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]:
        # Convert entire payload keys to camelCase as required by PlugNMeet protocol
        prepared = self._camelize_dict(payload)
        return self._post("/auth/room/create", prepared)

    def get_join_token(self, payload: Dict[str, Any]) -> Dict[str, Any]:
        # Convert entire payload keys to camelCase as required by PlugNMeet protocol
        prepared = self._camelize_dict(payload)
        return self._post("/auth/room/getJoinToken", prepared)

    def is_room_active(self, room_id: str) -> Dict[str, Any]:
        return self._post("/auth/room/isRoomActive", {"roomId": room_id})

    def get_recording_info(self, record_id: str) -> Dict[str, Any]:
        """Get detailed information about a recording."""
        return self._post("/auth/recording/recordingInfo", {"recordId": record_id})

    def get_recording_download_token(self, record_id: str) -> Dict[str, Any]:
        """Get a temporary download token for a recording."""
        return self._post("/auth/recording/getDownloadToken", {"recordId": record_id})

    def download_file(self, download_path: str, save_to: str) -> bool:
        """
        Download a file from PlugNMeet server.
        
        Args:
            download_path: The download path (e.g., '/download/recording/token_xxx')
            save_to: Local file path to save the downloaded file
            
        Returns:
            True if download successful, False otherwise
        """
        import logging
        logger = logging.getLogger(__name__)
        
        url = urljoin(f"{self.base_url}/", download_path.lstrip("/"))
        logger.info(f"[PlugNMeet] Downloading file from {url}")
        
        try:
            response = requests.get(url, stream=True, timeout=300)  # 5 minute timeout for large files
            response.raise_for_status()
            
            # Write file in chunks
            with open(save_to, 'wb') as f:
                for chunk in response.iter_content(chunk_size=8192):
                    if chunk:
                        f.write(chunk)
            
            logger.info(f"[PlugNMeet] File downloaded successfully to {save_to}")
            return True
            
        except requests.RequestException as exc:
            logger.error(f"[PlugNMeet] Failed to download file - error={str(exc)}")
            raise PlugNMeetError(f"Failed to download file: {str(exc)}") from exc

    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),
        }
        
        import logging
        logger = logging.getLogger(__name__)
        logger.debug(f"[PlugNMeet] POST {path} - Body: {body[:500]}")

        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.")
        
        if isinstance(data, dict) and data.get('status') is False:
            error_message = data.get('msg') or data.get('message') or "PlugNMeet operation failed."
            raise PlugNMeetError(
                error_message,
                status_code=response.status_code,
                response_data=data,
            )
        
        return data

    @staticmethod
    def _snake_to_camel(key: str) -> str:
        parts = key.split("_")
        if not parts:
            return key
        return parts[0] + "".join(p.capitalize() or "" for p in parts[1:])

    def _camelize_dict(self, obj: Any) -> Any:
        if isinstance(obj, dict):
            return {self._snake_to_camel(k): self._camelize_dict(v) for k, v in obj.items()}
        if isinstance(obj, list):
            return [self._camelize_dict(v) for v in obj]
        return obj

    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"]