email_tasks.py

from email import encoders
import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from email.mime.image import MIMEImage
from email.mime.base import MIMEBase

from django.conf import settings
from html2text import HTML2Text
from celery.utils.log import get_task_logger
from celery.exceptions import SoftTimeLimitExceeded, MaxRetriesExceededError

from recomed.celery import app


__author__ = 'adam.jorgensen.za@gmail.com'
logger = get_task_logger(__name__)

html_to_text = HTML2Text()
html_to_text.ignore_images = True


#TODO: Find a new SMTP server that doesn't limit us to 20 emails per hour
def send_email(to_address, subject, body_html, images=None, attachments=None, APP_ROOT=None):
    """
    Send an email. This is a Celery task and hence can be called asynchronously. SMTP settings are drawn from settings.py
    """
    try:
        logger.info("SENDING EMAIL TO: %s  SUBJECT: %s" % (to_address, subject))

        message_root = MIMEMultipart('related')
        message_root.preamble = 'This is a multi-part message in MIME format.'
        message_root['Subject'] = subject
        message_root['From'] = settings.EMAIL_HOST_USER
        message_root['To'] = ', '.join(to_address) if not isinstance(to_address, basestring) else to_address

        message_content = MIMEMultipart('alternative')
        message_root.attach(message_content)

        if images:
            for filename, image_id in images:
                with open('%simages/%s' % (APP_ROOT, filename), 'rb') as image_file:
                    image_content = MIMEImage(image_file.read())
                    image_content.add_header('Content-ID', '<%s>' % image_id)
                    message_root.attach(image_content)

        if attachments:
            for mime_main_type, mime_sub_type, filename, data in attachments:
                attachment = MIMEBase(mime_main_type, mime_sub_type)
                attachment.set_payload(data)
                encoders.encode_base64(attachment)
                attachment.add_header('Content-Disposition', 'attachment', filename=filename)
                message_root.attach(attachment)

        message_content.attach(MIMEText(html_to_text.handle(body_html), 'plain'))
        message_content.attach(MIMEText(body_html, 'html'))

        smtpserver = smtplib.SMTP_SSL(settings.EMAIL_HOST, settings.EMAIL_PORT)
        smtpserver.ehlo()
        smtpserver.login(settings.EMAIL_HOST_USER, settings.EMAIL_HOST_PASSWORD)

        # send email
        smtpserver.sendmail(settings.EMAIL_HOST_USER, to_address, message_root.as_string())
        smtpserver.quit()
    except Exception as exc:
        logger.error('Error(%s:%s) sending email with subject "%s" to "%s"' % (exc.__class__.__name__, str(exc), subject, to_address))
        raise exc
    return True


@app.task(bind=True, time_limit=600, soft_time_limit=520, max_retries=10, compression='bzip2', rate_limit='20/h')
def send_email_task(self, to_address, subject, body_html, images=None, attachments=None, APP_ROOT=None ):
    try:
        return send_email(to_address, subject, body_html, images, attachments, APP_ROOT=APP_ROOT)
    except (MemoryError, SoftTimeLimitExceeded) as exc:
        if isinstance(exc, MemoryError):
            logger.error('MemoryError while attempting to send email with subject "%s" to "%s". Scheduling retry.' % (subject, to_address))
        else:
            logger.error('Exceeded Soft Time Limit attempting to send email with subject "%s" to "%s". Scheduling retry.' % (subject, to_address))
        raise self.retry(exc=exc)
    except MaxRetriesExceededError as exc:
        logger.error('Retry limit reached attempting to send email with subject "%s" to "%s". Will not retry.' % (subject, to_address))
        return False