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

# Copyright © Cloud Linux GmbH & Cloud Linux Software, Inc 2010-2021 All Rights Reserved
#
# Licensed under CLOUD LINUX LICENSE AGREEMENT
# http://cloudlinux.com/docs/LICENSE.TXT

import logging
import os
import smtplib
import subprocess
from configparser import ConfigParser, SectionProxy
from email.message import EmailMessage
from socket import gethostname
from typing import Optional

from ..internal.constants import mail_template_location, mail_scripts_location
from ..internal.exceptions import XRayMailerError


class Mailer:
    """
    Class contains X-Ray e-mail send logic
    """
    def __init__(self):
        self.logger = logging.getLogger('mailer')
        self._sender = None

    @property
    def mail_server(self) -> tuple:
        """
        Local mail server address
        """
        return ('localhost', )

    @property
    def sender(self) -> str:
        """
        Retrieve 'From' mail address if it is not already set
        """
        if self._sender is None:
            self._sender = self.retrieve_mail_sender()
        return self._sender

    def retrieve_mail_sender(self) -> str:
        """
        'From' address (control panel admin or dummy one)
        """
        dummy_mail = f"xray.continuous@{gethostname()}"
        admin_mail = self.admin_email()
        return admin_mail if admin_mail is not None else dummy_mail

    def admin_email(self) -> Optional[str]:
        """
        Try to retrieve control panel admin e-mail
        """
        panel = self.get_control_panel()
        if panel is not None:
            get_email_script = f'{mail_scripts_location}/{panel}_email'
            try:
                p = subprocess.run([get_email_script],
                                   capture_output=True, text=True, check=True)
                return p.stdout.strip()
            except subprocess.CalledProcessError as e:
                self.logger.error('% script failed with: %s',
                                  get_email_script, str(e))
            except (OSError, ValueError, subprocess.SubprocessError) as e:
                self.logger.error('Failed to run script %s with: %s',
                                  get_email_script, str(e))

    def get_control_panel(self) -> Optional[str]:
        """
        Get control panel name
        """
        try:
            return subprocess.run(
                ['cldetect', '--detect-cp-name'],
                check=True, text=True,
                capture_output=True).stdout.strip()
        except (subprocess.CalledProcessError, AttributeError) as e:
            self.logger.error('cldetect utility failed with %s',
                              str(e))
        except (OSError, ValueError, subprocess.SubprocessError) as e:
            self.logger.error('Failed to run cldetect utility with %s',
                              str(e))

    @staticmethod
    def read_template(name: str = 'greeting') -> SectionProxy:
        """
        Get preformatted data for e-mail by name of template
        """
        tmpl = f'{mail_template_location}/{name}.ini'
        if os.path.exists(tmpl):
            config = ConfigParser(interpolation=None)
            config.read(tmpl)
            return config['data']
        raise XRayMailerError(
            f'Failed to find template {name} in {mail_template_location}')

    def _smtp_send(self, message: EmailMessage) -> None:
        """
        Send preformatted e-mail via localhost SMTP
        """
        self.logger.info('Try to send via smtp')
        try:
            with smtplib.SMTP(*self.mail_server) as server:
                result = server.send_message(message)
                self.logger.info('Send result: %s', result)
        except smtplib.SMTPException as e:
            raise XRayMailerError(f'smtp mailing failed: {str(e)}')
        except (ConnectionError, OSError) as e:
            raise XRayMailerError(f'smtp connection failed: {str(e)}')

    def _console_send(self, message: EmailMessage) -> None:
        """
        Send preformatted e-mail via sendmail utility
        """
        self.logger.info('Try to send via sendmail utility')
        cmd = ["/usr/sbin/sendmail", "-t", "-oi"]
        try:
            subprocess.run(cmd,
                           input=message.as_string(),
                           capture_output=True,
                           text=True, check=True)
        except (OSError, subprocess.CalledProcessError) as e:
            raise XRayMailerError(f'sendmail utility failed with {str(e)}')

    def _send(self, mail: EmailMessage) -> None:
        """
        Try to send mail via localhost smtp server,
        if fails -- try to use sendmail utility
        """
        try:
            self._smtp_send(mail)
        except XRayMailerError as e:
            self.logger.error(str(e))
            try:
                self._console_send(mail)
            except XRayMailerError as e:
                self.logger.error(str(e))
                self.logger.critical(
                    'Both smtp and sendmail failed to send message to %s',
                    mail['To'])

    def send_mail(self,
                  recipient: str,
                  template: str = 'greeting',
                  **kwargs) -> None:
        data = self.read_template(template)

        msg = EmailMessage()
        msg['Subject'] = data['subject']
        msg['From'] = self.sender
        msg['To'] = recipient
        msg.set_content(data['text'] % kwargs)
        msg.add_alternative(data['html'] % kwargs, subtype='html')

        self.logger.info('Generated mail --> %s', msg.as_string())

        self._send(msg)