# mail.py - mail sending bits for mercurial

#

# Copyright 2006 Olivia Mackall <olivia@selenic.com>

#

# This software may be used and distributed according to the terms of the

# GNU General Public License version 2 or any later version.

import email

import email.charset

import email.generator

import email.header

import email.message

import email.parser

import io

import os

import smtplib

import socket

import time

from typing import (

    Any,

    List,

    Optional,

    Tuple,

    Union,

)

from .i18n import _

from .pycompat import (

    open,

)

from . import (

    encoding,

    error,

    pycompat,

    sslutil,

    util,

)

from .utils import (

    procutil,

    stringutil,

    urlutil,

)

class STARTTLS(smtplib.SMTP):

    """Derived class to verify the peer certificate for STARTTLS.

    This class allows to pass any keyword arguments to SSL socket creation.

    """

    def __init__(self, ui, host=None, **kwargs):

        smtplib.SMTP.__init__(self, **kwargs)

        self._ui = ui

        self._host = host

    def starttls(self, keyfile=None, certfile=None, context=None):

        if not self.has_extn("starttls"):

            msg = "STARTTLS extension not supported by server"

            raise smtplib.SMTPException(msg)

        (resp, reply) = self.docmd("STARTTLS")

        if resp == 220:

            self.sock = sslutil.wrapsocket(

                self.sock,

                keyfile,

                certfile,

                ui=self._ui,

                serverhostname=self._host,

            )

            self.file = self.sock.makefile("rb")

            self.helo_resp = None

            self.ehlo_resp = None

            self.esmtp_features = {}

            self.does_esmtp = 0

        return (resp, reply)

class SMTPS(smtplib.SMTP):

    """Derived class to verify the peer certificate for SMTPS.

    This class allows to pass any keyword arguments to SSL socket creation.

    """

    def __init__(self, ui, keyfile=None, certfile=None, host=None, **kwargs):

        self.keyfile = keyfile

        self.certfile = certfile

        smtplib.SMTP.__init__(self, **kwargs)

        self._host = host

        self.default_port = smtplib.SMTP_SSL_PORT

        self._ui = ui

    def _get_socket(self, host, port, timeout):

        if self.debuglevel > 0:

            self._ui.debug(b'connect: %r\n' % ((host, port),))

        new_socket = socket.create_connection((host, port), timeout)

        new_socket = sslutil.wrapsocket(

            new_socket,

            self.keyfile,

            self.certfile,

            ui=self._ui,

            serverhostname=self._host,

        )

        self.file = new_socket.makefile('rb')

        return new_socket

def _pyhastls() -> bool:

    """Returns true iff Python has TLS support, false otherwise."""

    try:

        import ssl

        getattr(ssl, 'HAS_TLS', False)

        return True

    except ImportError:

        return False

def _smtp(ui):

    '''build an smtp connection and return a function to send mail'''

    local_hostname = ui.config(b'smtp', b'local_hostname')

    tls = ui.config(b'smtp', b'tls')

    # backward compatible: when tls = true, we use starttls.

    starttls = tls == b'starttls' or stringutil.parsebool(tls)

    smtps = tls == b'smtps'

    if (starttls or smtps) and not _pyhastls():

        raise error.Abort(_(b"can't use TLS: Python SSL support not installed"))

    mailhost = ui.config(b'smtp', b'host')

    if not mailhost:

        raise error.Abort(_(b'smtp.host not configured - cannot send mail'))

    if smtps:

        ui.note(_(b'(using smtps)\n'))

        s = SMTPS(ui, local_hostname=local_hostname, host=mailhost)

    elif starttls:

        s = STARTTLS(ui, local_hostname=local_hostname, host=mailhost)

    else:

        s = smtplib.SMTP(local_hostname=local_hostname)

    if smtps:

        defaultport = 465

    else:

        defaultport = 25

    mailport = urlutil.getport(ui.config(b'smtp', b'port', defaultport))

    ui.note(_(b'sending mail: smtp host %s, port %d\n') % (mailhost, mailport))

    s.connect(host=mailhost, port=mailport)

    if starttls:

        ui.note(_(b'(using starttls)\n'))

        s.ehlo()

        s.starttls()

        s.ehlo()

    if starttls or smtps:

        ui.note(_(b'(verifying remote certificate)\n'))

        sslutil.validatesocket(s.sock)

    try:

