Cut HTML strings without breaking words and markup

strHelper.php

<?php
/**
 * Cut HTML string before a max number of X chars without cutting a words or breaking the HTML markup.
 *
 * Try to cut after a </p> tag after 2/3 of the max length (for avoid to display only the first paraph) and if
 * this fail Cut after the position of the last char of the last word just before the max length and add '...'
 * at the end of the string
 *
 * usage : StrHelper::splitHtmlString($html, 1000); // For get a string that will never be bigger than 1000 chars
 *
 */
class StrHelper
{

    /**
     * Get position of the last char of the last word just before the Word limit
     *
     * @param string $string
     * @param int    $maxSize
     *
     * @return int
     */
    public static function getPosLastWord($string, $maxSize)
    {
        if (mb_strlen($string) <= $maxSize)
        {
            return mb_strlen($string);
        }

        $words = explode(' ', $string);
        $length = 0;

        foreach ($words as $word)
        {
            $wordLength = mb_strlen($word) + 1;

            if (($length + $wordLength) >= $maxSize)
            {
                return $length;
            }

            $length += $wordLength;
        }

        return $length;
    }

    /**
     * Create needed HTML tags for close all opened
     *
     * @param string $html
     *
     * @return string
     */
    public static function repairString($html)
    {
        $tidy = new Tidy();

        return $tidy->repairString($html, [
            'output-xml' => true,
            'input-xml'  => true
        ], 'utf8');
    }

    /**
     * Cut HTML string before a max number of $maxSize chars without cutting a words or breaking the HTML markup.
     *
     * Try to cut after a </p> tag after 2/3 of the max length (for avoid to display only the first paraph) and if
     * this fail Cut after the position of the last char of the last word just before the max length and add '...'
     * at the end of the string
     *
     * @param string $html
     * @param int    $maxSize
     *
     * @return string
     */
    public static function splitHtmlString($html, $maxSize)
    {
        if (mb_strlen($html) <= $maxSize)
        {
            return $html;
        }

        $posTagCloseParaph = mb_strpos($html, '</p>', ($maxSize / 3) * 2);

        if ($posTagCloseParaph !== false && $posTagCloseParaph <= $maxSize)
        {
            return self::repairString(mb_substr($html, 0, $posTagCloseParaph + 4));
        }

        $lastWord = self::getPosLastWord($html, $maxSize);

        if ($lastWord !== false)
        {
            return self::repairString(mb_substr($html, 0, $lastWord) . '...');
        }

        return $html;
    }
}