#
# Authors:
#   Rob Crittenden <rcritten@redhat.com>
#
# Copyright (C) 2012, 2019 Red Hat
# see file 'COPYING' for use and warranty information
#
# 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/>.
#
# Configure the automount client for ldap.

from __future__ import print_function

import logging
import sys
import os
import shutil
import time
import tempfile
import gssapi

import SSSDConfig

from six.moves.urllib.parse import urlsplit

from ipapython import ipachangeconf
from ipaclient import discovery
from ipaclient.install.client import (
    CLIENT_NOT_CONFIGURED,
    CLIENT_ALREADY_CONFIGURED,
)
from ipalib import api, errors
from ipalib.install import sysrestore
from ipalib.kinit import kinit_keytab
from ipalib.util import check_client_configuration
from ipapython import ipautil
from ipapython.ipa_log_manager import standard_logging_setup
from ipaplatform.constants import constants
from ipaplatform.tasks import tasks
from ipaplatform import services
from ipaplatform.paths import paths
from ipapython.admintool import ScriptError
from ipapython.config import IPAOptionParser


logger = logging.getLogger(os.path.basename(__file__))


def parse_options():
    usage = "%prog [options]\n"
    parser = IPAOptionParser(usage=usage)
    parser.add_option("--server", dest="server", help="FQDN of IPA server")
    parser.add_option(
        "--location",
        dest="location",
        default="default",
        help="Automount location",
    )
    parser.add_option(
        "--idmap-domain",
        dest="idmapdomain",
        default=None,
        help="nfs domain for idmapd.conf",
    )
    parser.add_option(
        "-d",
        "--debug",
        dest="debug",
        action="store_true",
        default=False,
        help="enable debugging",
    )
    parser.add_option(
        "-U",
        "--unattended",
        dest="unattended",
        action="store_true",
        default=False,
        help="unattended installation never prompts the user",
    )
    parser.add_option(
        "--uninstall",
        dest="uninstall",
        action="store_true",
        default=False,
        help="Unconfigure automount",
    )

    options, args = parser.parse_args()
    return options, args


def wait_for_sssd():
    """
    It takes a bit for sssd to get going, lets loop until it is
    serving data.

    This function returns nothing.
    """
    n = 0
    found = False
    time.sleep(1)
    while n < 10 and not found:
        try:
            ipautil.run([paths.GETENT, "passwd", "admin@%s" % api.env.realm])
            found = True
        except Exception:
            time.sleep(1)
            n = n + 1

    # This should never happen but if it does, may as well warn the user
    if not found:
        err_msg = (
            "Unable to find 'admin' user with "
            "'getent passwd admin@%s'!" % api.env.realm
        )
        logger.debug('%s', err_msg)
        print(err_msg)
        print(
            "This may mean that sssd didn't re-start properly after "
            "the configuration changes."
        )


def configure_autofs_sssd(fstore, statestore, autodiscover, options):
    try:
        sssdconfig = SSSDConfig.SSSDConfig()
        sssdconfig.import_config()
        domains = sssdconfig.list_active_domains()
    except Exception as e:
        sys.exit(e)

    try:
        sssdconfig.new_service('autofs')
    except SSSDConfig.ServiceAlreadyExists:
        pass
    except SSSDConfig.ServiceNotRecognizedError:
        logger.error("Unable to activate the Autofs service in SSSD config.")
        logger.info(
            "Please make sure you have SSSD built with autofs support "
            "installed."
        )
        logger.info(
            "Configure autofs support manually in /etc/sssd/sssd.conf."
        )
        sys.exit("Cannot create the autofs service in sssd.conf")

    sssdconfig.activate_service('autofs')

    domain = None
    for name in domains:
        domain = sssdconfig.get_domain(name)
        try:
            provider = domain.get_option('id_provider')
        except SSSDConfig.NoOptionError:
            continue
        if provider == "ipa":
            domain.add_provider('ipa', 'autofs')
            try:
                domain.get_option('ipa_automount_location')
                print('An automount location is already configured')
                sys.exit(CLIENT_ALREADY_CONFIGURED)
            except SSSDConfig.NoOptionError:
                domain.set_option('ipa_automount_location', options.location)
                break

    if domain is None:
        sys.exit('SSSD is not configured.')

    sssdconfig.save_domain(domain)
    sssdconfig.write(paths.SSSD_CONF)
    statestore.backup_state('autofs', 'sssd', True)

    sssd = services.service('sssd', api)
    sssd.restart()
    print("Restarting sssd, waiting for it to become available.")
    wait_for_sssd()


def configure_autofs_common(fstore, statestore, options):
    autofs = services.knownservices.autofs
    statestore.backup_state('autofs', 'enabled', autofs.is_enabled())
    statestore.backup_state('autofs', 'running', autofs.is_running())
    try:
        autofs.restart()
        print("Started %s" % autofs.service_name)
    except Exception as e:
        logger.error("%s failed to restart: %s", autofs.service_name, e)
    try:
        autofs.enable()
    except Exception as e:
        print(
            "Failed to configure automatic startup of the %s daemon"
            % (autofs.service_name)
        )
        logger.error(
            "Failed to enable automatic startup of the %s daemon: %s",
            autofs.service_name,
            str(e),
        )


