[FIX] event_sale: failed payment on soldout events

When there's a quotation for events registrations and the seats are
limited, if the customer pays the quoutation the payment will fail when
the quoutation gets confirmed.

With this change we prevent the customer from paying that event that is
soldout.

Steps to reproduce:

- Limit the seats for a given event.
- Set autoconfirmation on.
- Create a quotation for a ticket in that event.
- Use the customer preview link to go to the portal view.
- Pay the quotation (i.e. with demo payment method)
- The confirmation crashes as there aren't seats available.

This is an issue as well as the payment is already fulfilled at bank
level, but as the system crashes the callback isn't confirmed at Odoo.

addons/event_sale/__manifest__.py

@@ -24,6 +24,7 @@
         'views/event_registration_views.xml',
         'views/event_views.xml',
         'views/sale_order_views.xml',
+        'views/templates.xml',
         'data/event_sale_data.xml',
         'data/mail_data.xml',
         'report/event_event_templates.xml',

addons/event_sale/models/sale_order.py

@@ -7,6 +7,7 @@ class SaleOrder(models.Model):
     _inherit = "sale.order"
 
     attendee_count = fields.Integer('Attendee Count', compute='_compute_attendee_count')
+    has_soldout_event = fields.Boolean(compute="_compute_has_soldout_event")
 
     def write(self, vals):
         """ Synchronize partner from SO to registrations. This is done notably
@@ -52,6 +53,21 @@ def _compute_attendee_count(self):
         for sale_order in self:
             sale_order.attendee_count = attendee_count_data.get(sale_order.id, 0)
 
+    def _compute_has_soldout_event(self):
+        """Meant to be used in the portal to prevent customers from paying for an event
+        that is sold out. Not only because we'd overbook the event, but also because it
+        will probably crash on the confirmation of the order when the registrations
+        are created."""
+        self.has_soldout_event = False
+        for order in self.filtered(lambda x: x.state in ["draft", "sent"]):
+            order.has_soldout_event = bool(order.order_line.event_id.filtered(
+                lambda x: x.seats_limited and x.seats_max and x.seats_available <= 0
+            ))
+
+    def has_to_be_paid(self, include_draft=False):
+        has_to_be_paid = super().has_to_be_paid(include_draft=include_draft)
+        return has_to_be_paid and not self.has_soldout_event
+
     def unlink(self):
         self.order_line._unlink_associated_registrations()
         return super(SaleOrder, self).unlink()

addons/event_sale/views/templates.xml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="utf-8"?>
+<odoo>
+    <template id="sale_order_portal_template" inherit_id="sale.sale_order_portal_template" name="Event sale order portal">
+        <xpath expr="//div[@t-if='sale_order.is_expired']" position="before">
+            <div t-if="sale_order.has_soldout_event" class="alert alert-warning alert-dismissable d-print-none" role="alert">
+                <button type="button" class="close" data-dismiss="alert" aria-label="Close"></button>
+                <strong>The event is sold out!</strong> <a role="button" href="#discussion"><i class="fa fa-comment"/> Contact us for more information.</a>
+            </div>
+        </xpath>
+    </template>
+</odoo>