Wordpress - create query for multiple inserts

/**
 * Updatess the invitees database table
 */
function do_add_invitees_in_database(){

    /** Make sure there are invitees to add */
    if(empty($this->invitees['new'])) :
        return $_POST['add_successfull'] = true;
    endif;

    global $wpdb;

    /** Set the names of the fields to use */
    $fields = array(
        'invitee_created_by',
        'invitee_created_date',
        'invitee_last_edited_by',
        'invitee_last_edited_date',
        'event_id',
        'email',
        'first_name',
        'surname',
        'custom',
        'invited'
    );

    /** Get the creator ID */
    $creator_id = get_current_user_id();

    /** Make the chart creation date */
    $date_added = date('Y-m-d H:i:s', time());

    /** Insert the new invitees in to the database */
    $all_data = array();
    $values = array();
    foreach($this->invitees['new'] as $invitee) :

        $row = array(
            $creator_id,
            $date_added,
            '0',
            '0000-00-00 00:00:00',
            $_POST['event_id'],
            $invitee['email'],
            $invitee['first_name'],
            $invitee['surname'],
            $invitee['custom'],
            0
        );

        /** Make the data array */
        $data = array_combine($fields, $row);

        /** Update the array containing all data passed to the query (for debugging purposes) */
        $all_data[] = $data;

        /** Grab the VALUES() portion of the query (for this invitee) */
        $values[] = $this->_insert_replace_invitee_values($data);

    endforeach;

    /** Insert the new invitees in to the database */
    $result = $this->_insert_replace_invitee($wpdb->event_invitees, $values, $fields);

    /** Debug the query run by $wpdb->query() */
    $this->debug($all_data);

    /** If there were no errors, mark the invitaion additions as successfull */
    return $_POST['add_successfull'] = (!$this->error_found) ? true : false;

}

/**
 * Runs a query to either insert new rows into the database, or to replace existing rows (if ID is specified)
 *
 * @param required string $table    The name of the table that is being queried
 * @param required array $values    The values to insert or replace in the table
 * @param required array $fields    The fields that are to be populated by the $values
 * @param string $type              The type of job that is taking place ('INSERT' or 'REPLACE')
 * @return integer                  The number of rows affected by the query
 */
function _insert_replace_invitee($table, $values, $fields, $type = 'INSERT'){

    /** Make sure that we should be using this helper */
    if(!in_array(strtoupper($type), array('INSERT', 'REPLACE'))) :
        return false;
    endif;

    global $wpdb;

    $query = "{$type} INTO `$table` (`" . implode( '`,`', $fields ) . "`) VALUES " . join(','."\n", $values);

    $query = $wpdb->prepare('%1$s INTO %2$s'."\n\t".'(`%3$s`)'."\n".'VALUES'."\n\t", $type, $table, implode('`,`', $fields)).join(','."\n\t", $values);
    return $wpdb->query($query);

}

/**
 * Creates a string of values that should be inserted in to database for an invitee, or to replace existing rows (if ID is specified)
 *
 * @param required array $data      The data to use for the insert ('$key => $value' muse be defined)
 * @param required array $format    The formats to use for specific data
 * @param string $type              The type of job that is taking place ('INSERT' or 'REPLACE')
 * @return string                   The values for this invitee
 */
function _insert_replace_invitee_values($data, $format = null, $type = 'INSERT'){

    /** Make sure that we should be using this helper */
    if(!in_array(strtoupper($type), array('INSERT', 'REPLACE'))) :
        return false;
    endif;

    global $wpdb;

    /** Set up the formtas array */
    $formats = $format = (array)$format;    // Setup a $formats array (and ensure $format is also an array)
    $fields = array_keys($data);            // Grab the fields that are to be used from $data

    /** Work out which fields are to be formatted (and add default fromating to those not defined) */
    $formatted_fields = array();
    foreach($fields as $field) :

        if(!empty($format)) : // If $format is defined, check
            $filed_format = ($filed_format = array_shift($formats)) ? $filed_format : $format[0];
        else : // Set the format as defult to string
            $filed_format = '%s';
        endif;

        $formatted_fields[] = $filed_format;

    endforeach;

    return $wpdb->prepare(sprintf('(%1$s)', implode(",", $formatted_fields)), $data);

}