def uninstall(fstore, statestore):
    RESTORE_FILES = [
        paths.SYSCONFIG_AUTOFS,
        paths.SYSCONFIG_NFS,
        paths.IDMAPD_CONF,
    ]
    STATES = ['autofs', 'rpcidmapd', 'rpcgssd']

    if not statestore.get_state('autofs', 'sssd'):
        tasks.disable_ldap_automount(statestore)

    if not any(fstore.has_file(f) for f in RESTORE_FILES) or not any(
        statestore.has_state(s) for s in STATES
    ):
        print("IPA automount is not configured on this system")
        return CLIENT_NOT_CONFIGURED

    print("Restoring configuration")

    for filepath in RESTORE_FILES:
        if fstore.has_file(filepath):
            fstore.restore_file(filepath)
    if statestore.has_state('autofs'):
        enabled = statestore.restore_state('autofs', 'enabled')
        running = statestore.restore_state('autofs', 'running')
        sssd = statestore.restore_state('autofs', 'sssd')
        autofs = services.knownservices.autofs
        if not enabled:
            autofs.disable()
        if not running:
            autofs.stop()
        if sssd:
            try:
                sssdconfig = SSSDConfig.SSSDConfig()
                sssdconfig.import_config()
                sssdconfig.deactivate_service('autofs')
                domains = sssdconfig.list_active_domains()
                for name in domains:
                    domain = sssdconfig.get_domain(name)
                    try:
                        provider = domain.get_option('id_provider')
                    except SSSDConfig.NoOptionError:
                        continue
                    if provider == "ipa":
                        domain.remove_option('ipa_automount_location')
                        sssdconfig.save_domain(domain)
                        domain.remove_provider('autofs')
                        sssdconfig.save_domain(domain)
                        break
                sssdconfig.write(paths.SSSD_CONF)
                sssd = services.service('sssd', api)
                sssd.restart()
                wait_for_sssd()
            except Exception as e:
                print('Unable to restore SSSD configuration: %s' % str(e))
                logger.debug(
                    'Unable to restore SSSD configuration: %s', str(e)
                )

    # rpcidmapd and rpcgssd are static units now
    if statestore.has_state('rpcidmapd'):
        statestore.delete_state('rpcidmapd', 'enabled')
        statestore.delete_state('rpcidmapd', 'running')
    if statestore.has_state('rpcgssd'):
        statestore.delete_state('rpcgssd', 'enabled')
        statestore.delete_state('rpcgssd', 'running')

    nfsutils = services.knownservices['nfs-utils']
    try:
        nfsutils.restart()
    except Exception as e:
        logger.error("Failed to restart nfs client services (%s)", str(e))
        return 1
    return 0


def configure_nfs(fstore, statestore, options):
    """
    Configure secure NFS
    """
    # Newer Fedora releases ship /etc/nfs.conf instead of /etc/sysconfig/nfs
    # and do not require changes there. On these, SECURE_NFS_VAR == None
    if constants.SECURE_NFS_VAR:
        replacevars = {constants.SECURE_NFS_VAR: 'yes'}
        ipautil.backup_config_and_replace_variables(
            fstore, paths.SYSCONFIG_NFS, replacevars=replacevars
        )
        tasks.restore_context(paths.SYSCONFIG_NFS)
        print("Configured %s" % paths.SYSCONFIG_NFS)

    # Prepare the changes
    # We need to use IPAChangeConf as simple regexp substitution
    # does not cut it here
    conf = ipachangeconf.IPAChangeConf("IPA automount installer")
    conf.case_insensitive_sections = False
    conf.setOptionAssignment(" = ")
    conf.setSectionNameDelimiters(("[", "]"))

    if options.idmapdomain is None:
        # Set NFSv4 domain to the IPA domain
        changes = [conf.setOption('Domain', api.env.domain)]
    elif options.idmapdomain == 'DNS':
        # Rely on idmapd auto-detection (DNS)
        changes = [conf.rmOption('Domain')]
    else:
        # Set NFSv4 domain to what was provided
        changes = [conf.setOption('Domain', options.idmapdomain)]

    if changes is not None:
        section_with_changes = [conf.setSection('General', changes)]
        # Backup the file and apply the changes
        fstore.backup_file(paths.IDMAPD_CONF)
        conf.changeConf(paths.IDMAPD_CONF, section_with_changes)
        tasks.restore_context(paths.IDMAPD_CONF)
        print("Configured %s" % paths.IDMAPD_CONF)

    rpcgssd = services.knownservices.rpcgssd
    try:
        rpcgssd.restart()
    except Exception as e:
        logger.error("Failed to restart rpc-gssd (%s)", str(e))
    nfsutils = services.knownservices['nfs-utils']
    try:
        nfsutils.restart()
    except Exception as e:
        logger.error("Failed to restart nfs client services (%s)", str(e))


def configure_automount():
    statestore = sysrestore.StateFile(paths.IPA_CLIENT_SYSRESTORE)
    if not statestore.get_state('installation', 'automount'):
        # not called from ipa-client-install
        try:
            check_client_configuration()
        except ScriptError as e:
            print(e.msg)
            sys.exit(e.rval)

    fstore = sysrestore.FileStore(paths.IPA_CLIENT_SYSRESTORE)

    options, _args = parse_options()

    standard_logging_setup(
        paths.IPACLIENT_INSTALL_LOG,
        verbose=False,
        debug=options.debug,
        filemode='a',
        console_format='%(message)s',
    )

    cfg = dict(
        context='cli_installer',
        confdir=paths.ETC_IPA,
        in_server=False,
        debug=options.debug,
        verbose=0,
    )

