feat(frontend): admin card management with excel import/export

packages/frontend/src/components/CardTable.tsx

@@ -0,0 +1,47 @@
+import { useState } from 'react';
+import type { Card, CardCreateInput } from '@flashcard/shared';
+import { cardsApi } from '../api/cards.js';
+
+export function CardTable({ lessonId, cards, onChange }: { lessonId: number; cards: Card[]; onChange: () => void }) {
+  const [draft, setDraft] = useState<CardCreateInput>({ question: '', answer: '', hint: '' });
+
+  async function add() {
+    if (!draft.question.trim() || !draft.answer.trim()) return;
+    await cardsApi.create(lessonId, { question: draft.question.trim(), answer: draft.answer.trim(), hint: draft.hint?.trim() || null });
+    setDraft({ question: '', answer: '', hint: '' });
+    onChange();
+  }
+  async function update(c: Card, field: 'question' | 'answer' | 'hint', value: string) {
+    await cardsApi.update(c.id, { [field]: value || null });
+    onChange();
+  }
+  async function remove(id: number) {
+    if (!confirm('Verwijder kaart?')) return;
+    await cardsApi.remove(id);
+    onChange();
+  }
+
+  return (
+    <table className="w-full text-sm">
+      <thead><tr className="text-left text-slate-500">
+        <th className="py-2">Vraag</th><th>Antwoord</th><th>Hint</th><th></th>
+      </tr></thead>
+      <tbody>
+        {cards.map((c) => (
+          <tr key={c.id} className="border-t border-slate-200 dark:border-slate-800">
+            <td><input className="w-full bg-transparent py-1" defaultValue={c.question} onBlur={(e) => update(c, 'question', e.target.value)} /></td>
+            <td><input className="w-full bg-transparent py-1" defaultValue={c.answer} onBlur={(e) => update(c, 'answer', e.target.value)} /></td>
+            <td><input className="w-full bg-transparent py-1" defaultValue={c.hint ?? ''} onBlur={(e) => update(c, 'hint', e.target.value)} /></td>
+            <td><button className="text-xs text-red-600" onClick={() => remove(c.id)}>x</button></td>
+          </tr>
+        ))}
+        <tr className="border-t border-slate-200 dark:border-slate-800">
+          <td><input className="w-full bg-transparent py-1" placeholder="Nieuwe vraag" value={draft.question} onChange={(e) => setDraft({ ...draft, question: e.target.value })} /></td>
+          <td><input className="w-full bg-transparent py-1" placeholder="Antwoord" value={draft.answer} onChange={(e) => setDraft({ ...draft, answer: e.target.value })} /></td>
+          <td><input className="w-full bg-transparent py-1" placeholder="Hint (optioneel)" value={draft.hint ?? ''} onChange={(e) => setDraft({ ...draft, hint: e.target.value })} /></td>
+          <td><button className="rounded bg-blue-600 px-2 py-1 text-xs text-white" onClick={add}>+</button></td>
+        </tr>
+      </tbody>
+    </table>
+  );
+}

