Add homework system (admin, student, curator)

Admin:
- HomeworkEditor in lesson page: create/update/delete assignment description

Student:
- HomeworkSection in lesson page: view assignment, submit text + files
- Resubmission allowed until curator gives feedback
- Shows feedback from curator with date and name

Curator:
- New layout with Second Brain dark sidebar (replaces green theme)
- /curator/dashboard: stats cards (pending, total, reviewed this week)
- /curator/homework: list of all submissions, pending highlighted
- /curator/homework/[id]: review submission, write feedback, redirect after send

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/admin/homework-editor.tsx

@@ -0,0 +1,94 @@
+"use client";
+
+import { useState, useTransition } from "react";
+import { saveHomework, deleteHomework } from "@/app/admin/courses/[courseId]/modules/[moduleId]/lessons/[lessonId]/homework-actions";
+
+interface Props {
+  lessonId: string;
+  initial: { id: string; description: string } | null;
+}
+
+export function HomeworkEditor({ lessonId, initial }: Props) {
+  const [editing, setEditing] = useState(!initial);
+  const [text, setText] = useState(initial?.description ?? "");
+  const [saved, setSaved] = useState(false);
+  const [pending, startTransition] = useTransition();
+
+  const inputStyle = {
+    border: "2px solid var(--border)",
+    background: "var(--background)",
+    outline: "none",
+    width: "100%",
+    padding: "0.5rem 0.75rem",
+    fontSize: "0.875rem",
+    fontFamily: "inherit",
+    resize: "vertical" as const,
+    minHeight: "120px",
+  };
+
+  function handleSave() {
+    if (!text.trim()) return;
+    startTransition(async () => {
+      await saveHomework(lessonId, text.trim());
+      setSaved(true);
+      setEditing(false);
+      setTimeout(() => setSaved(false), 2000);
+    });
+  }
+
+  function handleDelete() {
+    if (!confirm("Удалить домашнее задание? Все сданные работы будут удалены.")) return;
+    startTransition(async () => {
+      await deleteHomework(lessonId);
+      setText("");
+      setEditing(true);
+    });
+  }
+
+  if (!editing && initial) {
+    return (
+      <div className="space-y-3">
+        <div className="px-4 py-3 text-sm whitespace-pre-wrap" style={{ border: "2px solid var(--border)", background: "var(--color-surface)" }}>
+          {text || initial.description}
+        </div>
+        <div className="flex gap-2">
+          <button onClick={() => setEditing(true)} className="btn-aubade text-xs px-3 py-1.5">
+            Редактировать
+          </button>
+          <button onClick={handleDelete} disabled={pending} className="text-xs px-3 py-1.5" style={{ color: "oklch(0.577 0.245 27.325)" }}>
+            Удалить ДЗ
+          </button>
+          {saved && <span className="text-xs self-center" style={{ color: "var(--muted-foreground)" }}>✓ Сохранено</span>}
+        </div>
+      </div>
+    );
+  }
+
+  return (
+    <div className="space-y-3">
+      <textarea
+        value={text}
+        onChange={(e) => setText(e.target.value)}
+        style={inputStyle}
+        placeholder="Опишите задание для студентов..."
+        onFocus={(e) => (e.currentTarget.style.borderColor = "var(--foreground)")}
+        onBlur={(e) => (e.currentTarget.style.borderColor = "var(--border)")}
+      />
+      <div className="flex items-center gap-2">
+        <button
+          onClick={handleSave}
+          disabled={pending || !text.trim()}
+          className="btn-aubade btn-aubade-accent text-xs px-4 py-1.5"
+          style={{ opacity: pending || !text.trim() ? 0.6 : 1 }}
+        >
+          {pending ? "Сохранение..." : "Сохранить задание"}
+        </button>
+        {initial && (
+          <button onClick={() => { setEditing(false); setText(initial.description); }} className="text-xs" style={{ color: "var(--muted-foreground)" }}>
+            Отмена
+          </button>
+        )}
+      </div>
+    </div>
+  );
+}

