(This is used in description to keep text formatting)
function keepMultipleSpaces($text)
{
    return str_replace('  ','  ',$text);

}
// ------------------------------------------------------------------------------------------
// Sniff browser language to display dates in the right format automatically.
// (Note that is may not work on your server if the corresponding local is not installed.)
function autoLocale()
{
    $loc='en_US'; // Default if browser does not send HTTP_ACCEPT_LANGUAGE
    if (isset($_SERVER['HTTP_ACCEPT_LANGUAGE'])) // eg. "fr,fr-fr;q=0.8,en;q=0.5,en-us;q=0.3"
    {   // (It's a bit crude, but it works very well. Prefered language is always presented first.)
        if (preg_match('/([a-z]{2}(-[a-z]{2})?)/i',$_SERVER['HTTP_ACCEPT_LANGUAGE'],$matches)) $loc=$matches[1];
    }
    setlocale(LC_TIME,$loc);  // LC_TIME = Set local for date/time format only.
}

// ------------------------------------------------------------------------------------------
// PubSubHubbub protocol support (if enabled)  [UNTESTED]
// (Source: http://aldarone.fr/les-flux-rss-shaarli-et-pubsubhubbub/ )
if (!empty($GLOBALS['config']['PUBSUBHUB_URL'])) include './publisher.php';
function pubsubhub()
{
    if (!empty($GLOBALS['config']['PUBSUBHUB_URL']))
    {
       $p = new Publisher($GLOBALS['config']['PUBSUBHUB_URL']);
       $topic_url = array (
                       indexUrl().'?do=atom',
                       indexUrl().'?do=rss'
                    );
       $p->publish_update($topic_url);
    }
}

// ------------------------------------------------------------------------------------------
// Session management

// Returns the IP address of the client (Used to prevent session cookie hijacking.)
function allIPs()
{
    $ip = $_SERVER["REMOTE_ADDR"];
    // Then we use more HTTP headers to prevent session hijacking from users behind the same proxy.
    if (isset($_SERVER['HTTP_X_FORWARDED_FOR'])) { $ip=$ip.'_'.$_SERVER['HTTP_X_FORWARDED_FOR']; }
    if (isset($_SERVER['HTTP_CLIENT_IP'])) { $ip=$ip.'_'.$_SERVER['HTTP_CLIENT_IP']; }
    return $ip;
}

// Check that user/password is correct.
function check_auth($login,$password)
{
    $hash = sha1($password.$login.$GLOBALS['salt']);
    if ($login==$GLOBALS['login'] && $hash==$GLOBALS['hash'])
    {   // Login/password is correct.
        $_SESSION['uid'] = sha1(uniqid('',true).'_'.mt_rand()); // generate unique random number (different than phpsessionid)
        $_SESSION['ip']=allIPs();                // We store IP address(es) of the client to make sure session is not hijacked.
        $_SESSION['username']=$login;
        $_SESSION['expires_on']=time()+INACTIVITY_TIMEOUT;  // Set session expiration.
        logm('Login successful');
        return True;
    }
    logm('Login failed for user '.$login);
    return False;
}

// Returns true if the user is logged in.
function isLoggedIn()
{
    if ($GLOBALS['config']['OPEN_SHAARLI']) return true;

    if (!isset($GLOBALS['login'])) return false;  // Shaarli is not configured yet.

    // If session does not exist on server side, or IP address has changed, or session has expired, logout.
    if (empty($_SESSION['uid']) || ($GLOBALS['disablesessionprotection']==false && $_SESSION['ip']!=allIPs()) || time()>=$_SESSION['expires_on'])
    {
        logout();
        return false;
    }
    if (!empty($_SESSION['longlastingsession']))  $_SESSION['expires_on']=time()+$_SESSION['longlastingsession']; // In case of "Stay signed in" checked.
    else $_SESSION['expires_on']=time()+INACTIVITY_TIMEOUT; // Standard session expiration date.

    return true;
}

// Force logout.
function logout() { if (isset($_SESSION)) { unset($_SESSION['uid']); unset($_SESSION['ip']); unset($_SESSION['username']); unset($_SESSION['privateonly']); }  }


// ------------------------------------------------------------------------------------------
// Brute force protection system
// Several consecutive failed logins will ban the IP address for 30 minutes.
if (!is_file($GLOBALS['config']['IPBANS_FILENAME'])) file_put_contents($GLOBALS['config']['IPBANS_FILENAME'], "array(),'BANS'=>array()),true).";\n?>");
include $GLOBALS['config']['IPBANS_FILENAME'];
// Signal a failed login. Will ban the IP if too many failures:
function ban_loginFailed()
{
    $ip=$_SERVER["REMOTE_ADDR"]; $gb=$GLOBALS['IPBANS'];
    if (!isset($gb['FAILURES'][$ip])) $gb['FAILURES'][$ip]=0;
    $gb['FAILURES'][$ip]++;
    if ($gb['FAILURES'][$ip]>($GLOBALS['config']['BAN_AFTER']-1))
    {
        $gb['BANS'][$ip]=time()+$GLOBALS['config']['BAN_DURATION'];
        logm('IP address banned from login');
    }
    $GLOBALS['IPBANS'] = $gb;
    file_put_contents($GLOBALS['config']['IPBANS_FILENAME'], "");
}

// Signals a successful login. Resets failed login counter.
function ban_loginOk()
{
    $ip=$_SERVER["REMOTE_ADDR"]; $gb=$GLOBALS['IPBANS'];
    unset($gb['FAILURES'][$ip]); unset($gb['BANS'][$ip]);
    $GLOBALS['IPBANS'] = $gb;
    file_put_contents($GLOBALS['config']['IPBANS_FILENAME'], "");
}

// Checks if the user CAN login. If 'true', the user can try to login.
function ban_canLogin()
{
    $ip=$_SERVER["REMOTE_ADDR"]; $gb=$GLOBALS['IPBANS'];
    if (isset($gb['BANS'][$ip]))
    {
        // User is banned. Check if the ban has expired:
        if ($gb['BANS'][$ip]<=time())
        {   // Ban expired, user can try to login again.
            logm('Ban lifted.');
            unset($gb['FAILURES'][$ip]); unset($gb['BANS'][$ip]);
            file_put_contents($GLOBALS['config']['IPBANS_FILENAME'], "");
            return true; // Ban has expired, user can login.
        }
        return false; // User is banned.
    }
    return true; // User is not banned.
}

// ------------------------------------------------------------------------------------------
// Process login form: Check if login/password is correct.
if (isset($_POST['login']))
{
    if (!ban_canLogin()) die('I said: NO. You are banned for the moment. Go away.');
    if (isset($_POST['password']) && tokenOk($_POST['token']) && (check_auth($_POST['login'], $_POST['password'])))
    {   // Login/password is ok.
        ban_loginOk();
        // If user wants to keep the session cookie even after the browser closes:
        if (!empty($_POST['longlastingsession']))
        {
            $_SESSION['longlastingsession']=31536000;  // (31536000 seconds = 1 year)
            $_SESSION['expires_on']=time()+$_SESSION['longlastingsession'];  // Set session expiration on server-side.

            $cookiedir = ''; if(dirname($_SERVER['SCRIPT_NAME'])!='/') $cookiedir=dirname($_SERVER["SCRIPT_NAME"]).'/';
            session_set_cookie_params($_SESSION['longlastingsession'],$cookiedir,$_SERVER['SERVER_NAME']); // Set session cookie expiration on client side
            // Note: Never forget the trailing slash on the cookie path !
            session_regenerate_id(true);  // Send cookie with new expiration date to browser.
        }
        else // Standard session expiration (=when browser closes)
        {
            $cookiedir = ''; if(dirname($_SERVER['SCRIPT_NAME'])!='/') $cookiedir=dirname($_SERVER["SCRIPT_NAME"]).'/';
            session_set_cookie_params(0,$cookiedir,$_SERVER['SERVER_NAME']); // 0 means "When browser closes"
            session_regenerate_id(true);
        }
        // Optional redirect after login:
        if (isset($_GET['post'])) { header('Location: ?post='.urlencode($_GET['post']).(!empty($_GET['title'])?'&title='.urlencode($_GET['title']):'').(!empty($_GET['source'])?'&source='.urlencode($_GET['source']):'')); exit; }
        if (isset($_POST['returnurl']))
        {
            if (endsWith($_POST['returnurl'],'?do=login')) { header('Location: ?'); exit; } // Prevent loops over login screen.
            header('Location: '.$_POST['returnurl']); exit;
        }
        header('Location: ?'); exit;
    }
    else
    {
        ban_loginFailed();
        $redir = '';
        if (isset($_GET['post'])) { $redir = '&post='.urlencode($_GET['post']).(!empty($_GET['title'])?'&title='.urlencode($_GET['title']):'').(!empty($_GET['source'])?'&source='.urlencode($_GET['source']):'');  }
        echo ''; // Redirect to login screen.
        exit;
    }
}

// ------------------------------------------------------------------------------------------
// Misc utility functions:

// Returns the server URL (including port and http/https), without path.
// eg. "http://myserver.com:8080"
// You can append $_SERVER['SCRIPT_NAME'] to get the current script URL.
function serverUrl()
{
    $https = (!empty($_SERVER['HTTPS']) && (strtolower($_SERVER['HTTPS'])=='on')) || $_SERVER["SERVER_PORT"]=='443'; // HTTPS detection.
    $serverport = ($_SERVER["SERVER_PORT"]=='80' || ($https && $_SERVER["SERVER_PORT"]=='443') ? '' : ':'.$_SERVER["SERVER_PORT"]);
    return 'http'.($https?'s':'').'://'.$_SERVER["SERVER_NAME"].$serverport;
}

