22 files changed, 367 insertions, 115 deletions

diff --git a/application/ApplicationUtils.php b/application/ApplicationUtils.php
index 5643f4a0..911873a0 100644
--- a/application/ApplicationUtils.php
+++ b/application/ApplicationUtils.php
@@ -149,12 +149,13 @@ class ApplicationUtils
     public static function checkPHPVersion($minVersion, $curVersion)
     {
         if (version_compare($curVersion, $minVersion) < 0) {
-            throw new Exception(
+            $msg = t(
                 'Your PHP version is obsolete!'
-                .' Shaarli requires at least PHP '.$minVersion.', and thus cannot run.'
-                .' Your PHP version has known security vulnerabilities and should be'
-                .' updated as soon as possible.'
+                 . ' Shaarli requires at least PHP %s, and thus cannot run.'
+                 . ' Your PHP version has known security vulnerabilities and should be'
+                 . ' updated as soon as possible.'
             );
+            throw new Exception(sprintf($msg, $minVersion));
         }
     }
 
@@ -179,7 +180,7 @@ class ApplicationUtils
             $rainTplDir.'/'.$conf->get('resource.theme'),
         ) as $path) {
             if (! is_readable(realpath($path))) {
-                $errors[] = '"'.$path.'" directory is not readable';
+                $errors[] = '"'.$path.'" '. t('directory is not readable');
             }
         }
 
@@ -191,10 +192,10 @@ class ApplicationUtils
             $conf->get('resource.raintpl_tmp'),
         ) as $path) {
             if (! is_readable(realpath($path))) {
-                $errors[] = '"'.$path.'" directory is not readable';
+                $errors[] = '"'.$path.'" '. t('directory is not readable');
             }
             if (! is_writable(realpath($path))) {
-                $errors[] = '"'.$path.'" directory is not writable';
+                $errors[] = '"'.$path.'" '. t('directory is not writable');
             }
         }
 
@@ -212,10 +213,10 @@ class ApplicationUtils
             }
 
             if (! is_readable(realpath($path))) {
-                $errors[] = '"'.$path.'" file is not readable';
+                $errors[] = '"'.$path.'" '. t('file is not readable');
             }
             if (! is_writable(realpath($path))) {
-                $errors[] = '"'.$path.'" file is not writable';
+                $errors[] = '"'.$path.'" '. t('file is not writable');
             }
         }
 
diff --git a/application/Cache.php b/application/Cache.php
index 5d050165..e5d43e61 100644
--- a/application/Cache.php
+++ b/application/Cache.php
@@ -13,7 +13,7 @@
 function purgeCachedPages($pageCacheDir)
 {
     if (! is_dir($pageCacheDir)) {
-        $error = 'Cannot purge '.$pageCacheDir.': no directory';
+        $error = sprintf(t('Cannot purge %s: no directory'), $pageCacheDir);
         error_log($error);
         return $error;
     }
diff --git a/application/FeedBuilder.php b/application/FeedBuilder.php
index 7377bcec..ebae18b4 100644
--- a/application/FeedBuilder.php
+++ b/application/FeedBuilder.php
@@ -148,11 +148,11 @@ class FeedBuilder
             $link['url'] = $pageaddr . $link['url'];
         }
         if ($this->usePermalinks === true) {
-            $permalink = '<a href="'. $link['url'] .'" title="Direct link">Direct link</a>';
+            $permalink = '<a href="'. $link['url'] .'" title="'. t('Direct link') .'">'. t('Direct link') .'</a>';
         } else {
-            $permalink = '<a href="'. $link['guid'] .'" title="Permalink">Permalink</a>';
+            $permalink = '<a href="'. $link['guid'] .'" title="'. t('Permalink') .'">'. t('Permalink') .'</a>';
         }
-        $link['description']  = format_description($link['description'], '', $pageaddr);
+        $link['description']  = format_description($link['description'], '', false, $pageaddr);
         $link['description'] .= PHP_EOL .'<br>&#8212; '. $permalink;
 
         $pubDate = $link['created'];
diff --git a/application/History.php b/application/History.php
index 5e3b1b72..35ec016a 100644
--- a/application/History.php
+++ b/application/History.php
@@ -171,7 +171,7 @@ class History
         }
 
         if (! is_writable($this->historyFilePath)) {
-            throw new Exception('History file isn\'t readable or writable');
+            throw new Exception(t('History file isn\'t readable or writable'));
         }
     }
 
