mail_utils.py

# -*- coding: utf-8 -*-

from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from random import shuffle, randint
import smtplib
import yaml
import json
import ssl


def email_meta_loader() -> dict:
        """Utility function to load email parameters."""

        with open('_config.yml') as config:
                meta = yaml.load(config, Loader=yaml.FullLoader)

        return meta


def load_emails(emails_path : str) -> list:
        """Utility function to load emails list."""

        with open(emails_path) as emails_file:
                emails = json.load(emails_file)

        return emails


def assign_partner(emails : list) -> list:
        """Utility function to match partners from emails list."""

        n = len(emails)
        if n < 2:
                raise ValueError(f'List must have at least 2 emails, it has {n} elements')

        shuffle(emails)
        start = 0
        while start < n - 1:
                # Choose the cut for the cycle
                cut = randint(start + 2, n - 1) if start + 2 < n - 1 else n
                if cut == n - 1: cut = n
                # Assign the cycle
                for i in range(start, cut):
                        emails[i]['assigned'] = emails[(i + 1) % cut]['name']
                # Reset the range
                start = cut
        # Make sure all emails are assigned to only one person. If not, repeat the shuffling until 
        # this is done:
        not_true = True
        while not_true:
            master_dict = {}
            not_true = False
            for i in range(n):
                if emails[i]['assigned'] not in master_dict.keys():
                    master_dict[emails[i]['assigned']] = 1
                else:
                    not_true = True
                    assign_partner(emails)
                    break
        return emails


def send_email(email : dict, user : dict) -> None:
        """Utility function to send email to a specific user."""

        # Setup email configurations:
        message = MIMEMultipart('alternative')
        message['Subject'] = email['subject']
        message['From'] = email['email']
        message['To'] = user['email']

        # Load email body:
        with open(email['body']) as body:
                html = body.read()

        html = html.format(user['name'], user['assigned'])
        body = MIMEText(html, 'html')
        message.attach(body)

        # Create secure connection with server and send email
        context = ssl.create_default_context()
        with smtplib.SMTP_SSL('smtp.gmail.com', 465, context=context) as server:
                server.login(email['email'], email['password'])
                server.sendmail(
                        email['email'], user['email'], message.as_string()
                )


if __name__ == "__main__":
        email = email_meta_loader()
        emails = load_emails(email['list'])
        assign_partner(emails)
        print(emails)