// Returns the absolute URL of current script, without the query.
// (eg. http://sebsauvage.net/links/)
function indexUrl()
{
    $scriptname = $_SERVER["SCRIPT_NAME"];
    // If the script is named 'index.php', we remove it (for better looking URLs,
    // eg. http://mysite.com/shaarli/?abcde instead of http://mysite.com/shaarli/index.php?abcde)
    if (endswith($scriptname,'index.php')) $scriptname = substr($scriptname,0,strlen($scriptname)-9);
    return serverUrl() . $scriptname;
}

// Returns the absolute URL of current script, WITH the query.
// (eg. http://sebsauvage.net/links/?toto=titi&spamspamspam=humbug)
function pageUrl()
{
    return indexUrl().(!empty($_SERVER["QUERY_STRING"]) ? '?'.$_SERVER["QUERY_STRING"] : '');
}

// Convert post_max_size/upload_max_filesize (eg.'16M') parameters to bytes.
function return_bytes($val)
{
    $val = trim($val); $last=strtolower($val[strlen($val)-1]);
    switch($last)
    {
        case 'g': $val *= 1024;
        case 'm': $val *= 1024;
        case 'k': $val *= 1024;
    }
    return $val;
}

// Try to determine max file size for uploads (POST).
// Returns an integer (in bytes)
function getMaxFileSize()
{
    $size1 = return_bytes(ini_get('post_max_size'));
    $size2 = return_bytes(ini_get('upload_max_filesize'));
    // Return the smaller of two:
    $maxsize = min($size1,$size2);
    // FIXME: Then convert back to readable notations ? (eg. 2M instead of 2000000)
    return $maxsize;
}

// Tells if a string start with a substring or not.
function startsWith($haystack,$needle,$case=true)
{
    if($case){return (strcmp(substr($haystack, 0, strlen($needle)),$needle)===0);}
    return (strcasecmp(substr($haystack, 0, strlen($needle)),$needle)===0);
}

// Tells if a string ends with a substring or not.
function endsWith($haystack,$needle,$case=true)
{
    if($case){return (strcmp(substr($haystack, strlen($haystack) - strlen($needle)),$needle)===0);}
    return (strcasecmp(substr($haystack, strlen($haystack) - strlen($needle)),$needle)===0);
}

/*  Converts a linkdate time (YYYYMMDD_HHMMSS) of an article to a timestamp (Unix epoch)
    (used to build the ADD_DATE attribute in Netscape-bookmarks file)
    PS: I could have used strptime(), but it does not exist on Windows. I'm too kind. */
function linkdate2timestamp($linkdate)
{
    $Y=$M=$D=$h=$m=$s=0;
    $r = sscanf($linkdate,'%4d%2d%2d_%2d%2d%2d',$Y,$M,$D,$h,$m,$s);
    return mktime($h,$m,$s,$M,$D,$Y);
}

/*  Converts a linkdate time (YYYYMMDD_HHMMSS) of an article to a RFC822 date.
    (used to build the pubDate attribute in RSS feed.)  */
function linkdate2rfc822($linkdate)
{
    return date('r',linkdate2timestamp($linkdate)); // 'r' is for RFC822 date format.
}

/*  Converts a linkdate time (YYYYMMDD_HHMMSS) of an article to a ISO 8601 date.
    (used to build the updated tags in ATOM feed.)  */
function linkdate2iso8601($linkdate)
{
    return date('c',linkdate2timestamp($linkdate)); // 'c' is for ISO 8601 date format.
}

/*  Converts a linkdate time (YYYYMMDD_HHMMSS) of an article to a localized date format.
    (used to display link date on screen)
    The date format is automatically chosen according to locale/languages sniffed from browser headers (see autoLocale()). */
function linkdate2locale($linkdate)
{
    return utf8_encode(strftime('%c',linkdate2timestamp($linkdate))); // %c is for automatic date format according to locale.
    // Note that if you use a local which is not installed on your webserver,
    // the date will not be displayed in the chosen locale, but probably in US notation.
}

// Parse HTTP response headers and return an associative array.
function http_parse_headers_shaarli( $headers )
{
    $res=array();
    foreach($headers as $header)
    {
        $i = strpos($header,': ');
        if ($i!==false)
        {
            $key=substr($header,0,$i);
            $value=substr($header,$i+2,strlen($header)-$i-2);
            $res[$key]=$value;
        }
    }
    return $res;
}

/* GET an URL.
   Input: $url : url to get (http://...)
          $timeout : Network timeout (will wait this many seconds for an anwser before giving up).
   Output: An array.  [0] = HTTP status message (eg. "HTTP/1.1 200 OK") or error message
                      [1] = associative array containing HTTP response headers (eg. echo getHTTP($url)[1]['Content-Type'])
                      [2] = data
    Example: list($httpstatus,$headers,$data) = getHTTP('http://sebauvage.net/');
             if (strpos($httpstatus,'200 OK')!==false)
                 echo 'Data type: '.htmlspecialchars($headers['Content-Type']);
             else
                 echo 'There was an error: '.htmlspecialchars($httpstatus)
*/
function getHTTP($url,$timeout=30)
{
    try
    {
        $options = array('http'=>array('method'=>'GET','timeout' => $timeout)); // Force network timeout
        $context = stream_context_create($options);
        $data=file_get_contents($url,false,$context,-1, 4000000); // We download at most 4 Mb from source.
        if (!$data) { return array('HTTP Error',array(),''); }
        $httpStatus=$http_response_header[0]; // eg. "HTTP/1.1 200 OK"
        $responseHeaders=http_parse_headers_shaarli($http_response_header);
        return array($httpStatus,$responseHeaders,$data);
    }
    catch (Exception $e)  // getHTTP *can* fail silentely (we don't care if the title cannot be fetched)
    {
        return array($e->getMessage(),'','');
    }
}

// Extract title from an HTML document.
// (Returns an empty string if not found.)
function html_extract_title($html)
{
  return preg_match('!!is', $html, $matches) ? trim(str_replace("\n",' ', $matches[1])) : '' ;
}

// ------------------------------------------------------------------------------------------
// Token management for XSRF protection
// Token should be used in any form which acts on data (create,update,delete,import...).
if (!isset($_SESSION['tokens'])) $_SESSION['tokens']=array();  // Token are attached to the session.

// Returns a token.
function getToken()
{
    $rnd = sha1(uniqid('',true).'_'.mt_rand().$GLOBALS['salt']);  // We generate a random string.
    $_SESSION['tokens'][$rnd]=1;  // Store it on the server side.
    return $rnd;
}

// Tells if a token is ok. Using this function will destroy the token.
// true=token is ok.
function tokenOk($token)
{
    if (isset($_SESSION['tokens'][$token]))
    {
        unset($_SESSION['tokens'][$token]); // Token is used: destroy it.
        return true; // Token is ok.
    }
    return false; // Wrong token, or already used.
}

// ------------------------------------------------------------------------------------------
/* This class is in charge of building the final page.
   (This is basically a wrapper around RainTPL which pre-fills some fields.)
   p = new pageBuilder;
   p.assign('myfield','myvalue');
   p.renderPage('mytemplate');

*/
class pageBuilder
{
    private $tpl; // RainTPL template

    function __construct()
    {
        $this->tpl=false;
    }

    private function initialize()
    {
        $this->tpl = new RainTPL;
        $this->tpl->assign('newversion',checkUpdate());
        $this->tpl->assign('feedurl',htmlspecialchars(indexUrl()));
        $searchcrits=''; // Search criteria
        if (!empty($_GET['searchtags'])) $searchcrits.='&searchtags='.urlencode($_GET['searchtags']);
        elseif (!empty($_GET['searchterm'])) $searchcrits.='&searchterm='.urlencode($_GET['searchterm']);
        $this->tpl->assign('searchcrits',$searchcrits);
        $this->tpl->assign('source',indexUrl());
        $this->tpl->assign('version',shaarli_version);
        $this->tpl->assign('scripturl',indexUrl());
        $this->tpl->assign('pagetitle','Shaarli');
        $this->tpl->assign('privateonly',!empty($_SESSION['privateonly'])); // Show only private links ?
        if (!empty($GLOBALS['title'])) $this->tpl->assign('pagetitle',$GLOBALS['title']);
        if (!empty($GLOBALS['pagetitle'])) $this->tpl->assign('pagetitle',$GLOBALS['pagetitle']);
        $this->tpl->assign('shaarlititle',empty($GLOBALS['title']) ? 'Shaarli': $GLOBALS['title'] );
        return;
    }

    // The following assign() method is basically the same as RainTPL (except that it's lazy)
    public function assign($what,$where)
    {
        if ($this->tpl===false) $this->initialize(); // Lazy initialization
        $this->tpl->assign($what,$where);
    }

    // Render a specific page (using a template).
    // eg. pb.renderPage('picwall')
    public function renderPage($page)
    {
        if ($this->tpl===false) $this->initialize(); // Lazy initialization
        $this->tpl->draw($page);
    }
}

// ------------------------------------------------------------------------------------------
/* Data storage for links.
   This object behaves like an associative array.
   Example:
      $mylinks = new linkdb();
      echo $mylinks['20110826_161819']['title'];
      foreach($mylinks as $link)
         echo $link['title'].' at url '.$link['url'].' ; description:'.$link['description'];

   Available keys:
       title : Title of the link
       url : URL of the link. Can be absolute or relative. Relative URLs are permalinks (eg.'?m-ukcw')
       description : description of the entry
       private : Is this link private ? 0=no, other value=yes
       linkdate : date of the creation of this entry, in the form YYYYMMDD_HHMMSS (eg.'20110914_192317')
       tags : tags attached to this entry (separated by spaces)

