CureTogether CVS-parser (with caching)

<?php
/*
    Download and extract data from CureTogether.com CVS-files.
        Optionally cache the data on local drive.
    See: http://weight.ulfben.com for an example.
*/
error_reporting(E_ALL);
ini_set('display_errors', '1');
class Crawler {
    private $_loginURL = 'http://curetogether.com/login.php';
    private $_conf = array();
    private $_cache = ''; //a filename to cache the results in
    private $_expire_time = 86400; //24*60*60
    function __construct($cache = '', $expire_time = 86400){
        $this->_cache = $cache;
        $this->_expire_time = $expire_time;
        $cookies = 'cookies.txt';
        $this->_conf = array(
            CURLOPT_USERAGENT => 'Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)',
            CURLOPT_HEADER => false,
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_COOKIEJAR  => $cookies,
            CURLOPT_COOKIEFILE => $cookies,
         );
        @ unlink($cookies);
    }
    function login($username, $password){
        $ch = curl_init();
        $_conf = $this->_conf;
        $_conf[CURLOPT_URL] = $this->_loginURL;
        $_conf[CURLOPT_POST] = true;
        $_conf[CURLOPT_POSTFIELDS] = $this->getPostFields(array('loginEmail' =>  $username, 'loginPassword' => $password)); //login form fields, edit accordingly
        $_conf[CURLOPT_FOLLOWLOCATION] = false;
        curl_setopt_array($ch, $_conf);
        curl_exec($ch);
        curl_close($ch);
    }
    function get($url, $username, $password){
        if($this->_cache && file_exists($this->_cache) && (time()-$this->_expire_time) < filemtime($this->_cache)){
            return file_get_contents($this->_cache);
        }
        if($username){
            $this->login($username, $password);
        }
        $ch = curl_init();
        $_conf = $this->_conf;
        $_conf[CURLOPT_URL] = $url;
        curl_setopt_array($ch, $_conf);
        $results = curl_exec($ch);
        curl_close($ch);
        $fh = @ fopen($this->_cache, 'w');
        if($fh !== false){
            fwrite($fh, (string) $results);
            fclose($fh);
        }
        return $results;
    }
    private function getPostFields($data){
        $return = array();
        foreach ($data as $key => $field){
            $return[] = $key . '=' . urldecode($field);
        }
        return implode('&', $return);
    }
}
$crawler = new Crawler('filename-for-cache.cvs');
$cvs = $crawler->get('http://curetogether.com/home/tracking/dd/', 'username', 'password');
$cvs = str_replace('"', '', $cvs); //all data fields are double-quoted
$cvs = array_filter(explode("\n", $cvs));

//start the parsing
$length = count($cvs);
$date_label = 'Measure Date'; //the date column is assumed, and its label given by curetogether. used to find all other labels.
$labels = array();
$sets = array(); //the CVS holds all labels you're tracking at curetogether, so lets parse them all into sets.
$first_line = 0; //the CVS starts with a bit of meta-data, then comes labels and then data.
while(strpos($cvs[$first_line], $date_label) === false){
    $first_line++;  //spin until we find the labels
}
$labels = explode(',', $cvs[$first_line]);
foreach($labels as $label){
    $sets[$label] = array();
}
$columncount = count($labels);

//extract the data fields
for($line = $first_line+1; $line < $length; $line++){ //data begins on the line after labels
    $values = explode(",", $cvs[$line]);
    $date = strtotime($values[0]); //assume first column is always the measuring date
    if($date === false){continue;}
    for($j = 1; $j < $columncount; $j++){ //get the rest of the columns.
        $val = $values[$j];
        if(empty($val)){continue;}
        $sets[$labels[$j]][$date] = $val;
    }
}

//pick the set you want, sort it and format for javascript output
$weight = $sets['Weight'];
ksort($weight);
$js_obj = '';
foreach($weight as $timestamp => $kg){
    $js_obj .= "[{$timestamp}000,{$kg}],"; //add 000 to timestamp for milliseconds.
}
$js_obj = '['. rtrim($js_obj, ',') . '];';
?>