import pytest
import pytest_asyncio
from fastapi.testclient import TestClient
from httpx import ASGITransport, AsyncClient
from sqlalchemy.ext.asyncio import async_sessionmaker, create_async_engine
from sqlalchemy.pool import NullPool

from app.config import settings
from app.db import Base, get_db
from app.main import app

# pytest-asyncio gives each test function its own event loop by default;
# asyncpg connections are bound to the loop they were opened on, so a pooled
# connection from one test's loop breaks the next test. NullPool sidesteps
# this by opening a fresh connection per checkout — scoped to this dedicated
# test engine so app.db.engine (used by production) is unaffected.
test_engine = create_async_engine(settings.database_url, poolclass=NullPool)
TestSessionLocal = async_sessionmaker(test_engine, expire_on_commit=False)


@pytest_asyncio.fixture(autouse=True)
async def _reset_db():
    async with test_engine.begin() as conn:
        await conn.run_sync(Base.metadata.drop_all)
        await conn.run_sync(Base.metadata.create_all)
    yield


async def _override_get_db():
    async with TestSessionLocal() as session:
        yield session


app.dependency_overrides[get_db] = _override_get_db


@pytest_asyncio.fixture
async def client():
    transport = ASGITransport(app=app)
    async with AsyncClient(transport=transport, base_url="https://test") as ac:
        yield ac


@pytest.fixture
def sync_client(monkeypatch):
    """Sync TestClient (supports WebSocket tests). The WS handler's session
    maker is swapped to the NullPool test engine so its writes land in the
    same test database the async fixtures see. The lifespan's engine is also
    swapped: TestClient runs the lifespan on its own portal loop, and the
    pooled production engine would carry connections across loops."""
    import app.main as main_module
    import app.ws as ws_module

    monkeypatch.setattr(ws_module, "session_maker", TestSessionLocal)
    monkeypatch.setattr(main_module, "engine", test_engine)
    with TestClient(app, base_url="https://testserver") as tc:
        yield tc


@pytest_asyncio.fixture
async def db_session():
    async with TestSessionLocal() as session:
        yield session