[-] BO: Auto-select the tax rules group most used on product creation

classes/Product.php

@@ -5215,6 +5215,23 @@ class ProductCore extends ObjectModel
 		);
 	}
 	
+	public static function getIdTaxRulesGroupMostUsed()
+	{
+		return Db::getInstance()->getValue('
+					SELECT id_tax_rules_group
+					FROM (
+						SELECT COUNT(*) n, product_shop.id_tax_rules_group
+						FROM '._DB_PREFIX_.'product p
+						'.Shop::addSqlAssociation('product', 'p').'
+						JOIN '._DB_PREFIX_.'tax_rules_group trg ON (product_shop.id_tax_rules_group = trg.id_tax_rules_group)
+						WHERE trg.active = 1
+						GROUP BY product_shop.id_tax_rules_group
+						ORDER BY n DESC
+						LIMIT 1
+					) most_used'
+				);
+	}
+
 	/**
 	 * For a given ean13 reference, returns the corresponding id
 	 *

controllers/admin/AdminProductsController.php

@@ -2876,13 +2876,15 @@ class AdminProductsControllerCore extends AdminController
 				'countries' => $countries,
 				'groups' => $groups,
 				'combinations' => $combinations,
-				'product' => $product,
 				'multi_shop' => Shop::isFeatureActive(),
 				'link' => new Link()
 			));
 		}
 		else
+		{
 			$this->displayWarning($this->l('You must save this product before adding specific pricing'));
+			$product->id_tax_rules_group = (int)Product::getIdTaxRulesGroupMostUsed();
+		}
 
 		// prices part
 		$data->assign(array(