# matrix-appservice-kakaotalk - A Matrix-KakaoTalk puppeting bridge.
# Copyright (C) 2022 Tulir Asokan, Andrew Ferrazzutti
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero 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 Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.
"""
Client functionality for the KakaoTalk API.
Currently a wrapper around a Node backend, but
the abstraction used here should be compatible
with any other potential backend.
"""

from __future__ import annotations

from typing import TYPE_CHECKING, cast, Type, Optional, Union

import logging
import urllib.request

from aiohttp import ClientSession
from aiohttp.client import _RequestContextManager
from yarl import URL

from mautrix.util.logging import TraceLogger

from ...config import Config
from ...rpc import RPCClient

from ..types.api.struct.profile import ProfileReqStruct, ProfileStruct
from ..types.bson import Long
from ..types.client.client_session import LoginResult
from ..types.chat.chat import Chatlog
from ..types.oauth import OAuthCredential, OAuthInfo
from ..types.request import (
    deserialize_result,
    ResultType,
    ResultListType,
    RootCommandResult,
    CommandResultDoneValue
)

from .types import PortalChannelInfo, UserInfoUnion

from .errors import InvalidAccessToken
from .error_helper import raise_unsuccessful_response

try:
    from aiohttp_socks import ProxyConnector
except ImportError:
    ProxyConnector = None

if TYPE_CHECKING:
    from mautrix.types import JSON
    from ...user import User


# TODO Consider defining an interface for this, with node/native backend as swappable implementations
# TODO If no state is stored, consider using free functions instead of classmethods
class Client:
    _rpc_client: RPCClient

    @classmethod
    async def init_cls(cls, config: Config) -> None:
        """Initialize RPC to the Node backend."""
        cls._rpc_client = RPCClient(config)
        await cls._rpc_client.connect()

    @classmethod
    async def stop_cls(cls) -> None:
        """Stop and disconnect from the Node backend."""
        await cls._rpc_client.disconnect()


    # region tokenless commands

    @classmethod
    async def generate_uuid(cls, used_uuids: set[str]) -> str:
        """Randomly generate a UUID for a (fake) device."""
        tries_remaining = 10
        while True:
            uuid = await cls._rpc_client.request("generate_uuid")
            if uuid not in used_uuids:
                return uuid
            tries_remaining -= 1
            if tries_remaining == 0:
                raise Exception(
                    "Unable to generate a UUID that hasn't been used before. "
                    "Either use a different RNG, or buy a lottery ticket"
                )

    @classmethod
    async def register_device(cls, passcode: str, **req: JSON) -> None:
        """Register a (fake) device that will be associated with the provided login credentials."""
        await cls._api_request_void("register_device", passcode=passcode, is_secret=True, **req)

    @classmethod
    async def login(cls, **req: JSON) -> OAuthCredential:
        """
        Obtain a session token by logging in with user-provided credentials.
        Must have first called register_device with these credentials.
        """
        # NOTE Actually returns a LoginData object, but this only needs an OAuthCredential
        return await cls._api_request_result(OAuthCredential, "login", is_secret=True, **req)

    # endregion


    http: ClientSession
    log: TraceLogger

    def __init__(self, user: User, log: Optional[TraceLogger] = None):
        """Create a per-user client object for user-specific client functionality."""
        self.user = user

        # TODO Let the Node backend use a proxy too!
        connector = None
        try:
            http_proxy = urllib.request.getproxies()["http"]
        except KeyError:
            pass
        else:
            if ProxyConnector:
                connector = ProxyConnector.from_url(http_proxy)
            else:
                self.log.warning("http_proxy is set, but aiohttp-socks is not installed")
        self.http = ClientSession(connector=connector)

        self.log = log or logging.getLogger("mw.ktclient")

    @property
    def _oauth_credential(self) -> JSON:
        return self.user.oauth_credential.serialize()

    def _get_user_data(self) -> JSON:
        return dict(
            mxid=self.user.mxid,
            oauth_credential=self._oauth_credential
        )

    # region HTTP

    def get(
        self,
        url: Union[str, URL],
        headers: Optional[dict[str, str]] = None,
        **kwargs,
    ) -> _RequestContextManager:
        # TODO Is auth ever needed?
        headers = {
            # TODO Are any default headers needed?
            #**self._headers,
            **(headers or {}),
        }
        url = URL(url)
        return self.http.get(url, headers=headers, **kwargs)