   We implement 3 interfaces:
     - ArrayAccess so that this object behaves like an associative array.
     - Iterator so that this object can be used in foreach() loops.
     - Countable interface so that we can do a count() on this object.
*/
class linkdb implements Iterator, Countable, ArrayAccess
{
    private $links; // List of links (associative array. Key=linkdate (eg. "20110823_124546"), value= associative array (keys:title,description...)
    private $urls;  // List of all recorded URLs (key=url, value=linkdate) for fast reserve search (url-->linkdate)
    private $keys;  // List of linkdate keys (for the Iterator interface implementation)
    private $position; // Position in the $this->keys array. (for the Iterator interface implementation.)
    private $loggedin; // Is the used logged in ? (used to filter private links)

    // Constructor:
    function __construct($isLoggedIn)
    // Input : $isLoggedIn : is the used logged in ?
    {
        $this->loggedin = $isLoggedIn;
        $this->checkdb(); // Make sure data file exists.
        $this->readdb();  // Then read it.
    }

    // ---- Countable interface implementation
    public function count() { return count($this->links); }

    // ---- ArrayAccess interface implementation
    public function offsetSet($offset, $value)
    {
        if (!$this->loggedin) die('You are not authorized to add a link.');
        if (empty($value['linkdate']) || empty($value['url'])) die('Internal Error: A link should always have a linkdate and url.');
        if (empty($offset)) die('You must specify a key.');
        $this->links[$offset] = $value;
        $this->urls[$value['url']]=$offset;
    }
    public function offsetExists($offset) { return array_key_exists($offset,$this->links); }
    public function offsetUnset($offset)
    {
        if (!$this->loggedin) die('You are not authorized to delete a link.');
        $url = $this->links[$offset]['url']; unset($this->urls[$url]);
        unset($this->links[$offset]);
    }
    public function offsetGet($offset) { return isset($this->links[$offset]) ? $this->links[$offset] : null; }

    // ---- Iterator interface implementation
    function rewind() { $this->keys=array_keys($this->links); rsort($this->keys); $this->position=0; } // Start over for iteration, ordered by date (latest first).
    function key() { return $this->keys[$this->position]; } // current key
    function current() { return $this->links[$this->keys[$this->position]]; } // current value
    function next() { ++$this->position; } // go to next item
    function valid() { return isset($this->keys[$this->position]); }    // Check if current position is valid.

    // ---- Misc methods
    private function checkdb() // Check if db directory and file exists.
    {
        if (!file_exists($GLOBALS['config']['DATASTORE'])) // Create a dummy database for example.
        {
             $this->links = array();
             $link = array('title'=>'Shaarli - sebsauvage.net','url'=>'http://sebsauvage.net/wiki/doku.php?id=php:shaarli','description'=>'Welcome to Shaarli ! This is a bookmark. To edit or delete me, you must first login.','private'=>0,'linkdate'=>'20110914_190000','tags'=>'opensource software');
             $this->links[$link['linkdate']] = $link;
             $link = array('title'=>'My secret stuff... - Pastebin.com','url'=>'http://pastebin.com/smCEEeSn','description'=>'SShhhh!!  I\'m a private link only YOU can see. You can delete me too.','private'=>1,'linkdate'=>'20110914_074522','tags'=>'secretstuff');
             $this->links[$link['linkdate']] = $link;
             file_put_contents($GLOBALS['config']['DATASTORE'], PHPPREFIX.base64_encode(gzdeflate(serialize($this->links))).PHPSUFFIX); // Write database to disk
        }
    }

    // Read database from disk to memory
    private function readdb()
    {
        // Read data
        $this->links=(file_exists($GLOBALS['config']['DATASTORE']) ? unserialize(gzinflate(base64_decode(substr(file_get_contents($GLOBALS['config']['DATASTORE']),strlen(PHPPREFIX),-strlen(PHPSUFFIX))))) : array() );
        // Note that gzinflate is faster than gzuncompress. See: http://www.php.net/manual/en/function.gzdeflate.php#96439

        // If user is not logged in, filter private links.
        if (!$this->loggedin)
        {
            $toremove=array();
            foreach($this->links as $link) { if ($link['private']!=0) $toremove[]=$link['linkdate']; }
            foreach($toremove as $linkdate) { unset($this->links[$linkdate]); }
        }

        // Keep the list of the mapping URLs-->linkdate up-to-date.
        $this->urls=array();
        foreach($this->links as $link) { $this->urls[$link['url']]=$link['linkdate']; }
    }

    // Save database from memory to disk.
    public function savedb()
    {
        if (!$this->loggedin) die('You are not authorized to change the database.');
        file_put_contents($GLOBALS['config']['DATASTORE'], PHPPREFIX.base64_encode(gzdeflate(serialize($this->links))).PHPSUFFIX);
        invalidateCaches();
    }

    // Returns the link for a given URL (if it exists). false it does not exist.
    public function getLinkFromUrl($url)
    {
        if (isset($this->urls[$url])) return $this->links[$this->urls[$url]];
        return false;
    }

    // Case insentitive search among links (in url, title and description). Returns filtered list of links.
    // eg. print_r($mydb->filterFulltext('hollandais'));
    public function filterFulltext($searchterms)
    {
        // FIXME: explode(' ',$searchterms) and perform a AND search.
        // FIXME: accept double-quotes to search for a string "as is" ?
        $filtered=array();
        $s = strtolower($searchterms);
        foreach($this->links as $l)
        {
            $found=   (strpos(strtolower($l['title']),$s)!==false)
                   || (strpos(strtolower($l['description']),$s)!==false)
                   || (strpos(strtolower($l['url']),$s)!==false)
                   || (strpos(strtolower($l['tags']),$s)!==false);
            if ($found) $filtered[$l['linkdate']] = $l;
        }
        krsort($filtered);
        return $filtered;
    }

    // Filter by tag.
    // You can specify one or more tags (tags can be separated by space or comma).
    // eg. print_r($mydb->filterTags('linux programming'));
    public function filterTags($tags,$casesensitive=false)
    {
        $t = str_replace(',',' ',($casesensitive?$tags:strtolower($tags)));
        $searchtags=explode(' ',$t);
        $filtered=array();
        foreach($this->links as $l)
        {
            $linktags = explode(' ',($casesensitive?$l['tags']:strtolower($l['tags'])));
            if (count(array_intersect($linktags,$searchtags)) == count($searchtags))
                $filtered[$l['linkdate']] = $l;
        }
        krsort($filtered);
        return $filtered;
    }

    // Filter by day. Day must be in the form 'YYYYMMDD' (eg. '20120125')
    // Sort order is: older articles first.
    // eg. print_r($mydb->filterDay('20120125'));
    public function filterDay($day)
    {
        $filtered=array();
        foreach($this->links as $l)
        {
            if (startsWith($l['linkdate'],$day)) $filtered[$l['linkdate']] = $l;
        }
        ksort($filtered);
        return $filtered;
    }
    // Filter by smallHash.
    // Only 1 article is returned.
    public function filterSmallHash($smallHash)
    {
        $filtered=array();
        foreach($this->links as $l)
        {
            if ($smallHash==smallHash($l['linkdate'])) // Yes, this is ugly and slow
            {
                $filtered[$l['linkdate']] = $l;
                return $filtered;
            }
        }
        return $filtered;
    }

    // Returns the list of all tags
    // Output: associative array key=tags, value=0
    public function allTags()
    {
        $tags=array();
        foreach($this->links as $link)
            foreach(explode(' ',$link['tags']) as $tag)
                if (!empty($tag)) $tags[$tag]=(empty($tags[$tag]) ? 1 : $tags[$tag]+1);
        arsort($tags); // Sort tags by usage (most used tag first)
        return $tags;
    }

    // Returns the list of days containing articles (oldest first)
    // Output: An array containing days (in format YYYYMMDD).
    public function days()
    {
        $linkdays=array();
        foreach(array_keys($this->links) as $day)
        {
            $linkdays[substr($day,0,8)]=0;
        }
        $linkdays=array_keys($linkdays);
        sort($linkdays);
        return $linkdays;
    }
}

// ------------------------------------------------------------------------------------------
// Ouput the last 50 links in RSS 2.0 format.
function showRSS()
{
    header('Content-Type: application/rss+xml; charset=utf-8');

    // $usepermalink : If true, use permalink instead of final link.
    // User just has to add 'permalink' in URL parameters. eg. http://mysite.com/shaarli/?do=rss&permalinks
    $usepermalinks = isset($_GET['permalinks']);

    // Cache system
    $query = $_SERVER["QUERY_STRING"];
    $cache = new pageCache(pageUrl(),startsWith($query,'do=rss') && !isLoggedIn());
    $cached = $cache->cachedVersion(); if (!empty($cached)) { echo $cached; exit; }

    // If cached was not found (or not usable), then read the database and build the response:
    $LINKSDB=new linkdb(isLoggedIn() || $GLOBALS['config']['OPEN_SHAARLI']);  // Read links from database (and filter private links if used it not logged in).

