"""Test fixtures: fresh temp-file SQLite DB per test session (spec §8.4)."""

import os
import tempfile

import httpx
import pytest

# Must be set before any app module is imported (engine binds at import time)
_tmpdir = tempfile.mkdtemp(prefix="calcount-test-")
os.environ["CALCOUNT_DATABASE_URL"] = f"sqlite:///{_tmpdir}/test.db"

from fastapi.testclient import TestClient  # noqa: E402

from database import run_migrations  # noqa: E402
from main import app  # noqa: E402


@pytest.fixture(scope="session")
def client():
    run_migrations()
    with TestClient(app) as c:
        yield c


@pytest.fixture
def off_mock(monkeypatch):
    """Replace _default_client() in services.off with a mock client backed
    by httpx.MockTransport. Tests assign off_mock.handler to control
    responses.

    Usage:
        def test_foo(client, off_mock):
            def handler(request):
                return httpx.Response(200, json={...})
            off_mock.handler = handler
            resp = client.get("/api/off/product/123")
    """
    state = _MockState()

    def _make_mock_client():
        return httpx.Client(
            transport=httpx.MockTransport(lambda req: state.handler(req))
        )

    import services.off as off_mod
    monkeypatch.setattr(off_mod, "_default_client", _make_mock_client)
    return state


class _MockState:
    """Mutable state so tests can set .handler after fixture injection."""
    def __init__(self):
        self.handler = None