packages/frontend/src/components/ImportDialog.tsx

@@ -0,0 +1,49 @@
+import { useState } from 'react';
+import { cardsApi, type ImportResult } from '../api/cards.js';
+
+export function ImportDialog({ lessonId, onClose, onDone }: { lessonId: number; onClose: () => void; onDone: () => void }) {
+  const [file, setFile] = useState<File | null>(null);
+  const [updateExisting, setUpdateExisting] = useState(true);
+  const [createMissing, setCreateMissing] = useState(false);
+  const [result, setResult] = useState<ImportResult | null>(null);
+  const [busy, setBusy] = useState(false);
+
+  async function run() {
+    if (!file) return;
+    setBusy(true);
+    try {
+      const r = await cardsApi.importXlsx(lessonId, file, { updateExisting, createMissingLessons: createMissing });
+      setResult(r);
+      onDone();
+    } finally { setBusy(false); }
+  }
+
+  return (
+    <div className="fixed inset-0 flex items-center justify-center bg-black/40">
+      <div className="w-full max-w-md rounded bg-white p-6 dark:bg-slate-900">
+        <h2 className="mb-3 text-lg font-semibold">Excel import</h2>
+        <p className="mb-3 text-xs text-slate-500">Kolommen: <code>question</code>, <code>answer</code>, <code>hint</code> (optioneel), <code>lesson_path</code> (optioneel, bv. "Spaans/Begroetingen").</p>
+        <input type="file" accept=".xlsx" onChange={(e) => setFile(e.target.files?.[0] ?? null)} />
+        <label className="mt-3 flex items-center gap-2 text-sm"><input type="checkbox" checked={updateExisting} onChange={(e) => setUpdateExisting(e.target.checked)} /> Bestaande kaarten bijwerken</label>
+        <label className="mt-1 flex items-center gap-2 text-sm"><input type="checkbox" checked={createMissing} onChange={(e) => setCreateMissing(e.target.checked)} /> Onbekende lessen aanmaken</label>
+        {result && (
+          <div className="mt-3 rounded bg-slate-100 p-2 text-xs dark:bg-slate-800">
+            <div>Toegevoegd: {result.inserted}</div>
+            <div>Bijgewerkt: {result.updated}</div>
+            <div>Overgeslagen: {result.skipped}</div>
+            {result.errors.length > 0 && (
+              <div className="text-red-600">
+                Fouten: {result.errors.length}
+                <ul>{result.errors.map((e, i) => <li key={i}>rij {e.row}: {e.message}</li>)}</ul>
+              </div>
+            )}
+          </div>
+        )}
+        <div className="mt-4 flex justify-end gap-2">
+          <button className="px-3 py-1" onClick={onClose}>Sluiten</button>
+          <button className="rounded bg-blue-600 px-3 py-1 text-white disabled:opacity-50" onClick={run} disabled={!file || busy}>Importeer</button>
+        </div>
+      </div>
+    </div>
+  );
+}

packages/frontend/src/pages/AdminLesson.tsx

@@ -0,0 +1,31 @@
+import { useEffect, useState } from 'react';
+import { Link, useParams } from 'react-router-dom';
+import type { Card } from '@flashcard/shared';
+import { cardsApi } from '../api/cards.js';
+import { CardTable } from '../components/CardTable.js';
+import { ImportDialog } from '../components/ImportDialog.js';
+
+export function AdminLessonPage() {
+  const { id } = useParams();
+  const lessonId = Number(id);
+  const [cards, setCards] = useState<Card[]>([]);
+  const [showImport, setShowImport] = useState(false);
+
+  async function refresh() { setCards(await cardsApi.list(lessonId)); }
+  useEffect(() => { refresh(); }, [lessonId]);
+
+  return (
+    <div className="mx-auto max-w-4xl p-6">
+      <Link to="/admin" className="text-sm text-blue-600">← Lessen</Link>
+      <h1 className="my-3 text-2xl font-semibold">Kaarten</h1>
+      <div className="mb-4 flex gap-2">
+        <button className="rounded bg-slate-200 px-3 py-1 dark:bg-slate-800" onClick={() => setShowImport(true)}>Importeer Excel</button>
+        <a className="rounded bg-slate-200 px-3 py-1 dark:bg-slate-800" href={cardsApi.exportUrl(lessonId, false)}>Exporteer Excel</a>
+        <a className="rounded bg-slate-200 px-3 py-1 dark:bg-slate-800" href={cardsApi.exportUrl(lessonId, true)}>Exporteer + sublessen</a>
+        <Link to={`/practice/${lessonId}/setup`} className="ml-auto rounded bg-green-600 px-3 py-1 text-white">Start oefenen →</Link>
+      </div>
+      <CardTable lessonId={lessonId} cards={cards} onChange={refresh} />
+      {showImport && <ImportDialog lessonId={lessonId} onClose={() => setShowImport(false)} onDone={refresh} />}
+    </div>
+  );
+}

packages/frontend/src/router.tsx

@@ -1,6 +1,7 @@
 import { createBrowserRouter, Navigate } from 'react-router-dom';
 import { Layout } from './components/Layout.js';
 import { AdminPage } from './pages/Admin.js';
+import { AdminLessonPage } from './pages/AdminLesson.js';
 
 export const router = createBrowserRouter([
   {
@@ -9,6 +10,7 @@ export const router = createBrowserRouter([
     children: [
       { index: true, element: <div className="p-6">Dashboard placeholder</div> },
       { path: 'admin', element: <AdminPage /> },
+      { path: 'admin/lessons/:id', element: <AdminLessonPage /> },
       { path: '*', element: <Navigate to="/" replace /> },
     ],
   },