<?php

// require_once 'Zend/Filter/Interface.php'

class Qs_Filter_EmailAddresses implements Zend_Filter_Interface
{
    protected $_posibleSeperators = "/[\n ;,]+/";
    protected $_separator = ', ';

    public function filter($value)
    {
        $valueArray = preg_split($this->_posibleSeperators, (string) $value);
        $this->_cleanEmails($valueArray);
        return implode($this->_separator, $valueArray);
    }

    protected function _cleanEmails(array &$emails)
    {
        $result = [];
        foreach ($emails as &$value) {
            $value = trim($value);
            if ('' != $value) {
                $result[] = $value;
            }
        }
        $emails = array_unique($result);
        return $this;
    }
}