# PyMod-Milter is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# PyMod-Milter is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with PyMod-Milter.  If not, see <http://www.gnu.org/licenses/>.
#

__all__ = ["main"]

import Milter
import argparse
import json
import logging
import logging.handlers
import os
import re
import sys

from pymodmilter import mailer
from pymodmilter import ModifyMilter
from pymodmilter import __version__ as version
from pymodmilter.config import MilterConfig


def main():
    python_version = ".".join([str(v) for v in sys.version_info[0:3]])
    python_version = f"{python_version}-{sys.version_info[3]}"

    "Run PyMod-Milter."
    parser = argparse.ArgumentParser(
        description="PyMod milter daemon",
        formatter_class=lambda prog: argparse.HelpFormatter(
            prog, max_help_position=45, width=140))

    parser.add_argument(
        "-c", "--config", help="Config file to read.",
        default="/etc/pymodmilter/pymodmilter.conf")

    parser.add_argument(
        "-s",
        "--socket",
        help="Socket used to communicate with the MTA.",
        default="")

    parser.add_argument(
        "-d",
        "--debug",
        help="Log debugging messages.",
        action="store_true")

    parser.add_argument(
        "-t",
        "--test",
        help="Check configuration.",
        action="store_true")

    parser.add_argument(
        "-v", "--version",
        help="Print version.",
        action="version",
        version=f"%(prog)s {version} (python {python_version})")

    args = parser.parse_args()

    root_logger = logging.getLogger()
    root_logger.setLevel(logging.DEBUG)

    # setup console log
    stdouthandler = logging.StreamHandler(sys.stdout)
    formatter = logging.Formatter("%(levelname)s: %(message)s")
    stdouthandler.setFormatter(formatter)
    root_logger.addHandler(stdouthandler)

    logger = logging.getLogger(__name__)

    if not args.debug:
        logger.setLevel(logging.INFO)

    try:
        logger.debug("read milter configuration")

        try:
            with open(args.config, "r") as fh:
                # remove lines with leading # (comments), they
                # are not allowed in json
                cfg = re.sub(r"(?m)^\s*#.*\n?", "", fh.read())
        except IOError as e:
            raise RuntimeError(f"unable to open/read config file: {e}")

        try:
            cfg = json.loads(cfg)
        except json.JSONDecodeError as e:
            cfg_text = [f"{n+1}: {l}" for n, l in enumerate(cfg.splitlines())]
            msg = "\n".join(cfg_text)
            raise RuntimeError(f"{e}\n{msg}")

        cfg = MilterConfig(cfg)

        if not args.debug:
            logger.setLevel(cfg.get_loglevel(args.debug))

        if args.socket:
            socket = args.socket
        elif cfg["socket"]:
            socket = cfg["socket"]
        else:
            raise RuntimeError(
                "listening socket is neither specified on the command line "
                "nor in the configuration file")

        if not cfg["rules"]:
            raise RuntimeError("no rules configured")

        for rule in cfg["rules"]:
            if not rule["actions"]:
                raise RuntimeError(
                    f"{rule['name']}: no actions configured")

    except (RuntimeError, AssertionError) as e:
        logger.error(f"error in config file: {e}")
        sys.exit(255)

    try:
        ModifyMilter.set_config(cfg, args.debug)
    except RuntimeError as e:
        logger.error(e)
        sys.exit(254)

    if args.test:
        print("Configuration OK")
        sys.exit(0)

    # setup console log for runtime
    formatter = logging.Formatter("%(asctime)s - %(levelname)s: %(message)s")
    stdouthandler.setFormatter(formatter)
    stdouthandler.setLevel(logging.DEBUG)

    # setup syslog
    sysloghandler = logging.handlers.SysLogHandler(
        address="/dev/log", facility=logging.handlers.SysLogHandler.LOG_MAIL)
    sysloghandler.setFormatter(
        logging.Formatter("pymodmilter: %(message)s"))
    root_logger.addHandler(sysloghandler)

    logger.info("pymodmilter starting")

    # register milter factory class
    Milter.factory = ModifyMilter
    Milter.set_exception_policy(Milter.TEMPFAIL)

    if args.debug:
        Milter.setdbg(1)

    rc = 0
    try:
        Milter.runmilter("pymodmilter", socketname=socket, timeout=600)
    except Milter.milter.error as e:
        logger.error(e)
        rc = 255

    mailer.queue.put(None)
    logger.info("pymodmilter stopped")

    sys.exit(rc)


if __name__ == "__main__":
    main()