        _smtp_login(ui, s, mailhost, mailport)

    except smtplib.SMTPException as inst:

        raise error.Abort(stringutil.forcebytestr(inst))

    def send(sender, recipients, msg):

        try:

            return s.sendmail(sender, recipients, msg)

        except smtplib.SMTPRecipientsRefused as inst:

            recipients = [r[1] for r in inst.recipients.values()]

            raise error.Abort(b'\n' + b'\n'.join(recipients))

        except smtplib.SMTPException as inst:

            raise error.Abort(stringutil.forcebytestr(inst))

    return send

def _smtp_login(ui, smtp, mailhost, mailport):

    """A hook for the keyring extension to perform the actual SMTP login.

    An already connected SMTP object of the proper type is provided, based on

    the current configuration.  The host and port to which the connection was

    established are provided for accessibility, since the SMTP object doesn't

    provide an accessor.  ``smtplib.SMTPException`` is raised on error.

    """

    username = ui.config(b'smtp', b'username')

    password = ui.config(b'smtp', b'password')

    if username:

        if password:

            password = encoding.strfromlocal(password)

        else:

            password = ui.getpass()

            if password is not None:

                password = encoding.strfromlocal(password)

    if username and password:

        ui.note(_(b'(authenticating to mail server as %s)\n') % username)

        username = encoding.strfromlocal(username)

        smtp.login(username, password)

def _sendmail(ui, sender, recipients, msg):

    '''send mail using sendmail.'''

    program = ui.config(b'email', b'method')

    def stremail(x):

        return procutil.shellquote(stringutil.email(encoding.strtolocal(x)))

    cmdline = b'%s -f %s %s' % (

        program,

        stremail(sender),

        b' '.join(map(stremail, recipients)),

    )

    ui.note(_(b'sending mail: %s\n') % cmdline)

    fp = procutil.popen(cmdline, b'wb')

    fp.write(util.tonativeeol(msg))

    ret = fp.close()

    if ret:

        raise error.Abort(

            b'%s %s'

            % (

                os.path.basename(procutil.shellsplit(program)[0]),

                procutil.explainexit(ret),

            )

        )

def _mbox(mbox, sender, recipients, msg):

    '''write mails to mbox'''

    # TODO: use python mbox library for proper locking

    with open(mbox, b'ab+') as fp:

        # Should be time.asctime(), but Windows prints 2-characters day

        # of month instead of one. Make them print the same thing.

        date = time.strftime('%a %b %d %H:%M:%S %Y', time.localtime())

        fp.write(

            b'From %s %s\n'

            % (encoding.strtolocal(sender), encoding.strtolocal(date))

        )

        fp.write(msg)

        fp.write(b'\n\n')

def connect(ui, mbox=None):

    """make a mail connection. return a function to send mail.

    call as sendmail(sender, list-of-recipients, msg)."""

    if mbox:

        open(mbox, b'wb').close()

        return lambda s, r, m: _mbox(mbox, s, r, m)

    if ui.config(b'email', b'method') == b'smtp':

        return _smtp(ui)

    return lambda s, r, m: _sendmail(ui, s, r, m)

def sendmail(ui, sender, recipients, msg, mbox=None):

    send = connect(ui, mbox=mbox)

    return send(sender, recipients, msg)

def validateconfig(ui):

    '''determine if we have enough config data to try sending email.'''