    # Bootstrap API early so that env object is available
    api.bootstrap(**cfg)

    if options.uninstall:
        return uninstall(fstore, statestore)

    ca_cert_path = None
    if os.path.exists(paths.IPA_CA_CRT):
        ca_cert_path = paths.IPA_CA_CRT

    if statestore.has_state('autofs'):
        print('An automount location is already configured')
        sys.exit(CLIENT_ALREADY_CONFIGURED)

    autodiscover = False
    ds = discovery.IPADiscovery()
    if not options.server:
        print("Searching for IPA server...")
        ret = ds.search(ca_cert_path=ca_cert_path)
        logger.debug('Executing DNS discovery')
        if ret == discovery.NO_LDAP_SERVER:
            logger.debug('Autodiscovery did not find LDAP server')
            s = urlsplit(api.env.xmlrpc_uri)
            server = [s.netloc]
            logger.debug('Setting server to %s', s.netloc)
        else:
            autodiscover = True
            if not ds.servers:
                sys.exit(
                    'Autodiscovery was successful but didn\'t return a server'
                )
            logger.debug(
                'Autodiscovery success, possible servers %s',
                ','.join(ds.servers),
            )
            server = ds.servers[0]
    else:
        server = options.server
        logger.debug("Verifying that %s is an IPA server", server)
        ldapret = ds.ipacheckldap(server, api.env.realm, ca_cert_path)
        if ldapret[0] == discovery.NO_ACCESS_TO_LDAP:
            print("Anonymous access to the LDAP server is disabled.")
            print("Proceeding without strict verification.")
            print(
                "Note: This is not an error if anonymous access has been "
                "explicitly restricted."
            )
        elif ldapret[0] == discovery.NO_TLS_LDAP:
            logger.warning("Unencrypted access to LDAP is not supported.")
        elif ldapret[0] != 0:
            sys.exit('Unable to confirm that %s is an IPA server' % server)

    if not autodiscover:
        print("IPA server: %s" % server)
        logger.debug('Using fixed server %s', server)
    else:
        print("IPA server: DNS discovery")
        logger.debug('Configuring to use DNS discovery')

    print("Location: %s" % options.location)
    logger.debug('Using automount location %s', options.location)

    ccache_dir = tempfile.mkdtemp()
    ccache_name = os.path.join(ccache_dir, 'ccache')
    try:
        try:
            host_princ = str('host/%s@%s' % (api.env.host, api.env.realm))
            kinit_keytab(host_princ, paths.KRB5_KEYTAB, ccache_name)
            os.environ['KRB5CCNAME'] = ccache_name
        except gssapi.exceptions.GSSError as e:
            sys.exit("Failed to obtain host TGT: %s" % e)

        # Finalize API when TGT obtained using host keytab exists
        api.finalize()

        # Now we have a TGT, connect to IPA
        try:
            api.Backend.rpcclient.connect()
        except errors.KerberosError as e:
            sys.exit('Cannot connect to the server due to ' + str(e))
        try:
            # Use the RPC directly so older servers are supported
            api.Backend.rpcclient.forward(
                'automountlocation_show',
                ipautil.fsdecode(options.location),
                version=u'2.0',
            )
        except errors.VersionError as e:
            sys.exit('This client is incompatible: ' + str(e))
        except errors.NotFound:
            sys.exit(
                "Automount location '%s' does not exist" % options.location
            )
        except errors.PublicError as e:
            sys.exit(
                "Cannot connect to the server due to generic error: %s"
                % str(e)
            )
    finally:
        shutil.rmtree(ccache_dir)

    if not options.unattended and not ipautil.user_input(
        "Continue to configure the system with these values?", False
    ):
        sys.exit("Installation aborted")

    try:
        configure_nfs(fstore, statestore, options)
        configure_autofs_sssd(fstore, statestore, autodiscover, options)
        configure_autofs_common(fstore, statestore, options)
    except Exception as e:
        logger.debug('Raised exception %s', e)
        print("Installation failed. Rolling back changes.")
        uninstall(fstore, statestore)
        return 1

    return 0


def main():
    try:
        if not os.geteuid() == 0:
            sys.exit("\nMust be run as root\n")
        configure_automount()
    except SystemExit as e:
        sys.exit(e)
    except RuntimeError as e:
        sys.exit(e)
    except (KeyboardInterrupt, EOFError):
        sys.exit(1)