email_utils.py

from typing import Union
import logging

import smtplib

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


LOG = logging.getLogger(__name__)


SMTP_DEBUG_LEVEL = 0  # 0 == off, 1 == debug, 2 == timestamps
SMTP_HOST = 'smtp.gmail.com'
SMTP_PORT = 587
SMTP_USER = ''
SMTP_PASSWORD = ''


def _log_success(method, response):
    resp_code, resp_msg = response
    # LOG.info(f'SMTP: SUCCESS <{method}: {{code={resp_code}, message={resp_msg}}}>')
    print(f'SMTP: SUCCESS <{method}: {{code={resp_code}, message={resp_msg}}}>')


def _log_failure(error):
    err_cls = error.__class__.__name__
    err_code, err_msg = error.args
    LOG.error(f'SMTP: FAILURE <smtplib.{err_cls} {{code={err_code}, message={err_msg}}}>')


def _fail_safely(func):

    def _try_and_catch(*args, **kwargs):
        try:
            return func(*args, **kwargs)
        except smtplib.SMTPException as e:
            _log_failure(e)
            return False

    return _try_and_catch


class Email:

    def __init__(self, sender=SMTP_USER, password=SMTP_PASSWORD, host=SMTP_HOST, port=SMTP_PORT):
        self.sender = sender
        self.password = password
        self.host = host
        self.port = port
        self.subject = None
        self.body = None
        self.attachments = []
        self.message = MIMEMultipart()

    def set_message(self, subject: Union[str, None], body: Union[str, None], html=False) -> None:
        self.subject = subject

        if body is None:
            self.body = None
        else:
            self.body = MIMEText(body, 'plain' if not html else 'html')

    def add_attachment(self, data: bytes, filename: str, mimetype=r'application\octet-stream') -> MIMEBase:
        attachment = MIMEBase(*mimetype.split('\\'))
        attachment.set_payload(data)
        encoders.encode_base64(attachment)
        attachment.add_header('Content-Disposition', f'attachment; filename="{filename}"')
        self.attachments.append(attachment)
        return attachment

    @_fail_safely
    def send(self, recipients: Union[str, list, tuple], cc=None, bcc=None) -> bool:
        self.message['Subject'] = self.subject
        self.message['From'] = self.sender
        self.message['To'] = recipients
        self.message['Cc'] = cc
        self.message['Bcc'] = bcc

        if self.body is not None:
            self.message.attach(self.body)

        for attachment in self.attachments:
            self.message.attach(attachment)

        print(f'SMTP: Creating TLS SMTP client {{host={self.host}, port={self.port}}}')
        with smtplib.SMTP(self.host, self.port) as smtp_client:
            smtp_client.set_debuglevel(SMTP_DEBUG_LEVEL)

            print(f'SMTP: Sending Email {{sender={self.sender}, recipients={recipients}, cc={cc}, bcc={bcc}}}')

            response = smtp_client.starttls()
            _log_success('starttls', response)

            response = smtp_client.login(self.sender, self.password)
            _log_success('login', response)

            smtp_client.send_message(self.message)
            LOG.info('SMTP: SUCCESS <send: Email sent successfully>')
            print('SMTP: SUCCESS <send: Email sent successfully>')

        self.subject = None
        self.body = None
        self.attachments = []
        self.message = MIMEMultipart()

        return True