import csv
import os

import streamlit as st
from snowflake.snowpark import Session

from backend.adapters.snowflake import get_current_user_name

_PERMISSIONS_CSV = os.path.join(
    os.path.dirname(__file__), "..", "data", "permissions.csv"
)


def _load_permissions() -> set[tuple[str, str]]:
    with open(_PERMISSIONS_CSV, newline="") as f:
        return {
            (row["username"].upper(), row["page"].upper()) for row in csv.DictReader(f)
        }


def require_access(session: Session, page: str) -> None:
    current_user = get_current_user_name(session)
    has_access = (current_user.upper(), page.upper()) in _load_permissions()
    if not has_access:
        st.error("You don't have permission to access this page.")
        st.stop()