from pydantic_settings import BaseSettings
import os

def _env(*names, default=None):
    for n in names:
        v = os.getenv(n)
        if v:
            return v
    return default

class Settings(BaseSettings):
    # support both custom DB_* names and common POSTGRES_* names from postgres images
    DB_USER: str = _env("DB_USER", "POSTGRES_USER", default="postgres")
    DB_PASS: str = _env("DB_PASS", "POSTGRES_PASSWORD", default="postgres")
    DB_NAME: str = _env("DB_NAME", "POSTGRES_DB", default="test_db")
    DB_HOST: str = _env("DB_HOST", "POSTGRES_HOST", "DB_HOST", default="db")
    DB_PORT: str = _env("DB_PORT", "POSTGRES_PORT", default="5432")

    # If explicit DB_* variables are provided, build DATABASE_URL from them (priority).
    # Otherwise fall back to explicit DATABASE_URL or DATABASE_URL_ASYNC env.
    _built_db_url: str | None = None
    if DB_USER and DB_PASS and DB_NAME and DB_HOST and DB_PORT:
        _built_db_url = f"postgresql+asyncpg://{DB_USER}:{DB_PASS}@{DB_HOST}:{DB_PORT}/{DB_NAME}"

    DATABASE_URL: str = _built_db_url or _env("DATABASE_URL", "DATABASE_URL_ASYNC", default="")


settings = Settings()