# This code is part of Ansible, but is an independent component.
# This particular file snippet, and this file snippet only, is BSD licensed.
# Modules you write using this snippet, which is embedded dynamically by Ansible
# still belong to the author of the module, and may assign their own license
# to the complete work.
#
# Copyright (c) 2016, Adfinis SyGroup AG
# Tobias Rueetschi <tobias.ruetschi@adfinis-sygroup.ch>
#
# Simplified BSD License (see LICENSES/BSD-2-Clause.txt or https://opensource.org/licenses/BSD-2-Clause)
# SPDX-License-Identifier: BSD-2-Clause

from __future__ import annotations

"""Univention Corporate Server (UCS) access module.

Provides the following functions for working with an UCS server.

  - ldap_search(filter, base=None, attr=None)
    Search the LDAP via Univention's LDAP wrapper (ULDAP)

  - config_registry()
    Return the UCR registry object

  - base_dn()
    Return the configured Base DN according to the UCR

  - uldap()
    Return a handle to the ULDAP LDAP wrapper

  - umc_module_for_add(module, container_dn, superordinate=None)
    Return a UMC module for creating a new object of the given type

  - umc_module_for_edit(module, object_dn, superordinate=None)
    Return a UMC module for editing an existing object of the given type


Any other module is not part of the "official" API and may change at any time.
"""

import re

__all__ = [
    "base_dn",
    "config_registry",
    "ldap_search",
    "uldap",
    "umc_module_for_add",
    "umc_module_for_edit",
]


_singletons: dict[str, object] = {}


def ldap_module():
    import ldap as orig_ldap

    return orig_ldap


def _singleton(name: str, constructor):
    if name in _singletons:
        return _singletons[name]
    _singletons[name] = constructor()
    return _singletons[name]


def config_registry():
    def construct():
        import univention.config_registry

        ucr = univention.config_registry.ConfigRegistry()
        ucr.load()
        return ucr

    return _singleton("config_registry", construct)


def base_dn():
    return config_registry()["ldap/base"]


def uldap():
    "Return a configured univention uldap object"

    def construct():
        try:
            secret_file = open("/etc/ldap.secret")
            bind_dn = f"cn=admin,{base_dn()}"
        except OSError:  # pragma: no cover
            secret_file = open("/etc/machine.secret")
            bind_dn = config_registry()["ldap/hostdn"]
        pwd_line = secret_file.readline()
        pwd = re.sub("\n", "", pwd_line)

        import univention.admin.uldap

        return univention.admin.uldap.access(
            host=config_registry()["ldap/master"],
            base=base_dn(),
            binddn=bind_dn,
            bindpw=pwd,
            start_tls=1,
        )

    return _singleton("uldap", construct)


def config():
    def construct():
        import univention.admin.config

        return univention.admin.config.config()

    return _singleton("config", construct)


def init_modules():
    def construct():
        import univention.admin.modules

        univention.admin.modules.update()
        return True

    return _singleton("modules_initialized", construct)


def position_base_dn():
    def construct():
        import univention.admin.uldap

        return univention.admin.uldap.position(base_dn())

    return _singleton("position_base_dn", construct)


def ldap_dn_tree_parent(dn, count=1):
    dn_array = dn.split(",")
    dn_array[0:count] = []
    return ",".join(dn_array)


def ldap_search(filter, base=None, attr=None):
    """Replaces uldaps search and uses a generator.
    !! Arguments are not the same."""

    if base is None:
        base = base_dn()
    msgid = uldap().lo.lo.search(base, ldap_module().SCOPE_SUBTREE, filterstr=filter, attrlist=attr)
    # I used to have a try: finally: here but there seems to be a bug in python
    # which swallows the KeyboardInterrupt
    # The abandon now doesn't make too much sense
    while True:
        result_type, result_data = uldap().lo.lo.result(msgid, all=0)
        if not result_data:
            break
        if result_type is ldap_module().RES_SEARCH_RESULT:  # pragma: no cover
            break
        else:
            if result_type is ldap_module().RES_SEARCH_ENTRY:
                yield from result_data
    uldap().lo.lo.abandon(msgid)


def module_by_name(module_name_: str):
    """Returns an initialized UMC module, identified by the given name.

    The module is a module specification according to the udm commandline.
    Example values are:
    * users/user
    * shares/share
    * groups/group

    If the module does not exist, a KeyError is raised.

    The modules are cached, so they won't be re-initialized
    in subsequent calls.
    """

    def construct():
        import univention.admin.modules

        init_modules()
        module = univention.admin.modules.get(module_name_)
        univention.admin.modules.init(uldap(), position_base_dn(), module)
        return module

    return _singleton(f"module/{module_name_}", construct)


def get_umc_admin_objects():
    """Convenience accessor for getting univention.admin.objects.

    This implements delayed importing, so the univention.* modules
    are not loaded until this function is called.
    """
    import univention.admin

    return univention.admin.objects


def umc_module_for_add(module: str, container_dn, superordinate=None):
    """Returns an UMC module object prepared for creating a new entry.

    The module is a module specification according to the udm commandline.
    Example values are:
        * users/user
        * shares/share
        * groups/group

    The container_dn MUST be the dn of the container (not of the object to
    be created itself!).
    """
    mod = module_by_name(module)

    position = position_base_dn()
    position.setDn(container_dn)

    # config, ldap objects from common module
    obj = mod.object(config(), uldap(), position, superordinate=superordinate)
    obj.open()

    return obj


def umc_module_for_edit(module: str, object_dn, superordinate=None):
    """Returns an UMC module object prepared for editing an existing entry.

    The module is a module specification according to the udm commandline.
    Example values are:
        * users/user
        * shares/share
        * groups/group

    The object_dn MUST be the dn of the object itself, not the container!
    """
    mod = module_by_name(module)

    objects = get_umc_admin_objects()

    position = position_base_dn()
    position.setDn(ldap_dn_tree_parent(object_dn))

    obj = objects.get(mod, config(), uldap(), position=position, superordinate=superordinate, dn=object_dn)
    obj.open()

    return obj


def create_containers_and_parents(container_dn):
    """Create a container and if needed the parents containers"""
    import univention.admin.uexceptions as uexcp

    if not container_dn.startswith("cn="):
        raise AssertionError()
    try:
        parent = ldap_dn_tree_parent(container_dn)
        obj = umc_module_for_add("container/cn", parent)
        obj["name"] = container_dn.split(",")[0].split("=")[1]
        obj["description"] = "container created by import"
    except uexcp.ldapError:
        create_containers_and_parents(parent)
        obj = umc_module_for_add("container/cn", parent)
        obj["name"] = container_dn.split(",")[0].split("=")[1]
        obj["description"] = "container created by import"