Telethon/telethon/client/account.py

import functools
import inspect
import typing

from .users import _NOT_A_REQUEST
from .. import helpers, utils
from ..tl import functions, TLRequest

if typing.TYPE_CHECKING:
    from .telegramclient import TelegramClient


# TODO Make use of :tl:`InvokeWithMessagesRange` somehow
#      For that, we need to use :tl:`GetSplitRanges` first.
class _TakeoutClient:
    """
    Proxy object over the client.
    """
    __PROXY_INTERFACE = ('__enter__', '__exit__', '__aenter__', '__aexit__')

    def __init__(self, finalize, client, request):
        # We use the name mangling for attributes to make them inaccessible
        # from within the shadowed client object and to distinguish them from
        # its own attributes where needed.
        self.__finalize = finalize
        self.__client = client
        self.__request = request
        self.__success = None

    @property
    def success(self):
        return self.__success

    @success.setter
    def success(self, value):
        self.__success = value

    async def __aenter__(self):
        # Enter/Exit behaviour is "overrode", we don't want to call start.
        client = self.__client
        if client.session.takeout_id is None:
            client.session.takeout_id = (await client(self.__request)).id
        elif self.__request is not None:
            raise ValueError("Can't send a takeout request while another "
                "takeout for the current session still not been finished yet.")
        return self

    async def __aexit__(self, exc_type, exc_value, traceback):
        if self.__success is None and self.__finalize:
            self.__success = exc_type is None

        if self.__success is not None:
            result = await self(functions.account.FinishTakeoutSessionRequest(
                self.__success))
            if not result:
                raise ValueError("Failed to finish the takeout.")
            self.session.takeout_id = None

    __enter__ = helpers._sync_enter
    __exit__ = helpers._sync_exit

    async def __call__(self, request, ordered=False):
        takeout_id = self.__client.session.takeout_id
        if takeout_id is None:
            raise ValueError('Takeout mode has not been initialized '
                '(are you calling outside of "with"?)')

        single = not utils.is_list_like(request)
        requests = ((request,) if single else request)
        wrapped = []
        for r in requests:
            if not isinstance(r, TLRequest):
                raise _NOT_A_REQUEST()
            await r.resolve(self, utils)
            wrapped.append(functions.InvokeWithTakeoutRequest(takeout_id, r))

        return await self.__client(
            wrapped[0] if single else wrapped, ordered=ordered)

    def __getattribute__(self, name):
        # We access class via type() because __class__ will recurse infinitely.
        # Also note that since we've name-mangled our own class attributes,
        # they'll be passed to __getattribute__() as already decorated. For
        # example, 'self.__client' will be passed as '_TakeoutClient__client'.
        # https://docs.python.org/3/tutorial/classes.html#private-variables
        if name.startswith('__') and name not in type(self).__PROXY_INTERFACE:
            raise AttributeError  # force call of __getattr__

        # Try to access attribute in the proxy object and check for the same
        # attribute in the shadowed object (through our __getattr__) if failed.
        return super().__getattribute__(name)

    def __getattr__(self, name):
        value = getattr(self.__client, name)
        if inspect.ismethod(value):
            # Emulate bound methods behavior by partially applying our proxy
            # class as the self parameter instead of the client.
            return functools.partial(
                getattr(self.__client.__class__, name), self)

        return value

    def __setattr__(self, name, value):
        if name.startswith('_{}__'.format(type(self).__name__.lstrip('_'))):
            # This is our own name-mangled attribute, keep calm.
            return super().__setattr__(name, value)
        return setattr(self.__client, name, value)


class AccountMethods:
    def takeout(
            self: 'TelegramClient',
            finalize: bool = True,
            *,
            contacts: bool = None,
            users: bool = None,
            chats: bool = None,
            megagroups: bool = None,
            channels: bool = None,
            files: bool = None,
            max_file_size: bool = None) -> 'TelegramClient':
        """
        Returns a :ref:`telethon-client` which calls methods behind a takeout session.

        It does so by creating a proxy object over the current client through
        which making requests will use :tl:`InvokeWithTakeoutRequest` to wrap
        them. In other words, returns the current client modified so that
        requests are done as a takeout:

        Some of the calls made through the takeout session will have lower
        flood limits. This is useful if you want to export the data from
        conversations or mass-download media, since the rate limits will
        be lower. Only some requests will be affected, and you will need
        to adjust the `wait_time` of methods like `client.iter_messages
        <telethon.client.messages.MessageMethods.iter_messages>`.

        By default, all parameters are `None`, and you need to enable those
        you plan to use by setting them to either `True` or `False`.

        You should ``except errors.TakeoutInitDelayError as e``, since this
        exception will raise depending on the condition of the session. You
        can then access ``e.seconds`` to know how long you should wait for
        before calling the method again.

        There's also a `success` property available in the takeout proxy
        object, so from the `with` body you can set the boolean result that
        will be sent back to Telegram. But if it's left `None` as by
        default, then the action is based on the `finalize` parameter. If
        it's `True` then the takeout will be finished, and if no exception
        occurred during it, then `True` will be considered as a result.
        Otherwise, the takeout will not be finished and its ID will be
        preserved for future usage as `client.session.takeout_id
        <telethon.sessions.abstract.Session.takeout_id>`.

        Arguments
            finalize (`bool`):
                Whether the takeout session should be finalized upon
                exit or not.

            contacts (`bool`):
                Set to `True` if you plan on downloading contacts.

            users (`bool`):
                Set to `True` if you plan on downloading information
                from users and their private conversations with you.

            chats (`bool`):
                Set to `True` if you plan on downloading information
                from small group chats, such as messages and media.

            megagroups (`bool`):
                Set to `True` if you plan on downloading information
                from megagroups (channels), such as messages and media.

            channels (`bool`):
                Set to `True` if you plan on downloading information
                from broadcast channels, such as messages and media.

            files (`bool`):
                Set to `True` if you plan on downloading media and
                you don't only wish to export messages.

            max_file_size (`int`):
                The maximum file size, in bytes, that you plan
                to download for each message with media.

        Example
            .. code-block:: python

                from telethon import errors

                try:
                    with client.takeout() as takeout:
                        client.get_messages('me')  # normal call
                        takeout.get_messages('me')  # wrapped through takeout (less limits)

                        for message in takeout.iter_messages(chat, wait_time=0):
                            ...  # Do something with the message

                except errors.TakeoutInitDelayError as e:
                    print('Must wait', e.seconds, 'before takeout')
        """
        request_kwargs = dict(
            contacts=contacts,
            message_users=users,
            message_chats=chats,
            message_megagroups=megagroups,
            message_channels=channels,
            files=files,
            file_max_size=max_file_size
        )
        arg_specified = (arg is not None for arg in request_kwargs.values())

        if self.session.takeout_id is None or any(arg_specified):
            request = functions.account.InitTakeoutSessionRequest(
                **request_kwargs)
        else:
            request = None

        return _TakeoutClient(finalize, self, request)

    async def end_takeout(self: 'TelegramClient', success: bool) -> bool:
        """
        Finishes the current takeout session.

        Arguments
            success (`bool`):
                Whether the takeout completed successfully or not.

        Returns
            `True` if the operation was successful, `False` otherwise.

        Example
            .. code-block:: python

                client.end_takeout(success=False)
        """
        try:
            async with _TakeoutClient(True, self, None) as takeout:
                takeout.success = success
        except ValueError:
            return False
        return True