digest: Add a management command to enqueue digest email recipients.

(imported from commit 70ff2c7a4dae654f4077041c45e2154b3ac7afb7)

zerver/management/commands/queue_digest_emails.py

@@ -0,0 +1,55 @@
+from __future__ import absolute_import
+import datetime
+import pytz
+
+from django.core.management.base import BaseCommand
+
+from zerver.lib.queue import queue_json_publish
+from zerver.models import UserActivity, get_user_profile_by_email
+
+VALID_DIGEST_DAYS = (1, 2, 3)
+def inactive_since(user_profile, cutoff):
+    # Hasn't used the app in the last 24 business-day hours.
+    most_recent_visit = [row.last_visit for row in \
+                             UserActivity.objects.filter(
+            user_profile=user_profile)]
+
+    if not most_recent_visit:
+        # This person has never used the app.
+        return True
+
+    last_visit = max(most_recent_visit)
+    return last_visit < cutoff
+
+def last_business_day():
+    one_day = datetime.timedelta(hours=24)
+    previous_day = datetime.datetime.now(tz=pytz.utc) - one_day
+    while previous_day.weekday() not in VALID_DIGEST_DAYS:
+        previous_day -= one_day
+    return previous_day
+
+# Changes to this should also be reflected in
+# zerver/worker/queue_processors.py:DigestWorker.consume()
+def queue_digest_recipient(user_profile, cutoff):
+    # Convert cutoff to epoch seconds for transit.
+    event = {"user_profile_id": user_profile.id,
+             "cutoff": cutoff.strftime('%s')}
+    queue_json_publish("digest_emails", event, lambda event: None)
+
+class Command(BaseCommand):
+    help = """Enqueue digest emails for users that haven't checked the app
+in a while.
+"""
+    def handle(self, *args, **options):
+        # To be really conservative while we don't have user timezones or
+        # special-casing for companies with non-standard workweeks, only
+        # try to send mail on Tuesdays, Wednesdays, and Thursdays.
+        if datetime.datetime.utcnow().weekday() not in VALID_DIGEST_DAYS:
+            return
+
+        for email in ["jesstess@zulip.com", "jessica.mckellar@gmail.com",
+                      "sipbtest@mit.edu", "jesstess+si@zulip.com"]:
+            user_profile = get_user_profile_by_email(email)
+            cutoff = last_business_day()
+            if inactive_since(user_profile, cutoff):
+                queue_digest_recipient(user_profile, cutoff)