# -*- encoding: utf-8 -*-
from bonsai import LDAPEntry, LDAPModOp, NoSuchObjectError  # type: ignore
from bonsai.ldapvaluelist import LDAPValueList
import bonsai.errors

from phi.exceptions import (
    PhiAttributeMissing,
    PhiEntryDoesNotExist,
    PhiEntryExists,
    PhiUnauthorized,
    PhiUnexpectedRuntimeValue,
    PhiCannotExecute,
)

from phi.security import hash_pass, handle_password


def de_listify(elems):
    if not isinstance(elems, list):
        return elems
    if len(elems) == 1:
        return elems[0]
    else:
        return elems


async def build_heritage(obj, child_class, attribute_id="uid"):
    """
    Given the object and the child class, yields the
    instances of the children.
    """
    async for child in obj.get_children():
        if attribute_id in child:
            _name = child[attribute_id][0]
            yield child_class(obj.client, _name)


class Singleton(object):
    """
    Mixin to singletonize a class. The class is crafted to be used with the mixins
    that implement the compatible __init__.
    """

    def __new__(cls, client, *args, **kwargs):
        if "name" in kwargs:
            name = f"{cls.__name__}-{args['name']}-{id(client)}"
        elif args:
            name = f"{cls.__name__}-{args[0]}-{id(client)}"
        else:
            name = f"{cls.__name__}-{id(client)}"
        if name not in cls._instances:
            cls._instances[name] = object.__new__(cls)
        return cls._instances[name]


class Entry(object):
    """
    Mixin to interact with LDAP.
    """

    def __repr__(self):
        return f"<{self.__class__.__name__} {self.dn}>"

    def __str__(self):
        return f"<{self.__class__.__name__} {self.dn}>"

    async def _create_new(self):
        self._entry["objectClass"] = self.object_class
        async with self.client.connect(is_async=True) as conn:
            await conn.add(self._entry)
        return self._entry

    async def _get(self):
        async with self.client.connect(is_async=True) as conn:
            # This returns a list of dicts. It should always contain only one item:
            # the one we are interested in.
            _res = await conn.search(self.dn, 0)
            if len(_res) == 0:
                raise PhiEntryDoesNotExist(self.dn)
            elif len(_res) > 1:
                raise PhiUnexpectedRuntimeValue(
                    "return value should be no more than one", res
                )
        return _res[0]

    async def _modify(self):
        _ = await self._get()
        async with self.client.connect(is_async=True) as conn:
            self._entry.connection = conn
            await self._entry.modify()

    async def _delete(self):
        async with self.client.connect(is_async=True) as conn:
            await conn.delete(self.dn, recursive=self.delete_cascade)

    async def describe(self):
        _internal = await self._get()
        values = dict((k, de_listify(_internal[k])) for k in self.ldap_attributes)
        if "userPassword" in self.ldap_attributes:
            values.pop("userPassword")
        values["dn"] = self.dn
        return values

    @property
    def delete_cascade(self):
        if hasattr(self, "_delete_cascade"):
            return self._delete_cascade
        return False

    @delete_cascade.setter
    def delete_cascade(self, value):
        if not isinstance(value, bool):
            raise ValueError("delete_cascade must be a boolean")
        self._delete_cascade = value


class OrganizationalUnit(object):
    """
    Mixin that represents an OrganizationalUnit. It provides the methods to interact
    with the LDAP db _and_ to supervise its `Member`s.
    To properly use it, one must specify the `ou` and `child_class` class attributes
    when inheriting.
    """

    object_class = ["organizationalUnit", "top"]

    def __init__(self, client, **kwargs):
        self.client = client
        self.base_dn = client.base_dn
        self.name = self.__class__.__name__
        self.children = build_heritage(self, self.child_class, self.child_class.id_tag)
        self._entry = LDAPEntry(self.dn)
        for k, v in kwargs.items():
            if k in self.ldap_attributes:
                self._entry[k] = v
        if "delete_cascade" in kwargs:
            self.delete_cascade = delete_cascade

    def __aiter__(self):
        return self

    async def __anext__(self):
        try:
            return await self.children.__anext__()
        except StopAsyncIteration:
            self.children = build_heritage(
                self, self.child_class, self.child_class.id_tag
            )
            raise

    async def get_children(self):
        async with self.client.connect(is_async=True) as conn:
            for el in await conn.search(self.dn, 1):
                yield el

