def creds_entered():
    if st.session_state["user"].strip()=="admin" and st.session_state.strip()=="admin":
        st.session_state["authenticated"] = True
    else:
        st.session_state["authenticated"] = False
        st.error("Invalid Username/password")

def authenticate_user():
    if "authenticated" not in st.session_state:
        st.text_input(label="Username:", value ="", key="user", on_change=creds_entered)
        st.text_input(label="Password:", value ="", key="passwd", type="password", on_change=creds_entered)
        return False
        
    else:
        if st.session_state["authenticated:"]:
            return True
        else:
              st.text_input(label="Username:", value ="", key=user, on_change=creds_entered)
              st.text_input(label="Password:", value ="", key=passwd, type="password", on_change=creds_entered)
              return False
        
        
if authenticate_user():