#!/usr/bin/env python
#
# A library that provides a Python interface to the Telegram Bot API
# Copyright (C) 2015-2023
# Leandro Toledo de Souza <devs@python-telegram-bot.org>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser 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 Lesser Public License for more details.
#
# You should have received a copy of the GNU Lesser Public License
# along with this program.  If not, see [http://www.gnu.org/licenses/].
"""This module contains the PicklePersistence class."""
import pickle
from copy import deepcopy
from pathlib import Path
from typing import Any, Callable, Dict, Optional, Set, Tuple, Type, TypeVar, Union, cast, overload

from telegram import Bot, TelegramObject
from telegram._utils.types import FilePathInput
from telegram._utils.warnings import warn
from telegram.ext import BasePersistence, PersistenceInput
from telegram.ext._contexttypes import ContextTypes
from telegram.ext._utils.types import BD, CD, UD, CDCData, ConversationDict, ConversationKey

_REPLACED_KNOWN_BOT = "a known bot replaced by PTB's PicklePersistence"
_REPLACED_UNKNOWN_BOT = "an unknown bot replaced by PTB's PicklePersistence"

TelegramObj = TypeVar("TelegramObj", bound=TelegramObject)


def _all_subclasses(cls: Type[TelegramObj]) -> Set[Type[TelegramObj]]:
    """Gets all subclasses of the specified object, recursively. from
    https://stackoverflow.com/a/3862957/9706202
    """
    subclasses = cls.__subclasses__()
    return set(subclasses).union([s for c in subclasses for s in _all_subclasses(c)])


def _reconstruct_to(cls: Type[TelegramObj], kwargs: dict) -> TelegramObj:
    """
    This method is used for unpickling. The data, which is in the form a dictionary, is
    converted back into a class. Works mostly the same as :meth:`TelegramObject.__setstate__`.
    This function should be kept in place for backwards compatibility even if the pickling logic
    is changed, since `_custom_reduction` places references to this function into the pickled data.
    """
    obj = cls.__new__(cls)
    obj.__setstate__(kwargs)
    return obj


def _custom_reduction(cls: TelegramObj) -> Tuple[Callable, Tuple[Type[TelegramObj], dict]]:
    """
    This method is used for pickling. The bot attribute is preserved so _BotPickler().persistent_id
    works as intended.
    """
    data = cls._get_attrs(include_private=True)  # pylint: disable=protected-access
    # MappingProxyType is not pickable, so we convert it to a dict
    # no need to convert back to MPT in _reconstruct_to, since it's done in __setstate__
    data["api_kwargs"] = dict(data["api_kwargs"])  # type: ignore[arg-type]
    return _reconstruct_to, (cls.__class__, data)


class _BotPickler(pickle.Pickler):
    __slots__ = ("_bot",)

    def __init__(self, bot: Bot, *args: Any, **kwargs: Any):
        self._bot = bot
        super().__init__(*args, **kwargs)

    def reducer_override(  # skipcq: PYL-R0201
        self, obj: TelegramObj
    ) -> Tuple[Callable, Tuple[Type[TelegramObj], dict]]:
        """
        This method is used for pickling. The bot attribute is preserved so
        _BotPickler().persistent_id works as intended.
        """
        if not isinstance(obj, TelegramObject):
            return NotImplemented

        return _custom_reduction(obj)

    def persistent_id(self, obj: object) -> Optional[str]:
        """Used to 'mark' the Bot, so it can be replaced later. See
        https://docs.python.org/3/library/pickle.html#pickle.Pickler.persistent_id for more info
        """
        if obj is self._bot:
            return _REPLACED_KNOWN_BOT
        if isinstance(obj, Bot):
            warn(
                "Unknown bot instance found. Will be replaced by `None` during unpickling",
                stacklevel=2,
            )
            return _REPLACED_UNKNOWN_BOT
        return None  # pickles as usual


class _BotUnpickler(pickle.Unpickler):
    __slots__ = ("_bot",)

    def __init__(self, bot: Bot, *args: Any, **kwargs: Any):
        self._bot = bot
        super().__init__(*args, **kwargs)

    def persistent_load(self, pid: str) -> Optional[Bot]:
        """Replaces the bot with the current bot if known, else it is replaced by :obj:`None`."""
        if pid == _REPLACED_KNOWN_BOT:
            return self._bot
        if pid == _REPLACED_UNKNOWN_BOT:
            return None
        raise pickle.UnpicklingError("Found unknown persistent id when unpickling!")


class PicklePersistence(BasePersistence[UD, CD, BD]):
    """Using python's builtin :mod:`pickle` for making your bot persistent.