    // Optionnaly filter the results:
    $linksToDisplay=array();
    if (!empty($_GET['searchterm'])) $linksToDisplay = $LINKSDB->filterFulltext($_GET['searchterm']);
    elseif (!empty($_GET['searchtags']))   $linksToDisplay = $LINKSDB->filterTags(trim($_GET['searchtags']));
    else $linksToDisplay = $LINKSDB;

    $pageaddr=htmlspecialchars(indexUrl());
    echo '';
    echo ''.$pageaddr.'';
    echo 'Shared linksen-en'.$pageaddr.''."\n\n";
    if (!empty($GLOBALS['config']['PUBSUBHUB_URL']))
    {
        echo '';
        echo '';
        echo '';
        echo '';
    }
    $i=0;
    $keys=array(); foreach($linksToDisplay as $key=>$value) { $keys[]=$key; }  // No, I can't use array_keys().
    while ($i<50 && $i'.$guid.''.$guid.'';
        else
            echo ''.$guid.''.$absurl.'';
        if (!$GLOBALS['config']['HIDE_TIMESTAMPS'] || isLoggedIn()) echo ''.htmlspecialchars($rfc822date)."\n";
        if ($link['tags']!='') // Adding tags to each RSS entry (as mentioned in RSS specification)
        {
            foreach(explode(' ',$link['tags']) as $tag) { echo ''.htmlspecialchars($tag).''."\n"; }
        }

        // Add permalink in description
        $descriptionlink = '(Permalink)';
        // If user wants permalinks first, put the final link in description
        if ($usepermalinks===true) $descriptionlink = '(Link)';
        if (strlen($link['description'])>0) $descriptionlink = '
'.$descriptionlink;
        echo ''."\n\n";
        $i++;
    }
    echo '';

    $cache->cache(ob_get_contents());
    ob_end_flush();
    exit;
}

// ------------------------------------------------------------------------------------------
// Ouput the last 50 links in ATOM format.
function showATOM()
{
    header('Content-Type: application/atom+xml; charset=utf-8');

    // $usepermalink : If true, use permalink instead of final link.
    // User just has to add 'permalink' in URL parameters. eg. http://mysite.com/shaarli/?do=atom&permalinks
    $usepermalinks = isset($_GET['permalinks']);

    // Cache system
    $query = $_SERVER["QUERY_STRING"];
    $cache = new pageCache(pageUrl(),startsWith($query,'do=atom') && !isLoggedIn());
    $cached = $cache->cachedVersion(); if (!empty($cached)) { echo $cached; exit; }
    // If cached was not found (or not usable), then read the database and build the response:

    $LINKSDB=new linkdb(isLoggedIn() || $GLOBALS['config']['OPEN_SHAARLI']);  // Read links from database (and filter private links if used it not logged in).


    // Optionnaly filter the results:
    $linksToDisplay=array();
    if (!empty($_GET['searchterm'])) $linksToDisplay = $LINKSDB->filterFulltext($_GET['searchterm']);
    elseif (!empty($_GET['searchtags']))   $linksToDisplay = $LINKSDB->filterTags(trim($_GET['searchtags']));
    else $linksToDisplay = $LINKSDB;

    $pageaddr=htmlspecialchars(indexUrl());
    $latestDate = '';
    $entries='';
    $i=0;
    $keys=array(); foreach($linksToDisplay as $key=>$value) { $keys[]=$key; }  // No, I can't use array_keys().
    while ($i<50 && $i';
        if ($usepermalinks===true)
            $entries.=''.$guid.'';
        else
            $entries.=''.$guid.'';
        if (!$GLOBALS['config']['HIDE_TIMESTAMPS'] || isLoggedIn()) $entries.=''.htmlspecialchars($iso8601date).'';

        // Add permalink in description
        $descriptionlink = htmlspecialchars('(Permalink)');
        // If user wants permalinks first, put the final link in description
        if ($usepermalinks===true) $descriptionlink = htmlspecialchars('(Link)');
        if (strlen($link['description'])>0) $descriptionlink = '<br>'.$descriptionlink;

        $entries.=''.htmlspecialchars(nl2br(keepMultipleSpaces(text2clickable(htmlspecialchars($link['description']))))).$descriptionlink."\n";
        if ($link['tags']!='') // Adding tags to each ATOM entry (as mentioned in ATOM specification)
        {
            foreach(explode(' ',$link['tags']) as $tag)
                { $entries.=''."\n"; }
        }
        $entries.="\n";
        $i++;
    }
    $feed='';
    $feed.='';
    if (!$GLOBALS['config']['HIDE_TIMESTAMPS'] || isLoggedIn()) $feed.=''.htmlspecialchars($latestDate).'';
    $feed.='';
    if (!empty($GLOBALS['config']['PUBSUBHUB_URL']))
    {
        $feed.='';
        $feed.='';
        $feed.='';
    }
    $feed.=''.htmlspecialchars($pageaddr).''.htmlspecialchars($pageaddr).'';
    $feed.=''.htmlspecialchars($pageaddr).''."\n\n"; // Yes, I know I should use a real IRI (RFC3987), but the site URL will do.
    $feed.=$entries;
    $feed.='';
    echo $feed;

    $cache->cache(ob_get_contents());
    ob_end_flush();
    exit;
}

// ------------------------------------------------------------------------------------------
// Daily RSS feed: 1 RSS entry per day giving all the links on that day.
// Gives the last 7 days (which have links).
// This RSS feed cannot be filtered.
function showDailyRSS()
{
    // Cache system
    $query = $_SERVER["QUERY_STRING"];
    $cache = new pageCache(pageUrl(),startsWith($query,'do=dailyrss') && !isLoggedIn());
    $cached = $cache->cachedVersion(); if (!empty($cached)) { echo $cached; exit; }
    // If cached was not found (or not usable), then read the database and build the response:
    $LINKSDB=new linkdb(isLoggedIn() || $GLOBALS['config']['OPEN_SHAARLI']);  // Read links from database (and filter private links if used it not logged in).

    /* Some Shaarlies may have very few links, so we need to look
       back in time (rsort()) until we have enough days ($nb_of_days).
    */
    $linkdates=array(); foreach($LINKSDB as $linkdate=>$value) { $linkdates[]=$linkdate; }
    rsort($linkdates);
    $nb_of_days=7; // We take 7 days.
    $today=Date('Ymd');
    $days=array();
    foreach($linkdates as $linkdate)
    {
        $day=substr($linkdate,0,8); // Extract day (without time)
        if (strcmp($day,$today)<0)
        {
            if (empty($days[$day])) $days[$day]=array();
            $days[$day][]=$linkdate;
        }
        if (count($days)>$nb_of_days) break; // Have we collected enough days ?
    }

    // Build the RSS feed.
    header('Content-Type: application/rss+xml; charset=utf-8');
    $pageaddr=htmlspecialchars(indexUrl());
    echo '';
    echo ''.$pageaddr.'';
    echo 'Daily shared linksen-en'.$pageaddr.''."\n";

    foreach($days as $day=>$linkdates) // For each day.
    {
        $daydate = utf8_encode(strftime('%A %d, %B %Y',linkdate2timestamp($day.'_000000'))); // Full text date
        $rfc822date = linkdate2rfc822($day.'_000000');
        $absurl=htmlspecialchars(indexUrl().'?do=daily&day='.$day);  // Absolute URL of the corresponding "Daily" page.
        echo ''.$absurl.''.$absurl.'';
        echo ''.htmlspecialchars($rfc822date)."";

        // Build the HTML body of this RSS entry.
        $html='';
        $href='';
        $links=array();
        // We pre-format some fields for proper output.
        foreach($linkdates as $linkdate)
        {
            $l = $LINKSDB[$linkdate];
            $l['formatedDescription']=nl2br(keepMultipleSpaces(text2clickable(htmlspecialchars($l['description']))));
            $l['thumbnail'] = thumbnail($l['url']);
            $l['localdate']=linkdate2locale($l['linkdate']);
            if (startsWith($l['url'],'?')) $l['url']=indexUrl().$l['url'];  // make permalink URL absolute
            $links[$linkdate]=$l;
        }
        // Then build the HTML for this day:
        $tpl = new RainTPL;
        $tpl->assign('links',$links);
        $html = $tpl->draw('dailyrss',$return_string=true);
        echo "\n";
        echo ''."\n\n\n";

    }
    echo '';

    $cache->cache(ob_get_contents());
    ob_end_flush();
    exit;
}

// "Daily" page.
function showDaily()
{
    $LINKSDB=new linkdb(isLoggedIn() || $GLOBALS['config']['OPEN_SHAARLI']);  // Read links from database (and filter private links if used it not logged in).


    $day=Date('Ymd',strtotime('-1 day')); // Yesterday, in format YYYYMMDD.
    if (isset($_GET['day'])) $day=$_GET['day'];

    $days = $LINKSDB->days();
    $i = array_search($day,$days);
    if ($i==false) { $i=count($days)-1; $day=$days[$i]; }
    $previousday='';
    $nextday='';
    if ($i!==false)
    {
        if ($i>1) $previousday=$days[$i-1];
        if ($ifilterDay($day);
    // We pre-format some fields for proper output.
    foreach($linksToDisplay as $key=>$link)
    {
        $taglist = explode(' ',$link['tags']);
        uasort($taglist, 'strcasecmp');
        $linksToDisplay[$key]['taglist']=$taglist;
        $linksToDisplay[$key]['formatedDescription']=nl2br(keepMultipleSpaces(text2clickable(htmlspecialchars($link['description']))));
        $linksToDisplay[$key]['thumbnail'] = thumbnail($link['url']);
    }

    /* We need to spread the articles on 3 columns.
       I did not want to use a javascript lib like http://masonry.desandro.com/
       so I manually spread entries with a simple method: I roughly evaluate the
       height of a div according to title and description length.
    */
    $columns=array(array(),array(),array()); // Entries to display, for each column.
    $fill=array(0,0,0);  // Rough estimate of columns fill.
    foreach($linksToDisplay as $key=>$link)
    {
        // Roughly estimate length of entry (by counting characters)
        // Title: 30 chars = 1 line. 1 line is 30 pixels height.
        // Description: 836 characters gives roughly 342 pixel height.
        // This is not perfect, but it's usually ok.
        $length=strlen($link['title'])+(342*strlen($link['description']))/836;
        if ($link['thumbnail']) $length +=100; // 1 thumbnails roughly takes 100 pixels height.
        // Then put in column which is the less filled:
        $smallest=min($fill); // find smallest value in array.
        $index=array_search($smallest,$fill); // find index of this smallest value.
        array_push($columns[$index],$link); // Put entry in this column.
        $fill[$index]+=$length;
    }
    $PAGE = new pageBuilder;
    $PAGE->assign('linksToDisplay',$linksToDisplay);
    $PAGE->assign('linkcount',count($LINKSDB));
    $PAGE->assign('col1',$columns[0]);
    $PAGE->assign('col1',$columns[0]);
    $PAGE->assign('col2',$columns[1]);
    $PAGE->assign('col3',$columns[2]);
    $PAGE->assign('day',utf8_encode(strftime('%A %d, %B %Y',linkdate2timestamp($day.'_000000'))));
    $PAGE->assign('previousday',$previousday);
    $PAGE->assign('nextday',$nextday);
    $PAGE->renderPage('daily');
    exit;
}


// ------------------------------------------------------------------------------------------
// Render HTML page (according to URL parameters and user rights)
function renderPage()
{
    $LINKSDB=new linkdb(isLoggedIn() || $GLOBALS['config']['OPEN_SHAARLI']);  // Read links from database (and filter private links if used it not logged in).