@@ -182,7 +182,7 @@ class History
     {
         $this->history = FileUtils::readFlatDB($this->historyFilePath, []);
         if ($this->history === false) {
-            throw new Exception('Could not parse history file');
+            throw new Exception(t('Could not parse history file'));
         }
     }
 
diff --git a/application/HttpUtils.php b/application/HttpUtils.php
index 00835966..c9371b55 100644
--- a/application/HttpUtils.php
+++ b/application/HttpUtils.php
@@ -76,7 +76,7 @@ function get_http_response($url, $timeout = 30, $maxBytes = 4194304)
     curl_setopt($ch, CURLOPT_USERAGENT,         $userAgent);
 
     // Max download size management
-    curl_setopt($ch, CURLOPT_BUFFERSIZE,        1024);
+    curl_setopt($ch, CURLOPT_BUFFERSIZE,        1024*16);
     curl_setopt($ch, CURLOPT_NOPROGRESS,        false);
     curl_setopt($ch, CURLOPT_PROGRESSFUNCTION,
         function($arg0, $arg1, $arg2, $arg3, $arg4 = 0) use ($maxBytes)
@@ -302,6 +302,13 @@ function server_url($server)
                 $port = $server['HTTP_X_FORWARDED_PORT'];
             }
 
+            // This is a workaround for proxies that don't forward the scheme properly.
+            // Connecting over port 443 has to be in HTTPS.
+            // See https://github.com/shaarli/Shaarli/issues/1022
+            if ($port == '443') {
+                $scheme = 'https';
+            }
+
             if (($scheme == 'http' && $port != '80')
                 || ($scheme == 'https' && $port != '443')
             ) {
diff --git a/application/Languages.php b/application/Languages.php
index c8b0a25a..357c7524 100644
--- a/application/Languages.php
+++ b/application/Languages.php
@@ -1,21 +1,164 @@
 <?php
 
