Graby\Graby::convert2Utf8 PHP Method

    private function convert2Utf8($html, $header = null)
    {
        if (empty($html) || empty($header)) {
            return $html;
        }
        $encoding = null;
        // remove strange things
        $html = str_replace('</[>', '', $html);
        if (is_array($header)) {
            $header = implode("\n", $header);
        }
        if (empty($header) || !preg_match_all('/([^;]+)(?:;\\s*charset=["\']?([^;"\'\\n]*))?/im', $header, $match, PREG_SET_ORDER)) {
            // error parsing the response
            $this->logger->log('debug', 'Could not find Content-Type header in HTTP response', ['header' => $header]);
        } else {
            // get last matched element (in case of redirects)
            $match = end($match);
            if (isset($match[2])) {
                $encoding = trim($match[2], "\"' \r\n\v\t");
            }
        }
        // TODO: check to see if encoding is supported (can we convert it?)
        // If it's not, result will be empty string.
        // For now we'll check for invalid encoding types returned by some sites, e.g. 'none'
        // Problem URL: http://facta.co.jp/blog/archives/20111026001026.html
        if (empty($encoding) || $encoding == 'none') {
            // search for encoding in HTML - only look at the first 50000 characters
            // Why 50000? See, for example, http://www.lemonde.fr/festival-de-cannes/article/2012/05/23/deux-cretes-en-goguette-sur-la-croisette_1705732_766360.html
            // TODO: improve this so it looks at smaller chunks first
            $html_head = substr($html, 0, 50000);
            if (preg_match('/^<\\?xml\\s+version=(?:"[^"]*"|\'[^\']*\')\\s+encoding=("[^"]*"|\'[^\']*\')/s', $html_head, $match)) {
                $encoding = trim($match[1], '"\'');
            } elseif (preg_match('/<meta\\s+http-equiv=["\']?Content-Type["\']? content=["\'][^;]+;\\s*charset=["\']?([^;"\'>]+)/i', $html_head, $match)) {
                $encoding = trim($match[1]);
            } elseif (preg_match_all('/<meta\\s+([^>]+)>/i', $html_head, $match)) {
                foreach ($match[1] as $_test) {
                    if (preg_match('/charset=["\']?([^"\']+)/i', $_test, $_m)) {
                        $encoding = trim($_m[1]);
                        break;
                    }
                }
            }
        }
        $encoding = strtolower(trim($encoding));
        // fix bad encoding values
        if ($encoding === 'iso-8850-1') {
            $encoding = 'iso-8859-1';
        }
        if (empty($encoding) || $encoding === 'iso-8859-1') {
            // replace MS Word smart qutoes
            $trans = array();
            $trans[chr(130)] = '&sbquo;';
            // Single Low-9 Quotation Mark
            $trans[chr(131)] = '&fnof;';
            // Latin Small Letter F With Hook
            $trans[chr(132)] = '&bdquo;';
            // Double Low-9 Quotation Mark
            $trans[chr(133)] = '&hellip;';
            // Horizontal Ellipsis
            $trans[chr(134)] = '&dagger;';
            // Dagger
            $trans[chr(135)] = '&Dagger;';
            // Double Dagger
            $trans[chr(136)] = '&circ;';
            // Modifier Letter Circumflex Accent
            $trans[chr(137)] = '&permil;';
            // Per Mille Sign
            $trans[chr(138)] = '&Scaron;';
            // Latin Capital Letter S With Caron
            $trans[chr(139)] = '&lsaquo;';
            // Single Left-Pointing Angle Quotation Mark
            $trans[chr(140)] = '&OElig;';
            // Latin Capital Ligature OE
            $trans[chr(145)] = '&lsquo;';
            // Left Single Quotation Mark
            $trans[chr(146)] = '&rsquo;';
            // Right Single Quotation Mark
            $trans[chr(147)] = '&ldquo;';
            // Left Double Quotation Mark
            $trans[chr(148)] = '&rdquo;';
            // Right Double Quotation Mark
            $trans[chr(149)] = '&bull;';
            // Bullet
            $trans[chr(150)] = '&ndash;';
            // En Dash
            $trans[chr(151)] = '&mdash;';
            // Em Dash
            $trans[chr(152)] = '&tilde;';
            // Small Tilde
            $trans[chr(153)] = '&trade;';
            // Trade Mark Sign
            $trans[chr(154)] = '&scaron;';
            // Latin Small Letter S With Caron
            $trans[chr(155)] = '&rsaquo;';
            // Single Right-Pointing Angle Quotation Mark
            $trans[chr(156)] = '&oelig;';
            // Latin Small Ligature OE
            $trans[chr(159)] = '&Yuml;';
            // Latin Capital Letter Y With Diaeresis
            $html = strtr($html, $trans);
        }
        if ($encoding !== 'utf-8') {
            $this->logger->log('debug', 'Converting to UTF-8', ['encoding' => $encoding]);
            return \SimplePie_Misc::change_encoding($html, $encoding, 'utf-8') ?: $html;
        }
        $this->logger->log('debug', 'Treating as UTF-8', ['encoding' => $encoding]);
        return $html;
    }