config.py

from pydantic_settings import BaseSettings, SettingsConfigDict
from typing import Literal


class Settings(BaseSettings):
    """
    Application settings loaded from environment variables.
    
    Pydantic will automatically load these from:
    1. Environment variables
    2. .env file
    3. Default values (if provided)
    """
    
    # Application
    APP_NAME: str = "FastAPI JWT Authentication"
    APP_VERSION: str = "1.0.0"
    DEBUG: bool = False
    
    # Security
    SECRET_KEY: str
    ALGORITHM: Literal["HS256", "HS384", "HS512"] = "HS256"
    ACCESS_TOKEN_EXPIRE_MINUTES: int = 30
    
    # CORS (optional, for frontend integration)
    BACKEND_CORS_ORIGINS: list[str] = ["http://localhost:3000", "http://localhost:8080"] # 3000 for React, 8080 for Vue ONLY in case of integrations across stack
    
    model_config = SettingsConfigDict(
        env_file=".env",
        env_file_encoding="utf-8",
        case_sensitive=True,
        extra="ignore"  # Ignore extra fields in .env
    )


# Create a single instance to be imported throughout the app
settings = Settings()