<?


function parse_duration($iso_duration, $allow_negative = true){
    // Parse duration parts
    $matches = array();
    preg_match('/^(-|)?P([0-9]+Y|)?([0-9]+M|)?([0-9]+D|)?T?([0-9]+H|)?([0-9]+M|)?([0-9]+S|)?$/', $iso_duration, $matches);
    if(!empty($matches)){       
        // Strip all but digits and -
        foreach($matches as &$match){
            $match = preg_replace('/((?!([0-9]|-)).)*/', '', $match);
        }   
        // Fetch min/plus symbol
        $result['symbol'] = ($matches[1] == '-') ? $matches[1] : '+'; // May be needed for actions outside this function.
        // Fetch duration parts
        $m = ($allow_negative) ? $matches[1] : '';
        $result['year']   = intval($m.$matches[2]);
        $result['month']  = intval($m.$matches[3]);
        $result['day']    = intval($m.$matches[4]);
        $result['hour']   = intval($m.$matches[5]);
        $result['minute'] = intval($m.$matches[6]);
        $result['second'] = intval($m.$matches[7]);     
        return $result; 
    }
    else{
        return false;
    }
}
function get_duration_seconds($iso_duration){
    // Get duration parts
    $duration = parse_duration($iso_duration, false);
    if($duration){
        extract($duration);
        $dparam  = $symbol; // plus/min symbol
        $dparam .= (!empty($year)) ? $year . 'Year' : '';
        $dparam .= (!empty($month)) ? $month . 'Month' : '';
        $dparam .= (!empty($day)) ? $day . 'Day' : '';
        $dparam .= (!empty($hour)) ? $hour . 'Hour' : '';
        $dparam .= (!empty($minute)) ? $minute . 'Minute' : '';
        $dparam .= (!empty($second)) ? $second . 'Second' : '';
        $date = '19700101UTC';
        return strtotime($date.$dparam) - strtotime($date);
    }
    else{
        // Not a valid iso duration
        return false;
    }
}
?>