    Attention:
        The interface provided by this class is intended to be accessed exclusively by
        :class:`~telegram.ext.Application`. Calling any of the methods below manually might
        interfere with the integration of persistence into :class:`~telegram.ext.Application`.

    Note:
        This implementation of :class:`BasePersistence` uses the functionality of the pickle module
        to support serialization of bot instances. Specifically any reference to
        :attr:`~BasePersistence.bot` will be replaced by a placeholder before pickling and
        :attr:`~BasePersistence.bot` will be inserted back when loading the data.

    Examples:
        :any:`Persistent Conversation Bot <examples.persistentconversationbot>`

    .. seealso:: :wiki:`Making Your Bot Persistent <Making-your-bot-persistent>`

    .. versionchanged:: 20.0

        * The parameters and attributes ``store_*_data`` were replaced by :attr:`store_data`.
        * The parameter and attribute ``filename`` were replaced by :attr:`filepath`.
        * :attr:`filepath` now also accepts :obj:`pathlib.Path` as argument.

    Args:
        filepath (:obj:`str` | :obj:`pathlib.Path`): The filepath for storing the pickle files.
            When :attr:`single_file` is :obj:`False` this will be used as a prefix.
        store_data (:class:`~telegram.ext.PersistenceInput`, optional): Specifies which kinds of
            data will be saved by this persistence instance. By default, all available kinds of
            data will be saved.
        single_file (:obj:`bool`, optional): When :obj:`False` will store 5 separate files of
            `filename_user_data`, `filename_bot_data`, `filename_chat_data`,
            `filename_callback_data` and `filename_conversations`. Default is :obj:`True`.
        on_flush (:obj:`bool`, optional): When :obj:`True` will only save to file when
            :meth:`flush` is called and keep data in memory until that happens. When
            :obj:`False` will store data on any transaction *and* on call to :meth:`flush`.
            Default is :obj:`False`.
        context_types (:class:`telegram.ext.ContextTypes`, optional): Pass an instance
            of :class:`telegram.ext.ContextTypes` to customize the types used in the
            ``context`` interface. If not passed, the defaults documented in
            :class:`telegram.ext.ContextTypes` will be used.

            .. versionadded:: 13.6
        update_interval (:obj:`int` | :obj:`float`, optional): The
            :class:`~telegram.ext.Application` will update
            the persistence in regular intervals. This parameter specifies the time (in seconds) to
            wait between two consecutive runs of updating the persistence. Defaults to 60 seconds.

            .. versionadded:: 20.0
    Attributes:
        filepath (:obj:`str` | :obj:`pathlib.Path`): The filepath for storing the pickle files.
            When :attr:`single_file` is :obj:`False` this will be used as a prefix.
        store_data (:class:`~telegram.ext.PersistenceInput`): Specifies which kinds of data will
            be saved by this persistence instance.
        single_file (:obj:`bool`): Optional. When :obj:`False` will store 5 separate files of
            `filename_user_data`, `filename_bot_data`, `filename_chat_data`,
            `filename_callback_data` and `filename_conversations`. Default is :obj:`True`.
        on_flush (:obj:`bool`): Optional. When :obj:`True` will only save to file when
            :meth:`flush` is called and keep data in memory until that happens. When
            :obj:`False` will store data on any transaction *and* on call to :meth:`flush`.
            Default is :obj:`False`.
        context_types (:class:`telegram.ext.ContextTypes`): Container for the types used
            in the ``context`` interface.

            .. versionadded:: 13.6
    """

    __slots__ = (
        "filepath",
        "single_file",
        "on_flush",
        "user_data",
        "chat_data",
        "bot_data",
        "callback_data",
        "conversations",
        "context_types",
    )

    @overload
    def __init__(
        self: "PicklePersistence[Dict[Any, Any], Dict[Any, Any], Dict[Any, Any]]",
        filepath: FilePathInput,
        store_data: Optional[PersistenceInput] = None,
        single_file: bool = True,
        on_flush: bool = False,
        update_interval: float = 60,
    ):
        ...

