CAllMailMessage::trimContent

static function trimContent(array &$fields, $trimLength, $filters)
{
	foreach ($filters as $filter)
	{
		if (is_array($filter))
		{
			$filter = array_filter(
				$filter,
				function ($name) use ($fields)
				{
					return isset($fields[$name]);
				}
			);

			$totalLength = array_reduce(
				$filter,
				function ($total, $name) use ($fields)
				{
					$length = BinaryString::getLength($fields[$name]);
					return $total + $length;
				},
				0
			);

			if ($totalLength === 0)
			{
				continue;
			}

			$overLength = 0;

			foreach ($filter as $subFilter)
			{
				$length = BinaryString::getLength($fields[$subFilter]);
				$ratio = $length / $totalLength;
				$over = ceil($trimLength * $ratio);
				$newLength = $length - $over;
				$fields[$subFilter] = $newLength > 0 ? BinaryString::getSubstring($fields[$subFilter], 0, $newLength) : '';
				$overLength += $newLength > 0 ? $over : $length;
			}

			$trimLength -= $overLength;
		}
		else
		{
			if (isset($fields[$filter]))
			{
				$length = BinaryString::getLength($fields[$filter]);
				$newLength = $length - $trimLength;
				$fields[$filter] = $newLength > 0 ? BinaryString::getSubstring($fields[$filter], 0, $newLength) : '';
				$trimLength -= $newLength > 0 ? $trimLength : $length;
			}
		}

		if ($trimLength <= 0)
		{
			break;
		}
	}

	return $fields;
}