[FIX] estate: prevent accepting multiple offers

Previously, it was possible to accept multiple offers for the same
property.

This commit adds a validation check in the `accept_offer` method. Now,
if a user attempts to accept an offer for a property that already has
an accepted offer, a UserError is raised to block the action.

Author: karimgamaleldin

estate/models/estate_property.py

@@ -89,7 +89,7 @@ def _onchange_garden(self):
 
 
     @api.constrains("selling_price", "expected_price")
-    def _check_selling_price_gt_90(self):
+    def _check_selling_price_vs_expected_price(self):
         for record in self:
             if not float_is_zero(record.selling_price, precision_digits=2) and float_compare(record.selling_price, record.expected_price * 0.9, precision_digits=2) < 0:
                 raise UserError("The selling price cannot be less than 90% of the expected price.")

estate/models/estate_property_offer.py

@@ -1,4 +1,5 @@
 from odoo import models, fields, api
+from odoo.exceptions import UserError
 
 class EstatePropertyOffer(models.Model):
     _name = 'estate.property.offer'
@@ -31,11 +32,21 @@ def _inverse_date_deadline(self):
 
     def accept_offer(self):
         for offer in self:
+            # Check no other offer has been accepted for the same property
+            if offer.property_id.offer_ids.filtered(lambda o: o.status == 'accepted'):
+                raise UserError('Another offer has already been accepted for this property.')
+        
+            # Accept the offer
             offer.status = 'accepted'
             offer.property_id.selling_price = offer.price
             offer.property_id.state = 'offer_accepted'
             offer.property_id.buyer_id = offer.partner_id
 
+            # Refuse all other offers for the same property
+            other_offers = offer.property_id.offer_ids.filtered(lambda o: o.id != offer.id and o.status != 'refused')
+            for other_offer in other_offers:
+                other_offer.status = 'refused'
+
     def refuse_offer(self):
         for offer in self:
             offer.status = 'refused'