    // -------- Display login form.
    if (isset($_SERVER["QUERY_STRING"]) && startswith($_SERVER["QUERY_STRING"],'do=login'))
    {
        if ($GLOBALS['config']['OPEN_SHAARLI']) { header('Location: ?'); exit; }  // No need to login for open Shaarli
        $token=''; if (ban_canLogin()) $token=getToken(); // Do not waste token generation if not useful.
        $PAGE = new pageBuilder;
        $PAGE->assign('token',$token);
        $PAGE->assign('returnurl',(isset($_SERVER['HTTP_REFERER']) ? $_SERVER['HTTP_REFERER']:''));
        $PAGE->renderPage('loginform');
        exit;
    }
    // -------- User wants to logout.
    if (isset($_SERVER["QUERY_STRING"]) && startswith($_SERVER["QUERY_STRING"],'do=logout'))
    {
        invalidateCaches();
        logout();
        header('Location: ?');
        exit;
    }

    // -------- Picture wall
    if (isset($_SERVER["QUERY_STRING"]) && startswith($_SERVER["QUERY_STRING"],'do=picwall'))
    {
        // Optionnaly filter the results:
        $links=array();
        if (!empty($_GET['searchterm'])) $links = $LINKSDB->filterFulltext($_GET['searchterm']);
        elseif (!empty($_GET['searchtags']))   $links = $LINKSDB->filterTags(trim($_GET['searchtags']));
        else $links = $LINKSDB;
        $body='';
        $linksToDisplay=array();

        // Get only links which have a thumbnail.
        foreach($links as $link)
        {
            $permalink='?'.htmlspecialchars(smallhash($link['linkdate']),ENT_QUOTES);
            $thumb=lazyThumbnail($link['url'],$permalink);
            if ($thumb!='') // Only output links which have a thumbnail.
            {
                $link['thumbnail']=$thumb; // Thumbnail HTML code.
                $link['permalink']=$permalink;
                $linksToDisplay[]=$link; // Add to array.
            }
        }
        $PAGE = new pageBuilder;
        $PAGE->assign('linkcount',count($LINKSDB));
        $PAGE->assign('linksToDisplay',$linksToDisplay);
        $PAGE->renderPage('picwall');
        exit;
    }

    // -------- Tag cloud
    if (isset($_SERVER["QUERY_STRING"]) && startswith($_SERVER["QUERY_STRING"],'do=tagcloud'))
    {
        $tags= $LINKSDB->allTags();
        // We sort tags alphabetically, then choose a font size according to count.
        // First, find max value.
        $maxcount=0; foreach($tags as $key=>$value) $maxcount=max($maxcount,$value);
        ksort($tags);
        $tagList=array();
        foreach($tags as $key=>$value)
        {
            $tagList[$key] = array('count'=>$value,'size'=>max(40*$value/$maxcount,8));
        }
        $PAGE = new pageBuilder;
        $PAGE->assign('linkcount',count($LINKSDB));
        $PAGE->assign('tags',$tagList);
        $PAGE->renderPage('tagcloud');
        exit;
    }

    // -------- User clicks on a tag in a link: The tag is added to the list of searched tags (searchtags=...)
    if (isset($_GET['addtag']))
    {
        // Get previous URL (http_referer) and add the tag to the searchtags parameters in query.
        if (empty($_SERVER['HTTP_REFERER'])) { header('Location: ?searchtags='.urlencode($_GET['addtag'])); exit; } // In case browser does not send HTTP_REFERER
        parse_str(parse_url($_SERVER['HTTP_REFERER'],PHP_URL_QUERY), $params);
        $params['searchtags'] = (empty($params['searchtags']) ?  trim($_GET['addtag']) : trim($params['searchtags']).' '.trim($_GET['addtag']));
        unset($params['page']); // We also remove page (keeping the same page has no sense, since the results are different)
        header('Location: ?'.http_build_query($params));
        exit;
    }

    // -------- User clicks on a tag in result count: Remove the tag from the list of searched tags (searchtags=...)
    if (isset($_GET['removetag']))
    {
        // Get previous URL (http_referer) and remove the tag from the searchtags parameters in query.
        if (empty($_SERVER['HTTP_REFERER'])) { header('Location: ?'); exit; } // In case browser does not send HTTP_REFERER
        parse_str(parse_url($_SERVER['HTTP_REFERER'],PHP_URL_QUERY), $params);
        if (isset($params['searchtags']))
        {
            $tags = explode(' ',$params['searchtags']);
            $tags=array_diff($tags, array($_GET['removetag'])); // Remove value from array $tags.
            if (count($tags)==0) unset($params['searchtags']); else $params['searchtags'] = implode(' ',$tags);
            unset($params['page']); // We also remove page (keeping the same page has no sense, since the results are different)
        }
        header('Location: ?'.http_build_query($params));
        exit;
    }

    // -------- User wants to change the number of links per page (linksperpage=...)
    if (isset($_GET['linksperpage']))
    {
        if (is_numeric($_GET['linksperpage'])) { $_SESSION['LINKS_PER_PAGE']=abs(intval($_GET['linksperpage'])); }
        // Make sure the referer is from Shaarli itself.
        $referer = '?';
        if (!empty($_SERVER['HTTP_REFERER']) && strcmp(parse_url($_SERVER['HTTP_REFERER'],PHP_URL_HOST),$_SERVER['SERVER_NAME'])==0)
            $referer = $_SERVER['HTTP_REFERER'];
        header('Location: '.$referer);
        exit;
    }

    // -------- User wants to see only private links (toggle)
    if (isset($_GET['privateonly']))
    {
        if (empty($_SESSION['privateonly']))
        {
            $_SESSION['privateonly']=1; // See only private links
        }
        else
        {
            unset($_SESSION['privateonly']); // See all links
        }
        // Make sure the referer is from Shaarli itself.
        $referer = '?';
        if (!empty($_SERVER['HTTP_REFERER']) && strcmp(parse_url($_SERVER['HTTP_REFERER'],PHP_URL_HOST),$_SERVER['SERVER_NAME'])==0)
            $referer = $_SERVER['HTTP_REFERER'];
        header('Location: '.$referer);
        exit;
    }

    // -------- Handle other actions allowed for non-logged in users:
    if (!isLoggedIn())
    {
        // User tries to post new link but is not loggedin:
        // Show login screen, then redirect to ?post=...
        if (isset($_GET['post']))
        {
            header('Location: ?do=login&post='.urlencode($_GET['post']).(!empty($_GET['title'])?'&title='.urlencode($_GET['title']):'').(!empty($_GET['source'])?'&source='.urlencode($_GET['source']):'')); // Redirect to login page, then back to post link.
            exit;
        }
        $PAGE = new pageBuilder;
        buildLinkList($PAGE,$LINKSDB); // Compute list of links to display
        $PAGE->renderPage('linklist');
        exit; // Never remove this one ! All operations below are reserved for logged in user.
    }

    // -------- All other functions are reserved for the registered user:

    // -------- Display the Tools menu if requested (import/export/bookmarklet...)
    if (isset($_SERVER["QUERY_STRING"]) && startswith($_SERVER["QUERY_STRING"],'do=tools'))
    {
        $PAGE = new pageBuilder;
        $PAGE->assign('linkcount',count($LINKSDB));
        $PAGE->assign('pageabsaddr',indexUrl());
        $PAGE->renderPage('tools');
        exit;
    }

    // -------- User wants to change his/her password.
    if (isset($_SERVER["QUERY_STRING"]) && startswith($_SERVER["QUERY_STRING"],'do=changepasswd'))
    {
        if ($GLOBALS['config']['OPEN_SHAARLI']) die('You are not supposed to change a password on an Open Shaarli.');
        if (!empty($_POST['setpassword']) && !empty($_POST['oldpassword']))
        {
            if (!tokenOk($_POST['token'])) die('Wrong token.'); // Go away !

