#! /usr/bin/python3

#   Copyright (c) 2022  Joey Schulze <joey@infodrom.org>
#
#   This program 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 2 of the License, or
#   (at your option) any later version.
#
#   This program 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 this program; if not, write to the Free Software
#   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.

import os
import sys
import pwd
import stat
import syslog
import signal
import pyinotify

from argparse import ArgumentParser, RawTextHelpFormatter, FileType
from configparser import ConfigParser


config = None


class DeviceHandler(pyinotify.ProcessEvent):
    def __init__(self):
        super().__init__()

    def process_IN_CREATE(self, event):
        uuid = os.path.basename(event.pathname)
        syslog.syslog(syslog.LOG_INFO, "New UUID available: {}".format(uuid))

        if config.has_section(uuid):
            syslog.syslog(syslog.LOG_INFO, "Destination {}".format(config.get(uuid, 'dest')))
            self.mount(uuid)

    def mount(self, uuid):
        dest = config.get(uuid, 'dest')
        user = config.get(uuid, 'user') if config.has_option(uuid, 'user') else 'root'
        group = config.get(uuid, 'group') if config.has_option(uuid, 'group') else user
        options = ''

        if config.has_option(uuid, 'options'):
            options += (',' if len(options) else '') + config.get(uuid, 'options')
            if 'shortname=' in options or 'fmask=' in options:
                uid = pwd.getpwnam(user).pw_uid
                gid = pwd.getpwnam(group).pw_gid
                options += (',' if len(options) else '') + 'uid={},gid={}'.format(self.uid, self.gid)

        if not os.path.isdir(dest):
            os.system("install -d -m 755 -o {user} -g {group} {dest}".format(
                user=user, group=group, dest=dest))

        cmd = "mount{opts} UUID={uuid} {dest}".format(
            uuid=uuid, dest=dest,
            opts=(' -o ' + options) if len(options) else '')
        syslog.syslog(syslog.LOG_DEBUG, cmd)
        os.system(cmd)
        self.assert_sudoers(uuid)

    def assert_sudoers(self, uuid):
        user = config.get(uuid, 'user') if config.has_option(uuid, 'user') else 'root'
        if user == 'root':
            return
        if config.has_option(uuid, 'sudoers') and config.get(uuid, 'sudoers').lower() == 'true':
            dest = os.path.join('/etc/sudoers.d', user + '-umount-' + os.path.basename(config.get(uuid, 'dest')))
            if not os.path.exists(dest):
                syslog.syslog(syslog.LOG_INFO, "Write new sudoers configuration {}".format(os.path.basename(dest)))
                with open(dest, 'w') as f:
                    print("{user} ALL=NOPASSWD: /bin/umount {dest}, /bin/umount {dest}/".format(
                        user=user, dest=config.get(uuid, 'dest')), file=f)


def parse_arguments():
    global config
    epilog = []
    parser = ArgumentParser(description='Infodrom Automounter',
                            formatter_class=RawTextHelpFormatter,
                            epilog='\r\n'.join(epilog))
    parser.add_argument('--config', '-C',
                        dest='config',
                        action='store',
                        default='/etc/automount.conf',
                        help='Read configuration')
    parser.add_argument('--with-exception',
                        dest='exception',
                        default=False,
                        action='store_true',
                        help='display full exception')
    args = parser.parse_args()

    config = ConfigParser()
    config.read(args.config, encoding='UTF-8')

    return args


def watch_uuid(path):
    wm = pyinotify.WatchManager()
    wm.add_watch(path, pyinotify.IN_CREATE)

    notifier = pyinotify.Notifier(wm, DeviceHandler())
    notifier.loop()


def main(args):
    syslog.openlog(os.path.basename(sys.argv[0]), syslog.LOG_PID, syslog.LOG_DAEMON)

    watch_uuid('/dev/disk/by-uuid')

    # print(config.sections())
    

if __name__ == '__main__':
    args = parse_arguments()
    try:
        main(args)
    except KeyboardInterrupt:
        pass
    except Exception as e:
        if args.exception:
            from traceback import format_exc
            print(e, file=sys.stderr)
            print(format_exc(), file=sys.stderr)
        else:
            print("An error occurred:", e)