Implement mail tracking

Signed-off-by: Victor "multun" Collod <victor.collod@prologin.org>

todo/mail/consumers/__init__.py

@@ -0,0 +1,9 @@
+def tracker_consumer(**kwargs):
+    def tracker_factory(producer):
+        # the import needs to be delayed until call to enable
+        # using the wrapper in the django settings
+        from .tracker import tracker_consumer
+
+        return tracker_consumer(producer, **kwargs)
+
+    return tracker_factory

todo/mail/consumers/tracker.py

@@ -0,0 +1,102 @@
+import logging
+
+from django.db import transaction
+from django.db.models import Count
+from email.charset import Charset as EMailCharset
+from html2text import html2text
+from todo.models import Comment, Task, TaskList
+
+logger = logging.getLogger(__name__)
+
+
+def part_decode(message):
+    charset = ("ascii", "ignore")
+    email_charset = message.get_content_charset()
+    if email_charset:
+        charset = (EMailCharset(email_charset).input_charset,)
+
+    body = message.get_payload(decode=True)
+    return body.decode(*charset)
+
+
+def message_find_mime(message, mime_type):
+    for submessage in message.walk():
+        if submessage.get_content_type() == mime_type:
+            return submessage
+
+
+def message_text(message):
+    text_part = message_find_mime(message, "text/plain")
+    if text_part is not None:
+        return part_decode(text_part)
+
+    html_part = message_find_mime(message, "text/html")
+    if html_part is not None:
+        return html2text(part_decode(html_part))
+
+    return ""
+
+
+def insert_message(task_list, message, priority):
+    if "message-id" not in message:
+        logger.warning("missing message id, ignoring message")
+        return
+
+    if "from" not in message:
+        logger.warning('missing "From" header, ignoring message')
+        return
+
+    if "subject" not in message:
+        logger.warning('missing "Subject" header, ignoring message')
+        return
+
+    logger.info(
+        "received message:\t"
+        f"[Subject: {message['subject']}]\t"
+        f"[Message-ID: {message['message-id']}]\t"
+        f"[To: {message['to']}]\t"
+        f"[From: {message['from']}]"
+    )
+
+    message_id = message["message-id"]
+    message_from = message["from"]
+    text = message_text(message)
+
+    related_messages = message.get("references", "").split()
+
+    # find the most relevant task to add a comment on.
+    # among tasks in the selected task list, find the task having the
+    # most email comments the current message references
+    best_task = (
+        Task.objects.filter(
+            task_list=task_list, comment__email_message_id__in=related_messages
+        )
+        .annotate(num_comments=Count("comment"))
+        .order_by("-num_comments")
+        .only("id")
+        .first()
+    )
+
+    with transaction.atomic():
+        if best_task is None:
+            best_task = Task.objects.create(
+                priority=priority, title=message["subject"], task_list=task_list
+            )
+        logger.info(f"using task: {repr(best_task)}")
+
+        comment, comment_created = Comment.objects.get_or_create(
+            task=best_task,
+            email_message_id=message_id,
+            defaults={"email_from": message_from, "body": text},
+        )
+        logger.info(f"created comment: {repr(comment)}")
+
+
+def tracker_consumer(producer, group=None, task_list_slug=None, priority=1):
+    task_list = TaskList.objects.get(group__name=group, slug=task_list_slug)
+    for message in producer:
+        try:
+            insert_message(task_list, message, priority)
+        except Exception:
+            # ignore exceptions during insertion, in order to avoid
+            logger.exception("got exception while inserting message")

todo/mail/producers/__init__.py

@@ -0,0 +1,9 @@
+def imap_producer(**kwargs):
+    def imap_producer_factory():
+        # the import needs to be delayed until call to enable
+        # using the wrapper in the django settings
+        from .imap import imap_producer
+
+        return imap_producer(**kwargs)
+
+    return imap_producer_factory

todo/mail/producers/imap.py

@@ -0,0 +1,100 @@
+import email
+import email.parser
+import imaplib
+import logging
+import time
+
+from email.policy import default
+from contextlib import contextmanager
+
+logger = logging.getLogger(__name__)
+
+
+def imap_check(command_tuple):
+    status, ids = command_tuple
+    assert status == "OK", ids
+
+
+@contextmanager
+def imap_connect(host, port, user, password):
+    conn = imaplib.IMAP4_SSL(host=host, port=port)
+    conn.login(user, password)
+    imap_check(conn.list())
+    try:
+        yield conn
+    finally:
+        conn.close()
+
+
+def parse_message(message):
+    for response_part in message:
+        if not isinstance(response_part, tuple):
+            continue
+
+        message_metadata, message_content = response_part
+        email_parser = email.parser.BytesFeedParser(policy=default)
+        email_parser.feed(message_content)
+        return email_parser.close()
+
+
+def search_message(conn, *filters):
+    status, message_ids = conn.search(None, *filters)
+    for message_id in message_ids[0].split():
+        status, message = conn.fetch(message_id, "(RFC822)")
+        yield message_id, parse_message(message)
+
+
+def imap_producer(
+    process_all=False,
+    preserve=False,
+    host=None,
+    port=993,
+    user=None,
+    password=None,
+    nap_duration=1,
+    input_folder="INBOX",
+):
+    logger.debug("starting IMAP worker")
+    imap_filter = "(ALL)" if process_all else "(UNSEEN)"
+
+    def process_batch():
+        logger.debug("starting to process batch")
+        # reconnect each time to avoid repeated failures due to a lost connection
+        with imap_connect(host, port, user, password) as conn:
+            # select the requested folder
+            imap_check(conn.select(input_folder, readonly=False))
+
+            try:
+                for message_uid, message in search_message(conn, imap_filter):
+                    logger.info(f"received message {message_uid}")
+                    try:
+                        yield message
+                    except Exception:
+                        logger.exception(
+                            f"something went wrong while processing {message_uid}"
+                        )
+                        raise
+
+                    if not preserve:
+                        # tag the message for deletion
+                        conn.uid("STORE", message_uid, "+FLAGS", "(\\Deleted)")
+                else:
+                    logger.debug("did not receive any message")
+            finally:
+                if not preserve:
+                    # flush deleted messages
+                    conn.expunge()
+
+    while True:
+        try:
+            yield from process_batch()
+        except (GeneratorExit, KeyboardInterrupt):
+            # the generator was closed, due to the consumer
+            # breaking out of the loop, or an exception occuring
+            raise
+        except Exception:
+            logger.exception("mail fetching went wrong, retrying")
+
+        # sleep to avoid using too much resources
+        # TODO: get notified when a new message arrives
+        time.sleep(nap_duration)