            // Make sure old password is correct.
            $oldhash = sha1($_POST['oldpassword'].$GLOBALS['login'].$GLOBALS['salt']);
            if ($oldhash!=$GLOBALS['hash']) { echo ''; exit; }
            // Save new password
            $GLOBALS['salt'] = sha1(uniqid('',true).'_'.mt_rand()); // Salt renders rainbow-tables attacks useless.
            $GLOBALS['hash'] = sha1($_POST['setpassword'].$GLOBALS['login'].$GLOBALS['salt']);
            writeConfig();
            echo '';
            exit;
        }
        else // show the change password form.
        {
            $PAGE = new pageBuilder;
            $PAGE->assign('linkcount',count($LINKSDB));
            $PAGE->assign('token',getToken());
            $PAGE->renderPage('changepassword');
            exit;
        }
    }

    // -------- User wants to change configuration
    if (isset($_SERVER["QUERY_STRING"]) && startswith($_SERVER["QUERY_STRING"],'do=configure'))
    {
        if (!empty($_POST['title']) )
        {
            if (!tokenOk($_POST['token'])) die('Wrong token.'); // Go away !
            $tz = 'UTC';
            if (!empty($_POST['continent']) && !empty($_POST['city']))
                if (isTZvalid($_POST['continent'],$_POST['city']))
                    $tz = $_POST['continent'].'/'.$_POST['city'];
            $GLOBALS['timezone'] = $tz;
            $GLOBALS['title']=$_POST['title'];
            $GLOBALS['redirector']=$_POST['redirector'];
            $GLOBALS['disablesessionprotection']=!empty($_POST['disablesessionprotection']);
            $GLOBALS['disablejquery']=!empty($_POST['disablejquery']);
            $GLOBALS['privateLinkByDefault']=!empty($_POST['privateLinkByDefault']);
            writeConfig();
            echo '';
            exit;
        }
        else // Show the configuration form.
        {
            $PAGE = new pageBuilder;
            $PAGE->assign('linkcount',count($LINKSDB));
            $PAGE->assign('token',getToken());
            $PAGE->assign('title',htmlspecialchars( empty($GLOBALS['title']) ? '' : $GLOBALS['title'] , ENT_QUOTES));
            $PAGE->assign('redirector',htmlspecialchars( empty($GLOBALS['redirector']) ? '' : $GLOBALS['redirector'] , ENT_QUOTES));
            list($timezone_form,$timezone_js) = templateTZform($GLOBALS['timezone']);
            $PAGE->assign('timezone_form',$timezone_form); // FIXME: put entire tz form generation in template ?
            $PAGE->assign('timezone_js',$timezone_js);
            $PAGE->renderPage('configure');
            exit;
        }
    }

    // -------- User wants to rename a tag or delete it
    if (isset($_SERVER["QUERY_STRING"]) && startswith($_SERVER["QUERY_STRING"],'do=changetag'))
    {
        if (empty($_POST['fromtag']))
        {
            $PAGE = new pageBuilder;
            $PAGE->assign('linkcount',count($LINKSDB));
            $PAGE->assign('token',getToken());
            $PAGE->renderPage('changetag');
            exit;
        }
        if (!tokenOk($_POST['token'])) die('Wrong token.');

        // Delete a tag:
        if (!empty($_POST['deletetag']) && !empty($_POST['fromtag']))
        {
            $needle=trim($_POST['fromtag']);
            $linksToAlter = $LINKSDB->filterTags($needle,true); // true for case-sensitive tag search.
            foreach($linksToAlter as $key=>$value)
            {
                $tags = explode(' ',trim($value['tags']));
                unset($tags[array_search($needle,$tags)]); // Remove tag.
                $value['tags']=trim(implode(' ',$tags));
                $LINKSDB[$key]=$value;
            }
            $LINKSDB->savedb(); // save to disk
            echo '';
            exit;
        }

        // Rename a tag:
        if (!empty($_POST['renametag']) && !empty($_POST['fromtag']) && !empty($_POST['totag']))
        {
            $needle=trim($_POST['fromtag']);
            $linksToAlter = $LINKSDB->filterTags($needle,true); // true for case-sensitive tag search.
            foreach($linksToAlter as $key=>$value)
            {
                $tags = explode(' ',trim($value['tags']));
                $tags[array_search($needle,$tags)] = trim($_POST['totag']); // Remplace tags value.
                $value['tags']=trim(implode(' ',$tags));
                $LINKSDB[$key]=$value;
            }
            $LINKSDB->savedb(); // save to disk
            echo '';
            exit;
        }
    }

    // -------- User wants to add a link without using the bookmarklet: show form.
    if (isset($_SERVER["QUERY_STRING"]) && startswith($_SERVER["QUERY_STRING"],'do=addlink'))
    {
        $PAGE = new pageBuilder;
        $PAGE->assign('linkcount',count($LINKSDB));
        $PAGE->renderPage('addlink');
        exit;
    }

    // -------- User clicked the "Save" button when editing a link: Save link to database.
    if (isset($_POST['save_edit']))
    {
        if (!tokenOk($_POST['token'])) die('Wrong token.'); // Go away !
        $tags = trim(preg_replace('/\s\s+/',' ', $_POST['lf_tags'])); // Remove multiple spaces.
        $linkdate=$_POST['lf_linkdate'];
        $url = trim($_POST['lf_url']);
        if (!startsWith($url,'http:') && !startsWith($url,'https:') && !startsWith($url,'ftp:') && !startsWith($url,'magnet:') && !startsWith($url,'?'))
            $url = 'http://'.$url;
        $link = array('title'=>trim($_POST['lf_title']),'url'=>$url,'description'=>trim($_POST['lf_description']),'private'=>(isset($_POST['lf_private']) ? 1 : 0),
                      'linkdate'=>$linkdate,'tags'=>str_replace(',',' ',$tags));
        if ($link['title']=='') $link['title']=$link['url']; // If title is empty, use the URL as title.
        $LINKSDB[$linkdate] = $link;
        $LINKSDB->savedb(); // save to disk
        pubsubhub();

        // If we are called from the bookmarklet, we must close the popup:
        if (isset($_GET['source']) && $_GET['source']=='bookmarklet') { echo ''; exit; }
        $returnurl = ( isset($_POST['returnurl']) ? $_POST['returnurl'] : '?' );
        $returnurl .= '#'.smallHash($linkdate);  // Scroll to the link which has been edited.
        header('Location: '.$returnurl); // After saving the link, redirect to the page the user was on.
        exit;
    }

    // -------- User clicked the "Cancel" button when editing a link.
    if (isset($_POST['cancel_edit']))
    {
        // If we are called from the bookmarklet, we must close the popup;
        if (isset($_GET['source']) && $_GET['source']=='bookmarklet') { echo ''; exit; }
        $returnurl = ( isset($_POST['returnurl']) ? $_POST['returnurl'] : '?' );
        $returnurl .= '#'.smallHash($_POST['lf_linkdate']);  // Scroll to the link which has been edited.
        header('Location: '.$returnurl); // After canceling, redirect to the page the user was on.
        exit;
    }

    // -------- User clicked the "Delete" button when editing a link : Delete link from database.
    if (isset($_POST['delete_link']))
    {
        if (!tokenOk($_POST['token'])) die('Wrong token.');
        // We do not need to ask for confirmation:
        // - confirmation is handled by javascript
        // - we are protected from XSRF by the token.
        $linkdate=$_POST['lf_linkdate'];
        unset($LINKSDB[$linkdate]);
        $LINKSDB->savedb(); // save to disk

        // If we are called from the bookmarklet, we must close the popup:
        if (isset($_GET['source']) && $_GET['source']=='bookmarklet') { echo ''; exit; }
        $returnurl = ( isset($_POST['returnurl']) ? $_POST['returnurl'] : '?' );
        if ($returnurl=='?') { $returnurl = (isset($_SERVER['HTTP_REFERER']) ? $_SERVER['HTTP_REFERER'] : '?'); }
        header('Location: '.$returnurl); // After deleting the link, redirect to the page the user was on.
        exit;
    }

    // -------- User clicked the "EDIT" button on a link: Display link edit form.
    if (isset($_GET['edit_link']))
    {
        $link = $LINKSDB[$_GET['edit_link']];  // Read database
        if (!$link) { header('Location: ?'); exit; } // Link not found in database.
        $PAGE = new pageBuilder;
        $PAGE->assign('linkcount',count($LINKSDB));
        $PAGE->assign('link',$link);
        $PAGE->assign('link_is_new',false);
        $PAGE->assign('token',getToken()); // XSRF protection.
        $PAGE->assign('http_referer',(isset($_SERVER['HTTP_REFERER']) ? $_SERVER['HTTP_REFERER'] : ''));
        $PAGE->renderPage('editlink');
        exit;
    }

    // -------- User want to post a new link: Display link edit form.
    if (isset($_GET['post']))
    {
        $url=$_GET['post'];

        // We remove the annoying parameters added by FeedBurner and GoogleFeedProxy (?utm_source=...)
        $i=strpos($url,'&utm_source='); if ($i!==false) $url=substr($url,0,$i);
        $i=strpos($url,'?utm_source='); if ($i!==false) $url=substr($url,0,$i);
        $i=strpos($url,'#xtor=RSS-'); if ($i!==false) $url=substr($url,0,$i);

        $link_is_new = false;
        $link = $LINKSDB->getLinkFromUrl($url); // Check if URL is not already in database (in this case, we will edit the existing link)
        if (!$link)
        {
            $link_is_new = true;  // This is a new link
            $linkdate = strval(date('Ymd_His'));
            $title = (empty($_GET['title']) ? '' : $_GET['title'] ); // Get title if it was provided in URL (by the bookmarklet).
            $description=''; $tags=''; $private=0;
            if (($url!='') && parse_url($url,PHP_URL_SCHEME)=='') $url = 'http://'.$url;
            // If this is an HTTP link, we try go get the page to extact the title (otherwise we will to straight to the edit form.)
            if (empty($title) && parse_url($url,PHP_URL_SCHEME)=='http')
            {
                list($status,$headers,$data) = getHTTP($url,4); // Short timeout to keep the application responsive.
                // FIXME: Decode charset according to specified in either 1) HTTP response headers or 2)  in html
                if (strpos($status,'200 OK')!==false) $title=html_entity_decode(html_extract_title($data),ENT_QUOTES,'UTF-8');

