#! /usr/bin/env python3
#
# GPOA - GPO Applier for Linux
#
# Copyright (C) 2019-2020 BaseALT Ltd.
#
# 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 <http://www.gnu.org/licenses/>.


import os
import sys
import argparse
import subprocess

from util.util import (
      runcmd
    , get_backends
    , get_default_policy_name
    , get_policy_entries
    , get_policy_variants
)
from util.config import GPConfig
from util.paths import get_custom_policy_dir


class Runner:
    __control_path = '/usr/sbin/control'
    __systemctl_path = '/bin/systemctl'

    def __init__(self):
        self.arguments = parse_arguments()

def parse_arguments():
    '''
    Parse CLI arguments.
    '''
    parser = argparse.ArgumentParser(prog='gpupdate-setup')
    subparsers = parser.add_subparsers(dest='action',
        metavar='action',
        help='Group Policy management actions (default action is status)')

    parser_list = subparsers.add_parser('list',
        help='List avalable types of local policy')
    parser_list = subparsers.add_parser('list-backends',
        help='Show list of available backends')
    parser_status = subparsers.add_parser('status',
        help='Show current Group Policy status')
    parser_enable = subparsers.add_parser('enable',
        help='Enable Group Policy subsystem')

    parser_disable = subparsers.add_parser('disable',
        help='Disable Group Policy subsystem')
    parser_update = subparsers.add_parser('update',
        help='Update state')
    parser_write = subparsers.add_parser('write',
        help='Operate on Group Policies (enable or disable)')
    parser_set_backend = subparsers.add_parser('set-backend',
        help='Set or change currently active backend')
    parser_default = subparsers.add_parser('default-policy',
        help='Show name of default policy')
    parser_active = subparsers.add_parser('active-policy',
        help='Show name of policy enabled')
    parser_active_backend = subparsers.add_parser('active-backend',
        help='Show currently configured backend')

    parser_set_backend.add_argument('backend',
        default='samba',
        type=str,
        nargs='?',
        const='backend',
        choices=['local', 'samba'],
        help='Backend (source of settings) name')

    parser_write.add_argument('status',
        choices=['enable', 'disable'],
        help='Enable or disable Group Policies')
    parser_write.add_argument('localpolicy',
        default=None,
        nargs='?',
        help='Name of local policy to enable')
    parser_write.add_argument('backend',
        default='samba',
        type=str,
        nargs='?',
        const='backend',
        choices=['local', 'samba'],
        help='Backend (source of settings) name')

    parser_enable.add_argument('--local-policy',
        default=None,
        help='Name of local policy to enable')
    parser_enable.add_argument('--backend',
        default='samba',
        type=str,
        choices=['local', 'samba'],
        help='Backend (source of settings) name')

    parser_update.add_argument('--local-policy',
        default=None,
        help='Name of local policy to enable')
    parser_update.add_argument('--backend',
        default='samba',
        type=str,
        choices=['local', 'samba'],
        help='Backend (source of settings) name')


    return parser.parse_args()

def validate_policy_name(policy_name):
    return policy_name in [os.path.basename(d) for d in get_policy_variants()]

def is_unit_enabled(unit_name, unit_global=False):
    '''
    Check that designated systemd unit is enabled
    '''
    command = ['/bin/systemctl', 'is-enabled', unit_name]
    if unit_global:
        command = ['/bin/systemctl', '--global', 'is-enabled', unit_name]
    value = runcmd(command)

