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

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

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

from mako.template import Template as MakoTemplate

from mylib.config import ConfigurableObject
from mylib.config import BooleanOption
from mylib.config import IntegerOption
from mylib.config import PasswordOption
from mylib.config import 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 datetime
    import sys

    import argparse

    # 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)