            }
            if ($url=='') $url='?'.smallHash($linkdate); // In case of empty URL, this is just a text (with a link that point to itself)
            $link = array('linkdate'=>$linkdate,'title'=>$title,'url'=>$url,'description'=>$description,'tags'=>$tags,'private'=>0);
        }

        $PAGE = new pageBuilder;
        $PAGE->assign('linkcount',count($LINKSDB));
        $PAGE->assign('link',$link);
        $PAGE->assign('link_is_new',$link_is_new);
        $PAGE->assign('token',getToken()); // XSRF protection.
        $PAGE->assign('http_referer',(isset($_SERVER['HTTP_REFERER']) ? $_SERVER['HTTP_REFERER'] : ''));
        $PAGE->renderPage('editlink');
        exit;
    }

    // -------- Export as Netscape Bookmarks HTML file.
    if (isset($_SERVER["QUERY_STRING"]) && startswith($_SERVER["QUERY_STRING"],'do=export'))
    {
        if (empty($_GET['what']))
        {
            $PAGE = new pageBuilder;
            $PAGE->assign('linkcount',count($LINKSDB));
            $PAGE->renderPage('export');
            exit;
        }
        $exportWhat=$_GET['what'];
        if (!array_intersect(array('all','public','private'),array($exportWhat))) die('What are you trying to export ???');

        header('Content-Type: text/html; charset=utf-8');
        header('Content-disposition: attachment; filename=bookmarks_'.$exportWhat.'_'.strval(date('Ymd_His')).'.html');
        $currentdate=date('Y/m/d H:i:s');
        echo <<




Bookmarks
HTML;
        foreach($LINKSDB as $link)
        {
            if ($exportWhat=='all' ||
               ($exportWhat=='private' && $link['private']!=0) ||
               ($exportWhat=='public' && $link['private']==0))
            {
                echo '
'.htmlspecialchars($link['title'])."\n";
                if ($link['description']!='') echo '
'.htmlspecialchars($link['description'])."\n";
            }
        }
                exit;
    }

    // -------- User is uploading a file for import
    if (isset($_SERVER["QUERY_STRING"]) && startswith($_SERVER["QUERY_STRING"],'do=upload'))
    {
        // If file is too big, some form field may be missing.
        if (!isset($_POST['token']) || (!isset($_FILES)) || (isset($_FILES['filetoupload']['size']) && $_FILES['filetoupload']['size']==0))
        {
            $returnurl = ( empty($_SERVER['HTTP_REFERER']) ? '?' : $_SERVER['HTTP_REFERER'] );
            echo '';
            exit;
        }
        if (!tokenOk($_POST['token'])) die('Wrong token.');
        importFile();
        exit;
    }

    // -------- Show upload/import dialog:
    if (isset($_SERVER["QUERY_STRING"]) && startswith($_SERVER["QUERY_STRING"],'do=import'))
    {
        $PAGE = new pageBuilder;
        $PAGE->assign('linkcount',count($LINKSDB));
        $PAGE->assign('token',getToken());
        $PAGE->assign('maxfilesize',getMaxFileSize());
        $PAGE->renderPage('import');
        exit;
    }

    // -------- Otherwise, simply display search form and links:
    $PAGE = new pageBuilder;
    $PAGE->assign('linkcount',count($LINKSDB));
    buildLinkList($PAGE,$LINKSDB); // Compute list of links to display
    $PAGE->renderPage('linklist');
    exit;
}

// -----------------------------------------------------------------------------------------------
// Process the import file form.
function importFile()
{
    if (!(isLoggedIn() || $GLOBALS['config']['OPEN_SHAARLI'])) { die('Not allowed.'); }
    $LINKSDB=new linkdb(isLoggedIn() || $GLOBALS['config']['OPEN_SHAARLI']);  // Read links from database (and filter private links if used it not logged in).
    $filename=$_FILES['filetoupload']['name'];
    $filesize=$_FILES['filetoupload']['size'];
    $data=file_get_contents($_FILES['filetoupload']['tmp_name']);
    $private = (empty($_POST['private']) ? 0 : 1); // Should the links be imported as private ?
    $overwrite = !empty($_POST['overwrite']) ; // Should the imported links overwrite existing ones ?
    $import_count=0;

    // Sniff file type:
    $type='unknown';
    if (startsWith($data,'')) $type='netscape'; // Netscape bookmark file (aka Firefox).

    // Then import the bookmarks.
    if ($type=='netscape')
    {
        // This is a standard Netscape-style bookmark file.
        // This format is supported by all browsers (except IE, of course), also delicious, diigo and others.
        foreach(explode('
',$data) as $html) // explode is very fast
        {
            $link = array('linkdate'=>'','title'=>'','url'=>'','description'=>'','tags'=>'','private'=>0);
            $d = explode('
',$html);
            if (startswith($d[0],'(.*?)!i',$d[0],$matches); $link['title'] = (isset($matches[1]) ? trim($matches[1]) : '');  // Get title
                $link['title'] = html_entity_decode($link['title'],ENT_QUOTES,'UTF-8');
                preg_match_all('! ([A-Z_]+)=\"(.*?)"!i',$html,$matches,PREG_SET_ORDER);  // Get all other attributes
                $raw_add_date=0;
                foreach($matches as $m)
                {
                    $attr=$m[1]; $value=$m[2];
                    if ($attr=='HREF') $link['url']=html_entity_decode($value,ENT_QUOTES,'UTF-8');
                    elseif ($attr=='ADD_DATE') $raw_add_date=intval($value);
                    elseif ($attr=='PRIVATE') $link['private']=($value=='0'?0:1);
                    elseif ($attr=='TAGS') $link['tags']=html_entity_decode(str_replace(',',' ',$value),ENT_QUOTES,'UTF-8');
                }
                if ($link['url']!='')
                {
                    if ($private==1) $link['private']=1;
                    $dblink = $LINKSDB->getLinkFromUrl($link['url']); // See if the link is already in database.
                    if ($dblink==false)
                    {  // Link not in database, let's import it...
                       if (empty($raw_add_date)) $raw_add_date=time(); // In case of shitty bookmark file with no ADD_DATE

                       // Make sure date/time is not already used by another link.
                       // (Some bookmark files have several different links with the same ADD_DATE)
                       // We increment date by 1 second until we find a date which is not used in db.
                       // (so that links that have the same date/time are more or less kept grouped by date, but do not conflict.)
                       while (!empty($LINKSDB[date('Ymd_His',$raw_add_date)])) { $raw_add_date++; }// Yes, I know it's ugly.
                       $link['linkdate']=date('Ymd_His',$raw_add_date);
                       $LINKSDB[$link['linkdate']] = $link;
                       $import_count++;
                    }
                    else // link already present in database.
                    {
                        if ($overwrite)
                        {   // If overwrite is required, we import link data, except date/time.
                            $link['linkdate']=$dblink['linkdate'];
                            $LINKSDB[$link['linkdate']] = $link;
                            $import_count++;
                        }
                    }

                }
            }
        }
        $LINKSDB->savedb();

        echo '';
    }
    else
    {
        echo '';
    }
}

// -----------------------------------------------------------------------------------------------
// Template for the list of links (
)
// This function fills all the necessary fields in the $PAGE for the template 'linklist.html'
function buildLinkList($PAGE,$LINKSDB)
{
    // ---- Filter link database according to parameters
    $linksToDisplay=array();
    $search_type='';
    $search_crits='';
    if (isset($_GET['searchterm'])) // Fulltext search
    {
        $linksToDisplay = $LINKSDB->filterFulltext(trim($_GET['searchterm']));
        $search_crits=htmlspecialchars(trim($_GET['searchterm']));
        $search_type='fulltext';
    }
    elseif (isset($_GET['searchtags'])) // Search by tag
    {
        $linksToDisplay = $LINKSDB->filterTags(trim($_GET['searchtags']));
        $search_crits=explode(' ',trim($_GET['searchtags']));
        $search_type='tags';
    }
    elseif (isset($_SERVER['QUERY_STRING']) && preg_match('/[a-zA-Z0-9-_@]{6}(&.+?)?/',$_SERVER['QUERY_STRING'])) // Detect smallHashes in URL
    {
        $linksToDisplay = $LINKSDB->filterSmallHash(substr(trim($_SERVER["QUERY_STRING"], '/'),0,6));
        if (count($linksToDisplay)==0)
        {
            header($_SERVER["SERVER_PROTOCOL"]." 404 Not Found");
            echo '
404 Not found.
Oh crap. The link you are trying to reach does not exist or has been deleted.';
            echo '
You would mind clicking here ?';
            exit;
        }
        $search_type='permalink';
    }
    else
        $linksToDisplay = $LINKSDB;  // otherwise, display without filtering.

    // Option: Show only private links
    if (!empty($_SESSION['privateonly']))
    {
        $tmp = array();
        foreach($linksToDisplay as $linkdate=>$link)
        {
            if ($link['private']!=0) $tmp[$linkdate]=$link;
        }
        $linksToDisplay=$tmp;
    }

    // ---- Handle paging.
    /* Can someone explain to me why you get the following error when using array_keys() on an object which implements the interface ArrayAccess ???
       "Warning: array_keys() expects parameter 1 to be array, object given in ... "
       If my class implements ArrayAccess, why won't array_keys() accept it ?  ( $keys=array_keys($linksToDisplay); )
    */
    $keys=array(); foreach($linksToDisplay as $key=>$value) { $keys[]=$key; } // Stupid and ugly. Thanks php.