    # endregion


    # region post-token commands

    async def renew(self) -> OAuthInfo:
        """Get a new set of tokens from a refresh token."""
        return await self._api_request_result(OAuthInfo, "renew", oauth_credential=self._oauth_credential)

    async def renew_and_save(self) -> None:
        """Renew and save the user's session tokens."""
        oauth_info = await self.renew()
        self.user.oauth_credential = oauth_info.credential
        await self.user.save()

    async def connect(self) -> LoginResult:
        """
        Start a new session by providing a token obtained from a prior login.
        Receive a snapshot of account state in response.
        """
        login_result = await self._api_user_request_result(LoginResult, "connect")
        assert self.user.ktid == login_result.userId, f"User ID mismatch: expected {self.user.ktid}, got {login_result.userId}"
        # TODO Skip if handlers are already listening. But this is idempotent and thus probably safe
        self._start_listen()
        return login_result

    async def disconnect(self) -> bool:
        connection_existed = await self._rpc_client.request("disconnect", mxid=self.user.mxid)
        self._stop_listen()
        return connection_existed

    async def fetch_logged_in_user(self, post_login: bool = False) -> ProfileStruct:
        profile_req_struct = await self._api_user_request_result(ProfileReqStruct, "get_own_profile")
        return profile_req_struct.profile

    async def get_profile(self, user_id: Long) -> ProfileStruct:
        profile_req_struct = await self._api_user_request_result(
            ProfileReqStruct,
            "get_profile",
            user_id=user_id.serialize()
        )
        return profile_req_struct.profile

    async def get_portal_channel_info(self, channel_id: Long) -> PortalChannelInfo:
        return await self._api_user_request_result(
            PortalChannelInfo,
            "get_portal_channel_info",
            channel_id=channel_id.serialize()
        )

    async def get_participants(self, channel_id: Long) -> list[UserInfoUnion]:
        return await self._api_user_request_result(
            ResultListType(UserInfoUnion),
            "get_participants",
            channel_id=channel_id.serialize()
        )

    async def get_chats(self, channel_id: Long, sync_from: Long | None, limit: int | None) -> list[Chatlog]:
        return await self._api_user_request_result(
            ResultListType(Chatlog),
            "get_chats",
            channel_id=channel_id.serialize(),
            sync_from=sync_from.serialize() if sync_from else None,
            limit=limit
        )

    async def send_message(self, channel_id: Long, text: str) -> Chatlog:
        return await self._api_user_request_result(
            Chatlog,
            "send_message",
            channel_id=channel_id.serialize(),
            text=text
        )


    # TODO Combine these into one

    async def _api_user_request_result(
        self, result_type: Type[ResultType], command: str, **data: JSON
    ) -> ResultType:
        renewed = False
        while True:
            try:
                return await self._api_request_result(result_type, command, **self._get_user_data(), **data)
            except InvalidAccessToken:
                if renewed:
                    raise
                await self.renew_and_save()
                renewed = True

    async def _api_user_request_void(self, command: str, **data: JSON) -> None:
        renewed = False
        while True:
            try:
                return await self._api_request_void(command, **self._get_user_data(), **data)
            except InvalidAccessToken:
                if renewed:
                    raise
                await self.renew_and_save()
                renewed = True

    # endregion


    # region listeners

    async def _on_message(self, data: dict[str, JSON]) -> None:
        await self.user.on_message(
            Chatlog.deserialize(data["chatlog"]),
            Long.deserialize(data["channelId"]),
            data["channelType"]
        )

    """ TODO
    async def _on_receipt(self, data: Dict[str, JSON]) -> None:
        await self.user.on_receipt(Receipt.deserialize(data["receipt"]))
    """


    def _start_listen(self) -> None:
        # TODO Automate this somehow, like with a fancy enum
        self._rpc_client.set_event_handlers(self._get_user_cmd("message"), [self._on_message])
        # TODO many more listeners

    def _stop_listen(self) -> None:
        # TODO Automate this somehow, like with a fancy enum
        self._rpc_client.set_event_handlers(self._get_user_cmd("message"), [])
        # TODO many more listeners

    def _get_user_cmd(self, command) -> str:
        return f"{command}:{self.user.mxid}"

    # endregion


    @classmethod
    async def _api_request_result(
        cls, result_type: Type[ResultType], command: str, **data: JSON
    ) -> ResultType:
        """
        Call a command via RPC, and return its result object.
        On failure, raise an appropriate exception.
        """
        resp = deserialize_result(
            result_type,
            await cls._rpc_client.request(command, **data)
        )
        if not resp.success:
            raise_unsuccessful_response(resp)
        # NOTE Not asserting against CommandResultDoneValue because it's generic!
        # TODO Check if there really is no way to do it.
        assert type(resp) is not RootCommandResult, "Result object missing from successful response"
        return cast(CommandResultDoneValue[ResultType], resp).result

    @classmethod
    async def _api_request_void(cls, command: str, **data: JSON) -> None:
        resp = RootCommandResult.deserialize(
            await cls._rpc_client.request(command, **data)
        )
        if not resp.success:
            raise_unsuccessful_response(resp)