+namespace Shaarli;
+
+use Gettext\GettextTranslator;
+use Gettext\Merge;
+use Gettext\Translations;
+use Gettext\Translator;
+use Gettext\TranslatorInterface;
+use Shaarli\Config\ConfigManager;
+
 /**
- * Wrapper function for translation which match the API
- * of gettext()/_() and ngettext().
+ * Class Languages
+ *
+ * Load Shaarli translations using 'gettext/gettext'.
+ * This class allows to either use PHP gettext extension, or a PHP implementation of gettext,
+ * with a fixed language, or dynamically using autoLocale().
  *
- * Not doing translation for now.
+ * Translation files PO/MO files follow gettext standard and must be placed under:
+ *   <translation path>/<language>/LC_MESSAGES/<domain>.[po|mo]
  *
- * @param string $text  Text to translate.
- * @param string $nText The plural message ID.
- * @param int    $nb    The number of items for plural forms.
+ * Pros/cons:
+ *   - gettext extension is faster
+ *   - gettext is very system dependent (PHP extension, the locale must be installed, and web server reloaded)
  *
- * @return String Text translated.
+ * Settings:
+ *   - translation.mode:
+ *     - auto: use default setting (PHP implementation)
+ *     - php: use PHP implementation
+ *     - gettext: use gettext wrapper
+ *   - translation.language:
+ *     - auto: use autoLocale() and the language change according to user HTTP headers
+ *     - fixed language: e.g. 'fr'
+ *   - translation.extensions:
+ *     - domain => translation_path: allow plugins and themes to extend the defaut extension
+ *       The domain must be unique, and translation path must be relative, and contains the tree mentioned above.
+ *
+ * @package Shaarli
  */
-function t($text, $nText = '', $nb = 0) {
-    if (empty($nText)) {
-        return $text;
+class Languages
+{
+    /**
+     * Core translations domain
+     */
+    const DEFAULT_DOMAIN = 'shaarli';
+
+    /**
+     * @var TranslatorInterface
+     */
+    protected $translator;
+
+    /**
+     * @var string
+     */
+    protected $language;
+
+    /**
+     * @var ConfigManager
+     */
+    protected $conf;
+
+    /**
+     * Languages constructor.
+     *
+     * @param string        $language lang determined by autoLocale(), can be overridden.
+     * @param ConfigManager $conf     instance.
+     */
+    public function __construct($language, $conf)
+    {
+        $this->conf = $conf;
+        $confLanguage = $this->conf->get('translation.language', 'auto');
+        if ($confLanguage === 'auto' || ! $this->isValidLanguage($confLanguage)) {
+            $this->language = substr($language, 0, 5);
+        } else {
+            $this->language = $confLanguage;
+        }
+
+        if (! extension_loaded('gettext')
+            || in_array($this->conf->get('translation.mode', 'auto'), ['auto', 'php'])
+        ) {
+            $this->initPhpTranslator();
+        } else {
+            $this->initGettextTranslator();
+        }
+
+        // Register default functions (e.g. '__()') to use our Translator
+        $this->translator->register();
+    }
+
+    /**
+     * Initialize the translator using php gettext extension (gettext dependency act as a wrapper).
+     */
+    protected function initGettextTranslator ()
+    {
+        $this->translator = new GettextTranslator();
+        $this->translator->setLanguage($this->language);
+        $this->translator->loadDomain(self::DEFAULT_DOMAIN, 'inc/languages');
+
+        foreach ($this->conf->get('translation.extensions', []) as $domain => $translationPath) {
+            if ($domain !== self::DEFAULT_DOMAIN) {
+                $this->translator->loadDomain($domain, $translationPath, false);
+            }
+        }
+    }
+
+    /**
+     * Initialize the translator using a PHP implementation of gettext.
+     *
+     * Note that if language po file doesn't exist, errors are ignored (e.g. not installed language).
+     */
+    protected function initPhpTranslator()
+    {
+        $this->translator = new Translator();
+        $translations = new Translations();
+        // Core translations
+        try {
+            /** @var Translations $translations */
+            $translations = $translations->addFromPoFile('inc/languages/'. $this->language .'/LC_MESSAGES/shaarli.po');
+            $translations->setDomain('shaarli');
+            $this->translator->loadTranslations($translations);
+        } catch (\InvalidArgumentException $e) {}
+
+
+        // Extension translations (plugins, themes, etc.).
+        foreach ($this->conf->get('translation.extensions', []) as $domain => $translationPath) {
+            if ($domain === self::DEFAULT_DOMAIN) {
+                continue;
+            }
+
+            try {
+                /** @var Translations $extension */
+                $extension = Translations::fromPoFile($translationPath . $this->language .'/LC_MESSAGES/'. $domain .'.po');
+                $extension->setDomain($domain);
+                $this->translator->loadTranslations($extension);
+            } catch (\InvalidArgumentException $e) {}
+        }
+    }
+
+    /**
+     * Checks if a language string is valid.
+     *
+     * @param string $language e.g. 'fr' or 'en_US'
+     *
+     * @return bool true if valid, false otherwise
+     */
+    protected function isValidLanguage($language)
+    {
+        return preg_match('/^[a-z]{2}(_[A-Z]{2})?/', $language) === 1;
+    }
+
+    /**
+     * Get the list of available languages for Shaarli.
+     *
+     * @return array List of available languages, with their label.
+     */
+    public static function getAvailableLanguages()
+    {
+        return [
+            'auto' => t('Automatic'),
+            'en' => t('English'),
+            'fr' => t('French'),
+        ];
     }
-    $actualForm = $nb > 1 ? $nText : $text;
-    return sprintf($actualForm, $nb);
 }
diff --git a/application/LinkDB.php b/application/LinkDB.php
index 22c1f0ab..c1661d52 100644
--- a/application/LinkDB.php
+++ b/application/LinkDB.php
@@ -133,16 +133,16 @@ class LinkDB implements Iterator, Countable, ArrayAccess
     {
         // TODO: use exceptions instead of "die"
         if (!$this->loggedIn) {
-            die('You are not authorized to add a link.');
+            die(t('You are not authorized to add a link.'));
         }
         if (!isset($value['id']) || empty($value['url'])) {
-            die('Internal Error: A link should always have an id and URL.');
+            die(t('Internal Error: A link should always have an id and URL.'));
         }
         if (($offset !== null && ! is_int($offset)) || ! is_int($value['id'])) {
-            die('You must specify an integer as a key.');
+            die(t('You must specify an integer as a key.'));
         }
         if ($offset !== null && $offset !== $value['id']) {
-            die('Array offset and link ID must be equal.');
+            die(t('Array offset and link ID must be equal.'));
         }
 
         // If the link exists, we reuse the real offset, otherwise new entry
@@ -248,13 +248,13 @@ class LinkDB implements Iterator, Countable, ArrayAccess
         $this->links = array();
         $link = array(
             'id' => 1,
-            'title'=>' Shaarli: the personal, minimalist, super-fast, no-database delicious clone',
+            'title'=> t('The personal, minimalist, super-fast, database free, bookmarking service'),
             'url'=>'https://shaarli.readthedocs.io',
-            'description'=>'Welcome to Shaarli! This is your first public bookmark. To edit or delete me, you must first login.
+            'description'=>t('Welcome to Shaarli! This is your first public bookmark. To edit or delete me, you must first login.
 
