a specific component from a parsed URL array.
 *
 * @internal
 *
 * @since 4.7.0
 * @access private
 *
 * @link https://www.php.net/manual/en/function.parse-url.php
 *
 * @param array|false $url_parts The parsed URL. Can be false if the URL failed to parse.
 * @param int         $component The specific component to retrieve. Use one of the PHP
 *                               predefined constants to specify which one.
 *                               Defaults to -1 (= return all parts as an array).
 * @return mixed False on parse failure; Array of URL components on success;
 *               When a specific component has been requested: null if the component
 *               doesn't exist in the given URL; a string or - in the case of
 *               PHP_URL_PORT - integer when it does. See parse_url()'s return values.
 */
function _get_component_from_parsed_url_array( $url_parts, $component = -1 ) {
	if ( -1 === $component ) {
		return $url_parts;
	}

	$key = _wp_translate_php_url_constant_to_key( $component );
	if ( false !== $key && is_array( $url_parts ) && isset( $url_parts[ $key ] ) ) {
		return $url_parts[ $key ];
	} else {
		return null;
	}
}

/**
 * Translate a PHP_URL_* constant to the named array keys PHP uses.
 *
 * @internal
 *
 * @since 4.7.0
 * @access private
 *
 * @link https://www.php.net/manual/en/url.constants.php
 *
 * @param int $constant PHP_URL_* constant.
 * @return string|false The named key or false.
 */
function _wp_translate_php_url_constant_to_key( $constant ) {
	$translation = array(
		PHP_URL_SCHEME   => 'scheme',
		PHP_URL_HOST     => 'host',
		PHP_URL_PORT     => 'port',
		PHP_URL_USER     => 'user',
		PHP_URL_PASS     => 'pass',
		PHP_URL_PATH     => 'path',
		PHP_URL_QUERY    => 'query',
		PHP_URL_FRAGMENT => 'fragment',
	);

	if ( isset( $translation[ $constant ] ) ) {
		return $translation[ $constant ];
	} else {
		return false;
	}
}