arbret/frontend/app/hooks/useRequireAuth.ts

"use client";

import { useEffect } from "react";
import { useRouter } from "next/navigation";
import { useAuth, PermissionType, Permission } from "../auth-context";

interface UseRequireAuthOptions {
  /** Required permission to access the page */
  requiredPermission?: PermissionType;
  /** Required role to access the page */
  requiredRole?: string;
  /** Where to redirect if permission check fails (defaults to best available page) */
  fallbackRedirect?: string;
}

interface UseRequireAuthResult {
  user: ReturnType<typeof useAuth>["user"];
  isLoading: boolean;
  isAuthorized: boolean;
}

/**
 * Hook that handles authentication and authorization checks.
 * Automatically redirects to login if not authenticated,
 * or to a fallback page if missing required permissions.
 */
export function useRequireAuth(options: UseRequireAuthOptions = {}): UseRequireAuthResult {
  const { requiredPermission, requiredRole, fallbackRedirect } = options;
  const { user, isLoading, hasPermission, hasRole } = useAuth();
  const router = useRouter();

  const isAuthorized = (() => {
    if (!user) return false;
    if (requiredPermission && !hasPermission(requiredPermission)) return false;
    if (requiredRole && !hasRole(requiredRole)) return false;
    return true;
  })();

  useEffect(() => {
    if (isLoading) return;

    if (!user) {
      router.push("/login");
      return;
    }

    if (!isAuthorized) {
      // Redirect to the most appropriate page based on permissions
      const redirect =
        fallbackRedirect ??
        (hasPermission(Permission.VIEW_ALL_EXCHANGES)
          ? "/admin/trades"
          : hasPermission(Permission.CREATE_EXCHANGE)
            ? "/exchange"
            : "/login");
      router.push(redirect);
    }
  }, [isLoading, user, isAuthorized, router, fallbackRedirect, hasPermission]);

  return {
    user,
    isLoading,
    isAuthorized,
  };
}