('|', $groups);
        }

        // loop through groups and find interest ID
        $migrated = 0;
        foreach ($groups as $key => $group_name_or_id) {
            // do we know the new interest ID?
            if (empty($map[ $grouping_id ]['groups'][ $group_name_or_id ])) {
                continue;
            }

            $interest_id = $map[ $grouping_id ]['groups'][ $group_name_or_id ];

            // add to interests data
            if (! in_array($interest_id, $data['INTERESTS'], false)) {
                ++$migrated;
                $data['INTERESTS'][] = $interest_id;
            }
        }

        // remove old grouping ID if we migrated all groups.
        if ($migrated === count($groups)) {
            unset($data['GROUPINGS'][ $grouping_key ]);
        }
    }

    // if everything went well, this is now empty & moved to new INTERESTS key.
    if (empty($data['GROUPINGS'])) {
        unset($data['GROUPINGS']);
    }

    // is this empty? just unset it then.
    if (empty($data['INTERESTS'])) {
        unset($data['INTERESTS']);
    }

    return $data;
}

/**
 * Guesses merge vars based on given data & current request.
 *
 * @since 3.0
 * @access public
 *
 * @param array $data
 *
 * @return array
 */
function mc4wp_add_name_data($data)
{

    // Guess first and last name
    if (! empty($data['NAME']) && empty($data['FNAME']) && empty($data['LNAME'])) {
        $data['NAME'] = trim($data['NAME']);
        $strpos       = strpos($data['NAME'], ' ');

        if ($strpos !== false) {
            $data['FNAME'] = trim(substr($data['NAME'], 0, $strpos));
            $data['LNAME'] = trim(substr($data['NAME'], $strpos));
        } else {
            $data['FNAME'] = $data['NAME'];
        }
    }

    // Set name value
    if (empty($data['NAME']) && ! empty($data['FNAME']) && ! empty($data['LNAME'])) {
        $data['NAME'] = sprintf('%s %s', $data['FNAME'], $data['LNAME']);
    }

    return $data;
}

/**
 * Gets the "email type" for new subscribers.
 *
 * Possible return values are either "html" or "text"
 *
 * @access public
 * @since 3.0
 *
 * @return string
 */
function mc4wp_get_email_type()
{
    $email_type = 'html';

    /**
     * Filters the email type preference for this new subscriber.
     *
     * @param string $email_type
     */
    $email_type = (string) apply_filters('mc4wp_email_type', $email_type);

    return $email_type;
}

/**
 *
 * @ignore
 * @return bool
 */
function _mc4wp_use_sslverify()
{

    // Disable for all transports other than CURL
    if (! function_exists('curl_version')) {
        return false;
    }

    $curl = curl_version();

    // Disable if OpenSSL is not installed
    if (empty($curl['ssl_version'])) {
        return false;
    }

    // Disable if on WP 4.4, see https://core.trac.wordpress.org/ticket/34935
    if ($GLOBALS['wp_version'] === '4.4') {
        return false;
    }

    return true;
}

/**
 * This will replace the first half of a string with "*" characters.
 *
 * @param string $string
 * @return string
 */
function mc4wp_obfuscate_string($string)
{
    if (false === is_string($string) || $string === '') {
        return $string;
    }

    $length = strlen($string);
    if ($length <= 2) {
        return $string;
    }
    $keep = (int) floor($length / 3);
    $keep = (int) min($keep, 4);
    return substr($string, 0, $keep) . str_repeat('*', $length - ($keep * 2)) . substr($string, -$keep);
}

/**
 * @param array $m
 * @return string
 * @internal
 * @ignore
 */
function _mc4wp_obfuscate_email_addresses_callback($m)
{
    return mc4wp_obfuscate_string($m[1]) . '@' . mc4wp_obfuscate_string($m[2]);
}

/**
 * Obfuscates email addresses in a string.
 *
 * @param string $string String possibly containing email address
 * @return string
 */
function mc4wp_obfuscate_email_addresses($string)
{
    return preg_replace_callback('/([A-Z0-9._%+-]{1,64})@([A-Z0-9.-]{1,253}\.[A-Z]{2,63})/i', '_mc4wp_obfuscate_email_addresses_callback', $string);
}

