[FIX] website_sale: make invoice website_id depend on originating SO instead of partner

Steps to Reproduce
- Install E-Commerce app
- Add Demo payment provider in Test mode
- Go to Settings > Website > Invoicing and activate Automatic Invoice
- Go to Settings > Website and set the domain for:
	- My Website -we'll refer to it as website_1- as http://[IP_address]:[port] such as http://127.0.0.1:8069
	- My Website 2 -we'll refer to it as website_2- as http://[IP_address]:[port] such as http://127.0.0.2:8069
- Create a new product with Invoicing Policy as Ordered quantities
- Go to website_2 and add the new product to the cart and checkout
- With Debug mode on, Check the Emails sent via Settings > Technical > Email > Emails

Current Behavior
Two emails are automatically sent:
- An SO email that opens website_2 when clicking on View Sales Order button which is correct as we purchased the product through website_2
- An Invoice email that opens website_1 when clicking one View Invoice button which is WRONG as it should follow its originating SO and opens website_2 as well

Expected Behavior
Both SO and invoice emails should refer to the website where the SO was created -website_2 in our use case-

Observations
The automatic invoice always refer to website_1 regardless of the website where the SO was originally created.

Investigation
The website_id of the invoice is decided by the corresponding field https://github.com/odoo/odoo/blob/322889ea0a24c5eff2e3289502a2f606cb4048d0/addons/website_sale/models/account_move.py#L10-L13
- As noticed it's a related field to the partner_id.website_id which is False
- That's why the invoice website_id is also False leading to the preview button to fall back to website_1
- The partner_id.website_id is always False unless you manually added the field to the view and then set the website_id. Our case will work correctly if you set the website_id for the user/customer to website_2
- I also tried to sign up at website_2 to see if the website_id will be set accordingly but it stayed as False

Proposed Solution
make the invoice website_id relates to the originating SO instead of the partner

opw-3685742

closes odoo/odoo#154376

X-original-commit: 361e8f68af9c9656764906c8a44d22e1fed090a8
Signed-off-by: Ali Hassan Youssef (alhy) <alhy@odoo.com>

addons/website_sale/models/account_move.py

@@ -1,14 +1,14 @@
 # -*- coding: utf-8 -*-
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
-from odoo import fields, models
+from odoo import api, fields, models
 
 
 class AccountMove(models.Model):
     _inherit = 'account.move'
 
     website_id = fields.Many2one(
-        'website', related='partner_id.website_id', string='Website',
+        'website', compute='_compute_website_id', string='Website',
         help='Website through which this invoice was created for eCommerce orders.',
         store=True, readonly=True, tracking=True)
 
@@ -18,3 +18,12 @@ class AccountMove(models.Model):
             # URL should always be relative, safety check
             action['url'] = f'/@{action["url"]}'
         return action
+
+    @api.depends('partner_id')  # Dummy depends to trigger compute, will be dropped in master
+    def _compute_website_id(self):
+        for move in self:
+            source_websites = move.line_ids.sale_line_ids.order_id.website_id
+            if len(source_websites) == 1:
+                move.website_id = source_websites
+            else:
+                move.website_id = False

addons/website_sale/tests/__init__.py

@@ -26,3 +26,4 @@ from . import test_website_editor
 from . import test_website_sale_reorder_from_portal
 from . import test_website_sale_snippets
 from . import test_website_sale_fiscal_position
+from . import test_website_sale_invoice

addons/website_sale/tests/test_website_sale_invoice.py

@@ -0,0 +1,35 @@
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+from odoo.tests import tagged
+from odoo.tools import mute_logger
+
+from odoo.addons.account_payment.tests.common import AccountPaymentCommon
+from odoo.addons.sale.tests.common import SaleCommon
+
+
+@tagged('-at_install', 'post_install')
+class TestWebsiteSaleInvoice(AccountPaymentCommon, SaleCommon):
+
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+
+        cls.website = cls.env['website'].create({
+            'name': 'Test Website'
+        })
+
+    def test_automatic_invoice_website_id(self):
+        # Set automatic invoice
+        self.env['ir.config_parameter'].sudo().set_param('sale.automatic_invoice', 'True')
+
+        # Create SO on Test Website
+        self.sale_order.website_id = self.website.id
+
+        # Create the payment
+        self.amount = self.sale_order.amount_total
+        tx = self._create_transaction(flow='redirect', sale_order_ids=[self.sale_order.id], state='done')
+        with mute_logger('odoo.addons.sale.models.payment_transaction'):
+            tx._reconcile_after_done()
+
+        self.assertEqual(self.sale_order.website_id.id, self.website.id)
+        self.assertEqual(self.sale_order.invoice_ids.website_id.id, self.website.id)