-To learn how to use Shaarli, consult the link "Help/documentation" at the bottom of this page.
+To learn how to use Shaarli, consult the link "Documentation" at the bottom of this page.
 
-You use the community supported version of the original Shaarli project, by Sebastien Sauvage.',
+You use the community supported version of the original Shaarli project, by Sebastien Sauvage.'),
             'private'=>0,
             'created'=> new DateTime(),
             'tags'=>'opensource software'
@@ -264,9 +264,9 @@ You use the community supported version of the original Shaarli project, by Seba
 
         $link = array(
             'id' => 0,
-            'title'=>'My secret stuff... - Pastebin.com',
+            'title'=> t('My secret stuff... - Pastebin.com'),
             'url'=>'http://sebsauvage.net/paste/?8434b27936c09649#bR7XsXhoTiLcqCpQbmOpBi3rq2zzQUC5hBI7ZT1O3x8=',
-            'description'=>'Shhhh! I\'m a private link only YOU can see. You can delete me too.',
+            'description'=> t('Shhhh! I\'m a private link only YOU can see. You can delete me too.'),
             'private'=>1,
             'created'=> new DateTime('1 minute ago'),
             'tags'=>'secretstuff',
@@ -289,13 +289,15 @@ You use the community supported version of the original Shaarli project, by Seba
             return;
         }
 
+        $this->urls = [];
+        $this->ids = [];
         $this->links = FileUtils::readFlatDB($this->datastore, []);
 
         $toremove = array();
         foreach ($this->links as $key => &$link) {
             if (! $this->loggedIn && $link['private'] != 0) {
                 // Transition for not upgraded databases.
-                $toremove[] = $key;
+                unset($this->links[$key]);
                 continue;
             }
 
@@ -329,14 +331,10 @@ You use the community supported version of the original Shaarli project, by Seba
                 }
                 $link['shorturl'] = smallHash($link['linkdate']);
             }
-        }
 
-        // If user is not logged in, filter private links.
-        foreach ($toremove as $offset) {
-            unset($this->links[$offset]);
+            $this->urls[$link['url']] = $key;
+            $this->ids[$link['id']] = $key;
         }
-
-        $this->reorder();
     }
 
     /**
@@ -346,6 +344,7 @@ You use the community supported version of the original Shaarli project, by Seba
      */
     private function write()
     {
+        $this->reorder();
         FileUtils::writeFlatDB($this->datastore, $this->links);
     }
 
@@ -528,8 +527,8 @@ You use the community supported version of the original Shaarli project, by Seba
             return $a['created'] < $b['created'] ? 1 * $order : -1 * $order;
         });
 
-        $this->urls = array();
-        $this->ids = array();
+        $this->urls = [];
+        $this->ids = [];
         foreach ($this->links as $key => $link) {
             $this->urls[$link['url']] = $key;
             $this->ids[$link['id']] = $key;
diff --git a/application/LinkFilter.php b/application/LinkFilter.php
index 99ecd1e2..12376e27 100644
--- a/application/LinkFilter.php
+++ b/application/LinkFilter.php
@@ -444,5 +444,11 @@ class LinkFilter
 
 class LinkNotFoundException extends Exception
 {
-    protected $message = 'The link you are trying to reach does not exist or has been deleted.';
+    /**
+     * LinkNotFoundException constructor.
+     */
+    public function __construct()
+    {
+        $this->message =  t('The link you are trying to reach does not exist or has been deleted.');
+    }
 }
diff --git a/application/LinkUtils.php b/application/LinkUtils.php
index 267e62cd..e3d95d08 100644
--- a/application/LinkUtils.php
+++ b/application/LinkUtils.php
@@ -102,12 +102,13 @@ function count_private($links)
  *
  * @param string $text       input string.
  * @param string $redirector if a redirector is set, use it to gerenate links.
+ * @param bool   $urlEncode  Use `urlencode()` on the URL after the redirector or not.
  *
  * @return string returns $text with all links converted to HTML links.
  *
  * @see Function inspired from http://www.php.net/manual/en/function.preg-replace.php#85722
  */
-function text2clickable($text, $redirector = '')
+function text2clickable($text, $redirector = '', $urlEncode = true)
 {
     $regex = '!(((?:https?|ftp|file)://|apt:|magnet:)\S+[a-z0-9\(\)]/?)!si';
 
