<?php

namespace Sabre\VObject;

/**
 * Useful utilities for working with various strings.
 *
 * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
 * @author Evert Pot (http://evertpot.com/)
 * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
 */
class StringUtil {

    /**
     * Returns true or false depending on if a string is valid UTF-8
     *
     * @param string $str
     * @return bool
     */
    static function isUTF8($str) {

        // First check.. mb_check_encoding
        if (!mb_check_encoding($str, 'UTF-8')) {
            return false;
        }

        // Control characters
        if (preg_match('%(?:[\x00-\x08\x0B-\x0C\x0E\x0F])%', $str)) {
            return false;
        }

        return true;

    }

    /**
     * This method tries its best to convert the input string to UTF-8.
     *
     * Currently only ISO-5991-1 input and UTF-8 input is supported, but this
     * may be expanded upon if we receive other examples.
     *
     * @param string $str
     * @return string
     */
    static function convertToUTF8($str) {

        $encoding = mb_detect_encoding($str , array('UTF-8','ISO-8859-1'), true);

        if ($encoding === 'ISO-8859-1') {
            $newStr = utf8_encode($str);
        } else {
            $newStr = $str;
        }

        // Removing any control characters
        return (preg_replace('%(?:[\x00-\x08\x0B-\x0C\x0E\x0F])%', '', $newStr));

    }

}