/**
 * Truncates a debug log message to a reasonable maximum size.
 *
 * @param string $message
 * @return string
 */
function mc4wp_truncate_log_message($message)
{
    /**
     * Filters the maximum length of a debug log message in bytes.
     *
     * Return 0 or a negative value to disable truncation.
     *
     * @param int $max_length Maximum message length in bytes.
     */
    $max_length = (int) apply_filters('mc4wp_debug_log_message_max_length', 8192);

    if ($max_length <= 0) {
        return $message;
    }

    $length = strlen($message);
    if ($length <= $max_length) {
        return $message;
    }

    $suffix = sprintf('... [truncated, original length: %d bytes]', $length);

    if (strlen($suffix) >= $max_length) {
        return substr($message, 0, $max_length);
    }

    return substr($message, 0, $max_length - strlen($suffix)) . $suffix;
}

/**
 * Refreshes Mailchimp lists. This can take a while if the connected Mailchimp account has many lists.
 *
 * @return void
 */
function mc4wp_refresh_mailchimp_lists()
{
    $mailchimp = new MC4WP_MailChimp();
    $mailchimp->refresh_lists();
}

/**
* Get element from array, allows for dot notation eg: "foo.bar"
*
* @param array $array
* @param string|null $key
* @param mixed $default
* @return mixed
*/
function mc4wp_array_get($array, $key, $default = null)
{
    if ($key === null) {
        return $array;
    }

    if (isset($array[ $key ])) {
        return $array[ $key ];
    }

    foreach (explode('.', $key) as $segment) {
        if (! is_array($array) || ! array_key_exists($segment, $array)) {
            return $default;
        }

        $array = $array[ $segment ];
    }

    return $array;
}

/**
 * Filters string and strips out all HTML tags and attributes, except what's in our whitelist.
 *
 * @param string $string The string to apply KSES whitelist on
 * @return string
 * @since 4.8.8
 */
function mc4wp_kses($string)
{
    $always_allowed_attr = array_fill_keys(
        [
            'aria-describedby',
            'aria-details',
            'aria-label',
            'aria-labelledby',
            'aria-hidden',
            'class',
            'id',
            'style',
            'title',
            'role',
            'data-*',
            'tabindex',
        ],
        true
    );
    $input_allowed_attr  = array_merge(
        $always_allowed_attr,
        array_fill_keys(
            [
                'type',
                'required',
                'placeholder',
                'value',
                'name',
                'step',
                'min',
                'max',
                'checked',
                'width',
                'autocomplete',
                'autofocus',
                'minlength',
                'maxlength',
                'size',
                'pattern',
                'disabled',
                'readonly',
            ],
            true
        )
    );

    $allowed = [
        'p'        => $always_allowed_attr,
        'label'    => array_merge($always_allowed_attr, [ 'for' => true ]),
        'input'    => $input_allowed_attr,
        'button'   => $input_allowed_attr,
        'fieldset' => $always_allowed_attr,
        'legend'   => $always_allowed_attr,
        'ul'       => $always_allowed_attr,
        'ol'       => $always_allowed_attr,
        'li'       => $always_allowed_attr,
        'select'   => array_merge($input_allowed_attr, [ 'multiple' => true ]),
        'option'   => array_merge($input_allowed_attr, [ 'selected' => true ]),
        'optgroup' => [
            'disabled' => true,
            'label' => true,
        ],
        'textarea' => array_merge(
            $input_allowed_attr,
            [
                'rows' => true,
                'cols' => true,
            ]
        ),
        'div'      => $always_allowed_attr,
        'strong'   => $always_allowed_attr,
        'b'         => $always_allowed_attr,
        'i'         => $always_allowed_attr,
        'br'        => [],
        'em'       => $always_allowed_attr,
        'span'     => $always_allowed_attr,
        'a'        => array_merge($always_allowed_attr, [ 'href' => true ]),
        'img'      => array_merge(
            $always_allowed_attr,
            [
                'src' => true,
                'alt' => true,
                'width' => true,
                'height' => true,
                'srcset' => true,
                'sizes' => true,
                'referrerpolicy' => true,
            ]
        ),
        'u' => $always_allowed_attr,
    ];

    return wp_kses($string, $allowed);
}

/**
 * Helper function for safely deprecating a changed filter hook.
 *
 * @param string $old_hook
 * @param string $new_hook
 *
 * @return void
 */
function mc4wp_apply_deprecated_filters($old_hook, $new_hook)
{
    add_filter($new_hook, function ($value, $a = null, $b = null, $c = null) use ($new_hook, $old_hook) {
        return apply_filters_deprecated($old_hook, [ $value, $a, $b, $c ], '4.9.0', $new_hook);
    }, 10, 3);
}