"""Configuration module for loading environment variables."""
import os
from typing import Optional
from dotenv import load_dotenv

# Load environment variables from .env file
load_dotenv()


class Config:
    """Application configuration."""
    
    # Telegram Bot Token
    BOT_TOKEN: Optional[str] = os.getenv("BOT_TOKEN")
    if not BOT_TOKEN:
        raise ValueError("BOT_TOKEN environment variable is required")
    
    # Database configuration
    DATABASE_URL: Optional[str] = os.getenv("DATABASE_URL")
    if not DATABASE_URL:
        raise ValueError("DATABASE_URL environment variable is required")
    
    # Notification settings
    NOTIFICATION_TIME: str = os.getenv("NOTIFICATION_TIME", "09:00") or "09:00"
    TIMEZONE: str = os.getenv("TIMEZONE", "UTC") or "UTC"
    
    @classmethod
    def validate(cls) -> None:
        """Validate that all required configuration is present."""
        if not cls.BOT_TOKEN:
            raise ValueError("BOT_TOKEN is required")
        if not cls.DATABASE_URL:
            raise ValueError("DATABASE_URL is required")