@@ -117,8 +118,9 @@ function text2clickable($text, $redirector = '')
     // Redirector is set, urlencode the final URL.
     return preg_replace_callback(
         $regex,
-        function ($matches) use ($redirector) {
-            return '<a href="' . $redirector . urlencode($matches[1]) .'">'. $matches[1] .'</a>';
+        function ($matches) use ($redirector, $urlEncode) {
+            $url = $urlEncode ? urlencode($matches[1]) : $matches[1];
+            return '<a href="' . $redirector . $url .'">'. $matches[1] .'</a>';
         },
         $text
     );
@@ -164,12 +166,13 @@ function space2nbsp($text)
  *
  * @param string $description shaare's description.
  * @param string $redirector  if a redirector is set, use it to gerenate links.
+ * @param bool   $urlEncode  Use `urlencode()` on the URL after the redirector or not.
  * @param string $indexUrl    URL to Shaarli's index.
- *
+
  * @return string formatted description.
  */
-function format_description($description, $redirector = '', $indexUrl = '') {
-    return nl2br(space2nbsp(hashtag_autolink(text2clickable($description, $redirector), $indexUrl)));
+function format_description($description, $redirector = '', $urlEncode = true, $indexUrl = '') {
+    return nl2br(space2nbsp(hashtag_autolink(text2clickable($description, $redirector, $urlEncode), $indexUrl)));
 }
 
 /**
diff --git a/application/NetscapeBookmarkUtils.php b/application/NetscapeBookmarkUtils.php
index 31796367..dd7057f8 100644
--- a/application/NetscapeBookmarkUtils.php
+++ b/application/NetscapeBookmarkUtils.php
@@ -32,11 +32,10 @@ class NetscapeBookmarkUtils
     {
         // see tpl/export.html for possible values
         if (! in_array($selection, array('all', 'public', 'private'))) {
-            throw new Exception('Invalid export selection: "'.$selection.'"');
+            throw new Exception(t('Invalid export selection:') .' "'.$selection.'"');
         }
 
         $bookmarkLinks = array();
-
         foreach ($linkDb as $link) {
             if ($link['private'] != 0 && $selection == 'public') {
                 continue;
@@ -79,14 +78,14 @@ class NetscapeBookmarkUtils
         $duration=0
     )
     {
-        $status = 'File '.$filename.' ('.$filesize.' bytes) ';
+        $status = sprintf(t('File %s (%d bytes) '), $filename, $filesize);
         if ($importCount == 0 && $overwriteCount == 0 && $skipCount == 0) {
-            $status .= 'has an unknown file format. Nothing was imported.';
+            $status .= t('has an unknown file format. Nothing was imported.');
         } else {
-            $status .= 'was successfully processed in '. $duration .' seconds: ';
-            $status .= $importCount.' links imported, ';
-            $status .= $overwriteCount.' links overwritten, ';
-            $status .= $skipCount.' links skipped.';
+            $status .= vsprintf(
+                t('was successfully processed in %d seconds: %d links imported, %d links overwritten, %d links skipped.'),
+                [$duration, $importCount, $overwriteCount, $skipCount]
+            );
         }
         return $status;
     }
diff --git a/application/PageBuilder.php b/application/PageBuilder.php
index 291860ad..468f144b 100644
--- a/application/PageBuilder.php
+++ b/application/PageBuilder.php
@@ -32,12 +32,14 @@ class PageBuilder
      *
      * @param ConfigManager $conf   Configuration Manager instance (reference).
      * @param LinkDB        $linkDB instance.
+     * @param string        $token  Session token
      */
-    public function __construct(&$conf, $linkDB = null)
+    public function __construct(&$conf, $linkDB = null, $token = null)
     {
         $this->tpl = false;
         $this->conf = $conf;
         $this->linkDB = $linkDB;
+        $this->token = $token;
     }
 
     /**
@@ -92,7 +94,7 @@ class PageBuilder
         $this->tpl->assign('showatom', $this->conf->get('feed.show_atom', true));
         $this->tpl->assign('feed_type', $this->conf->get('feed.show_atom', true) !== false ? 'atom' : 'rss');
         $this->tpl->assign('hide_timestamps', $this->conf->get('privacy.hide_timestamps', false));
-        $this->tpl->assign('token', getToken($this->conf));
+        $this->tpl->assign('token', $this->token);
 
         if ($this->linkDB !== null) {
             $this->tpl->assign('tags', $this->linkDB->linksCountPerTag());
@@ -159,9 +161,12 @@ class PageBuilder
      *
      * @param string $message A messate to display what is not found
      */
-    public function render404($message = 'The page you are trying to reach does not exist or has been deleted.')
+    public function render404($message = '')
     {
-        header($_SERVER['SERVER_PROTOCOL'] . ' 404 Not Found');
+        if (empty($message)) {
+            $message = t('The page you are trying to reach does not exist or has been deleted.');
+        }
+        header($_SERVER['SERVER_PROTOCOL'] .' '. t('404 Not Found'));
         $this->tpl->assign('error_message', $message);
         $this->renderPage('404');
     }
diff --git a/application/PluginManager.php b/application/PluginManager.php
index 59ece4fa..cf603845 100644
--- a/application/PluginManager.php
+++ b/application/PluginManager.php
@@ -188,6 +188,9 @@ class PluginManager
             $metaData[$plugin] = parse_ini_file($metaFile);
             $metaData[$plugin]['order'] = array_search($plugin, $this->authorizedPlugins);
 
