import io
import threading
from pathlib import Path

import pytest

from nisse_core.oplog import OpLog
from nisse_core.state.store import StateStore
from nisse_core.state.worker import InlineWorker, SerialWorker


@pytest.fixture
def worker() -> SerialWorker:
    w = SerialWorker()
    w.start()
    yield w
    w.stop(timeout=5)


def test_jobs_run_in_order_on_the_worker_thread(worker: SerialWorker) -> None:
    seen: list[tuple[int, str]] = []
    for n in range(3):
        worker.submit(lambda n=n: seen.append((n, threading.current_thread().name)))
    worker.call(lambda: None)  # drains everything queued before it

    assert [n for n, _ in seen] == [0, 1, 2]
    assert {name for _, name in seen} == {"nisse-worker"}


def test_call_returns_the_result_and_raises_the_error(worker: SerialWorker) -> None:
    assert worker.call(lambda: 42) == 42

    def boom() -> None:
        raise ValueError("bad job")

    with pytest.raises(ValueError, match="bad job"):
        worker.call(boom)


def test_a_failed_job_is_reported_and_the_worker_carries_on() -> None:
    errors: list[BaseException] = []
    worker = SerialWorker(on_error=errors.append)
    worker.start()

    def boom() -> None:
        raise RuntimeError("lost job")

    worker.submit(boom)
    assert worker.call(lambda: "still here") == "still here"
    assert [str(e) for e in errors] == ["lost job"]
    worker.stop(timeout=5)


def test_call_from_the_worker_itself_runs_inline(worker: SerialWorker) -> None:
    # Queueing behind itself would deadlock.
    assert worker.call(lambda: worker.call(lambda: "nested")) == "nested"


def test_the_store_is_usable_only_from_the_thread_that_owns_it(
    worker: SerialWorker, tmp_path: Path
) -> None:
    store = worker.call(
        lambda: StateStore(tmp_path / "state.db", oplog=OpLog("t", io.StringIO()))
    )
    assert worker.call(store.active_item) is None
    # The tripwire the worker design keeps on: any other thread fails loudly.
    with pytest.raises(Exception, match="same thread"):
        store.active_item()
    worker.call(store.close)


def test_inline_worker_defers_a_job_submitted_from_inside_a_job() -> None:
    worker = InlineWorker()
    order: list[str] = []

    def outer() -> None:
        order.append("outer start")
        worker.submit(lambda: order.append("inner"))
        order.append("outer end")

    worker.submit(outer)
    assert order == ["outer start", "outer end", "inner"]
    assert not worker.busy