    // If there is only a single link, we change on-the-fly the title of the page.
    if (count($linksToDisplay)==1) $GLOBALS['pagetitle'] = $linksToDisplay[$keys[0]]['title'].' - '.$GLOBALS['title'];

    // Select articles according to paging.
    $pagecount = ceil(count($keys)/$_SESSION['LINKS_PER_PAGE']);
    $pagecount = ($pagecount==0 ? 1 : $pagecount);
    $page=( empty($_GET['page']) ? 1 : intval($_GET['page']));
    $page = ( $page<1 ? 1 : $page );
    $page = ( $page>$pagecount ? $pagecount : $page );
    $i = ($page-1)*$_SESSION['LINKS_PER_PAGE']; // Start index.
    $end = $i+$_SESSION['LINKS_PER_PAGE'];
    $linkDisp=array(); // Links to display
    while ($i<$end && $i1) $next_page_url='?page='.($page-1).$searchterm.$searchtags;

    $token = ''; if (isLoggedIn()) $token=getToken();

    // Fill all template fields.
    $PAGE->assign('linkcount',count($LINKSDB));
    $PAGE->assign('previous_page_url',$previous_page_url);
    $PAGE->assign('next_page_url',$next_page_url);
    $PAGE->assign('page_current',$page);
    $PAGE->assign('page_max',$pagecount);
    $PAGE->assign('result_count',count($linksToDisplay));
    $PAGE->assign('search_type',$search_type);
    $PAGE->assign('search_crits',$search_crits);
    $PAGE->assign('redirector',empty($GLOBALS['redirector']) ? '' : $GLOBALS['redirector']); // optional redirector URL
    $PAGE->assign('token',$token);
    $PAGE->assign('links',$linkDisp);
    return;
}

// Compute the thumbnail for a link.
//
// with a link to the original URL.
// Understands various services (youtube.com...)
// Input: $url = url for which the thumbnail must be found.
//        $href = if provided, this URL will be followed instead of $url
// Returns an associative array with thumbnail attributes (src,href,width,height,style,alt)
// Some of them may be missing.
// Return an empty array if no thumbnail available.
function computeThumbnail($url,$href=false)
{
    if (!$GLOBALS['config']['ENABLE_THUMBNAILS']) return array();
    if ($href==false) $href=$url;

    // For most hosts, the URL of the thumbnail can be easily deduced from the URL of the link.
    // (eg. http://www.youtube.com/watch?v=spVypYk4kto --->  http://img.youtube.com/vi/spVypYk4kto/default.jpg )
    //                                     ^^^^^^^^^^^                                 ^^^^^^^^^^^
    $domain = parse_url($url,PHP_URL_HOST);
    if ($domain=='youtube.com' || $domain=='www.youtube.com')
    {
        parse_str(parse_url($url,PHP_URL_QUERY), $params); // Extract video ID and get thumbnail
        if (!empty($params['v'])) return array('src'=>'http://img.youtube.com/vi/'.$params['v'].'/default.jpg',
                                               'href'=>$href,'width'=>'120','height'=>'90','alt'=>'YouTube thumbnail');
    }
    if ($domain=='youtu.be') // Youtube short links
    {
        $path = parse_url($url,PHP_URL_PATH);
        return array('src'=>'http://img.youtube.com/vi'.$path.'/default.jpg',
                     'href'=>$href,'width'=>'120','height'=>'90','alt'=>'YouTube thumbnail');
    }
    if ($domain=='pix.toile-libre.org') // pix.toile-libre.org image hosting
    {
        parse_str(parse_url($url,PHP_URL_QUERY), $params); // Extract image filename.
        if (!empty($params) && !empty($params['img'])) return array('src'=>'http://pix.toile-libre.org/upload/thumb/'.urlencode($params['img']),
                                                                    'href'=>$href,'style'=>'max-width:120px; max-height:150px','alt'=>'pix.toile-libre.org thumbnail');
    }

    if ($domain=='imgur.com')
    {
        $path = parse_url($url,PHP_URL_PATH);
        if (startsWith($path,'/a/')) return array(); // Thumbnails for albums are not available.
        if (startsWith($path,'/r/')) return array('src'=>'http://i.imgur.com/'.basename($path).'s.jpg',
                                                  'href'=>$href,'width'=>'90','height'=>'90','alt'=>'imgur.com thumbnail');
        if (startsWith($path,'/gallery/')) return array('src'=>'http://i.imgur.com'.substr($path,8).'s.jpg',
                                                        'href'=>$href,'width'=>'90','height'=>'90','alt'=>'imgur.com thumbnail');

        if (substr_count($path,'/')==1) return array('src'=>'http://i.imgur.com/'.substr($path,1).'s.jpg',
                                                     'href'=>$href,'width'=>'90','height'=>'90','alt'=>'imgur.com thumbnail');
    }
    if ($domain=='i.imgur.com')
    {
        $pi = pathinfo(parse_url($url,PHP_URL_PATH));
        if (!empty($pi['filename'])) return array('src'=>'http://i.imgur.com/'.$pi['filename'].'s.jpg',
                                                  'href'=>$href,'width'=>'90','height'=>'90','alt'=>'imgur.com thumbnail');
    }
    if ($domain=='dailymotion.com' || $domain=='www.dailymotion.com')
    {
        if (strpos($url,'dailymotion.com/video/')!==false)
        {
            $thumburl=str_replace('dailymotion.com/video/','dailymotion.com/thumbnail/video/',$url);
            return array('src'=>$thumburl,
                         'href'=>$href,'width'=>'120','style'=>'height:auto;','alt'=>'DailyMotion thumbnail');
        }
    }
    if (endsWith($domain,'.imageshack.us'))
    {
        $ext=strtolower(pathinfo($url,PATHINFO_EXTENSION));
        if ($ext=='jpg' || $ext=='jpeg' || $ext=='png' || $ext=='gif')
        {
            $thumburl = substr($url,0,strlen($url)-strlen($ext)).'th.'.$ext;
            return array('src'=>$thumburl,
                         'href'=>$href,'width'=>'120','style'=>'height:auto;','alt'=>'imageshack.us thumbnail');
        }
    }

    // Some other hosts are SLOW AS HELL and usually require an extra HTTP request to get the thumbnail URL.
    // So we deport the thumbnail generation in order not to slow down page generation
    // (and we also cache the thumbnail)

    if (!$GLOBALS['config']['ENABLE_LOCALCACHE']) return array(); // If local cache is disabled, no thumbnails for services which require the use a local cache.

    if ($domain=='flickr.com' || endsWith($domain,'.flickr.com')
        || $domain=='vimeo.com'
        || $domain=='ted.com' || endsWith($domain,'.ted.com')
        || $domain=='xkcd.com' || endsWith($domain,'.xkcd.com')
    )
    {
        if ($domain=='vimeo.com')
        {   // Make sure this vimeo url points to a video (/xxx... where xxx is numeric)
            $path = parse_url($url,PHP_URL_PATH);
            if (!preg_match('!/\d+.+?!',$path)) return array(); // This is not a single video URL.
        }
        if ($domain=='xkcd.com' || endsWith($domain,'.xkcd.com'))
        {   // Make sure this url points to a single comic (/xxx... where xxx is numeric)
            $path = parse_url($url,PHP_URL_PATH);
            if (!preg_match('!/\d+.+?!',$path)) return array();
        }
        if ($domain=='ted.com' || endsWith($domain,'.ted.com'))
        {   // Make sure this TED url points to a video (/talks/...)
            $path = parse_url($url,PHP_URL_PATH);
            if ("/talks/" !== substr($path,0,7)) return array(); // This is not a single video URL.
        }
        $sign = hash_hmac('sha256', $url, $GLOBALS['salt']); // We use the salt to sign data (it's random, secret, and specific to each installation)
        return array('src'=>indexUrl().'?do=genthumbnail&hmac='.htmlspecialchars($sign).'&url='.urlencode($url),
                     'href'=>$href,'width'=>'120','style'=>'height:auto;','alt'=>'thumbnail');
    }

    // For all other, we try to make a thumbnail of links ending with .jpg/jpeg/png/gif
    // Technically speaking, we should download ALL links and check their Content-Type to see if they are images.
    // But using the extension will do.
    $ext=strtolower(pathinfo($url,PATHINFO_EXTENSION));
    if ($ext=='jpg' || $ext=='jpeg' || $ext=='png' || $ext=='gif')
    {
        $sign = hash_hmac('sha256', $url, $GLOBALS['salt']); // We use the salt to sign data (it's random, secret, and specific to each installation)
        return array('src'=>indexUrl().'?do=genthumbnail&hmac='.htmlspecialchars($sign).'&url='.urlencode($url),
                     'href'=>$href,'width'=>'120','style'=>'height:auto;','alt'=>'thumbnail');
    }
    return array(); // No thumbnail.

}


// Returns the HTML code to display a thumbnail for a link
// with a link to the original URL.
// Understands various services (youtube.com...)
// Input: $url = url for which the thumbnail must be found.
//        $href = if provided, this URL will be followed instead of $url
// Returns '' if no thumbnail available.
function thumbnail($url,$href=false)
{
    $t = computeThumbnail($url,$href);
    if (count($t)==0) return ''; // Empty array = no thumbnail for this URL.

    $html='';

    // Lazy image (only loaded by javascript when in the viewport).
    if (!empty($GLOBALS['disablejquery'])) // (except if jQuery is disabled)
        $html.='Sessions do not seem to work correctly on your server.
';
        echo 'Make sure the variable session.save_path is set correctly in your php config, and that you have write access to it.
';
        echo 'It currently points to '.session_save_path().'

Click to try again.