# This file is part of Cockpit.
#
# Copyright (C) 2022 Red Hat, Inc.
#
# 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 3 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, see <https://www.gnu.org/licenses/>.

import asyncio
import glob
import grp
import json
import logging
import os
import pwd
from pathlib import Path
from typing import Dict, Optional

from cockpit._vendor.systemd_ctypes import Variant, bus, inotify, pathwatch

from . import config

logger = logging.getLogger(__name__)


class cockpit_LoginMessages(bus.Object):
    messages: Optional[str] = None

    def __init__(self):
        fdstr = os.environ.pop('COCKPIT_LOGIN_MESSAGES_MEMFD', None)
        if fdstr is None:
            logger.debug("COCKPIT_LOGIN_MESSAGES_MEMFD wasn't set.  No login messages today.")
            return

        logger.debug("Trying to read login messages from fd %s", fdstr)
        try:
            with open(int(fdstr), 'r') as login_messages:
                login_messages.seek(0)
                self.messages = login_messages.read()
        except (ValueError, OSError, UnicodeDecodeError) as exc:
            # ValueError - the envvar wasn't an int
            # OSError - the fd wasn't open, or other read failure
            # UnicodeDecodeError - didn't contain utf-8
            # For all of these, we simply failed to get the message.
            logger.debug("Reading login messages failed: %s", exc)
        else:
            logger.debug("Successfully read login messages: %s", self.messages)

    @bus.Interface.Method(out_types=['s'])
    def get(self):
        return self.messages or '{}'

    @bus.Interface.Method(out_types=[])
    def dismiss(self):
        self.messages = None


class cockpit_Machines(bus.Object):
    path: Path
    watch: pathwatch.PathWatch
    pending_notify: Optional[asyncio.Handle]

    # D-Bus implementation
    machines = bus.Interface.Property('a{sa{sv}}')

    @machines.getter
    def get_machines(self) -> Dict[str, Dict[str, Variant]]:
        results: Dict[str, Dict[str, Variant]] = {}

        for filename in glob.glob(f'{self.path}/*.json'):
            with open(filename) as fp:
                try:
                    contents = json.load(fp)
                except json.JSONDecodeError:
                    logger.warning('Invalid JSON in file %s.  Ignoring.', filename)
                    continue
                # merge
                for hostname, attrs in contents.items():
                    results[hostname] = {key: Variant(value) for key, value in attrs.items()}

        return results

    @bus.Interface.Method(in_types=['s', 's', 'a{sv}'])
    def update(self, filename: str, hostname: str, attrs: Dict[str, Variant]) -> None:
        try:
            with self.path.joinpath(filename).open() as fp:
                contents = json.load(fp)
        except json.JSONDecodeError as exc:
            # Refuse to replace corrupted file
            raise bus.BusError('cockpit.Machines.Error', f'File {filename} is in invalid format: {exc}.') from exc
        except FileNotFoundError:
            # But an empty file is an expected case
            contents = {}

        contents.setdefault(hostname, {}).update({key: value.value for key, value in attrs.items()})

        self.path.mkdir(parents=True, exist_ok=True)
        with open(self.path.joinpath(filename), 'w') as fp:
            json.dump(contents, fp, indent=2)

    def notify(self):
        def _notify_now():
            self.properties_changed('cockpit.Machines', {}, ['Machines'])
            self.pending_notify = None

        # avoid a flurry of update notifications
        if self.pending_notify is None:
            self.pending_notify = asyncio.get_running_loop().call_later(1.0, _notify_now)

    # inotify events
    def do_inotify_event(self, mask: inotify.Event, cookie: int, name: Optional[str]) -> None:
        self.notify()

    def do_identity_changed(self, fd: Optional[int], errno: Optional[int]) -> None:
        self.notify()

    def __init__(self):
        self.path = config.lookup_config('machines.d')

        # ignore the first callback
        self.pending_notify = ...
        self.watch = pathwatch.PathWatch(str(self.path), self)
        self.pending_notify = None


class cockpit_User(bus.Object):
    name = bus.Interface.Property('s', value='')
    full = bus.Interface.Property('s', value='')
    id = bus.Interface.Property('i', value=0)
    gid = bus.Interface.Property('i', value=0)
    home = bus.Interface.Property('s', value='')
    shell = bus.Interface.Property('s', value='')
    groups = bus.Interface.Property('as', value=[])

    def __init__(self):
        user = pwd.getpwuid(os.getuid())
        self.name = user.pw_name
        self.full = user.pw_gecos
        self.id = user.pw_uid
        self.gid = user.pw_gid
        self.home = user.pw_dir
        self.shell = user.pw_shell

        # We want the primary group first in the list, without duplicates.
        # This is a bit awkward because `set()` is unordered...
        groups = [grp.getgrgid(user.pw_gid).gr_name]
        for gr in grp.getgrall():
            if user.pw_name in gr.gr_mem and gr.gr_name not in groups:
                groups.append(gr.gr_name)
        self.groups = groups


EXPORTS = [
    ('/LoginMessages', cockpit_LoginMessages),
    ('/machines', cockpit_Machines),
    ('/user', cockpit_User),
]