diff --git a/application/controllers/admin/authentication.php b/application/controllers/admin/authentication.php
index 1bcf92b1493..ec0289ffc77 100644
--- a/application/controllers/admin/authentication.php
+++ b/application/controllers/admin/authentication.php
@@ -31,10 +31,11 @@ class Authentication extends Survey_Common_Action
     /**
      * Show login screen and parse login data
      * Will redirect or echo json depending on ajax call
-     * @return void
+     * This function is called while accessing the login page: index.php/admin/authentication/sa/login
      */
     public function index()
     {
+        // The page should be shown only for non logged in users
         $this->_redirectIfLoggedIn();
 
         // Result can be success, fail or data for template
@@ -77,59 +78,65 @@ public function index()
 
     /**
      * Prepare login and return result
+     * It checks if the authdb plugin is registered and active
      * @return array Either success, failure or plugin data (used in login form)
      */
     public static function prepareLogin()
     {
         $aData = array();
 
-        // Make sure after first run / update the authdb plugin is registered and active
-        // it can not be deactivated
-        if (!class_exists('Authdb', false)) {
-            $plugin = Plugin::model()->findByAttributes(array('name'=>'Authdb'));
-            if (!$plugin) {
-                $plugin = new Plugin();
-                $plugin->name = 'Authdb';
-                $plugin->active = 1;
-                $plugin->save();
-                App()->getPluginManager()->loadPlugin('Authdb', $plugin->id);
-            } else {
-                $plugin->active = 1;
-                $plugin->save();
-            }
-        }
-
+        // In Authdb, the plugin event "beforeLogin" checks if the url param "onepass" is set
+        // if yes, it will call  AuthPluginBase::setAuthPlugin to set to true the plugin private parameter "_stop", so the form will not be displayed
+        // @see: application/core/plugins/Authdb/Authdb.php: function beforeLogin()
         $beforeLogin = new PluginEvent('beforeLogin');
         $beforeLogin->set('identity', new LSUserIdentity('', ''));
-
         App()->getPluginManager()->dispatchEvent($beforeLogin);
+
         /* @var $identity LSUserIdentity */
-        $identity = $beforeLogin->get('identity');
+        $identity = $beforeLogin->get('identity');                              // Why here?
 
+        // If the plugin private parameter "_stop" is false and the login form has not been submitted: render the login form
         if (!$beforeLogin->isStopped() && is_null(App()->getRequest()->getPost('login_submit')) )
         {
+            // First step: set the value of $aData['defaultAuth']
+            // This variable will be used to select the default value of the Authentication method selector
+            // which is shown only if there is more than one plugin auth on...
+            // @see application/views/admin/authentication/login.php
+
+            // First it checks if the current plugin force the authentication default value...
+            // NB: A plugin SHOULD NOT be able to over pass the configuration file
+            // @see: http://img.memecdn.com/knees-weak-arms-are-heavy_c_3011277.jpg
             if (!is_null($beforeLogin->get('default'))) {
                 $aData['defaultAuth'] = $beforeLogin->get('default');
             }
             else {
+                // THen, it checks if the the user set a different default plugin auth in application/config/config.php
+                // eg: 'config'=>array()'debug'=>2,'debugsql'=>0, 'default_displayed_auth_method'=>'muh_auth_method')
                 if (App()->getPluginManager()->isPluginActive(Yii::app()->getConfig('default_displayed_auth_method'))) {
                         $aData['defaultAuth'] = Yii::app()->getConfig('default_displayed_auth_method');
-                    }
-                    else {
+                    }else {
                         $aData['defaultAuth'] = 'Authdb';
                     }
             }
+
+            // Call the plugin method newLoginForm
+            // For Authdb:  @see: application/core/plugins/Authdb/Authdb.php: function newLoginForm()
             $newLoginForm = new PluginEvent('newLoginForm');
-            App()->getPluginManager()->dispatchEvent($newLoginForm);
+            App()->getPluginManager()->dispatchEvent($newLoginForm);            // inject the HTML of the form inside the private varibale "_content" of the plugin
             $aData['summary'] = self::getSummary('logout');
-            $aData['pluginContent'] = $newLoginForm->getAllContent();
+            $aData['pluginContent'] = $newLoginForm->getAllContent();           // Retreives the private varibale "_content" , and parse it to $aData['pluginContent'], which will be  rendered in application/views/admin/authentication/login.php
         }
         else
         {
+            // The form has been submited, or the plugin has been stoped (so normally, the value of login/password are available)
+
              // Handle getting the post and populating the identity there
-            $authMethod = App()->getRequest()->getPost('authMethod', $identity->plugin);
+            $authMethod = App()->getRequest()->getPost('authMethod', $identity->plugin);      // If form has been submitted, $_POST['authMethod'] is set, else  $identity->plugin should be set, ELSE: TODO error
             $identity->plugin = $authMethod;
 
+            // Call the function afterLoginFormSubmit of the plugin.
+            // For Authdb, it calls AuthPluginBase::afterLoginFormSubmit()
+            // which set the plugin's private variables _username and _password with the POST informations if it's a POST request else it does nothing
             $event = new PluginEvent('afterLoginFormSubmit');
             $event->set('identity', $identity);
             App()->getPluginManager()->dispatchEvent($event, array($authMethod));