    method = ui.config(b'email', b'method')

    if method == b'smtp':

        if not ui.config(b'smtp', b'host'):

            raise error.Abort(

                _(

                    b'smtp specified as email transport, '

                    b'but no smtp host configured'

                )

            )

    else:

        command = procutil.shellsplit(method)

        command = command[0] if command else b''

        if not (command and procutil.findexe(command)):

            raise error.Abort(

                _(b'%r specified as email transport, but not in PATH') % command

            )

def codec2iana(cs: str) -> str:

    ''' '''

    cs = email.charset.Charset(cs).input_charset.lower()

    # "latin1" normalizes to "iso8859-1", standard calls for "iso-8859-1"

    if cs.startswith("iso") and not cs.startswith("iso-"):

        return "iso-" + cs[3:]

    return cs

def mimetextpatch(

    s: bytes,

    subtype: str = 'plain',

    display: bool = False,

) -> email.message.Message:

    """Return MIME message suitable for a patch.

    Charset will be detected by first trying to decode as us-ascii, then utf-8,

    and finally the global encodings. If all those fail, fall back to

    ISO-8859-1, an encoding with that allows all byte sequences.

    Transfer encodings will be used if necessary."""

    cs = [

        'us-ascii',

        'utf-8',

        pycompat.sysstr(encoding.encoding),

        pycompat.sysstr(encoding.fallbackencoding),

    ]

    if display:

        cs = ['us-ascii']

    for charset in cs:

        try:

            s.decode(charset)

            return mimetextqp(s, subtype, codec2iana(charset))

        except UnicodeDecodeError:

            pass

    return mimetextqp(s, subtype, "iso-8859-1")

def mimetextqp(

    body: bytes, subtype: str, charset: str

) -> email.message.Message:

    """Return MIME message.

    Quoted-printable transfer encoding will be used if necessary.

    """

    cs = email.charset.Charset(charset)

    msg = email.message.Message()

    msg.set_type('text/' + subtype)

    for line in body.splitlines():

        if len(line) > 950:

            cs.body_encoding = email.charset.QP

            break

    # On Python 2, this simply assigns a value. Python 3 inspects

    # body and does different things depending on whether it has

    # encode() or decode() attributes. We can get the old behavior

    # if we pass a str and charset is None and we call set_charset().

    # But we may get into  trouble later due to Python attempting to

    # encode/decode using the registered charset (or attempting to

    # use ascii in the absence of a charset).

    msg.set_payload(body, cs)

    return msg

def _charsets(ui: Any) -> List[str]:

    '''Obtains charsets to send mail parts not containing patches.'''

    charsets = [

        pycompat.sysstr(cs.lower())

        for cs in ui.configlist(b'email', b'charsets')

    ]

    fallbacks = [

        pycompat.sysstr(encoding.fallbackencoding.lower()),

        pycompat.sysstr(encoding.encoding.lower()),

        'utf-8',

    ]

    for cs in fallbacks:  # find unique charsets while keeping order

        if cs not in charsets:

            charsets.append(cs)

    return [cs for cs in charsets if not cs.endswith('ascii')]

def _encode(ui: Any, s: bytes, charsets: List[str]) -> Tuple[bytes, str]:

    """Returns (converted) string, charset tuple.

    Finds out best charset by cycling through sendcharsets in descending

    order. Tries both encoding and fallbackencoding for input. Only as

    last resort send as is in fake ascii.

    Caveat: Do not use for mail parts containing patches!"""

    sendcharsets = charsets or _charsets(ui)

    if not isinstance(s, bytes):

        # We have unicode data, which we need to try and encode to

        # some reasonable-ish encoding. Try the encodings the user

        # wants, and fall back to garbage-in-ascii.

        for ocs in sendcharsets:

            try:

                return s.encode(ocs), ocs

            except UnicodeEncodeError:

                pass

            except LookupError:

                ui.warn(

                    _(b'ignoring invalid sendcharset: %s\n')