feat: topics router — create, list, unlock/lock

backend/routers/topics.py

@@ -1,3 +1,71 @@
-from fastapi import APIRouter
+from fastapi import APIRouter, Depends, HTTPException
+from pydantic import BaseModel
+
+from backend.auth.deps import require_instructor
+from backend.db import queries
 
 router = APIRouter()
+
+
+class CreateTopicRequest(BaseModel):
+    batch_id: str
+    name: str
+
+
+class UpdateTopicRequest(BaseModel):
+    is_unlocked: bool
+
+
+def _topic_out(topic, question_count: int = 0) -> dict:
+    return {
+        "id": str(topic["id"]),
+        "batch_id": str(topic["batch_id"]),
+        "name": topic["name"],
+        "is_unlocked": topic["is_unlocked"],
+        "order_index": topic["order_index"],
+        "question_count": question_count,
+    }
+
+
+@router.post("")
+async def create_topic(
+    body: CreateTopicRequest,
+    user: dict = Depends(require_instructor),
+):
+    batch = await queries.get_batch_by_id(body.batch_id)
+    if not batch or str(batch["instructor_id"]) != user["user_id"]:
+        raise HTTPException(403, "Batch not found or not yours")
+    existing = await queries.get_topics_by_batch_id(body.batch_id)
+    order_index = len(existing)
+    topic = await queries.create_topic(body.batch_id, body.name, order_index)
+    return _topic_out(topic)
+
+
+@router.get("")
+async def list_topics(
+    batch_id: str,
+    user: dict = Depends(require_instructor),
+):
+    topics = await queries.get_topics_by_batch_id(batch_id)
+    result = []
+    for t in topics:
+        count = await queries.get_question_count_by_topic(str(t["id"]))
+        result.append(_topic_out(t, count))
+    return result
+
+
+@router.patch("/{topic_id}")
+async def update_topic(
+    topic_id: str,
+    body: UpdateTopicRequest,
+    user: dict = Depends(require_instructor),
+):
+    topic = await queries.get_topic_by_id(topic_id)
+    if not topic:
+        raise HTTPException(404, "Topic not found")
+    batch = await queries.get_batch_by_id(str(topic["batch_id"]))
+    if not batch or str(batch["instructor_id"]) != user["user_id"]:
+        raise HTTPException(403, "Topic does not belong to your batch")
+    updated = await queries.set_topic_unlock(topic_id, body.is_unlocked)
+    count = await queries.get_question_count_by_topic(topic_id)
+    return _topic_out(updated, count)