import { useMemo } from 'react';
import { Navigate, useLocation } from 'react-router-dom';
import { useAtom } from 'jotai';
import {
  backendUserAtom,
  isAuthenticatedAtom,
  authInitialCheckDoneAtom,
  guestSessionAtom,
  guestSessionHydratedAtom,
} from '@/atoms/auth';
import { hasSessionToken } from '@/services/backend';
import { ROUTES } from '@/utils/constants';

interface ProtectedRouteProps {
  children: React.ReactNode;
  /** Allow access while name/age are still missing (profile completion page). */
  allowIncompleteProfile?: boolean;
}

const AuthBootSpinner = () => (
  <div className="flex h-full min-h-0 flex-1 items-center justify-center">
    <div className="h-12 w-12 animate-spin rounded-full border-2 border-neon-cyan/30 border-t-neon-cyan" />
  </div>
);

export function ProtectedRoute({ children, allowIncompleteProfile = false }: ProtectedRouteProps) {
  const [isAuthenticated] = useAtom(isAuthenticatedAtom);
  const [backendUser] = useAtom(backendUserAtom);
  const [authInitialCheckDone] = useAtom(authInitialCheckDoneAtom);
  const [guestSession] = useAtom(guestSessionAtom);
  const [guestSessionHydrated] = useAtom(guestSessionHydratedAtom);
  const location = useLocation();
  // Stabilize Navigate `state` — a new object every render re-triggers Navigate's
  // useEffect (deps include `state`) and can blow the update depth limit.
  const loginRedirectState = useMemo(
    () => ({ from: { pathname: location.pathname } }),
    [location.pathname],
  );
  const hasToken = hasSessionToken();
  const canUseBackendUser = Boolean(backendUser && hasToken);

  if (!authInitialCheckDone) {
    return <AuthBootSpinner />;
  }

  if (!guestSessionHydrated) {
    return <AuthBootSpinner />;
  }

  if (!isAuthenticated && !guestSession) {
    return <Navigate to={ROUTES.LOGIN} state={loginRedirectState} replace />;
  }

  // Incomplete-profile gate only when a live session exists. Stale backendUser
  // without a token must not bounce / ↔ /profile forever.
  if (!allowIncompleteProfile && canUseBackendUser && !backendUser!.profileComplete) {
    return <Navigate to={ROUTES.PROFILE} replace />;
  }

  return <div className="flex h-full min-h-0 flex-1 flex-col overflow-hidden">{children}</div>;
}