import { useEffect, useState, useMemo } from "react";
import { UserProfile } from "../types";

export function useAuth() {
  const [accessToken, setAccessToken] = useState<string | null>(() => localStorage.getItem("accessToken"));

  const parseJwtPayload = (token: string) => {
    try {
      const payloadPart = token.split(".")[1];
      if (!payloadPart) return null;
      const normalized = payloadPart.replace(/-/g, "+").replace(/_/g, "/");
      const padded = normalized + "=".repeat((4 - (normalized.length % 4)) % 4);
      return JSON.parse(atob(padded));
    } catch (e) {
      return null;
    }
  };

  useEffect(() => {
    const handler = () => setAccessToken(localStorage.getItem("accessToken"));
    window.addEventListener("storage", handler);
    return () => window.removeEventListener("storage", handler);
  }, []);

  const profile = useMemo<UserProfile | null>(() => {
    const data = sessionStorage.getItem("userProfile");
    if (data) {
      return JSON.parse(data);
    }
    if (!accessToken) {
      return null;
    }
    const payload = parseJwtPayload(accessToken);
    if (payload && (payload.pwdResetRequired === 0 || payload.pwdResetRequired === 1)) {
      return { pwdResetRequired: Number(payload.pwdResetRequired) } as UserProfile;
    }
    return null;
  }, [accessToken]);

  const isAuthed = !!accessToken;
  const logout = () => {
    localStorage.removeItem("accessToken");
    localStorage.removeItem("refreshToken");
    sessionStorage.removeItem("userProfile");
    setAccessToken(null);
  };

  return { accessToken, isAuthed, profile, logout };
}