From b0945a10d9fb3216fe213a8f0ce9d37c0104fea1 Mon Sep 17 00:00:00 2001
From: Martin Rejman <martin.rejman@pirati.cz>
Date: Fri, 24 May 2019 00:21:54 +0200
Subject: [PATCH] Odesilani newsletteru po castech kvuli limitu API.

---
 src/nalodeni/news.py | 77 +++++++++++++++++++++++++-------------------
 1 file changed, 44 insertions(+), 33 deletions(-)

diff --git a/src/nalodeni/news.py b/src/nalodeni/news.py
index 7c2439c..4aa9120 100644
--- a/src/nalodeni/news.py
+++ b/src/nalodeni/news.py
@@ -391,47 +391,58 @@ def msg_send(request, id, realSend=False):
         }
 
     if realSend:
+        def chunks(l, n):
+            """Yield successive n-sized chunks from l."""
+            for i in range(0, len(l), n):
+                yield l[i:i + n]
+
         from django.core.mail import get_connection, EmailMultiAlternatives
         import quopri
 
-        mailgun_backend = get_connection('anymail.backends.mailgun.EmailBackend')
+        for recip_part in chunks(recipients_email, 500):
+            # process by part, MailGun API hsa a limit of 1000 messages
 
-        header_from = '%s <%s>' % (
-                appSettings.ANYMAIL['FROM_NAME'],
-                appSettings.ANYMAIL['FROM_EMAIL'],
-            )
-        html_message = render_to_string(template, context)
-        plain_message = html2text.html2text(html_message)
+            mailgun_backend = get_connection('anymail.backends.mailgun.EmailBackend')
 
-        ema = EmailMultiAlternatives(
-                "%s - %s" % (obj.news.name, obj.title),
-                plain_message, header_from )
-        ema.connection = mailgun_backend
+            header_from = '%s <%s>' % (
+                    appSettings.ANYMAIL['FROM_NAME'],
+                    appSettings.ANYMAIL['FROM_EMAIL'],
+                )
+            html_message = render_to_string(template, context)
+            plain_message = html2text.html2text(html_message)
 
-        if use_public_to_email:
-            ema.to = [ appSettings.ANYMAIL['PUBLIC_TO_EMAIL'] ]
-        else:
-            # pouzit kontaktni nebo registracni email uzivatele
-            eml = rcp.email_contact_active
-            if eml is None or len(eml.strip()) == 0:
-                eml = rcp.email
-            ema.to = [ eml ]
+            ema = EmailMultiAlternatives(
+                    "%s - %s" % (obj.news.name, obj.title),
+                    plain_message, header_from )
+            ema.connection = mailgun_backend
 
-        ema.bcc = recipients_email
-        if obj.news.replyToEmail is not None:
-            try:
-                eml = obj.news.replyToEmail.strip()
-                validate_email(eml)
-                ema.extra_headers = {
-                    'Reply-To' : eml,
-                    }
-            except ValidationError:
-                messages.error(request, "Odpovědní email '%s' není ve tvaru emailu. Odesílání zrušeno." % (eml,) )
-                messages.info(request, "Chybu může opravit správce tohoto newsletteru." )
-                return redirect('nalodeni:news_list_show', lid=obj.news_id)
+            if use_public_to_email:
+                ema.to = [ appSettings.ANYMAIL['PUBLIC_TO_EMAIL'] ]
+            else:
+                # pouzit kontaktni nebo registracni email uzivatele
+                eml = rcp.email_contact_active
+                if eml is None or len(eml.strip()) == 0:
+                    eml = rcp.email
+                ema.to = [ eml ]
 
-        ema.attach_alternative(html_message, "text/html")
-        ema.send()
+            ema.bcc = recip_part
+            if obj.news.replyToEmail is not None:
+                try:
+                    eml = obj.news.replyToEmail.strip()
+                    validate_email(eml)
+                    ema.extra_headers = {
+                        'Reply-To' : eml,
+                        }
+                except ValidationError:
+                    messages.error(request, "Odpovědní email '%s' není ve tvaru emailu. Odesílání zrušeno." % (eml,) )
+                    messages.info(request, "Chybu může opravit správce tohoto newsletteru." )
+                    return redirect('nalodeni:news_list_show', lid=obj.news_id)
+
+            ema.attach_alternative(html_message, "text/html")
+            ema.send()
+
+            messages.info(request, "Zpráva odeslána %s uživatelům." % len(recip_part) )
+            # end of partial send
 
         if update_sent_ts:
             obj.sent_ts = datetime.now()