src/components/student/homework-section.tsx

@@ -0,0 +1,195 @@
+"use client";
+
+import { useState, useTransition } from "react";
+import { submitHomework } from "@/app/(student)/courses/[slug]/lessons/[lessonId]/homework-actions";
+
+interface HWFile { name: string; url: string; size: number }
+
+interface Feedback {
+  id: string;
+  text: string;
+  createdAt: Date;
+  curator: { name: string };
+}
+
+interface Submission {
+  id: string;
+  text: string | null;
+  files: HWFile[];
+  submittedAt: Date;
+  feedbacks: Feedback[];
+}
+
+interface Props {
+  homework: { id: string; description: string };
+  submission: Submission | null;
+  slug: string;
+  lessonId: string;
+}
+
+function formatSize(bytes: number) {
+  if (bytes < 1024) return `${bytes} Б`;
+  if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(0)} КБ`;
+  return `${(bytes / 1024 / 1024).toFixed(1)} МБ`;
+}
+
+export function HomeworkSection({ homework, submission, slug, lessonId }: Props) {
+  const [text, setText] = useState(submission?.text ?? "");
+  const [files, setFiles] = useState<HWFile[]>(submission?.files ?? []);
+  const [uploading, setUploading] = useState(false);
+  const [pending, startTransition] = useTransition();
+  const [editing, setEditing] = useState(!submission);
+
+  const isReviewed = submission && submission.feedbacks.length > 0;
+
+  const inputStyle = {
+    border: "2px solid var(--border)",
+    background: "var(--background)",
+    outline: "none",
+    width: "100%",
+    padding: "0.5rem 0.75rem",
+    fontSize: "0.875rem",
+    fontFamily: "inherit",
+    resize: "vertical" as const,
+    minHeight: "140px",
+  };
+
+  async function handleFileUpload(e: React.ChangeEvent<HTMLInputElement>) {
+    const file = e.target.files?.[0];
+    if (!file) return;
+    setUploading(true);
+    const fd = new FormData();
+    fd.append("file", file);
+    const res = await fetch("/api/student/homework-upload", { method: "POST", body: fd });
+    const data = await res.json();
+    if (data.url) setFiles((prev) => [...prev, data]);
+    setUploading(false);
+    e.target.value = "";
+  }
+
+  function removeFile(url: string) {
+    setFiles((prev) => prev.filter((f) => f.url !== url));
+  }
+
+  function handleSubmit() {
+    startTransition(() => submitHomework(homework.id, slug, lessonId, text, files));
+    setEditing(false);
+  }
+
+  return (
+    <div className="space-y-4">
+      {/* Assignment description */}
+      <div className="px-4 py-3 text-sm whitespace-pre-wrap" style={{ border: "2px solid var(--border)", background: "var(--color-surface)" }}>
+        {homework.description}
+      </div>
+
+      {/* Submitted & reviewed */}
+      {isReviewed && (
+        <div className="space-y-3">
+          <div className="space-y-2">
+            <p className="text-xs font-bold uppercase tracking-widest" style={{ color: "var(--muted-foreground)" }}>Ваш ответ</p>
+            <div className="px-4 py-3 text-sm whitespace-pre-wrap opacity-70" style={{ border: "2px solid var(--border)" }}>
+              {submission!.text || "—"}
+            </div>
+          </div>
+          {submission!.feedbacks.map((fb) => (
+            <div key={fb.id} className="px-4 py-3 space-y-1" style={{ border: "2px solid var(--foreground)", background: "var(--accent)" }}>
+              <div className="flex items-center justify-between">
+                <p className="text-xs font-bold uppercase tracking-widest">Обратная связь</p>
+                <span className="text-xs" style={{ color: "var(--muted-foreground)" }}>
+                  {fb.curator.name} · {new Date(fb.createdAt).toLocaleDateString("ru-RU")}
+                </span>
+              </div>
+              <p className="text-sm whitespace-pre-wrap">{fb.text}</p>
+            </div>
+          ))}
+        </div>
+      )}
+
+      {/* Submitted, pending review */}
