from sqlalchemy import create_engine, select
from sqlalchemy.orm import Session, sessionmaker

from allmende_payment_system.models import User

SQLALCHEMY_DATABASE_URL = "sqlite:///./aps_db.db"
engine = create_engine(SQLALCHEMY_DATABASE_URL)
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)


def create_tables():
    from allmende_payment_system.models import Base

    Base.metadata.create_all(bind=engine)


def ensure_user(user_info: dict, session: Session) -> User:
    """
    Retrieve an existing user or create a new one if it doesn't exist.
    This function queries the database for a user with the given username.
    If found, it returns the existing user. If not found, it creates a new user
    with the provided information, adds it to the session, and returns it.

    :param user_info: Dictionary containing user information with keys:
        - "username" (str): The unique username to search for or create
        - "display_name" (str, optional): The display name for the new user
    :param session: SQLAlchemy session for database operations
    :return: The existing or newly created user object
    """
    statement = select(User).where(User.username == user_info["username"])

    if user := session.scalars(statement).one_or_none():
        return user

    user = User(
        username=user_info["username"], display_name=user_info.get("display_name")
    )
    session.add(user)
    session.flush()

    return user