FitTrackee/fittrackee/emails/email.py

import logging
import smtplib
import ssl
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from typing import Dict, List, Optional, Type, Union

from babel.support import Translations
from flask import Flask
from jinja2 import Environment, FileSystemLoader, select_autoescape
from urllib3.util import parse_url

from .exceptions import InvalidEmailUrlScheme

email_log = logging.getLogger('fittrackee_api_email')
email_log.setLevel(logging.DEBUG)


class EmailMessage:
    def __init__(
        self, sender: str, recipient: str, subject: str, html: str, text: str
    ) -> None:
        self.sender = sender
        self.recipient = recipient
        self.subject = subject
        self.html = html
        self.text = text

    def generate_message(self) -> MIMEMultipart:
        message = MIMEMultipart('alternative')
        message['Subject'] = self.subject
        message['From'] = self.sender
        message['To'] = self.recipient
        part1 = MIMEText(self.text, 'plain')
        part2 = MIMEText(self.html, 'html')
        message.attach(part1)
        message.attach(part2)
        return message


class EmailTemplate:
    def __init__(
        self,
        template_directory: str,
        translations_directory: str,
        languages: List[str],
    ) -> None:
        self._translations = self._get_translations(
            translations_directory, languages
        )
        self._env = Environment(
            autoescape=select_autoescape(['html', 'htm', 'xml']),
            loader=FileSystemLoader(template_directory),
            extensions=['jinja2.ext.i18n'],
        )

    @staticmethod
    def _get_translations(
        translations_directory: str, languages: List[str]
    ) -> Dict:
        translations = {}
        for language in languages:
            translations[language] = Translations.load(
                dirname=translations_directory, locales=[language]
            )
        return translations

    def _load_translation(self, lang: str) -> None:
        self._env.install_gettext_translations(  # type: ignore
            self._translations[lang],
            newstyle=True,
        )

    def get_content(
        self, template_name: str, lang: str, part: str, data: Dict
    ) -> str:
        self._load_translation(lang)
        template = self._env.get_template(f'{template_name}/{part}')
        return template.render(data)

    def get_all_contents(self, template: str, lang: str, data: Dict) -> Dict:
        output = {}
        for part in ['subject.txt', 'body.txt', 'body.html']:
            output[part] = self.get_content(template, lang, part, data)
        return output

    def get_message(
        self, template: str, lang: str, sender: str, recipient: str, data: Dict
    ) -> MIMEMultipart:
        output = self.get_all_contents(template, lang, data)
        message = EmailMessage(
            sender,
            recipient,
            output['subject.txt'],
            output['body.html'],
            output['body.txt'],
        )
        return message.generate_message()


class EmailService:
    def __init__(self, app: Optional[Flask] = None) -> None:
        self.host = 'localhost'
        self.port = 25
        self.use_tls = False
        self.use_ssl = False
        self.username = None
        self.password = None
        self.sender_email = 'no-reply@example.com'
        self.email_template: Optional[EmailTemplate] = None
        if app is not None:
            self.init_email(app)

    def init_email(self, app: Flask) -> None:
        parsed_url = self.parse_email_url(app.config['EMAIL_URL'])
        self.host = parsed_url['host']
        self.port = parsed_url['port']
        self.use_tls = parsed_url['use_tls']
        self.use_ssl = parsed_url['use_ssl']
        self.username = parsed_url['username']
        self.password = parsed_url['password']
        self.sender_email = app.config['SENDER_EMAIL']
        self.email_template = EmailTemplate(
            app.config['TEMPLATES_FOLDER'],
            app.config['TRANSLATIONS_FOLDER'],
            app.config['LANGUAGES'],
        )

    @staticmethod
    def parse_email_url(email_url: str) -> Dict:
        parsed_url = parse_url(email_url)
        if parsed_url.scheme != 'smtp':
            raise InvalidEmailUrlScheme()
        credentials = (
            parsed_url.auth.split(':') if parsed_url.auth else [None, None]
        )
        return {
            'host': parsed_url.host,
            'port': 25 if parsed_url.port is None else parsed_url.port,
            'use_tls': True if parsed_url.query == 'tls=True' else False,
            'use_ssl': True if parsed_url.query == 'ssl=True' else False,
            'username': credentials[0],
            'password': credentials[1],
        }

    @property
    def smtp(self) -> Type[Union[smtplib.SMTP_SSL, smtplib.SMTP]]:
        return smtplib.SMTP_SSL if self.use_ssl else smtplib.SMTP

    def send(
        self, template: str, lang: str, recipient: str, data: Dict
    ) -> None:
        if not self.email_template:
            raise Exception('No email template defined.')
        message = self.email_template.get_message(
            template, lang, self.sender_email, recipient, data
        )
        connection_params = {}
        if self.use_ssl or self.use_tls:
            context = ssl.create_default_context()
        if self.use_ssl:
            connection_params.update({'context': context})
        with self.smtp(
            self.host, self.port, **connection_params  # type: ignore
        ) as smtp:
            if self.use_tls:
                smtp.ehlo()
                smtp.starttls(context=context)
                smtp.ehlo()
            if self.username and self.password:
                smtp.login(self.username, self.password)  # type: ignore
            smtp.sendmail(self.sender_email, recipient, message.as_string())
            smtp.quit()