+            if (isset($metaData[$plugin]['description'])) {
+                $metaData[$plugin]['description'] = t($metaData[$plugin]['description']);
+            }
             // Read parameters and format them into an array.
             if (isset($metaData[$plugin]['parameters'])) {
                 $params = explode(';', $metaData[$plugin]['parameters']);
@@ -203,7 +206,7 @@ class PluginManager
                 $metaData[$plugin]['parameters'][$param]['value'] = '';
                 // Optional parameter description in parameter.PARAM_NAME=
                 if (isset($metaData[$plugin]['parameter.'. $param])) {
-                    $metaData[$plugin]['parameters'][$param]['desc'] = $metaData[$plugin]['parameter.'. $param];
+                    $metaData[$plugin]['parameters'][$param]['desc'] = t($metaData[$plugin]['parameter.'. $param]);
                 }
             }
         }
@@ -237,6 +240,6 @@ class PluginFileNotFoundException extends Exception
      */
     public function __construct($pluginName)
     {
-        $this->message = 'Plugin "'. $pluginName .'" files not found.';
+        $this->message = sprintf(t('Plugin "%s" files not found.'), $pluginName);
     }
 }
diff --git a/application/SessionManager.php b/application/SessionManager.php
new file mode 100644
index 00000000..71f0b38d
--- /dev/null
+++ b/application/SessionManager.php
@@ -0,0 +1,83 @@
+<?php
+namespace Shaarli;
+
+/**
+ * Manages the server-side session
+ */
+class SessionManager
+{
+    protected $session = [];
+
+    /**
+     * Constructor
+     *
+     * @param array         $session The $_SESSION array (reference)
+     * @param ConfigManager $conf    ConfigManager instance
+     */
+    public function __construct(& $session, $conf)
+    {
+        $this->session = &$session;
+        $this->conf = $conf;
+    }
+
+    /**
+     * Generates a session token
+     *
+     * @return string token
+     */
+    public function generateToken()
+    {
+        $token = sha1(uniqid('', true) .'_'. mt_rand() . $this->conf->get('credentials.salt'));
+        $this->session['tokens'][$token] = 1;
+        return $token;
+    }
+
+    /**
+     * Checks the validity of a session token, and destroys it afterwards
+     *
+     * @param string $token The token to check
+     *
+     * @return bool true if the token is valid, else false
+     */
+    public function checkToken($token)
+    {
+        if (! isset($this->session['tokens'][$token])) {
+            // the token is wrong, or has already been used
+            return false;
+        }
+
+        // destroy the token to prevent future use
+        unset($this->session['tokens'][$token]);
+        return true;
+    }
+
+    /**
+     * Validate session ID to prevent Full Path Disclosure.
+     *
+     * See #298.
+     * The session ID's format depends on the hash algorithm set in PHP settings
+     *
+     * @param string $sessionId Session ID
+     *
+     * @return true if valid, false otherwise.
+     *
+     * @see http://php.net/manual/en/function.hash-algos.php
+     * @see http://php.net/manual/en/session.configuration.php
+     */
+    public static function checkId($sessionId)
+    {
+        if (empty($sessionId)) {
+            return false;
+        }
+
+        if (!$sessionId) {
+            return false;
+        }
+
+        if (!preg_match('/^[a-zA-Z0-9,-]{2,128}$/', $sessionId)) {
+            return false;
+        }
+
+        return true;
+    }
+}
diff --git a/application/Updater.php b/application/Updater.php
index 72b2def0..8d2bd577 100644
--- a/application/Updater.php
+++ b/application/Updater.php
@@ -73,7 +73,7 @@ class Updater
         }
 
         if ($this->methods === null) {
-            throw new UpdaterException('Couldn\'t retrieve Updater class methods.');
+            throw new UpdaterException(t('Couldn\'t retrieve Updater class methods.'));
         }
 
         foreach ($this->methods as $method) {
@@ -436,6 +436,15 @@ class Updater
         }
         return true;
     }
+
+    /**
+     * Save the datastore -> the link order is now applied when links are saved.
+     */
+    public function updateMethodReorderDatastore()
+    {
+        $this->linkDB->save($this->conf->get('resource.page_cache'));
+        return true;
+    }
 }
 