    # If first line of stdout is equal to "enabled" and return code
    # is zero then unit is considered enabled.
    rc = value[0]
    result = []
    try:
        result = value[1].replace('\n', '')
    except IndexError as exc:
        return False

    if result == 'enabled' and rc == 0:
        return True

    return False

def get_status():
    '''
    Check that gpupdate.service and gpupdate-user.service are enabled.
    '''
    is_gpupdate = is_unit_enabled('gpupdate.service')
    is_gpupdate_user = is_unit_enabled('gpupdate-user.service', unit_global=True)

    if is_gpupdate and is_gpupdate_user:
        return True

    return False

def get_active_policy_name():
    '''
    Show the name of an active Local Policy template
    '''
    config = GPConfig()
    return os.path.basename(config.get_local_policy_template())

def get_active_backend():
    config = GPConfig()
    return config.get_backend()

def rollback_on_error(command_name):
    '''
    Disable group policy services in case command returns error code
    '''
    if 0 != runcmd(command_name)[0]:
        disable_gp()
        return False
    return True

def disable_gp():
    '''
    Consistently disable group policy services
    '''
    cmd_set_global_policy = ['/usr/sbin/control', 'system-policy', 'remote']
    cmd_set_local_policy = ['/usr/sbin/control', 'system-policy', 'local']
    cmd_disable_gpupdate_service = ['/bin/systemctl', 'disable', 'gpupdate.service']
    cmd_disable_gpupdate_user_service = ['/bin/systemctl', '--global', 'disable', 'gpupdate-user.service']
    cmd_disable_gpupdate_timer = ['/bin/systemctl', 'disable', 'gpupdate.timer']
    cmd_disable_gpupdate_user_timer = ['/bin/systemctl', '--global', 'disable', 'gpupdate-user.timer']
    cmd_control_system_auth = ['/usr/sbin/control', 'system-auth']
    cmd_disable_gpupdate_scripts_service = ['/bin/systemctl', 'disable', 'gpupdate-scripts-run.service']
    cmd_disable_gpupdate_scripts_user_service = ['/bin/systemctl', '--global', 'disable', 'gpupdate-scripts-run-user.service']

    config = GPConfig()

    auth_result = 'local'
    try:
        auth_result = runcmd(cmd_control_system_auth)[1][0]
    except Exception as exc:
        print(str(exc))

    if auth_result != 'local':
        runcmd(cmd_set_global_policy)
    else:
        runcmd(cmd_set_local_policy)
    runcmd(cmd_disable_gpupdate_service)
    runcmd(cmd_disable_gpupdate_user_service)
    runcmd(cmd_disable_gpupdate_timer)
    runcmd(cmd_disable_gpupdate_user_timer)
    runcmd(cmd_disable_gpupdate_scripts_service)
    runcmd(cmd_disable_gpupdate_scripts_user_service)
    config.set_local_policy_template()
    config.set_backend()

def enable_gp(policy_name, backend_type):
    '''
    Consistently enable group policy services
    '''
    cmd_set_gpupdate_policy = ['/usr/sbin/control', 'system-policy', 'gpupdate']
    cmd_gpoa_nodomain = ['/usr/sbin/gpoa', '--nodomain', '--loglevel', '5']
    cmd_enable_gpupdate_service = ['/bin/systemctl', 'enable', 'gpupdate.service']
    cmd_enable_gpupdate_user_service = ['/bin/systemctl', '--global', 'enable', 'gpupdate-user.service']
    cmd_enable_gpupdate_timer = ['/bin/systemctl', 'enable', 'gpupdate.timer']
    cmd_enable_gpupdate_user_timer = ['/bin/systemctl', '--global', 'enable', 'gpupdate-user.timer']
    cmd_enable_gpupdate_scripts_service = ['/bin/systemctl', 'enable', 'gpupdate-scripts-run.service']
    cmd_enable_gpupdate_user_scripts_service = ['/bin/systemctl', '--global', 'enable', 'gpupdate-scripts-run-user.service']

    config = GPConfig()

    custom_policy_dir = get_custom_policy_dir()
    if not os.path.isdir(custom_policy_dir):
        os.makedirs(custom_policy_dir)

    target_policy_name = get_default_policy_name()
    if policy_name:
        if validate_policy_name(policy_name):
            target_policy_name = policy_name
    print (target_policy_name)

    config.set_local_policy_template(target_policy_name)
    config.set_backend(backend_type)

