python-mylib/mylib/email.py

""" Email client to forge and send emails """

import email.utils
import logging
import os
import smtplib
from email.encoders import encode_base64
from email.mime.base import MIMEBase
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText

from mako.template import Template as MakoTemplate

from mylib.config import (
    BooleanOption,
    ConfigurableObject,
    IntegerOption,
    PasswordOption,
    StringOption,
)

log = logging.getLogger(__name__)


class EmailClient(
    ConfigurableObject
):  # pylint: disable=useless-object-inheritance,too-many-instance-attributes
    """
    Email client

    This class abstract all interactions with the SMTP server.
    """

    _config_name = "email"
    _config_comment = "Email"
    _defaults = {
        "smtp_host": "localhost",
        "smtp_port": 25,
        "smtp_ssl": False,
        "smtp_tls": False,
        "smtp_user": None,
        "smtp_password": None,
        "smtp_debug": False,
        "sender_name": "No reply",
        "sender_email": "noreply@localhost",
        "encoding": "utf-8",
        "catch_all_addr": None,
        "just_try": False,
    }

    templates = {}

    def __init__(self, templates=None, **kwargs):
        super().__init__(**kwargs)

        assert templates is None or isinstance(templates, dict)
        self.templates = templates if templates else {}

    # pylint: disable=arguments-differ,arguments-renamed
    def configure(self, use_smtp=True, just_try=True, **kwargs):
        """Configure options on registered mylib.Config object"""
        section = super().configure(**kwargs)

        if use_smtp:
            section.add_option(
                StringOption,
                "smtp_host",
                default=self._defaults["smtp_host"],
                comment="SMTP server hostname/IP address",
            )
            section.add_option(
                IntegerOption,
                "smtp_port",
                default=self._defaults["smtp_port"],
                comment="SMTP server port",
            )
            section.add_option(
                BooleanOption,
                "smtp_ssl",
                default=self._defaults["smtp_ssl"],
                comment="Use SSL on SMTP server connection",
            )
            section.add_option(
                BooleanOption,
                "smtp_tls",
                default=self._defaults["smtp_tls"],
                comment="Use TLS on SMTP server connection",
            )
            section.add_option(
                StringOption,
                "smtp_user",
                default=self._defaults["smtp_user"],
                comment="SMTP authentication username",
            )
            section.add_option(
                PasswordOption,
                "smtp_password",
                default=self._defaults["smtp_password"],
                comment='SMTP authentication password (set to "keyring" to use XDG keyring)',
                username_option="smtp_user",
                keyring_value="keyring",
            )
            section.add_option(
                BooleanOption,
                "smtp_debug",
                default=self._defaults["smtp_debug"],
                comment="Enable SMTP debugging",
            )

        section.add_option(
            StringOption,
            "sender_name",
            default=self._defaults["sender_name"],
            comment="Sender name",
        )
        section.add_option(
            StringOption,
            "sender_email",
            default=self._defaults["sender_email"],
            comment="Sender email address",
        )
        section.add_option(
            StringOption, "encoding", default=self._defaults["encoding"], comment="Email encoding"
        )
        section.add_option(
            StringOption,
            "catch_all_addr",
            default=self._defaults["catch_all_addr"],
            comment="Catch all sent emails to this specified email address",
        )

        if just_try:
            section.add_option(
                BooleanOption,
                "just_try",
                default=self._defaults["just_try"],
                comment="Just-try mode: do not really send emails",
            )

        return section

    def forge_message(
        self,
        rcpt_to,
        subject=None,
        html_body=None,
        text_body=None,  # pylint: disable=too-many-arguments,too-many-locals
        attachment_files=None,
        attachment_payloads=None,
        sender_name=None,
        sender_email=None,
        encoding=None,
        template=None,
        **template_vars,
    ):
        """
        Forge a message

        :param rcpt_to:             The recipient of the email. Could be a tuple(name, email) or
                                    just the email of the recipient.
        :param subject:             The subject of the email.
        :param html_body:           The HTML body of the email
        :param text_body:           The plain text body of the email
        :param attachment_files:    List of filepaths to attach
        :param attachment_payloads: List of tuples with filename and payload to attach
        :param sender_name:         Custom sender name (default: as defined on initialization)
        :param sender_email:        Custom sender email (default: as defined on initialization)
        :param encoding:            Email content encoding (default: as defined on initialization)
        :param template:            The name of a template to use to forge this email

        All other parameters will be consider as template variables.
        """
        msg = MIMEMultipart("alternative")
        msg["To"] = email.utils.formataddr(rcpt_to) if isinstance(rcpt_to, tuple) else rcpt_to
        msg["From"] = email.utils.formataddr(
            (
                sender_name or self._get_option("sender_name"),
                sender_email or self._get_option("sender_email"),
            )
        )
        if subject:
            msg["Subject"] = subject.format(**template_vars)
        msg["Date"] = email.utils.formatdate(None, True)
        encoding = encoding if encoding else self._get_option("encoding")
        if template:
            assert template in self.templates, f"Unknwon template {template}"
            # Handle subject from template
            if not subject:
                assert self.templates[template].get(
                    "subject"
                ), f"No subject defined in template {template}"
                msg["Subject"] = self.templates[template]["subject"].format(**template_vars)

