from contextlib import asynccontextmanager
from fastapi import FastAPI, Depends
from fastapi.middleware.cors import CORSMiddleware
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from database import engine, get_db, Base
from models import Counter


@asynccontextmanager
async def lifespan(app: FastAPI):
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)
    yield


app = FastAPI(lifespan=lifespan)

app.add_middleware(
    CORSMiddleware,
    allow_origins=["http://localhost:3000"],
    allow_methods=["*"],
    allow_headers=["*"],
)


async def get_or_create_counter(db: AsyncSession) -> Counter:
    result = await db.execute(select(Counter).where(Counter.id == 1))
    counter = result.scalar_one_or_none()
    if not counter:
        counter = Counter(id=1, value=0)
        db.add(counter)
        await db.commit()
        await db.refresh(counter)
    return counter


@app.get("/api/counter")
async def get_counter(db: AsyncSession = Depends(get_db)):
    counter = await get_or_create_counter(db)
    return {"value": counter.value}


@app.post("/api/counter/increment")
async def increment_counter(db: AsyncSession = Depends(get_db)):
    counter = await get_or_create_counter(db)
    counter.value += 1
    await db.commit()
    return {"value": counter.value}