 /**
@@ -482,7 +491,7 @@ class UpdaterException extends Exception
         }
 
         if (! empty($this->method)) {
-            $out .= 'An error occurred while running the update '. $this->method . PHP_EOL;
+            $out .= t('An error occurred while running the update ') . $this->method . PHP_EOL;
         }
 
         if (! empty($this->previous)) {
@@ -522,11 +531,11 @@ function read_updates_file($updatesFilepath)
 function write_updates_file($updatesFilepath, $updates)
 {
     if (empty($updatesFilepath)) {
-        throw new Exception('Updates file path is not set, can\'t write updates.');
+        throw new Exception(t('Updates file path is not set, can\'t write updates.'));
     }
 
     $res = file_put_contents($updatesFilepath, implode(';', $updates));
     if ($res === false) {
-        throw new Exception('Unable to write updates in '. $updatesFilepath . '.');
+        throw new Exception(t('Unable to write updates in '. $updatesFilepath . '.'));
     }
 }
diff --git a/application/Utils.php b/application/Utils.php
index 4a2f5561..97b12fcf 100644
--- a/application/Utils.php
+++ b/application/Utils.php
@@ -182,36 +182,6 @@ function generateLocation($referer, $host, $loopTerms = array())
 }
 
 /**
- * Validate session ID to prevent Full Path Disclosure.
- *
- * See #298.
- * The session ID's format depends on the hash algorithm set in PHP settings
- *
- * @param string $sessionId Session ID
- *
- * @return true if valid, false otherwise.
- *
- * @see http://php.net/manual/en/function.hash-algos.php
- * @see http://php.net/manual/en/session.configuration.php
- */
-function is_session_id_valid($sessionId)
-{
-    if (empty($sessionId)) {
-        return false;
-    }
-
-    if (!$sessionId) {
-        return false;
-    }
-
-    if (!preg_match('/^[a-zA-Z0-9,-]{2,128}$/', $sessionId)) {
-        return false;
-    }
-
-    return true;
-}
-
-/**
  * Sniff browser language to set the locale automatically.
  * Note that is may not work on your server if the corresponding locale is not installed.
  *
@@ -452,7 +422,7 @@ function get_max_upload_size($limitPost, $limitUpload, $format = true)
  */
 function alphabetical_sort(&$data, $reverse = false, $byKeys = false)
 {
-    $callback = function($a, $b) use ($reverse) {
+    $callback = function ($a, $b) use ($reverse) {
         // Collator is part of PHP intl.
         if (class_exists('Collator')) {
             $collator = new Collator(setlocale(LC_COLLATE, 0));
@@ -470,3 +440,18 @@ function alphabetical_sort(&$data, $reverse = false, $byKeys = false)
         usort($data, $callback);
     }
 }
+
+/**
+ * Wrapper function for translation which match the API
+ * of gettext()/_() and ngettext().
+ *
+ * @param string $text   Text to translate.
+ * @param string $nText  The plural message ID.
+ * @param int    $nb     The number of items for plural forms.
+ * @param string $domain The domain where the translation is stored (default: shaarli).
+ *
+ * @return string Text translated.
+ */
+function t($text, $nText = '', $nb = 1, $domain = 'shaarli') {
+    return dn__($domain, $text, $nText, $nb);
+}
diff --git a/application/config/ConfigJson.php b/application/config/ConfigJson.php
index 9ef2ef56..8c8d5610 100644
--- a/application/config/ConfigJson.php
+++ b/application/config/ConfigJson.php
@@ -22,10 +22,15 @@ class ConfigJson implements ConfigIO
         $data = json_decode($data, true);
         if ($data === null) {
             $errorCode = json_last_error();
-            $error  = 'An error occurred while parsing JSON configuration file ('. $filepath .'): error code #';
-            $error .= $errorCode. '<br>➜ <code>' . json_last_error_msg() .'</code>';
+            $error  = sprintf(
+                'An error occurred while parsing JSON configuration file (%s): error code #%d',
+                $filepath,
+                $errorCode
+            );
+            $error .= '<br>➜ <code>' . json_last_error_msg() .'</code>';
             if ($errorCode === JSON_ERROR_SYNTAX) {
-                $error .= '<br>Please check your JSON syntax (without PHP comment tags) using a JSON lint tool such as ';
+                $error .= '<br>';
+                $error .= 'Please check your JSON syntax (without PHP comment tags) using a JSON lint tool such as ';
                 $error .= '<a href="http://jsonlint.com/">jsonlint.com</a>.';
             }
             throw new \Exception($error);
@@ -44,8 +49,8 @@ class ConfigJson implements ConfigIO
         if (!file_put_contents($filepath, $data)) {
             throw new \IOException(
                 $filepath,
-                'Shaarli could not create the config file.
-                Please make sure Shaarli has the right to write in the folder is it installed in.'
+                t('Shaarli could not create the config file. '.
+                  'Please make sure Shaarli has the right to write in the folder is it installed in.')
             );
         }
     }
diff --git a/application/config/ConfigManager.php b/application/config/ConfigManager.php
index 7ff2fe67..9e4c9f63 100644
--- a/application/config/ConfigManager.php
+++ b/application/config/ConfigManager.php
@@ -132,7 +132,7 @@ class ConfigManager
     public function set($setting, $value, $write = false, $isLoggedIn = false)
     {
         if (empty($setting) || ! is_string($setting)) {
-            throw new \Exception('Invalid setting key parameter. String expected, got: '. gettype($setting));
+            throw new \Exception(t('Invalid setting key parameter. String expected, got: '). gettype($setting));
         }
 
