string( $user->subscriptions ) )
			continue;

		$subscriptions = array_intersect( $topics, explode( ',', $user->subscriptions ) );
		if ( empty( $subscriptions ) || !is_array( $subscriptions ) )
			continue;

		$subscriptions_joined = implode( ',', $subscriptions );
		$values[]             = "('{$user->user_id}', '{$key}', '{$subscriptions_joined}')";

		// Cleanup
		unset( $subscriptions, $subscriptions_joined );
	}

	if ( !count( $values ) ) {
		$result = __( 'Nothing to remove!', 'buddyboss' );
		return array( 0, sprintf( $statement, $result ) );
	}

	$sql_delete = "DELETE FROM `{$wpdb->usermeta}` WHERE `meta_key` = '{$key}';";
	if ( is_wp_error( $wpdb->query( $sql_delete ) ) )
		return array( 4, sprintf( $statement, $result ) );

	foreach ( array_chunk( $values, 10000 ) as $chunk ) {
		$chunk = "\n" . implode( ",\n", $chunk );
		$sql_insert = "INSERT INTO `{$wpdb->usermeta}` (`user_id`, `meta_key`, `meta_value`) VALUES $chunk;";
		if ( is_wp_error( $wpdb->query( $sql_insert ) ) ) {
			return array( 5, sprintf( $statement, $result ) );
		}
	}

	return array( 0, sprintf( $statement, __( 'Complete!', 'buddyboss' ) ) );
}