# Source code for scrapy.mail

    """
    Mail sending helpers

    See documentation in docs/topics/email.rst
    """
    import logging
    from email import encoders as Encoders
    from email.mime.base import MIMEBase
    from email.mime.multipart import MIMEMultipart
    from email.mime.nonmultipart import MIMENonMultipart
    from email.mime.text import MIMEText
    from email.utils import formatdate
    from io import BytesIO

    from twisted.internet import defer, ssl

    from scrapy.utils.misc import arg_to_iter
    from scrapy.utils.python import to_bytes

    logger = logging.getLogger(__name__)

    # Defined in the email.utils module, but undocumented:
    # https://github.com/python/cpython/blob/v3.9.0/Lib/email/utils.py#L42
    COMMASPACE = ", "

    def _to_bytes_or_none(text):
        if text is None:
            return None
        return to_bytes(text)

    class MailSender:
        def __init__(
            self, smtphost='localhost', mailfrom='scrapy@localhost', smtpuser=None,
            smtppass=None, smtpport=25, smtptls=False, smtpssl=False, debug=False
        ):
            self.smtphost = smtphost
            self.smtpport = smtpport
            self.smtpuser = _to_bytes_or_none(smtpuser)
            self.smtppass = _to_bytes_or_none(smtppass)
            self.smtptls = smtptls
            self.smtpssl = smtpssl
            self.mailfrom = mailfrom
            self.debug = debug

        @classmethod
        def from_settings(cls, settings):
            return cls(
                smtphost=settings['MAIL_HOST'],
                mailfrom=settings['MAIL_FROM'],
                smtpuser=settings['MAIL_USER'],
                smtppass=settings['MAIL_PASS'],
                smtpport=settings.getint('MAIL_PORT'),
                smtptls=settings.getbool('MAIL_TLS'),
                smtpssl=settings.getbool('MAIL_SSL'),
            )

        def send(self, to, subject, body, cc=None, attachs=(), mimetype='text/plain', charset=None, _callback=None):
            from twisted.internet import reactor
            if attachs:
                msg = MIMEMultipart()
            else:
                msg = MIMENonMultipart(*mimetype.split('/', 1))

            to = list(arg_to_iter(to))
            cc = list(arg_to_iter(cc))

            msg['From'] = self.mailfrom
            msg['To'] = COMMASPACE.join(to)
            msg['Date'] = formatdate(localtime=True)
            msg['Subject'] = subject
            rcpts = to[:]
            if cc:
                rcpts.extend(cc)
                msg['Cc'] = COMMASPACE.join(cc)

            if charset:
                msg.set_charset(charset)

            if attachs:
                msg.attach(MIMEText(body, 'plain', charset or 'us-ascii'))
                for attach_name, mimetype, f in attachs:
                    part = MIMEBase(*mimetype.split('/'))
                    part.set_payload(f.read())
                    Encoders.encode_base64(part)
                    part.add_header('Content-Disposition', 'attachment', filename=attach_name)
                    msg.attach(part)
            else:
                msg.set_payload(body)

            if _callback:
                _callback(to=to, subject=subject, body=body, cc=cc, attach=attachs, msg=msg)

            if self.debug:
                logger.debug('Debug mail sent OK: To=%(mailto)s Cc=%(mailcc)s '
                             'Subject="%(mailsubject)s" Attachs=%(mailattachs)d',
                             {'mailto': to, 'mailcc': cc, 'mailsubject': subject,
                              'mailattachs': len(attachs)})
                return

            dfd = self._sendmail(rcpts, msg.as_string().encode(charset or 'utf-8'))
            dfd.addCallbacks(
                callback=self._sent_ok,
                errback=self._sent_failed,
                callbackArgs=[to, cc, subject, len(attachs)],
                errbackArgs=[to, cc, subject, len(attachs)],
            )
            reactor.addSystemEventTrigger('before', 'shutdown', lambda: dfd)
            return dfd

        def _sent_ok(self, result, to, cc, subject, nattachs):
            logger.info('Mail sent OK: To=%(mailto)s Cc=%(mailcc)s '
                        'Subject="%(mailsubject)s" Attachs=%(mailattachs)d',
                        {'mailto': to, 'mailcc': cc, 'mailsubject': subject,
                         'mailattachs': nattachs})

        def _sent_failed(self, failure, to, cc, subject, nattachs):
            errstr = str(failure.value)
            logger.error('Unable to send mail: To=%(mailto)s Cc=%(mailcc)s '
                         'Subject="%(mailsubject)s" Attachs=%(mailattachs)d'
                         '- %(mailerr)s',
                         {'mailto': to, 'mailcc': cc, 'mailsubject': subject,
                          'mailattachs': nattachs, 'mailerr': errstr})

        def _sendmail(self, to_addrs, msg):
            # Import twisted.mail here because it is not available in python3
            from twisted.internet import reactor
            from twisted.mail.smtp import ESMTPSenderFactory
            msg = BytesIO(msg)
            d = defer.Deferred()
            factory = ESMTPSenderFactory(
                self.smtpuser, self.smtppass, self.mailfrom, to_addrs, msg, d,
                heloFallback=True, requireAuthentication=False, requireTransportSecurity=self.smtptls,
            )
            factory.noisy = False

            if self.smtpssl:
                reactor.connectSSL(self.smtphost, self.smtpport, factory, ssl.ClientContextFactory())
            else:
                reactor.connectTCP(self.smtphost, self.smtpport, factory)

            return d