+      {submission && !isReviewed && !editing && (
+        <div className="space-y-3">
+          <div className="flex items-center justify-between">
+            <div className="flex items-center gap-2">
+              <span className="text-xs px-2 py-0.5 font-bold uppercase tracking-widest" style={{ border: "2px solid var(--border)", background: "var(--color-surface)", color: "var(--muted-foreground)" }}>
+                На проверке
+              </span>
+              <span className="text-xs" style={{ color: "var(--muted-foreground)" }}>
+                Сдано {new Date(submission.submittedAt).toLocaleDateString("ru-RU")}
+              </span>
+            </div>
+            <button onClick={() => setEditing(true)} className="text-xs underline" style={{ color: "var(--muted-foreground)" }}>
+              Изменить
+            </button>
+          </div>
+          {submission.text && (
+            <div className="px-4 py-3 text-sm whitespace-pre-wrap" style={{ border: "2px solid var(--border)" }}>
+              {submission.text}
+            </div>
+          )}
+          {submission.files.length > 0 && (
+            <div className="space-y-1">
+              {submission.files.map((f) => (
+                <a key={f.url} href={f.url} target="_blank" rel="noopener noreferrer"
+                  className="flex items-center gap-2 px-3 py-2 text-xs"
+                  style={{ border: "2px solid var(--border)" }}>
+                  <span>📎</span>
+                  <span className="flex-1 underline">{f.name}</span>
+                  <span style={{ color: "var(--muted-foreground)" }}>{formatSize(f.size)}</span>
+                </a>
+              ))}
+            </div>
+          )}
+        </div>
+      )}
+
+      {/* Form */}
+      {editing && !isReviewed && (
+        <div className="space-y-3">
+          <textarea
+            value={text}
+            onChange={(e) => setText(e.target.value)}
+            style={inputStyle}
+            placeholder="Напишите ваш ответ..."
+            onFocus={(e) => (e.currentTarget.style.borderColor = "var(--foreground)")}
+            onBlur={(e) => (e.currentTarget.style.borderColor = "var(--border)")}
+          />
+
+          {/* File list */}
+          {files.length > 0 && (
+            <div className="space-y-1">
+              {files.map((f) => (
+                <div key={f.url} className="flex items-center gap-2 px-3 py-2 text-xs" style={{ border: "2px solid var(--border)" }}>
+                  <span>📎</span>
+                  <span className="flex-1">{f.name}</span>
+                  <span style={{ color: "var(--muted-foreground)" }}>{formatSize(f.size)}</span>
+                  <button onClick={() => removeFile(f.url)} style={{ color: "oklch(0.577 0.245 27.325)" }}>✕</button>
+                </div>
+              ))}
+            </div>
+          )}
+
+          <div className="flex items-center gap-2 flex-wrap">
+            <button
+              onClick={handleSubmit}
+              disabled={pending || (!text.trim() && files.length === 0)}
+              className="btn-aubade btn-aubade-accent text-sm px-5 py-2"
+              style={{ opacity: pending || (!text.trim() && files.length === 0) ? 0.6 : 1 }}
+            >
+              {pending ? "Отправка..." : submission ? "Обновить ответ" : "Сдать работу"}
+            </button>
+            <label className="btn-aubade text-xs px-3 py-2 cursor-pointer">
+              {uploading ? "Загрузка..." : "📎 Прикрепить файл"}
+              <input type="file" className="sr-only" onChange={handleFileUpload} disabled={uploading} />
+            </label>
+            {submission && (
+              <button onClick={() => setEditing(false)} className="text-xs" style={{ color: "var(--muted-foreground)" }}>
+                Отмена
+              </button>
+            )}
+          </div>
+        </div>
+      )}
+    </div>
+  );
+}