society-self-service/ssmain/email.py

#    Society Self-Service
#    Copyright © 2018-2020  Yingtong Li (RunasSudo)
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU Affero General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU Affero General Public License for more details.
#
#    You should have received a copy of the GNU Affero General Public License
#    along with this program.  If not, see <https://www.gnu.org/licenses/>.

import boto3
from botocore.exceptions import ClientError
import premailer

from django.conf import settings
from django.template import loader
from jinja2 import Markup

from selfserv.mdx_urlize import UrlizeExtension

import logging
import markdown

# Debugging
import subprocess
import tempfile
import time

class Emailer:
	def __init__(self):
		self.client = boto3.client('ses', aws_access_key_id=settings.AWS_KEY_ID, aws_secret_access_key=settings.AWS_SECRET, region_name=settings.AWS_REGION)
		self.template = loader.get_template('ssmain/email/rendered.html')
	
	def markdown(self, x):
		return markdown.markdown(x, extensions=[UrlizeExtension(), 'fenced_code'])
	
	def boto3_send(self, *args, **kwargs):
		for i in range(0, 10):
			try:
				self.client.send_email(*args, **kwargs)
				return
			except ClientError as e:
				if e['Error']['Code'] == 'Throttling' and e['Error']['Message'] == 'Maximum sending rate exceeded.':
					wait_time = max(10*(2**i), 5000)
					#self.stdout.write(self.style.NOTICE('Reached maximum sending rate, waiting {} ms'.format(wait_time)))
					time.sleep(wait_time/1000)
				else:
					raise e
		raise Exception('Reached maximum number of retries')
	
	def send_raw_mail(self, recipients, subject, content_txt, content_html):
		if settings.EMAIL_DEBUG:
			with tempfile.NamedTemporaryFile(mode='w', encoding='utf-8', suffix='.eml') as f:
				print('Subject:' + subject + '\nContent-Type: multipart/alternative; boundary=boundary\n\n--boundary\nContent-Type: text/html; charset=utf-8\n\n' + content_html + '\n--boundary\nContent-Type: text/plain; charset=utf-8\n\n' + content_txt + '\n--boundary', file=f)
				subprocess.run(['thunderbird', f.name])
				time.sleep(5)
		else:
			self.boto3_send(
				Destination={
					'ToAddresses': recipients,
				},
				Message={
					'Body': {
						'Html': {
							'Charset': 'utf-8',
							'Data': content_html,
						},
						'Text': {
							'Charset': 'utf-8',
							'Data': content_txt,
						},
					},
					'Subject': {
						'Charset': 'utf-8',
						'Data': subject,
					},
				},
				Source='{} <{}>'.format(settings.ORG_NAME, settings.AWS_SENDER_EMAIL),
			)
	
	def render_mail(self, template_loc, params={}):
		params['baseurl'] = 'https://' + settings.ALLOWED_HOSTS[0]
		
		template = loader.get_template(template_loc)
		content_txt = template.render(params)
		
		content_markdown = self.markdown(content_txt)
		content_html = self.template.render({'email_content': Markup(content_markdown)})
		
		content_html = premailer.Premailer(content_html, cssutils_logging_level=logging.ERROR, strip_important=False).transform()
		
		return content_txt, content_html
	
	def send_mail(self, recipients, subject, template_loc, params):
		content_txt, content_html = self.render_mail(template_loc, params)
		self.send_raw_mail(recipients, subject, content_txt, content_html)