import json
import hmac
import hashlib
from typing import Any, Dict, Optional
from urllib.parse import urljoin

import requests
from django.conf import settings
from django.core.exceptions import ImproperlyConfigured


class PlugNMeetError(Exception):
    def __init__(self, message: str, *, status_code: Optional[int] = None, response_data: Optional[Dict[str, Any]] = None):
        super().__init__(message)
        self.status_code = status_code
        self.response_data = response_data or {}


class PlugNMeetClient:
    def __init__(self, *, base_url: Optional[str] = None, api_key: Optional[str] = None, api_secret: Optional[str] = None, timeout: Optional[float] = None):
        self.base_url = (base_url or getattr(settings, "PLUGNMEET_SERVER_URL", "")).rstrip("/")
        self.api_key = api_key or getattr(settings, "PLUGNMEET_API_KEY", "")
        self.api_secret = api_secret or getattr(settings, "PLUGNMEET_API_SECRET", "")
        self.timeout = timeout or getattr(settings, "PLUGNMEET_TIMEOUT", 10.0)

        if not self.base_url or not self.api_key or not self.api_secret:
            raise ImproperlyConfigured("PlugNMeet integration settings are incomplete.")

    def create_room(self, payload: Dict[str, Any]) -> Dict[str, Any]:
        return self._post("/auth/room/create", payload)

    def get_join_token(self, payload: Dict[str, Any]) -> Dict[str, Any]:
        return self._post("/auth/room/getJoinToken", payload)

    def _post(self, path: str, payload: Dict[str, Any]) -> Dict[str, Any]:
        url = urljoin(f"{self.base_url}/", path.lstrip("/"))
        body = json.dumps(payload, ensure_ascii=False, separators=(",", ":"))
        headers = {
            "Content-Type": "application/json",
            "API-KEY": self.api_key,
            "HASH-SIGNATURE": self._build_signature(body),
        }

        try:
            response = requests.post(url, data=body.encode("utf-8"), headers=headers, timeout=self.timeout)
        except requests.RequestException as exc:
            raise PlugNMeetError("Failed to reach PlugNMeet server.") from exc

        if response.status_code >= 400:
            response_data = self._safe_json(response)
            raise PlugNMeetError(
                "PlugNMeet server returned an error.",
                status_code=response.status_code,
                response_data=response_data,
            )

        data = self._safe_json(response)
        if data is None:
            raise PlugNMeetError("PlugNMeet server returned an invalid response format.")
        return data

    def _build_signature(self, body: str) -> str:
        digest = hmac.new(self.api_secret.encode("utf-8"), body.encode("utf-8"), hashlib.sha256)
        return digest.hexdigest()

    @staticmethod
    def _safe_json(response: requests.Response) -> Optional[Dict[str, Any]]:
        try:
            return response.json()
        except ValueError:
            return None


__all__ = ["PlugNMeetClient", "PlugNMeetError"]