todo/management/commands/mail_worker.py

@@ -0,0 +1,32 @@
+import logging
+import sys
+
+from django.core.management.base import BaseCommand, CommandError
+from django.conf import settings
+
+logger = logging.getLogger(__name__)
+
+
+class Command(BaseCommand):
+    help = "Starts a mail worker"
+
+    def add_arguments(self, parser):
+        parser.add_argument("worker_name")
+
+    def handle(self, *args, **options):
+        if not hasattr(settings, "TODO_MAIL_TRACKERS"):
+            logger.error("missing TODO_MAIL_TRACKERS setting")
+            sys.exit(1)
+
+        worker_name = options["worker_name"]
+        tracker = settings.TODO_MAIL_TRACKERS.get(worker_name, None)
+        if tracker is None:
+            logger.error(
+                f"couldn't find configuration for {worker_name} in TODO_MAIL_TRACKERS"
+            )
+            sys.exit(1)
+
+        producer = tracker["producer"]
+        consumer = tracker["consumer"]
+
+        consumer(producer())

todo/migrations/0008_mail_tracker.py

@@ -0,0 +1,46 @@
+# Generated by Django 2.1.4 on 2018-12-21 14:01
+
+from django.conf import settings
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [("todo", "0007_auto_update_created_date")]
+
+    operations = [
+        migrations.AddField(
+            model_name="comment",
+            name="email_from",
+            field=models.CharField(blank=True, max_length=320, null=True),
+        ),
+        migrations.AddField(
+            model_name="comment",
+            name="email_message_id",
+            field=models.TextField(blank=True, null=True),
+        ),
+        migrations.AlterField(
+            model_name="comment",
+            name="author",
+            field=models.ForeignKey(
+                blank=True,
+                null=True,
+                on_delete=django.db.models.deletion.CASCADE,
+                to=settings.AUTH_USER_MODEL,
+            ),
+        ),
+        migrations.AlterField(
+            model_name="task",
+            name="created_by",
+            field=models.ForeignKey(
+                null=True,
+                on_delete=django.db.models.deletion.CASCADE,
+                related_name="todo_created_by",
+                to=settings.AUTH_USER_MODEL,
+            ),
+        ),
+        migrations.AlterUniqueTogether(
+            name="comment", unique_together={("task", "email_message_id")}
+        ),
+    ]

todo/models.py

@@ -1,5 +1,6 @@
 from __future__ import unicode_literals
 import datetime
+import textwrap
 
 from django.conf import settings
 from django.contrib.auth.models import Group
@@ -32,7 +33,10 @@ class Task(models.Model):
     completed = models.BooleanField(default=False)
     completed_date = models.DateField(blank=True, null=True)
     created_by = models.ForeignKey(
-        settings.AUTH_USER_MODEL, related_name="todo_created_by", on_delete=models.CASCADE
+        settings.AUTH_USER_MODEL,
+        null=True,
+        related_name="todo_created_by",
+        on_delete=models.CASCADE,
     )
     assigned_to = models.ForeignKey(
         settings.AUTH_USER_MODEL,
@@ -73,14 +77,35 @@ class Comment(models.Model):
     a comment and change task details at the same time. Rolling our own since it's easy.
     """
 
-    author = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
+    author = models.ForeignKey(
+        settings.AUTH_USER_MODEL, on_delete=models.CASCADE, blank=True, null=True
+    )
     task = models.ForeignKey(Task, on_delete=models.CASCADE)
     date = models.DateTimeField(default=datetime.datetime.now)
+    email_from = models.CharField(max_length=320, blank=True, null=True)
+    email_message_id = models.TextField(blank=True, null=True)
+
     body = models.TextField(blank=True)
 
+    class Meta:
+        # an email should only appear once per task
+        unique_together = ("task", "email_message_id")
+
+    @property
+    def author_text(self):
+        if self.author is not None:
+            return str(self.author)
+
+        assert self.email_message_id is not None
+        return str(self.email_from)
+
+    @property
     def snippet(self):
+        body_snippet = textwrap.shorten(self.body, width=35, placeholder="...")
         # Define here rather than in __str__ so we can use it in the admin list_display
-        return "{author} - {snippet}...".format(author=self.author, snippet=self.body[:35])
+        return "{author} - {snippet}...".format(
+            author=self.author_text, snippet=body_snippet
+        )
 
     def __str__(self):
         return self.snippet()

todo/templates/todo/task_detail.html

@@ -96,8 +96,7 @@
       <h5>Comments on this task</h5>
       {% for comment in comment_list %}
         <p>
-          <strong>{{ comment.author.first_name }}
-            {{ comment.author.last_name }},
+          <strong>{{ comment.author_text }},
             {{ comment.date|date:"F d Y P" }}
           </strong>
         </p>