<?
    // init
    ini_set('display_errors',"1");                      // show errors
    date_default_timezone_set("Asia/Hong_Kong");    // set timezone
    /**
     * Removes invalid XML
     *
     * @access public
     * @param string $value
     * @return string
     */
    function stripInvalidXml($value)
    {
        $ret = "";
        $current;
        if (empty($value)) 
        {
            return $ret;
        }
        $length = strlen($value);
        for ($i=0; $i < $length; $i++)
        {
            $current = ord($value{$i});
            if (($current == 0x9) ||
                ($current == 0xA) ||
                ($current == 0xD) ||
                (($current >= 0x20) && ($current <= 0xD7FF)) ||
                (($current >= 0xE000) && ($current <= 0xFFFD)) ||
                (($current >= 0x10000) && ($current <= 0x10FFFF)))
            {
                $ret .= chr($current);
            }
            else
            {
                $ret .= " ";
            }
        }
        return $ret;
    }
    // get params
    $method = (isset($_GET['method'])) ? $_GET['method'] : (isset($_POST['method']) ? $_POST['method'] : 'get_rss');
    $limit  = (isset($_GET['limit'])) ? (int)$_GET['limit'] : (isset($_POST['limit'])   ? (int)$_POST['limit'] : 200);
    // globals
    $feeds = array(
        (object) array(
            'name' => 'News',
            'url' => 'http://dhanara.aishk.edu.hk/feed/'
        )
    );
    // output
    switch ($method) {
        case 'get_rss':
            // json data
            $items = array();
            // loop over feeds
            foreach ($feeds as $feed) {
                // fetch RSS feed
                $ch = curl_init($feed->url);
                curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
                curl_setopt($ch, CURLOPT_HEADER, 0);
                curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
                $data = curl_exec($ch);
                curl_close($ch);
                // remove invalid characters from the xml
                $data = stripInvalidXml($data); 
                // parse RSS
                $rss = new SimpleXmlElement($data, LIBXML_NOCDATA);
                // counter
                $count = 0;
                // loop through each item
                foreach($rss->channel->item as $item) {
                    // increment counter
                    $count++;
                    // generate a integer for a unique id 
                    $id = (int) hexdec(substr(sha1($item->title.$item->description),0,8));

                    $enclosure = "";

                    if($item->enclosure && $item->enclosure->attributes()) {
                        $enclosure = $item->enclosure->attributes()->url;
                    }
                    $image = preg_match('/<img\s+[^>]*src="([^"]*)"/', $item->description, $matches);
                    if (isset($matches[1])) {
                        $image = $matches[1];
                    }elseif (isset($matches[2])) {
                        $image = $matches[2];
                    }else{
                        $image = null;
                    }
                    // add items to array used in response
                    $items[] = array(
                        'id' => $id,
                        'title' => (string) $item->title,
                        'feed' => (string) $feed->name,
                        'url' => (string) $item->link,
                        'description' => strip_tags($item->description),
                        'list_order' => $count,
                        'featured_image' => $image,
                        'content' => $item->children('content', true)->encoded
                    );
                }
            }
            // json header
            header("Content-type: application/json");
            // print output
            echo json_encode(
                array(
                    'result' => array_slice($items,0,$limit),
                    'error' => null,
                ),
                JSON_PRETTY_PRINT
            );
        break;
    }