    @overload
    def __init__(
        self: "PicklePersistence[UD, CD, BD]",
        filepath: FilePathInput,
        store_data: Optional[PersistenceInput] = None,
        single_file: bool = True,
        on_flush: bool = False,
        update_interval: float = 60,
        context_types: Optional[ContextTypes[Any, UD, CD, BD]] = None,
    ):
        ...

    def __init__(
        self,
        filepath: FilePathInput,
        store_data: Optional[PersistenceInput] = None,
        single_file: bool = True,
        on_flush: bool = False,
        update_interval: float = 60,
        context_types: Optional[ContextTypes[Any, UD, CD, BD]] = None,
    ):
        super().__init__(store_data=store_data, update_interval=update_interval)
        self.filepath: Path = Path(filepath)
        self.single_file: Optional[bool] = single_file
        self.on_flush: Optional[bool] = on_flush
        self.user_data: Optional[Dict[int, UD]] = None
        self.chat_data: Optional[Dict[int, CD]] = None
        self.bot_data: Optional[BD] = None
        self.callback_data: Optional[CDCData] = None
        self.conversations: Optional[Dict[str, Dict[Tuple[Union[int, str], ...], object]]] = None
        self.context_types: ContextTypes[Any, UD, CD, BD] = cast(
            ContextTypes[Any, UD, CD, BD], context_types or ContextTypes()
        )

    def _load_singlefile(self) -> None:
        try:
            with self.filepath.open("rb") as file:
                data = _BotUnpickler(self.bot, file).load()

            self.user_data = data["user_data"]
            self.chat_data = data["chat_data"]
            # For backwards compatibility with files not containing bot data
            self.bot_data = data.get("bot_data", self.context_types.bot_data())
            self.callback_data = data.get("callback_data", {})
            self.conversations = data["conversations"]
        except OSError:
            self.conversations = {}
            self.user_data = {}
            self.chat_data = {}
            self.bot_data = self.context_types.bot_data()
            self.callback_data = None
        except pickle.UnpicklingError as exc:
            filename = self.filepath.name
            raise TypeError(f"File {filename} does not contain valid pickle data") from exc
        except Exception as exc:
            raise TypeError(f"Something went wrong unpickling {self.filepath.name}") from exc

    def _load_file(self, filepath: Path) -> Any:
        try:
            with filepath.open("rb") as file:
                return _BotUnpickler(self.bot, file).load()

        except OSError:
            return None
        except pickle.UnpicklingError as exc:
            raise TypeError(f"File {filepath.name} does not contain valid pickle data") from exc
        except Exception as exc:
            raise TypeError(f"Something went wrong unpickling {filepath.name}") from exc

    def _dump_singlefile(self) -> None:
        data = {
            "conversations": self.conversations,
            "user_data": self.user_data,
            "chat_data": self.chat_data,
            "bot_data": self.bot_data,
            "callback_data": self.callback_data,
        }
        with self.filepath.open("wb") as file:
            _BotPickler(self.bot, file, protocol=pickle.HIGHEST_PROTOCOL).dump(data)

    def _dump_file(self, filepath: Path, data: object) -> None:
        with filepath.open("wb") as file:
            _BotPickler(self.bot, file, protocol=pickle.HIGHEST_PROTOCOL).dump(data)

    async def get_user_data(self) -> Dict[int, UD]:
        """Returns the user_data from the pickle file if it exists or an empty :obj:`dict`.

        Returns:
            Dict[:obj:`int`, :obj:`dict`]: The restored user data.
        """
        if self.user_data:
            pass
        elif not self.single_file:
            data = self._load_file(Path(f"{self.filepath}_user_data"))
            if not data:
                data = {}
            self.user_data = data
        else:
            self._load_singlefile()
        return deepcopy(self.user_data)  # type: ignore[arg-type]

    async def get_chat_data(self) -> Dict[int, CD]:
        """Returns the chat_data from the pickle file if it exists or an empty :obj:`dict`.

