import importlib
import logging
from base64 import b64decode
from datetime import datetime, timezone
from os import walk
from types import ModuleType
from typing import Any, Dict, Optional

import jwt
from starlette.requests import Request

from .config import CoreConfig


class _MissingSentinel:
    __slots__: tuple[str, ...] = ()

    def __eq__(self, other) -> bool:
        return False

    def __bool__(self) -> bool:
        return False

    def __hash__(self) -> int:
        return 0

    def __repr__(self):
        return "..."


MISSING: Any = _MissingSentinel()
"""This is different from `None` in that its type is `Any`, and so it can be used
as a placeholder for values that are *definitely* going to be initialized,
so they don't have to be typed as `T | None`, which makes type checkers
angry when an attribute is accessed.

This can also be used for when `None` has actual meaning as a value, and so a
separate value is needed to mean "unset"."""


class Utils:
    real_title_port = None
    real_title_port_ssl = None

    @classmethod
    def get_all_titles(cls) -> Dict[str, ModuleType]:
        ret: Dict[str, Any] = {}

        for root, dirs, files in walk("titles"):
            for dir in dirs:
                if not dir.startswith("__"):
                    try:
                        mod = importlib.import_module(f"titles.{dir}")
                        if hasattr(mod, "game_codes") and hasattr(
                            mod, "index"
                        ):  # Minimum required to function
                            ret[dir] = mod

                    except ImportError as e:
                        logging.getLogger("core").error(f"get_all_titles: {dir} - {e}")
                        raise
            return ret

    @classmethod
    def get_ip_addr(cls, req: Request) -> str:
        ip = req.headers.get("x-forwarded-for", req.client.host)
        return ip.split(", ")[0]

    @classmethod
    def get_title_port(cls, cfg: CoreConfig):
        if cls.real_title_port is not None:
            return cls.real_title_port

        cls.real_title_port = (
            cfg.server.proxy_port
            if cfg.server.is_using_proxy and cfg.server.proxy_port
            else cfg.server.port
        )

        return cls.real_title_port

    @classmethod
    def get_title_port_ssl(cls, cfg: CoreConfig):
        if cls.real_title_port_ssl is not None:
            return cls.real_title_port_ssl

        cls.real_title_port_ssl = (
            cfg.server.proxy_port_ssl
            if cfg.server.is_using_proxy and cfg.server.proxy_port_ssl
            else 443
        )

        return cls.real_title_port_ssl


def create_sega_auth_key(
    aime_id: int,
    game: str,
    place_id: int,
    keychip_id: str,
    b64_secret: str,
    exp_seconds: int = 86400,
    err_logger: str = "aimedb",
) -> Optional[str]:
    logger = logging.getLogger(err_logger)
    try:
        return jwt.encode(
            {
                "aime_id": aime_id,
                "game": game,
                "place_id": place_id,
                "keychip_id": keychip_id,
                "exp": int(datetime.now(tz=timezone.utc).timestamp()) + exp_seconds,
            },
            b64decode(b64_secret),
            algorithm="HS256",
        )
    except jwt.InvalidKeyError:
        logger.error("Failed to encode Sega Auth Key because the secret is invalid!")
        return None
    except Exception as e:
        logger.error(f"Unknown exception occoured when encoding Sega Auth Key! {e}")
        return None


def decode_sega_auth_key(
    token: str, b64_secret: str, err_logger: str = "aimedb"
) -> Optional[Dict]:
    logger = logging.getLogger(err_logger)
    try:
        return jwt.decode(
            token,
            "secret",
            b64decode(b64_secret),
            algorithms=["HS256"],
            options={"verify_signature": True},
        )
    except jwt.ExpiredSignatureError:
        logger.error("Sega Auth Key failed to validate due to an expired signature!")
        return None
    except jwt.InvalidSignatureError:
        logger.error("Sega Auth Key failed to validate due to an invalid signature!")
        return None
    except jwt.DecodeError as e:
        logger.error(f"Sega Auth Key failed to decode! {e}")
        return None
    except jwt.InvalidTokenError as e:
        logger.error(f"Sega Auth Key is invalid! {e}")
        return None
    except Exception as e:
        logger.error(f"Unknown exception occoured when decoding Sega Auth Key! {e}")
        return None