feat(billing): outbound webhook engine (HMAC + retry/backoff)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

fusion_centralize_billing/models/webhook.py

@@ -1,7 +1,19 @@
 # -*- coding: utf-8 -*-
 # Copyright 2026 Nexa Systems Inc.
 # License OPL-1
-from odoo import fields, models
+import hashlib
+import hmac
+import json
+import logging
+from datetime import timedelta
+
+import requests
+
+from odoo import api, fields, models
+
+_logger = logging.getLogger(__name__)
+
+MAX_ATTEMPTS = 8
 
 
 class FusionBillingWebhook(models.Model):
@@ -40,3 +52,50 @@ class FusionBillingWebhook(models.Model):
     next_retry_at = fields.Datetime()
     signature = fields.Char(help="HMAC-SHA256 of the payload using the service webhook_secret.")
     last_error = fields.Text()
+
+    @api.model
+    def _sign(self, secret, body):
+        return hmac.new((secret or '').encode(), body.encode(), hashlib.sha256).hexdigest()
+
+    @api.model
+    def _enqueue(self, service, event_type, payload):
+        body = json.dumps(payload, sort_keys=True, separators=(',', ':'))
+        return self.create({
+            'service_id': service.id,
+            'event_type': event_type,
+            'payload': payload,
+            'signature': self._sign(service.webhook_secret, body),
+            'state': 'pending',
+            'next_retry_at': fields.Datetime.now(),
+        })
+
+    @api.model
+    def _cron_dispatch(self):
+        now = fields.Datetime.now()
+        due = self.search([
+            ('state', 'in', ('pending', 'failed')),
+            ('next_retry_at', '<=', now),
+        ], limit=100)
+        for wh in due:
+            body = json.dumps(wh.payload, sort_keys=True, separators=(',', ':'))
+            try:
+                resp = requests.post(
+                    wh.service_id.webhook_url,
+                    data=body,
+                    headers={'Content-Type': 'application/json',
+                             'X-Fusion-Signature': wh.signature,
+                             'X-Fusion-Event': wh.event_type},
+                    timeout=10,
+                )
+                ok = 200 <= resp.status_code < 300
+            except Exception as e:  # noqa: BLE001 - record and retry
+                ok = False
+                wh.last_error = str(e)[:500]
+            wh.attempts += 1
+            if ok:
+                wh.state = 'sent'
+            elif wh.attempts >= MAX_ATTEMPTS:
+                wh.state = 'dead'
+            else:
+                wh.state = 'failed'
+                wh.next_retry_at = now + timedelta(minutes=2 ** wh.attempts)

fusion_centralize_billing/tests/__init__.py

@@ -2,3 +2,4 @@ from . import test_identity
 from . import test_charge
 from . import test_usage
 from . import test_api
+from . import test_webhook

fusion_centralize_billing/tests/test_webhook.py

@@ -0,0 +1,53 @@
+# -*- coding: utf-8 -*-
+import hashlib
+import hmac
+import json
+from unittest.mock import patch
+
+from odoo.tests.common import TransactionCase, tagged
+
+
+@tagged('post_install', '-at_install')
+class TestWebhookEngine(TransactionCase):
+
+    def setUp(self):
+        super().setUp()
+        self.service = self.env['fusion.billing.service'].sudo().create({
+            'name': 'NexaCloud', 'code': 'nexacloud',
+            'webhook_url': 'https://api.vps.nexasystems.ca/billing/webhook',
+            'webhook_secret': 'whsec_test',
+        })
+        self.Webhook = self.env['fusion.billing.webhook'].sudo()
+
+    def test_enqueue_signs_payload(self):
+        wh = self.Webhook._enqueue(self.service, 'invoice.payment_failed', {'invoice': 'INV-1'})
+        self.assertEqual(wh.state, 'pending')
+        body = json.dumps({'invoice': 'INV-1'}, sort_keys=True, separators=(',', ':'))
+        expected = hmac.new(b'whsec_test', body.encode(), hashlib.sha256).hexdigest()
+        self.assertEqual(wh.signature, expected)
+
+    def test_dispatch_marks_sent_on_2xx(self):
+        wh = self.Webhook._enqueue(self.service, 'invoice.paid', {'invoice': 'INV-2'})
+
+        class _Resp:
+            status_code = 200
+            text = 'ok'
+
+        with patch('odoo.addons.fusion_centralize_billing.models.webhook.requests.post',
+                   return_value=_Resp()) as mock_post:
+            self.Webhook._cron_dispatch()
+            self.assertTrue(mock_post.called)
+        self.assertEqual(wh.state, 'sent')
+
+    def test_dispatch_retries_then_deadletters(self):
+        wh = self.Webhook._enqueue(self.service, 'invoice.paid', {'invoice': 'INV-3'})
+        wh.write({'attempts': 7})  # already past max
+
+        class _Resp:
+            status_code = 500
+            text = 'err'
+
+        with patch('odoo.addons.fusion_centralize_billing.models.webhook.requests.post',
+                   return_value=_Resp()):
+            self.Webhook._cron_dispatch()
+        self.assertEqual(wh.state, 'dead')