import os
import httpx
from typing import Any, Dict

class BackupClient:
    _instance = None

    def __new__(cls):
        if cls._instance is None:
            cls._instance = super(BackupClient, cls).__new__(cls)
            cls._instance._initialized = False
        return cls._instance

    def __init__(self):
        if self._initialized:
            return
        
        self.backup_url = os.environ.get('BACKUP_URL')
        if not self.backup_url:
            raise ValueError("BACKUP_URL environment variable is not set")
        
        self._initialized = True    
        
    async def push(self, data: Dict[str, Any]) -> Dict[str, Any]:
        """
        Push data to Backup Sheet via POST request
        
        :param data: Dictionary containing the data to be pushed
        :return: Response from the sheet
        """
        try:
            async with httpx.AsyncClient(follow_redirects=True) as client:
                response = await client.post(
                    self.backup_url, 
                    headers={
                      "Content-Type": "application/json",
                    },
                    json=data
                )
                response.raise_for_status() 
                return response.json()

        except httpx.HTTPStatusError as e:
            raise Exception(f"HTTP error occurred: {e}")
        except httpx.RequestError as e:
            raise Exception(f"An error occurred while requesting: {e}")
        except Exception as e:
            raise Exception(f"An unexpected error occurred: {e}")