from functools import lru_cache
from pydantic_settings import BaseSettings, SettingsConfigDict
from pydantic import Field


class Settings(BaseSettings):
    # -----------------------
    # App
    # -----------------------
    app_name: str = "MyApp"
    env: str = "PROD"
    debug: bool = False

    # -----------------------
    # Database / Cache
    # -----------------------
    database_url: str = Field(..., description="Async database DSN")
    redis_url: str

    # -----------------------
    # Security / API Keys
    # -----------------------
    openai_api_key: str
    stripe_api_key: str

    model_config = SettingsConfigDict(
        env_file=".env",
        env_file_encoding="utf-8",
        case_sensitive=False,
    )


@lru_cache
def get_settings() -> Settings:
    """
    避免多次实例化 Settings（FastAPI 官方推荐）
    """
    return Settings()


settings = get_settings()

# -----------------------
# Global constants
# -----------------------
BASE_CURRENCY = "EUR"