<?php

class Qs_Filter_Phone implements Zend_Filter_Interface
{
    protected $_format = Qs_Form_Element_Phone::DOT_FORMAT;

    /**
     * @param string|null $format
     * @throws Qs_Exception
     */
    public function __construct($format = null)
    {
        if (null !== $format) {
            if (!in_array($format, [Qs_Form_Element_Phone::DOT_FORMAT, Qs_Form_Element_Phone::DASH_FORMAT])) {
                throw new Qs_Exception('Unknown phone format.');
            }
            $this->_format = $format;
        }
    }

    /**
     * @param  string $value
     * @throws Zend_Filter_Exception If filtering $value is impossible
     * @return string
     */
    public function filter($value)
    {
        $filtered = '';
        if ($value) {
            if (Qs_Form_Element_Phone::DOT_FORMAT == $this->_format) {
                $filtered = $this->_getDotFormat($value);
            } else {
                $filtered = $this->_getDashFormat($value);
            }
        }
        return $filtered;
    }

    /**
     * @param string $value
     * @return string
     */
    protected function _clearPhone($value)
    {
        $value = preg_replace('/\D+/', '', $value);
        return substr($value, 0, 16);
    }

    /**
     * @param string $value
     * @return string
     */
    protected function _getDotFormat($value)
    {
        $formatted = '';
        $steps = [3, 3, 4];
        $stepsSum = 10;

        $value = $this->_clearPhone($value);
        $length = strlen($value);

        foreach (array_keys($steps) as $i) {
            $step = ($length > $steps[$i]) ? $steps[$i] : $length;
            $formatted .= substr($value, 0, $step);
            if ($step == $steps[$i]) {
                $formatted .= '.';
            }
            $value = substr($value, $step);
            $length = strlen($value);

            if ('' == $value) {
                break;
            }
        }

        if (strlen($formatted) > ($stepsSum + 2)) {
            $formatted = substr($formatted, 0, ($stepsSum + 2));
        }

        if ('' != $value) {
            $formatted .= ' ext. ' . $value;
        }

        return $formatted;
    }

    /**
     * @param string $value
     * @return string
     */
    protected function _getDashFormat($value)
    {
        $formatted = '(';

        $value = $this->_clearPhone($value);

        $valueLength = strlen($value);
        for ($i = 0; $i < $valueLength; $i++) {
            $formatted .= $value[$i];
            if (($i == 2) && $value[$i + 1] != '') {
                $formatted .= ') ';
            }
            if (($i == 5) && $value[$i + 1] != '') {
                $formatted .= '-';
            }
            if (($i == 9 && $valueLength > 10) && $value[$i + 1] != '') {
                $formatted .= ' ext. ';
            }
        }

        if ($formatted == '(') {
            $formatted = '';
        }

        return $formatted;
    }
}