[ADD] forwardport: email reminders

After 6 months of sitting unmerged, forward ports will now trigger a
monthly email.

Or would, if an email server was configured on the mergebot, but
adding this now should allow debugging its working and tracking the
generation of emails through the "Delivery Failed" collection. This
way if we ever decide to actually do the thing we can just enable an
SMTP server.

Fixes #801

Author: xmo-odoo

forwardport/models/project.py

@@ -14,6 +14,7 @@
 from __future__ import annotations
 
 import builtins
+import collections
 import datetime
 import itertools
 import json
@@ -24,6 +25,7 @@
 
 import dateutil.relativedelta
 import requests
+from markupsafe import Markup
 
 from odoo import models, fields, api
 from odoo.exceptions import UserError
@@ -522,7 +524,8 @@ def _make_fp_message(self, commit):
         return msg
 
     def _reminder(self):
-        for _, prs in groupby(self.search([
+        emails = collections.defaultdict(self.browse)
+        for source, prs in groupby(self.search([
             ('source_id', '!=', False),
             ('blocked', '!=', False),
             ('state', 'in', ['opened', 'validated', 'approved', 'ready', 'error']),
@@ -532,18 +535,49 @@ def _reminder(self):
             # will most likely lead to their parent being validated (?)
             for pr in set(prs).difference(p.parent_id for p in prs):
                 # reminder every 7 days for the first 4 weeks, then every 4 weeks
-                if (pr.reminder_next - pr.create_date) < datetime.timedelta(days=28):
+                age = pr.reminder_next - pr.create_date
+                if age < datetime.timedelta(days=28):
                     pr.reminder_next += datetime.timedelta(days=7)
                 else:
                     pr.reminder_next += datetime.timedelta(days=28)
 
+                # after 6 months, start sending emails
+                if age > datetime.timedelta(weeks=26):
+                    if author := source.author.email:
+                        emails[author] |= prs
+                    if reviewer := source.reviewed_by.email:
+                        emails[reviewer] |= prs
                 self.env.ref('runbot_merge.forwardport.reminder')._send(
                     repository=pr.repository,
                     pull_request=pr.number,
                     token_field='fp_github_token',
                     format_args={'pr': pr, 'source': pr.source_id},
                 )
 
+        try:
+            self.env['mail.mail'].sudo().create([
+                {
+                    'email_to': email,
+                    'subject': f"You have {len(prs)} outstanding forward ports",
+                    'body': Markup(
+                        "<p>The following forward-ports are more than 6 months old "
+                        "and were either created or approved by you.</p>"
+                        "<p>Please process them appropriately (merge or close them)"
+                        "at the earliest.</p>"
+                        "<ul>{}</ul>"
+                    ).format(Markup("").join(
+                        Markup('<li><a href="{link}">{name}</a></li>').format(
+                            name=pr.display_name,
+                            link=pr.github_url,
+                        )
+                        for pr in prs
+                    ))
+                }
+                for email, prs in emails.items()
+            ])
+        except Exception:
+            _logger.exception("Failed to create mail")
+
 
 map_author = operator.itemgetter('name', 'email', 'date')
 map_committer = operator.itemgetter('name', 'email')