    # Enable oddjobd_gpupdate in PAM config
    if not rollback_on_error(cmd_set_gpupdate_policy):
        return
    # Bootstrap the Group Policy engine
    if not rollback_on_error(cmd_gpoa_nodomain):
        return
    # Enable gpupdate.service
    if not rollback_on_error(cmd_enable_gpupdate_service):
        return
    if not is_unit_enabled('gpupdate.service'):
        disable_gp()
        return
    # Enable gpupdate-setup.service for all users
    if not rollback_on_error(cmd_enable_gpupdate_user_service):
        return
    if not is_unit_enabled('gpupdate-user.service', unit_global=True):
        disable_gp()
        return

        # Enable gpupdate-scripts-run.service
    if not rollback_on_error(cmd_enable_gpupdate_scripts_service):
        return
    if not is_unit_enabled('gpupdate-scripts-run.service'):
        disable_gp()
        return
    # Enable gpupdate-scripts-run-user.service for all users
    if not rollback_on_error(cmd_enable_gpupdate_user_scripts_service):
        return
    if not is_unit_enabled('gpupdate-scripts-run-user.service', unit_global=True):
        disable_gp()
        return

    # Enable gpupdate.timer
    if not rollback_on_error(cmd_enable_gpupdate_timer):
        return
    if not is_unit_enabled('gpupdate.timer'):
        disable_gp()
        return
    # Enable gpupdate-setup.timer for all users
    if not rollback_on_error(cmd_enable_gpupdate_user_timer):
        return
    if not is_unit_enabled('gpupdate-user.timer', unit_global=True):
        disable_gp()
        return

def act_list():
    '''
    Show list of available templates of Local Policy
    '''
    for entry in get_policy_variants():
        print(entry.rpartition('/')[2])

def act_list_backends():
    '''
    List backends supported by GPOA
    '''
    backends = get_backends()
    for backend in backends:
        print(backend)

def act_status():
    '''
    Check that group policy services are enabled
    '''
    if get_status():
        print('enabled')
    else:
        print('disabled')

def act_set_backend(backend_name):
    config = GPConfig()
    config.set_backend(backend_name)

def act_write(status, localpolicy, backend):
    '''
    Enable or disable group policy services
    '''
    if status == 'enable' or status == '#t':
        enable_gp(localpolicy, backend)
    if status == 'disable' or status == '#f':
        disable_gp()

def act_enable(localpolicy, backend):
    '''
    Enable group policy services
    '''
    enable_gp(localpolicy, backend)

def act_active_policy():
    '''
    Print active Local Policy template name to stdout
    '''
    print(get_active_policy_name())

def act_active_backend():
    '''
    Print currently configured backend.
    '''
    print(get_active_backend())

def act_default_policy():
    '''
    Print default Local Policy template name to stdout
    '''
    print(get_default_policy_name())

def main():
    arguments = parse_arguments()

    action = dict()
    action['list'] = act_list
    action['list-backends'] = act_list_backends
    action['status'] = act_status
    action['set-backend'] = act_set_backend
    action['write'] = act_write
    action['enable'] = act_enable
    action['update'] = act_enable
    action['disable'] = disable_gp
    action['active-policy'] = act_active_policy
    action['active-backend'] = act_active_backend
    action['default-policy'] = act_default_policy

    if arguments.action == None:
        action['status']()
    elif arguments.action == 'update':
        if get_status():
            action[arguments.action](arguments.local_policy, arguments.backend)
    elif arguments.action == 'enable':
        action[arguments.action](arguments.local_policy, arguments.backend)
    elif arguments.action == 'write':
        action[arguments.action](arguments.status, arguments.localpolicy, arguments.backend)
    elif arguments.action == 'set-backend':
        action[arguments.action](arguments.backend)
    else:
        action[arguments.action]()

if __name__ == '__main__':
    main()