            # Put HTML part in last one to prefered it
            parts = []
            if self.templates[template].get("text"):
                if isinstance(self.templates[template]["text"], MakoTemplate):
                    parts.append(
                        (self.templates[template]["text"].render(**template_vars), "plain")
                    )
                else:
                    parts.append(
                        (self.templates[template]["text"].format(**template_vars), "plain")
                    )
            if self.templates[template].get("html"):
                if isinstance(self.templates[template]["html"], MakoTemplate):
                    parts.append((self.templates[template]["html"].render(**template_vars), "html"))
                else:
                    parts.append((self.templates[template]["html"].format(**template_vars), "html"))

            for body, mime_type in parts:
                msg.attach(MIMEText(body.encode(encoding), mime_type, _charset=encoding))
        else:
            assert subject, "No subject provided"
            if text_body:
                msg.attach(MIMEText(text_body.encode(encoding), "plain", _charset=encoding))
            if html_body:
                msg.attach(MIMEText(html_body.encode(encoding), "html", _charset=encoding))
        if attachment_files:
            for filepath in attachment_files:
                with open(filepath, "rb") as fp:
                    part = MIMEBase("application", "octet-stream")
                    part.set_payload(fp.read())
                    encode_base64(part)
                    part.add_header(
                        "Content-Disposition",
                        f'attachment; filename="{os.path.basename(filepath)}"',
                    )
                    msg.attach(part)
        if attachment_payloads:
            for filename, payload in attachment_payloads:
                part = MIMEBase("application", "octet-stream")
                part.set_payload(payload)
                encode_base64(part)
                part.add_header("Content-Disposition", f'attachment; filename="{filename}"')
                msg.attach(part)
        return msg

    def send(self, rcpt_to, msg=None, subject=None, just_try=False, **forge_args):
        """
        Send an email

        :param rcpt_to:     The recipient of the email. Could be a tuple(name, email)
                            or just the email of the recipient.
        :param msg:         The message of this email (as MIMEBase or derivated classes)
        :param subject:     The subject of the email (only if the message is not provided
                            using msg parameter)
        :param just_try:    Enable just try mode (do not really send email, default: as defined on
                            initialization)

        All other parameters will be consider as parameters to forge the message
        (only if the message is not provided using msg parameter).
        """
        msg = msg if msg else self.forge_message(rcpt_to, subject, **forge_args)

        if just_try or self._get_option("just_try"):
            log.debug(
                'Just-try mode: do not really send this email to %s (subject="%s")',
                rcpt_to,
                subject or msg.get("subject", "No subject"),
            )
            return True

        catch_addr = self._get_option("catch_all_addr")
        if catch_addr:
            log.debug("Catch email originaly send to %s to %s", rcpt_to, catch_addr)
            rcpt_to = catch_addr

        smtp_host = self._get_option("smtp_host")
        smtp_port = self._get_option("smtp_port")
        try:
            if self._get_option("smtp_ssl"):
                logging.info("Establish SSL connection to server %s:%s", smtp_host, smtp_port)
                server = smtplib.SMTP_SSL(smtp_host, smtp_port)
            else:
                logging.info("Establish connection to server %s:%s", smtp_host, smtp_port)
                server = smtplib.SMTP(smtp_host, smtp_port)
                if self._get_option("smtp_tls"):
                    logging.info("Start TLS on SMTP connection")
                    server.starttls()
        except smtplib.SMTPException:
            log.error("Error connecting to SMTP server %s:%s", smtp_host, smtp_port, exc_info=True)
            return False

        if self._get_option("smtp_debug"):
            server.set_debuglevel(True)

        smtp_user = self._get_option("smtp_user")
        smtp_password = self._get_option("smtp_password")
        if smtp_user and smtp_password:
            try:
                log.info("Try to authenticate on SMTP connection as %s", smtp_user)
                server.login(smtp_user, smtp_password)
            except smtplib.SMTPException:
                log.error(
                    "Error authenticating on SMTP server %s:%s with user %s",
                    smtp_host,
                    smtp_port,
                    smtp_user,
                    exc_info=True,
                )
                return False

        error = False
        try:
            log.info("Sending email to %s", rcpt_to)
            server.sendmail(
                self._get_option("sender_email"),
                [rcpt_to[1] if isinstance(rcpt_to, tuple) else rcpt_to],
                msg.as_string(),
            )
        except smtplib.SMTPException:
            error = True
            log.error("Error sending email to %s", rcpt_to, exc_info=True)
        finally:
            server.quit()

        return not error


if __name__ == "__main__":
    # Run tests
    import argparse
    import datetime
    import sys

