[FIX] sale_stock: properly check routes

For some unknown reason, the salepocalypse project completely screwed up
the availability check of the product. This commit adds back the check
as it used to be.

opw-653991

addons/sale_stock/sale_stock.py

@@ -128,13 +128,7 @@ class SaleOrderLine(models.Model):
                 uom=self.product_uom.id,
                 warehouse_id=self.order_id.warehouse_id.id
             )
-            if float_compare(product.virtual_available, self.product_uom_qty, precision_digits=precision) == -1:
-                # Check if MTO, Cross-Dock or Drop-Shipping
-                is_available = False
-                for route in self.route_id+self.product_id.route_ids:
-                    for pull in route.pull_ids:
-                        if pull.location_id.id == self.order_id.warehouse_id.lot_stock_id.id:
-                            is_available = True
+                is_available = self._check_routing()
                 if not is_available:
                     warning_mess = {
                         'title': _('Not enough inventory!'),
@@ -195,6 +189,38 @@ class SaleOrderLine(models.Model):
             }
         return {}
 
+    def _check_routing(self):
+        """ Verify the route of the product based on the warehouse
+            return True if the product availibility in stock does not need to be verified,
+            which is the case in MTO, Cross-Dock or Drop-Shipping
+        """
+        is_available = False
+        product_routes = self.route_id or self.product_id.route_ids
+
+        # Check MTO
+        wh_mto_route = self.order_id.warehouse_id.mto_pull_id.route_id
+        if wh_mto_route and wh_mto_route <= product_routes:
+            is_available = True
+        else:
+            mto_route_id = False
+            try:
+                mto_route_id = self.env['stock.warehouse']._get_mto_route()
+            except models.except_orm:
+                # if route MTO not found in ir_model_data, we treat the product as in MTS
+                pass
+            if mto_route_id and mto_route_id in product_routes.ids:
+                is_available = True
+
+        # Check Drop-Shipping
+        if not is_available:
+            for pull_rule in product_routes.mapped('pull_ids'):
+                if pull_rule.picking_type_id.default_location_src_id.usage == 'supplier' and\
+                        pull_rule.picking_type_id.default_location_dest_id.usage == 'customer':
+                    is_available = True
+                    break
+
+        return is_available
+
 
 class StockLocationRoute(models.Model):
     _inherit = "stock.location.route"