# 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 import version as twisted_version
    from twisted.internet import defer, ssl
    from twisted.python.versions import Version

    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 attachs:
                if charset:
                    msg.set_charset(charset)
                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, charset)

            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,
                },
            )
            return failure

        def _sendmail(self, to_addrs, msg):
            from twisted.internet import reactor

            msg = BytesIO(msg)
            d = defer.Deferred()

            factory = self._create_sender_factory(to_addrs, msg, d)

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

            return d

        def _create_sender_factory(self, to_addrs, msg, d):
            from twisted.mail.smtp import ESMTPSenderFactory

            factory_keywords = {
                "heloFallback": True,
                "requireAuthentication": False,
                "requireTransportSecurity": self.smtptls,
            }

            # Newer versions of twisted require the hostname to use STARTTLS
            if twisted_version >= Version("twisted", 21, 2, 0):
                factory_keywords["hostname"] = self.smtphost

            factory = ESMTPSenderFactory(
                self.smtpuser,
                self.smtppass,
                self.mailfrom,
                to_addrs,
                msg,
                d,
                **factory_keywords
            )
            factory.noisy = False
            return factory