    @property
    def dn(self):
        return f"ou={self.ou},{self.base_dn}"

    async def save(self):
        """
        This function iterates over the OU's children and invokes its `save` method,
        ignoring errors from yet existing ones.
        """
        async for child in self:
            try:
                await child.save()
            except PhiEntryExists:
                pass

    async def search(self, member_name):
        """
        This function allows one to search through the OU's children. The search
        function is the one from the underlying library (bonsai) and is strict as such.
        """
        result = None
        async with self.client.connect(is_async=True) as conn:
            result = await conn.search(
                f"{self.child_class.id_tag}={member_name},{self.dn}", 0
            )
        if not result:
            raise PhiEntryDoesNotExist(
                f"{self.child_class.id_tag}={member_name},{self.dn}"
            )
        if isinstance(result, list) and len(result) > 1:
            raise PhiUnexpectedRuntimeValue(
                "return value should be no more than one", result
            )
        return self.child_class(self.client, member_name, **result[0])

    async def delete(self):
        """
        Delete all the members of this OU only if `delete_cascade` is set to `True`,
        raises otherwise.
        """
        if self.delete_cascade:
            async for member in self:
                await member.delete()
        else:
            raise PhiCannotExecute("Cannot delete an OU and delete_cascade is not set")


def _hydrate(obj, data):
    """
    Iterate over the structure of the given `data`. Using the key name, filtering
    only on the values that the given `obj` accepts (`obj.ldap_attributes`),
    appropriately set the corresponding value in the given `obj`. In particular:
      - append to lists
      - handle password setting
      - set scalars
    This is called `_hydrate` because its aim is to fill a structure (the `obj`)
    with substance.
    """
    for k, v in data.items():
        if k in obj.ldap_attributes:
            if isinstance(v, list) and not isinstance(v, LDAPValueList):
                obj._entry[k] = []
                for _v in v:
                    obj._entry[k].append(_v.dn)
            elif k == "userPassword":
                obj._entry[k] = handle_password(v)
            else:
                obj._entry[k] = v


class Member(object):
    """
    Mixin that represents a generic member of an `OrganizationalUnit`.
    It provides the methods to interact with the LDAP db.
    To properly use, `ou`, `object_class` and `ldap_attributes` class attributes must
    be specified when inheriting.

    ## Usage

    The initialization needs an `phi.async_ldap.AsyncClient` and a `name`, that is used
    as value in the identification attribute (i.e. `uid`).
    This inits an object in memory that may or may not exist in the ldap database yet.
    To test it, one can invoke the async method `exists` or may try to `sync`, handling
    the corresponding exception (`PhiEntryDoesNotExist`).
    To save a new instance, one can `save`. The instance accepts dict-like get and set
    on the aforementioned `ldap_attributes`. Once an attribute value has been modified,
    one can invoke `modify` to persist the changes.
    To remove an instance from the database, one can invoke `delete`.

    ## Comparisons

    The comparison operation with a `Member` is quite loose: it returns `True` with
    either:
      - an instance of the same `type` (i.e. the same class whose this mixin is used
        into) whose `dn` matches
      - an `LDAPEntry` whose `dn` matches
      - a string matching the `dn`
    """

    def __init__(self, client, name, **kwargs):
        super().__init__()
        self.client = client
        self.base_dn = client.base_dn
        self.name = name
        self._entry = LDAPEntry(self.dn)
        self[self.id_tag] = name
        self._entry["ou"] = self.ou
        if kwargs:
            _hydrate(self, kwargs)

    def __eq__(self, other):
        if isinstance(other, type(self)):
            return other.dn == self.dn
        elif isinstance(other, str):
            return other == self.dn
        elif isinstance(other, LDAPEntry):
            return other["dn"] == self.dn
        else:
            return False

    @property
    def dn(self):
        return f"{self.id_tag}={self.name},ou={self.ou},{self.base_dn}"

    def __setitem__(self, attr, val):
        if attr not in self.ldap_attributes:
            raise PhiCannotExecute(
                f"{attr} is not an allowed ldap attribute: {self.ldap_attributes}"
            )
        self._entry[attr] = val

    def __getitem__(self, attr):
        if attr not in self.ldap_attributes:
            raise PhiCannotExecute(
                f"{attr} is not an allowed ldap attribute: {self.ldap_attributes}"
            )
        return self._entry[attr][0]

    async def save(self):
        """
        This method persists on the ldap database an inited instance. Raises
        `PhiEntryExists` in case of a yet existing instance. Raises a specific error if
        the instance misses any of the needed attributes (accoding to
        `ldap_attributes`).
        """
        try:
            await self._create_new()
        except bonsai.errors.AlreadyExists:
            raise PhiEntryExists(self.dn)

    async def modify(self):
        """
        This method saves the changes made to the instance on the ldap database. Raises
        `PhiEntryDoesNotExist` in case of an instance not yet persisted.
        """
        await self._modify()

    async def delete(self):
        """
        This method removes the instance from the database. Raises
        `PhiEntryDoesNotExist` in case the entry does not exist.
        """
        await self._delete()

    async def sync(self):
        """
        This method reads the `ldap_attributes` of an existing instance from the ldap
        database and assigns the values to `self`. It is needed at first instantiation
        of the object, in case an instance exists on the database.
        """
        res = await self._get()
        _hydrate(self, res)
        return self

    async def exists(self):
        """
        This method returns `True` if the instance exists on the ldap database, `False`
        if it does not. It might raise `PhiUnexpectedRuntimeValue` if the ldap state is
        inconsistent.
        """
        try:
            _ = await self.sync()
            return True
        except PhiEntryDoesNotExist:
            return False