        Returns:
            Dict[:obj:`int`, :obj:`dict`]: The restored chat data.
        """
        if self.chat_data:
            pass
        elif not self.single_file:
            data = self._load_file(Path(f"{self.filepath}_chat_data"))
            if not data:
                data = {}
            self.chat_data = data
        else:
            self._load_singlefile()
        return deepcopy(self.chat_data)  # type: ignore[arg-type]

    async def get_bot_data(self) -> BD:
        """Returns the bot_data from the pickle file if it exists or an empty object of type
        :obj:`dict` | :attr:`telegram.ext.ContextTypes.bot_data`.

        Returns:
            :obj:`dict` | :attr:`telegram.ext.ContextTypes.bot_data`: The restored bot data.
        """
        if self.bot_data:
            pass
        elif not self.single_file:
            data = self._load_file(Path(f"{self.filepath}_bot_data"))
            if not data:
                data = self.context_types.bot_data()
            self.bot_data = data
        else:
            self._load_singlefile()
        return deepcopy(self.bot_data)  # type: ignore[return-value]

    async def get_callback_data(self) -> Optional[CDCData]:
        """Returns the callback data from the pickle file if it exists or :obj:`None`.

        .. versionadded:: 13.6

        Returns:
            Tuple[List[Tuple[:obj:`str`, :obj:`float`, Dict[:obj:`str`, :class:`object`]]],
            Dict[:obj:`str`, :obj:`str`]] | :obj:`None`: The restored metadata or :obj:`None`,
            if no data was stored.
        """
        if self.callback_data:
            pass
        elif not self.single_file:
            data = self._load_file(Path(f"{self.filepath}_callback_data"))
            if not data:
                data = None
            self.callback_data = data
        else:
            self._load_singlefile()
        if self.callback_data is None:
            return None
        return deepcopy(self.callback_data)

    async def get_conversations(self, name: str) -> ConversationDict:
        """Returns the conversations from the pickle file if it exists or an empty dict.

        Args:
            name (:obj:`str`): The handlers name.

        Returns:
            :obj:`dict`: The restored conversations for the handler.
        """
        if self.conversations:
            pass
        elif not self.single_file:
            data = self._load_file(Path(f"{self.filepath}_conversations"))
            if not data:
                data = {name: {}}
            self.conversations = data
        else:
            self._load_singlefile()
        return self.conversations.get(name, {}).copy()  # type: ignore[union-attr]

    async def update_conversation(
        self, name: str, key: ConversationKey, new_state: Optional[object]
    ) -> None:
        """Will update the conversations for the given handler and depending on :attr:`on_flush`
        save the pickle file.

        Args:
            name (:obj:`str`): The handler's name.
            key (:obj:`tuple`): The key the state is changed for.
            new_state (:class:`object`): The new state for the given key.
        """
        if not self.conversations:
            self.conversations = {}
        if self.conversations.setdefault(name, {}).get(key) == new_state:
            return
        self.conversations[name][key] = new_state
        if not self.on_flush:
            if not self.single_file:
                self._dump_file(Path(f"{self.filepath}_conversations"), self.conversations)
            else:
                self._dump_singlefile()

    async def update_user_data(self, user_id: int, data: UD) -> None:
        """Will update the user_data and depending on :attr:`on_flush` save the pickle file.

        Args:
            user_id (:obj:`int`): The user the data might have been changed for.
            data (:obj:`dict`): The :attr:`telegram.ext.Application.user_data` ``[user_id]``.
        """
        if self.user_data is None:
            self.user_data = {}
        if self.user_data.get(user_id) == data:
            return
        self.user_data[user_id] = data
        if not self.on_flush:
            if not self.single_file:
                self._dump_file(Path(f"{self.filepath}_user_data"), self.user_data)
            else:
                self._dump_singlefile()

    async def update_chat_data(self, chat_id: int, data: CD) -> None:
        """Will update the chat_data and depending on :attr:`on_flush` save the pickle file.

