feat: batches router — create, get mine, get by id

backend/routers/batches.py

@@ -1,3 +1,51 @@
-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 CreateBatchRequest(BaseModel):
+    name: str
+
+
+def _batch_out(batch) -> dict:
+    return {
+        "id": str(batch["id"]),
+        "name": batch["name"],
+        "instructor_id": str(batch["instructor_id"]),
+        "class_code": batch["class_code"],
+    }
+
+
+@router.post("")
+async def create_batch(
+    body: CreateBatchRequest,
+    user: dict = Depends(require_instructor),
+):
+    existing = await queries.get_batch_by_instructor_id(user["user_id"])
+    if existing:
+        raise HTTPException(400, "You already have a batch")
+    batch = await queries.create_batch(body.name, user["user_id"])
+    return _batch_out(batch)
+
+
+@router.get("/mine")
+async def get_my_batch(user: dict = Depends(require_instructor)):
+    batch = await queries.get_batch_by_instructor_id(user["user_id"])
+    if not batch:
+        raise HTTPException(404, "No batch found")
+    return _batch_out(batch)
+
+
+@router.get("/{batch_id}")
+async def get_batch(
+    batch_id: str,
+    user: dict = Depends(require_instructor),
+):
+    batch = await queries.get_batch_by_id(batch_id)
+    if not batch:
+        raise HTTPException(404, "Batch not found")
+    return _batch_out(batch)