import hmac
import streamlit as st
from streamlit_gsheets import GSheetsConnection


conn = st.connection("gsheets", type=GSheetsConnection)


def get_user_id_from_email_if_exists(email: str) -> int:
    # returns -1 if id not found
    df_email = conn.read(
        worksheet="users",
        usecols=[0, 1],
    )
    df_email = df_email[df_email.email.notna()]
    for row in df_email.itertuples():
        if row.email.lower() == email.lower():
            return row.id
    return -1


def get_password_from_user_id(user_id: int) -> str | None:
    try:
        df_pass = conn.read(
            worksheet=f"user-{user_id}",
            usecols=[0],
        )
        return df_pass.password[0]
    except Exception:
        return None


def check_password():
    """Returns `True` if the user had a correct password."""

    def login_form():
        """Form with widgets to collect user information"""
        with st.form("Credentials"):
            st.text_input("Email", key="email")
            st.text_input("Password", type="password", key="password")
            st.form_submit_button("Log in", on_click=password_entered)

    def password_entered():
        """Checks whether a password entered by the user is correct."""
        # check if email exists
        if user_id := get_user_id_from_email_if_exists(st.session_state["email"]):
            if password := get_password_from_user_id(user_id):
                if hmac.compare_digest(
                    st.session_state["password"],
                    password,
                ):
                    st.session_state["password_correct"] = True
                    del st.session_state["password"]  # Don't store the email or password.
                    del st.session_state["email"]
                    del password
                    return
        st.session_state["password_correct"] = False

    # Return True if the email + password is validated.
    if st.session_state.get("password_correct", False):
        return True

    # Show inputs for email + password.
    login_form()
    if st.session_state.get("password_correct", True) is False:
        st.error("😕 User not known or password incorrect")
    return False