Initial import

backend/main.py

@@ -0,0 +1,45 @@
+from fastapi import FastAPI, Depends, HTTPException, status
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy import select
+
+from database.session import get_db
+from database.models import Ticket, TicketStatus
+from core.redis import acquire_seat_lock, release_seat_lock
+from api.routers.auth import router as auth_router
+
+app = FastAPI(title="Ticketing System API")
+
+app.include_router(auth_router)
+
+@app.post("/api/seats/{seat_id}/lock", status_code=status.HTTP_200_OK)
+async def lock_seat(seat_id: int, user_id: int, db: AsyncSession = Depends(get_db)):
+    # 1. Проверяем статус в БД (грязное чтение, чтобы отсеять уже выкупленные билеты)
+    query = select(Ticket).where(Ticket.seat_id == seat_id)
+    result = await db.execute(query)
+    ticket = result.scalar_one_or_none()
+
+    if ticket and ticket.status != TicketStatus.AVAILABLE:
+        raise HTTPException(status_code=409, detail="Seat is already booked or locked in DB")
+
+    # 2. Пытаемся захватить распределенную блокировку в Redis (15 минут по ТЗ)
+    locked = await acquire_seat_lock(seat_id=seat_id, user_id=user_id)
+    if not locked:
+        raise HTTPException(status_code=409, detail="Seat is currently locked by another user")
+
+    # 3. Лок наш. Пишем статус в PostgreSQL
+    try:
+        if not ticket:
+            ticket = Ticket(seat_id=seat_id, user_id=user_id, status=TicketStatus.LOCKED)
+            db.add(ticket)
+        else:
+            ticket.status = TicketStatus.LOCKED
+            ticket.user_id = user_id
+        
+        await db.commit()
+        return {"message": "Seat locked successfully", "seat_id": seat_id, "status": "LOCKED"}
+        
+    except Exception as e:
+        # Критически важно: если БД отвалилась, снимаем лок в Redis, иначе место зависнет на 15 минут
+        await release_seat_lock(seat_id)
+        await db.rollback()
+        raise HTTPException(status_code=500, detail="Database transaction failed")