# Authors: Rob Crittenden <rcritten@redhat.com>
#
# Copyright (C) 2011  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/>.
#

from ipaserver.install.plugins.baseupdate import DSRestart
from ipaserver.install.ldapupdate import LDAPUpdate
from ipapython.ipautil import wait_for_open_socket
from ipalib import api
from ipalib import backend
from ipaplatform.paths import paths
from ipapython.dn import DN

class updateclient(backend.Executioner):
    """
    Backend used for applying LDAP updates via plugins

    An update plugin can be executed before the file-based plugins or
    afterward. Each plugin returns three values:

    1. restart: dirsrv will be restarted AFTER this update is
                 applied.
    2. updates: A list of updates to be applied.

    The value of an update is a dictionary with the following possible
    values:
      - dn: DN, equal to the dn attribute
      - updates: list of updates against the dn
      - default: list of the default entry to be added if it doesn't
                 exist
      - deleteentry: list of dn's to be deleted (typically single dn)

    For example, this update file:

      dn: cn=global_policy,cn=$REALM,cn=kerberos,$SUFFIX
      replace:krbPwdLockoutDuration:10::600
      replace: krbPwdMaxFailure:3::6

    Generates this list which contain the update dictionary:

    [
      dict(
        'dn': 'cn=global_policy,cn=EXAMPLE.COM,cn=kerberos,dc=example,dc=com',
        'updates': ['replace:krbPwdLockoutDuration:10::600',
                    'replace:krbPwdMaxFailure:3::6']
      )
    ]

    Here is another example showing how a default entry is configured:

      dn: cn=Managed Entries,cn=etc,$SUFFIX
      default: objectClass: nsContainer
      default: objectClass: top
      default: cn: Managed Entries

    This generates:

    [
      dict(
        'dn': 'cn=Managed Entries,cn=etc,dc=example,dc=com',
        'default': ['objectClass:nsContainer',
                    'objectClass:top',
                    'cn:Managed Entries'
                   ]
       )
    ]

    Note that the variable substitution in both examples has been completed.

    A PRE_UPDATE plugin is executed before file-based updates.

    A POST_UPDATE plugin is executed after file-based updates.

    Plugins are executed automatically when ipa-ldap-updater is run
    in upgrade mode (--upgrade). They are not executed normally otherwise.
    To execute plugins as well use the --plugins flag.

    Either may make changes directly in LDAP or can return updates in
    update format.
    """
    def create_context(self, dm_password):
        if dm_password:
            autobind = False
        else:
            autobind = True
        self.Backend.ldap2.connect(bind_dn=DN(('cn', 'Directory Manager')), bind_pw=dm_password, autobind=autobind)

    def order(self, updatetype):
        """Return plugins of the given updatetype in sorted order.
        """
        ordered = [plugin for plugin in api.Updater()
                   if plugin.updatetype == updatetype]
        ordered.sort(key=lambda p: p.order)
        return ordered

    def update(self, updatetype, dm_password, ldapi):
        """
        Execute all update plugins of type updatetype.
        """
        self.create_context(dm_password)
        kw = dict()
        result = []
        ld = LDAPUpdate(dm_password=dm_password, sub_dict={}, ldapi=ldapi)
        for update in self.order(updatetype):
            restart, res = self.run(update.name, **kw)

            ld.update_from_dict(res)
            if restart:
                # connection has to be closed before restart, otherwise
                # ld instance will try to reuse old non-valid connection
                ld.close_connection()
                self.restart(dm_password)

        self.destroy_context()

        return result

    def run(self, method, **kw):
        """
        Execute the update plugin.
        """
        return self.Updater[method](**kw)

    def restart(self, dm_password):
        dsrestart = DSRestart()
        socket_name = paths.SLAPD_INSTANCE_SOCKET_TEMPLATE % \
            api.env.realm.replace('.','-')
        self.destroy_context()
        dsrestart.create_instance()
        wait_for_open_socket(socket_name)
        self.create_context(dm_password)

api.register(updateclient)