DRY out email sending code and normalize behavior

This refactor removes duplicated logic for deciding whom the messages get sent to.
It also normalizes behavior ensuring that all CCed addresses are sent to in all cases that CCed individuals should be notified.

helpdesk/lib.py

@@ -9,142 +9,22 @@ lib.py - Common functions (eg multipart e-mail)
 import logging
 import mimetypes
 import os
-from smtplib import SMTPException
 
 from django.conf import settings
 from django.db.models import Q
-from django.utils import six
 from django.utils.encoding import smart_text
 from django.utils.safestring import mark_safe
 
 from helpdesk.models import Attachment, EmailTemplate
 
-import six
-
 from model_utils import Choices
 
-if six.PY3:
-    from base64 import encodebytes as b64encode
-    from base64 import decodebytes as b64decode
-else:
-    from base64 import urlsafe_b64encode as b64encode
-    from base64 import urlsafe_b64decode as b64decode
+from base64 import encodebytes as b64encode
+from base64 import decodebytes as b64decode
 
 logger = logging.getLogger('helpdesk')
 
 
-def send_templated_mail(template_name,
-                        context,
-                        recipients,
-                        sender=None,
-                        bcc=None,
-                        fail_silently=False,
-                        files=None):
-    """
-    send_templated_mail() is a wrapper around Django's e-mail routines that
-    allows us to easily send multipart (text/plain & text/html) e-mails using
-    templates that are stored in the database. This lets the admin provide
-    both a text and a HTML template for each message.
-
-    template_name is the slug of the template to use for this message (see
-        models.EmailTemplate)
-
-    context is a dictionary to be used when rendering the template
-
-    recipients can be either a string, eg 'a@b.com', or a list of strings.
-
-    sender should contain a string, eg 'My Site <me@z.com>'. If you leave it
-        blank, it'll use settings.DEFAULT_FROM_EMAIL as a fallback.
-
-    bcc is an optional list of addresses that will receive this message as a
-        blind carbon copy.
-
-    fail_silently is passed to Django's mail routine. Set to 'True' to ignore
-        any errors at send time.
-
-    files can be a list of tuples. Each tuple should be a filename to attach,
-        along with the File objects to be read. files can be blank.
-
-    """
-    from django.core.mail import EmailMultiAlternatives
-    from django.template import engines
-    from_string = engines['django'].from_string
-
-    from helpdesk.models import EmailTemplate
-    from helpdesk.settings import HELPDESK_EMAIL_SUBJECT_TEMPLATE, \
-        HELPDESK_EMAIL_FALLBACK_LOCALE
-
-    locale = context['queue'].get('locale') or HELPDESK_EMAIL_FALLBACK_LOCALE
-
-    try:
-        t = EmailTemplate.objects.get(template_name__iexact=template_name, locale=locale)
-    except EmailTemplate.DoesNotExist:
-        try:
-            t = EmailTemplate.objects.get(template_name__iexact=template_name, locale__isnull=True)
-        except EmailTemplate.DoesNotExist:
-            logger.warning('template "%s" does not exist, no mail sent', template_name)
-            return  # just ignore if template doesn't exist
-
-    subject_part = from_string(
-        HELPDESK_EMAIL_SUBJECT_TEMPLATE % {
-            "subject": t.subject
-        }).render(context).replace('\n', '').replace('\r', '')
-
-    footer_file = os.path.join('helpdesk', locale, 'email_text_footer.txt')
-
-    text_part = from_string(
-        "%s{%% include '%s' %%}" % (t.plain_text, footer_file)
-    ).render(context)
-
-    email_html_base_file = os.path.join('helpdesk', locale, 'email_html_base.html')
-    # keep new lines in html emails
-    if 'comment' in context:
-        context['comment'] = mark_safe(context['comment'].replace('\r\n', '<br>'))
-
-    html_part = from_string(
-        "{%% extends '%s' %%}{%% block title %%}"
-        "%s"
-        "{%% endblock %%}{%% block content %%}%s{%% endblock %%}" %
-        (email_html_base_file, t.heading, t.html)
-    ).render(context)
-
-    if isinstance(recipients, str):
-        if recipients.find(','):
-            recipients = recipients.split(',')
-    elif type(recipients) != list:
-        recipients = [recipients]
-
-    msg = EmailMultiAlternatives(subject_part, text_part,
-                                 sender or settings.DEFAULT_FROM_EMAIL,
-                                 recipients, bcc=bcc)
-    msg.attach_alternative(html_part, "text/html")
-
-    if files:
-        for filename, filefield in files:
-            mime = mimetypes.guess_type(filename)
-            if mime[0] is not None and mime[0] == "text/plain":
-                with open(filefield.path, 'r') as attachedfile:
-                    content = attachedfile.read()
-                    msg.attach(filename, content)
-            else:
-                if six.PY3:
-                    msg.attach_file(filefield.path)
-                else:
-                    with open(filefield.path, 'rb') as attachedfile:
-                        content = attachedfile.read()
-                        msg.attach(filename, content)
-
-    logger.debug('Sending email to: {!r}'.format(recipients))
-
-    try:
-        return msg.send()
-    except SMTPException as e:
-        logger.exception('SMTPException raised while sending email to {}'.format(recipients))
-        if not fail_silently:
-            raise e
-        return 0
-
-
 def query_to_dict(results, descriptions):
     """
     Replacement method for cursor.dictfetchall() as that method no longer