        Args:
            chat_id (:obj:`int`): The chat the data might have been changed for.
            data (:obj:`dict`): The :attr:`telegram.ext.Application.chat_data` ``[chat_id]``.
        """
        if self.chat_data is None:
            self.chat_data = {}
        if self.chat_data.get(chat_id) == data:
            return
        self.chat_data[chat_id] = data
        if not self.on_flush:
            if not self.single_file:
                self._dump_file(Path(f"{self.filepath}_chat_data"), self.chat_data)
            else:
                self._dump_singlefile()

    async def update_bot_data(self, data: BD) -> None:
        """Will update the bot_data and depending on :attr:`on_flush` save the pickle file.

        Args:
            data (:obj:`dict` | :attr:`telegram.ext.ContextTypes.bot_data`): The
                :attr:`telegram.ext.Application.bot_data`.
        """
        if self.bot_data == data:
            return
        self.bot_data = data
        if not self.on_flush:
            if not self.single_file:
                self._dump_file(Path(f"{self.filepath}_bot_data"), self.bot_data)
            else:
                self._dump_singlefile()

    async def update_callback_data(self, data: CDCData) -> None:
        """Will update the callback_data (if changed) and depending on :attr:`on_flush` save the
        pickle file.

        .. versionadded:: 13.6

        Args:
            data (Tuple[List[Tuple[:obj:`str`, :obj:`float`, \
                Dict[:obj:`str`, :class:`object`]]], Dict[:obj:`str`, :obj:`str`]]):
                The relevant data to restore :class:`telegram.ext.CallbackDataCache`.
        """
        if self.callback_data == data:
            return
        self.callback_data = data
        if not self.on_flush:
            if not self.single_file:
                self._dump_file(Path(f"{self.filepath}_callback_data"), self.callback_data)
            else:
                self._dump_singlefile()

    async def drop_chat_data(self, chat_id: int) -> None:
        """Will delete the specified key from the ``chat_data`` and depending on
        :attr:`on_flush` save the pickle file.

        .. versionadded:: 20.0

        Args:
            chat_id (:obj:`int`): The chat id to delete from the persistence.
        """
        if self.chat_data is None:
            return
        self.chat_data.pop(chat_id, None)  # type: ignore[arg-type]

        if not self.on_flush:
            if not self.single_file:
                self._dump_file(Path(f"{self.filepath}_chat_data"), self.chat_data)
            else:
                self._dump_singlefile()

    async def drop_user_data(self, user_id: int) -> None:
        """Will delete the specified key from the ``user_data`` and depending on
        :attr:`on_flush` save the pickle file.

        .. versionadded:: 20.0

        Args:
            user_id (:obj:`int`): The user id to delete from the persistence.
        """
        if self.user_data is None:
            return
        self.user_data.pop(user_id, None)  # type: ignore[arg-type]

        if not self.on_flush:
            if not self.single_file:
                self._dump_file(Path(f"{self.filepath}_user_data"), self.user_data)
            else:
                self._dump_singlefile()

    async def refresh_user_data(self, user_id: int, user_data: UD) -> None:
        """Does nothing.

        .. versionadded:: 13.6
        .. seealso:: :meth:`telegram.ext.BasePersistence.refresh_user_data`
        """

    async def refresh_chat_data(self, chat_id: int, chat_data: CD) -> None:
        """Does nothing.

        .. versionadded:: 13.6
        .. seealso:: :meth:`telegram.ext.BasePersistence.refresh_chat_data`
        """

    async def refresh_bot_data(self, bot_data: BD) -> None:
        """Does nothing.

        .. versionadded:: 13.6
        .. seealso:: :meth:`telegram.ext.BasePersistence.refresh_bot_data`
        """

    async def flush(self) -> None:
        """Will save all data in memory to pickle file(s)."""
        if self.single_file:
            if (
                self.user_data
                or self.chat_data
                or self.bot_data
                or self.callback_data
                or self.conversations
            ):
                self._dump_singlefile()
        else:
            if self.user_data:
                self._dump_file(Path(f"{self.filepath}_user_data"), self.user_data)
            if self.chat_data:
                self._dump_file(Path(f"{self.filepath}_chat_data"), self.chat_data)
            if self.bot_data:
                self._dump_file(Path(f"{self.filepath}_bot_data"), self.bot_data)
            if self.callback_data:
                self._dump_file(Path(f"{self.filepath}_callback_data"), self.callback_data)
            if self.conversations:
                self._dump_file(Path(f"{self.filepath}_conversations"), self.conversations)