import os
from pathlib import Path

BASE_DIR = Path(__file__).resolve().parent
SECRET_FILE = BASE_DIR / ".secret_key"

DEFAULT_SENSORS_PORT = 8001


def load_secret_key() -> str:
    """Return a stable key used to sign the main app session cookies."""
    key = os.environ.get("SECRET_KEY")
    if key:
        return key
    if SECRET_FILE.exists():
        return SECRET_FILE.read_text().strip()
    return "dev-secret-key-change-me"


def sensors_database_uri() -> str:
    """Database owned by the sensors API (sensors and readouts only)."""
    configured = os.environ.get("SENSORS_DATABASE_URL") or os.environ.get("DATABASE_URL")
    if configured:
        return configured
    db_path = os.environ.get(
        "SENSORS_DB_PATH", os.environ.get("DB_PATH", str(BASE_DIR / "sensors.db"))
    )
    return f"sqlite:///{db_path}"


def users_database_uri() -> str:
    """Database owned by the main app (user accounts only)."""
    configured = os.environ.get("USERS_DATABASE_URL")
    if configured:
        return configured
    db_path = os.environ.get("USERS_DB_PATH", str(BASE_DIR / "main_app.db"))
    return f"sqlite:///{db_path}"


def sensors_api_url() -> str:
    """Base URL used by the main app to call the sensors API (server-to-server)."""
    configured = os.environ.get("SENSORS_API_URL")
    if configured:
        return configured.rstrip("/")
    return f"http://localhost:{DEFAULT_SENSORS_PORT}"