         // During the ConfigIO transition, map legacy settings to the new ones.
@@ -339,6 +339,10 @@ class ConfigManager
         $this->setEmpty('redirector.url', '');
         $this->setEmpty('redirector.encode_url', true);
 
+        $this->setEmpty('translation.language', 'auto');
+        $this->setEmpty('translation.mode', 'php');
+        $this->setEmpty('translation.extensions', []);
+
         $this->setEmpty('plugins', array());
     }
 
diff --git a/application/config/ConfigPhp.php b/application/config/ConfigPhp.php
index 2633824d..2f66e8e0 100644
--- a/application/config/ConfigPhp.php
+++ b/application/config/ConfigPhp.php
@@ -118,8 +118,8 @@ class ConfigPhp implements ConfigIO
         ) {
             throw new \IOException(
                 $filepath,
-                'Shaarli could not create the config file.
-                Please make sure Shaarli has the right to write in the folder is it installed in.'
+                t('Shaarli could not create the config file. '.
+                  'Please make sure Shaarli has the right to write in the folder is it installed in.')
             );
         }
     }
diff --git a/application/config/exception/MissingFieldConfigException.php b/application/config/exception/MissingFieldConfigException.php
index 6346c6a9..9e0a9359 100644
--- a/application/config/exception/MissingFieldConfigException.php
+++ b/application/config/exception/MissingFieldConfigException.php
@@ -18,6 +18,6 @@ class MissingFieldConfigException extends \Exception
     public function __construct($field)
     {
         $this->field = $field;
-        $this->message = 'Configuration value is required for '. $this->field;
+        $this->message = sprintf(t('Configuration value is required for %s'), $this->field);
     }
 }
diff --git a/application/config/exception/PluginConfigOrderException.php b/application/config/exception/PluginConfigOrderException.php
index f9d68750..f82ec26e 100644
--- a/application/config/exception/PluginConfigOrderException.php
+++ b/application/config/exception/PluginConfigOrderException.php
@@ -12,6 +12,6 @@ class PluginConfigOrderException extends \Exception
      */
     public function __construct()
     {
-        $this->message = 'An error occurred while trying to save plugins loading order.';
+        $this->message = t('An error occurred while trying to save plugins loading order.');
     }
 }
diff --git a/application/config/exception/UnauthorizedConfigException.php b/application/config/exception/UnauthorizedConfigException.php
index 79672c1b..72311fae 100644
--- a/application/config/exception/UnauthorizedConfigException.php
+++ b/application/config/exception/UnauthorizedConfigException.php
@@ -13,6 +13,6 @@ class UnauthorizedConfigException extends \Exception
      */
     public function __construct()
     {
-        $this->message = 'You are not authorized to alter config.';
+        $this->message = t('You are not authorized to alter config.');
     }
 }
diff --git a/application/exceptions/IOException.php b/application/exceptions/IOException.php
index b563b23d..18e46b77 100644
--- a/application/exceptions/IOException.php
+++ b/application/exceptions/IOException.php
@@ -16,7 +16,7 @@ class IOException extends Exception
     public function __construct($path, $message = '')
     {
         $this->path = $path;
-        $this->message = empty($message) ? 'Error accessing' : $message;
+        $this->message = empty($message) ? t('Error accessing') : $message;
         $this->message .= ' "' . $this->path .'"';
     }
 }