Message::removeForwardHead

protected function removeForwardHead(&$text)
{
	if (!trim($text))
		return $text;

	$data = static::reduceTags($text);

	$shortHeadRegex = '/(?:^|n)s*
		-{3,}.{4,40}?-{3,}[tx20]*n
		(?(?:[tx20]*n)?
		(?.{5,50}d),?x20
		[^dn]{0,20}(?d{1,2}:d{2}(?::d{2})?x20?(?:am|pm)?),?x20
		(?.+):(?:s*n)?)
	/ix'.BX_UTF_PCRE_MODIFIER;

	$hasMarker = preg_match($shortHeadRegex, $data);
	$fullHeadRegex = '/(?:^|nn)s*
		(?-{3,}.{4,40}?-{3,}[tx20]*n)'.($hasMarker ? '' : '?').'
		(?(?:[tx20]*n)?
		(?(?:[^:n]{1,20}:[tx20]+.+(?:n|$)){2,6}))
		s*(?:n|$)
	/x'.BX_UTF_PCRE_MODIFIER;

	if (preg_match($fullHeadRegex, $data, $matches, PREG_OFFSET_CAPTURE))
	{
		$score  = (int) !empty($matches['marker'][0]);
		$score += $this->scoreFullHead($matches['lines'][0]);

		if ($score > 1)
		{
			// @TODO: MainTextBinaryString::getSubstring()
			$pattern = preg_replace(
				array('/.+/', '/n/'), array('.+', 'n'),
				array(substr($data, 0, $matches['head'][1]), $matches['head'][0])
			);

			return preg_replace_callback(
				sprintf('/^(%s)(%s)/', $pattern[0], $pattern[1]),
				function($matches)
				{
					return sprintf("%snn%s", $matches[1], Message::reduceHead($matches[2]));
				},
				$text
			);
		}
	}

	if (preg_match($shortHeadRegex, $data, $matches, PREG_OFFSET_CAPTURE))
	{
		$score  = 0;
		$score += $this->scoreShortHead($matches['head'][0]);

		if ($score > 0)
		{
			// @TODO: MainTextBinaryString::getSubstring()
			$pattern = preg_replace(
				array('/.+/', '/n/'), array('.+', 'n'),
				array(substr($data, 0, $matches['head'][1]), $matches['head'][0])
			);

			return preg_replace_callback(
				sprintf('/^(%s)(%s)/', $pattern[0], $pattern[1]),
				function($matches)
				{
					return sprintf("%snn%s", $matches[1], Message::reduceHead($matches[2]));
				},
				$text
			);
		}
	}

	return $text;
}