Show groups in current shop context, only.

Provided by @chitmann with pull request #876, thank you very much!

Traumflug's review edits:

 - Squashed 11 commits into one.

 - Some whitespace nitpicking.

 - Used 'sg' instead of 'shop_group' in SQL code to meet
   formatting guidelines.

 - Backticks around field names in SQL code for the same reason.

 - Moved method description from the commit message to the method
   comment.

classes/Group.php

@@ -97,7 +97,11 @@ public function __construct($id = null, $idLang = null, $idShop = null)
 
     /**
      * @param int      $idLang
-     * @param int|bool $idShop
+     * @param int|bool $idShop: false  --> Return all groups.
+     *                          true   --> Return groups associated with
+     *                                     current shop (from context).
+     *                          number --> Return groups associated with the
+     *                                     specific shop with this ID.
      *
      * @return array|false|mysqli_result|null|PDOStatement|resource
      *
@@ -109,15 +113,17 @@ public function __construct($id = null, $idLang = null, $idShop = null)
     public static function getGroups($idLang, $idShop = false)
     {
         $shopCriteria = '';
-        if ($idShop) {
+        if (is_int($idShop)) {
+            $shopCriteria = ' INNER JOIN `'._DB_PREFIX_.'group_shop` gs ON (gs.`id_group` = g.`id_group` AND gs.`id_shop` = '.$idShop.')';
+        } elseif ($idShop) {
             $shopCriteria = Shop::addSqlAssociation('group', 'g');
         }
 
         return Db::getInstance(_PS_USE_SQL_SLAVE_)->executeS(
             (new DbQuery())
                 ->select('DISTINCT g.`id_group`, g.`reduction`, g.`price_display_method`, gl.`name`')
                 ->from('group', 'g')
-                ->leftJoin('group_lang', 'gl', 'g.`id_group` = gl.`id_group` AND gl.`id_lang` = '.(int) $idLang)
+                ->leftJoin('group_lang', 'gl', 'g.`id_group` = gl.`id_group` AND gl.`id_lang` = '.(int) $idLang.$shopCriteria)
                 ->orderBy('g.`id_group` ASC')
         );
     }

controllers/admin/AdminCategoriesController.php

@@ -685,7 +685,7 @@ public function renderForm()
                     'type'              => 'group',
                     'label'             => $this->l('Group access'),
                     'name'              => 'groupBox',
-                    'values'            => Group::getGroups($this->context->language->id),
+                    'values'            => Group::getGroups($this->context->language->id, true),
                     'info_introduction' => $this->l('You now have three default customer groups.'),
                     'unidentified'      => $unidentifiedGroupInformation,
                     'guest'             => $guestGroupInformation,

controllers/admin/AdminPaymentController.php

@@ -297,7 +297,7 @@ public function renderView()
                 'icon'       => 'icon-money',
             ],
             [
-                'items'      => Group::getGroups($this->context->language->id),
+                'items'      => Group::getGroups($this->context->language->id, true),
                 'title'      => $this->l('Group restrictions'),
                 'desc'       => $this->l('Please mark each checkbox for the customer group(s), for which you want the payment module(s) to be available.'),
                 'name_id'    => 'group',

controllers/admin/AdminProductsController.php

@@ -3844,7 +3844,7 @@ public function initFormPrices($obj)
         if ($obj->id) {
             $shops = Shop::getShops();
             $countries = Country::getCountries($this->context->language->id);
-            $groups = Group::getGroups($this->context->language->id);
+            $groups = Group::getGroups($this->context->language->id, true);
             $currencies = Currency::getCurrencies();
             $attributes = $obj->getAttributesGroups((int) $this->context->language->id);
             $combinations = [];