import { useEffect, useState } from "react";
import { NavLink, Navigate, Route, Routes, useNavigate } from "react-router-dom";
import { api } from "./api";
import { useAuth } from "./auth";
import Icon from "./components/Icon";
import BrandMark from "./components/BrandMark";
import Login from "./pages/Login";
import Dashboard from "./pages/Dashboard";
import Products from "./pages/Products";
import ProductForm from "./pages/ProductForm";
import CheckIn from "./pages/CheckIn";
import CheckOut from "./pages/CheckOut";
import Groups from "./pages/Groups";
import Categories from "./pages/Categories";
import Locations from "./pages/Locations";
import PackageTypes from "./pages/PackageTypes";
import Units from "./pages/Units";
import Users from "./pages/Users";
import ShoppingList from "./pages/ShoppingList";
import History from "./pages/History";
import Transfer from "./pages/Transfer";
import Settings from "./pages/Settings";

const navClass = ({ isActive }) => (isActive ? "nav-link active" : "nav-link");

function NavItem({ to, icon, label, end }) {
  return (
    <NavLink to={to} end={end} className={navClass}>
      <Icon name={icon} size={17} />
      <span className="label">{label}</span>
    </NavLink>
  );
}

function Sidebar() {
  const { user, isAdmin, logout } = useAuth();
  const navigate = useNavigate();
  const [dashboards, setDashboards] = useState([]);

  // Die Dashboards des Benutzers stehen als eigene Eintraege in der Leiste.
  // Sie aendern sich beim Anlegen und Loeschen, deshalb horcht die Leiste auf
  // das Ereignis, das die Dashboard-Seite dabei ausloest.
  useEffect(() => {
    function laden() {
      api.dashboards().then((a) => setDashboards(a.dashboards)).catch(() => {});
    }
    laden();
    window.addEventListener("dashboards-geaendert", laden);
    return () => window.removeEventListener("dashboards-geaendert", laden);
  }, []);

  function handleLogout() {
    logout();
    navigate("/login");
  }

  return (
    <aside className="sidebar">
      <div className="sidebar-brand">
        <BrandMark />
      </div>
      <nav className="sidebar-nav">
        <NavItem to="/" end icon="dashboard" label="Übersicht" />
        {/* Ab dem zweiten Dashboard lohnt die Aufzaehlung; bei einem einzigen
            waere sie nur eine Verdopplung von "Übersicht". */}
        {dashboards.length > 1 && dashboards.map((d, index) => (
          <NavLink key={d.id} to={index === 0 ? "/" : `/d/${d.id}`} end
                   className={({ isActive }) => (isActive ? "nav-link sub active" : "nav-link sub")}>
            <span className="label">{d.name}</span>
          </NavLink>
        ))}
        <NavItem to="/checkin" icon="checkin" label="Einlagern" />
        <NavItem to="/checkout" icon="checkout" label="Auslagern" />
        <NavItem to="/products" icon="package" label="Produkte" />
        <NavItem to="/groups" icon="tag" label="Gruppen" />
        <NavItem to="/categories" icon="package" label="Kategorien" />
        <NavItem to="/shopping" icon="cart" label="Einkaufsliste" />
        <NavItem to="/history" icon="history" label="Verlauf" />
        {isAdmin && (
          <>
            <div className="nav-section">Verwaltung</div>
            <NavItem to="/locations" icon="location" label="Lagerorte" />
            <NavItem to="/units" icon="box" label="Einheiten" />
            <NavItem to="/package-types" icon="package" label="Gebinde" />
            <NavItem to="/users" icon="users" label="Benutzer" />
            <NavItem to="/transfer" icon="history" label="Import / Export" />
            <NavItem to="/settings" icon="settings" label="Einstellungen" />
          </>
        )}
      </nav>
      <div className="sidebar-foot">
        <div className="sidebar-user">
          <span className="name">{user?.username}</span>
          <span className="role">{isAdmin ? "Administrator" : "Benutzer"}</span>
        </div>
        <button className="btn-icon" onClick={handleLogout} title="Abmelden">
          <Icon name="logout" size={18} />
        </button>
      </div>
    </aside>
  );
}

function Protected({ children, adminOnly = false }) {
  const { user, isAdmin, loading } = useAuth();
  if (loading) return <div className="center muted" style={{ padding: 60 }}>Lädt…</div>;
  if (!user) return <Navigate to="/login" replace />;
  if (adminOnly && !isAdmin) return <Navigate to="/" replace />;
  return (
    <div className="app-shell">
      <Sidebar />
      <div className="main">
        <div className="content">{children}</div>
      </div>
    </div>
  );
}

export default function App() {
  const { user, loading } = useAuth();

  return (
    <Routes>
      <Route
        path="/login"
        element={loading ? null : user ? <Navigate to="/" replace /> : <Login />}
      />
      <Route path="/" element={<Protected><Dashboard /></Protected>} />
      <Route path="/d/:id" element={<Protected><Dashboard /></Protected>} />
      <Route path="/checkin" element={<Protected><CheckIn /></Protected>} />
      <Route path="/checkout" element={<Protected><CheckOut /></Protected>} />
      <Route path="/products" element={<Protected><Products /></Protected>} />
      <Route path="/products/new" element={<Protected adminOnly><ProductForm /></Protected>} />
      <Route path="/products/:id" element={<Protected><ProductForm /></Protected>} />
      <Route path="/groups" element={<Protected><Groups /></Protected>} />
      <Route path="/categories" element={<Protected><Categories /></Protected>} />
      <Route path="/shopping" element={<Protected><ShoppingList /></Protected>} />
      <Route path="/history" element={<Protected><History /></Protected>} />
      <Route path="/locations" element={<Protected adminOnly><Locations /></Protected>} />
      <Route path="/units" element={<Protected adminOnly><Units /></Protected>} />
      <Route path="/package-types" element={<Protected adminOnly><PackageTypes /></Protected>} />
      <Route path="/users" element={<Protected adminOnly><Users /></Protected>} />
      <Route path="/transfer" element={<Protected adminOnly><Transfer /></Protected>} />
      <Route path="/settings" element={<Protected adminOnly><Settings /></Protected>} />
      <Route path="*" element={<Navigate to="/" replace />} />
    </Routes>
  );
}