    # Options parser
    parser = argparse.ArgumentParser()

    parser.add_argument(
        "-v", "--verbose", action="store_true", dest="verbose", help="Enable verbose mode"
    )

    parser.add_argument(
        "-d", "--debug", action="store_true", dest="debug", help="Enable debug mode"
    )

    parser.add_argument(
        "-l", "--log-file", action="store", type=str, dest="logfile", help="Log file path"
    )

    parser.add_argument(
        "-j", "--just-try", action="store_true", dest="just_try", help="Enable just-try mode"
    )

    email_opts = parser.add_argument_group("Email options")

    email_opts.add_argument(
        "-H", "--smtp-host", action="store", type=str, dest="email_smtp_host", help="SMTP host"
    )

    email_opts.add_argument(
        "-P", "--smtp-port", action="store", type=int, dest="email_smtp_port", help="SMTP port"
    )

    email_opts.add_argument(
        "-S", "--smtp-ssl", action="store_true", dest="email_smtp_ssl", help="Use SSL"
    )

    email_opts.add_argument(
        "-T", "--smtp-tls", action="store_true", dest="email_smtp_tls", help="Use TLS"
    )

    email_opts.add_argument(
        "-u", "--smtp-user", action="store", type=str, dest="email_smtp_user", help="SMTP username"
    )

    email_opts.add_argument(
        "-p",
        "--smtp-password",
        action="store",
        type=str,
        dest="email_smtp_password",
        help="SMTP password",
    )

    email_opts.add_argument(
        "-D",
        "--smtp-debug",
        action="store_true",
        dest="email_smtp_debug",
        help="Debug SMTP connection",
    )

    email_opts.add_argument(
        "-e",
        "--email-encoding",
        action="store",
        type=str,
        dest="email_encoding",
        help="SMTP encoding",
    )

    email_opts.add_argument(
        "-f",
        "--sender-name",
        action="store",
        type=str,
        dest="email_sender_name",
        help="Sender name",
    )

    email_opts.add_argument(
        "-F",
        "--sender-email",
        action="store",
        type=str,
        dest="email_sender_email",
        help="Sender email",
    )

    email_opts.add_argument(
        "-C",
        "--catch-all",
        action="store",
        type=str,
        dest="email_catch_all",
        help="Catch all sent email: specify catch recipient email address",
    )

    test_opts = parser.add_argument_group("Test email options")

    test_opts.add_argument(
        "-t",
        "--to",
        action="store",
        type=str,
        dest="test_to",
        help="Test email recipient",
    )

    test_opts.add_argument(
        "-m",
        "--mako",
        action="store_true",
        dest="test_mako",
        help="Test mako templating",
    )

    options = parser.parse_args()

    if not options.test_to:
        parser.error("You must specify test email recipient using -t/--to parameter")
        sys.exit(1)

    # Initialize logs
    logformat = "%(asctime)s - Test EmailClient - %(levelname)s - %(message)s"
    if options.debug:
        loglevel = logging.DEBUG
    elif options.verbose:
        loglevel = logging.INFO
    else:
        loglevel = logging.WARNING

    if options.logfile:
        logging.basicConfig(filename=options.logfile, level=loglevel, format=logformat)
    else:
        logging.basicConfig(level=loglevel, format=logformat)

    if options.email_smtp_user and not options.email_smtp_password:
        import getpass

        options.email_smtp_password = getpass.getpass("Please enter SMTP password: ")

    logging.info("Initialize Email client")
    email_client = EmailClient(
        smtp_host=options.email_smtp_host,
        smtp_port=options.email_smtp_port,
        smtp_ssl=options.email_smtp_ssl,
        smtp_tls=options.email_smtp_tls,
        smtp_user=options.email_smtp_user,
        smtp_password=options.email_smtp_password,
        smtp_debug=options.email_smtp_debug,
        sender_name=options.email_sender_name,
        sender_email=options.email_sender_email,
        catch_all_addr=options.email_catch_all,
        just_try=options.just_try,
        encoding=options.email_encoding,
        templates=dict(
            test=dict(
                subject="Test email",
                text=(
                    "Just a test email sent at {sent_date}."
                    if not options.test_mako
                    else MakoTemplate("Just a test email sent at ${sent_date}.")
                ),
                html=(
                    "<strong>Just a test email.</strong> <small>(sent at {sent_date})</small>"
                    if not options.test_mako
                    else MakoTemplate(
                        "<strong>Just a test email.</strong> <small>(sent at ${sent_date})</small>"
                    )
                ),
            )
        ),
    )

    logging.info("Send a test email to %s", options.test_to)
    if email_client.send(options.test_to, template="test", sent_date=datetime.datetime.now()):
        logging.info("Test email sent")
        sys.exit(0)
    logging.error("Fail to send test email")
    sys.exit(1)