#!/opt/mailman/venv/bin/python3
#
# Written by Thomas Schneider <qsuscs@qsuscs.de>
# This script is placed in public domain.  If this is not applicable, consider
# it licensed under the CC-0:
# <https://creativecommons.org/publicdomain/zero/1.0/>

# Command Line Arguments (reverse engineered)
# $1 LMTP Port
# $2 ????
# $3 LMTP Host
# std_in message text

import logging
logger = logging.getLogger(__name__)

# Format time and message
FORMAT = '%(asctime)s %(message)s'
# Set Date Format
DATEFMT = '%Y-%m-%d %H:%M:%S %Z'
LEVEL=logging.INFO
LOGFILE='/opt/mailman/logs/courier-to-mailman.log'
logging.basicConfig(filename=LOGFILE, level=LEVEL, format=FORMAT, datefmt=DATEFMT)

try:
    import os
    import sys
    import smtplib
    from email.parser import HeaderParser
    import pprint

    logger.info('Starting Logging (inside try)')

    # Setup LTMP connection 
    lmtp_host = sys.argv[3] if len(sys.argv) > 3 else 'localhost'
    lmtp_port = sys.argv[1] if len(sys.argv) > 1 else 8024
    logger.info('lmtp_host: %s lmtp_port: %s', lmtp_host, lmtp_port)
    # class smtplib.LMTP(host='', port=LMTP_PORT, local_hostname=None, source_address=None)
    logger.info('lmtp_port: %s', lmtp_port)
    lmtp = smtplib.LMTP(lmtp_host, int(lmtp_port))
    logger.info('lmtp_port (lmtp setup): %s', lmtp_port)

    try:
        # Unfortunately qmail sends to local bare LF for end line, while
        # SMTP requires CRLF, so normalize to that. Error message without this:
        # "Line too long (see RFC5321 4.5.3.1.6)"
        # https://gitlab.com/mailman/mailman/-/issues/1133
        content = sys.stdin.buffer.read()
        content = content.replace(b'\r\n', b'\n').replace(b'\r', b'\n').replace(b'\n', b'\r\n')
        header = content.strip()
        headers = dict(HeaderParser().parsestr(header.decode('utf-8')))
        header_to = headers['To']

        # See <https://qmail.notqmail.org/qmail-manual-html/man8/qmail-command.html>
        # for qmail command docs and supplied environment variables.
        # We need to replace "1" with an empty string, as qmail only supports EXT,
        # EXT2, EXT3, EXT4.
        arg_ext_tmp = sys.argv[2] if len(sys.argv) > 2 else "1"
        arg_ext = arg_ext_tmp if arg_ext_tmp != "1" else ""
        lmtp.sendmail(
            os.environ['SENDER'],
            header_to,
            #sys.stdin.buffer.read()
            content
        )
    except smtplib.SMTPResponseException as e:
        logger.error('lmtp error on send')
        logger.exception('Got exception Traceback:')
        logger.error('lmtp failed errorno: %s, message: %s', e.errno, e.strerror)
        if 400 <= e.smtp_code < 500:
            exit(111)
        # otherwise, it's either a 5xx aka permanent error or something else
        # is already b0rked, thus raise -> exit(100) -> have qmail return a
        # 5xx error
        else:
            raise
except Exception as e:
    logger.error('lmtp error')
    logger.exception('Got exception Traceback:')
    logger.error('lmtp failed errorno: %s, message: %s', e.errno, e.strerror)
    exit(100)

logger.info('Bottom of script, ending log')