from typing import \
    TypeVar, Callable, Awaitable, \
    List, Dict, Optional, \
    Any, cast

# pylint: disable-next=wrong-import-order
from typing_extensions import \
    ParamSpec, Concatenate

from abc import \
    ABC, abstractmethod

from datetime import datetime

import hmac, hashlib, json

from websockets.client import WebSocketClientProtocol

from bfxapi.websocket.exceptions import \
    ConnectionNotOpen, ActionRequiresAuthentication

_S = TypeVar("_S", bound="Connection")

_R = TypeVar("_R")

_P = ParamSpec("_P")

class Connection(ABC):
    _HEARTBEAT = "hb"

    def __init__(self, host: str) -> None:
        self._host = host

        self._authentication: bool = False

        self.__protocol: Optional[WebSocketClientProtocol] = None

    @property
    def open(self) -> bool:
        return self.__protocol is not None and \
            self.__protocol.open

    @property
    def authentication(self) -> bool:
        return self._authentication

    @property
    def _websocket(self) -> WebSocketClientProtocol:
        return cast(WebSocketClientProtocol, self.__protocol)

    @_websocket.setter
    def _websocket(self, protocol: WebSocketClientProtocol) -> None:
        self.__protocol = protocol

    @abstractmethod
    async def start(self) -> None:
        ...

    @staticmethod
    def _require_websocket_connection(
        function: Callable[Concatenate[_S, _P], Awaitable[_R]]
    ) -> Callable[Concatenate[_S, _P], Awaitable[_R]]:
        async def wrapper(self: _S, *args: Any, **kwargs: Any) -> _R:
            if self.open:
                return await function(self, *args, **kwargs)

            raise ConnectionNotOpen("No open connection with the server.")

        return wrapper

    @staticmethod
    def _require_websocket_authentication(
        function: Callable[Concatenate[_S, _P], Awaitable[_R]]
    ) -> Callable[Concatenate[_S, _P], Awaitable[_R]]:
        async def wrapper(self: _S, *args: Any, **kwargs: Any) -> _R:
            if not self.authentication:
                raise ActionRequiresAuthentication("To perform this action you need to " \
                    "authenticate using your API_KEY and API_SECRET.")

            internal = Connection._require_websocket_connection(function)

            return await internal(self, *args, **kwargs)

        return wrapper

    @staticmethod
    def _get_authentication_message(
        api_key: str,
        api_secret: str,
        filters: Optional[List[str]] = None
    ) -> str:
        message: Dict[str, Any] = \
            { "event": "auth", "filter": filters, "apiKey": api_key }

        message["authNonce"] = round(datetime.now().timestamp() * 1_000_000)

        message["authPayload"] = f"AUTH{message['authNonce']}"

        auth_sig = hmac.new(
            key=api_secret.encode("utf8"),
            msg=message["authPayload"].encode("utf8"),
            digestmod=hashlib.sha384
        )

        message["authSig"] = auth_sig.hexdigest()

        return json.dumps(message)