"""Python nodes run in a worker process, and stay there when things go wrong."""

import sys
import threading
import time
from collections.abc import Iterator

import pytest

from app.flow.artifacts import ArtifactStore
from app.flow.messages import DType, MessageSpec
from app.flow.worker_main import ARTIFACT_DIR_ENV
from app.flow.workers import NodeCancelled, NodeTimeout, PythonWorkerPool


@pytest.fixture
def pool() -> Iterator[PythonWorkerPool]:
    # One worker: a respawn is then provably the same slot coming back.
    worker_pool = PythonWorkerPool(python=sys.executable, size=1)
    worker_pool.start()
    yield worker_pool
    worker_pool.stop()


def run(pool: PythonWorkerPool, code: str, node: str = "demo", **kwargs):
    return pool.run(
        "demo", node, code, kwargs, {"factor": 2}, f"demo.{node}", timeout=5
    )


def test_a_node_returns_its_value_and_what_it_printed(pool, capsys):
    result = run(
        pool,
        "def process(value, params):\n"
        "    print('seen', value)\n"
        "    return {'out': value * params['factor']}\n",
        value=21,
    )
    assert result == {"out": 42}
    # The proxy writes them to stdout, which is where the engine's tee is.
    assert "seen 21" in capsys.readouterr().out


def test_a_failure_keeps_its_class_and_points_at_the_node(pool):
    with pytest.raises(Exception) as caught:
        run(pool, "def process(params):\n    raise ValueError('bad input')\n")

    # The engine renders a node error as "<class>: <message>", so both have to
    # survive the trip.
    assert type(caught.value).__name__ == "ValueError"
    assert str(caught.value) == "bad input"
    assert "<node demo." in caught.value.remote_traceback
    assert "ValueError: bad input" in caught.value.remote_traceback


def test_a_node_that_kills_its_worker_is_an_ordinary_error(pool):
    with pytest.raises(Exception, match="worker died"):
        run(pool, "import os\n\n\ndef process(params):\n    os._exit(1)\n")

    assert run(pool, "def process(params):\n    return {'out': 1}\n") == {"out": 1}


def test_a_node_that_runs_too_long_is_killed_and_the_pool_recovers(pool):
    started = time.monotonic()
    with pytest.raises(NodeTimeout):
        pool.run(
            "demo",
            "slow",
            "import time\n\n\ndef process(params):\n    time.sleep(30)\n",
            {},
            {},
            "demo.slow",
            timeout=1,
        )
    assert time.monotonic() - started < 10

    # The killed worker's slot is refilled on the next call.
    assert run(pool, "def process(params):\n    return {'out': 2}\n") == {"out": 2}


def test_a_running_node_can_be_cancelled(pool):
    def stop_it() -> None:
        for _ in range(100):
            if pool.cancel("demo.slow"):
                return
            time.sleep(0.05)

    stopper = threading.Thread(target=stop_it)
    stopper.start()
    try:
        with pytest.raises(NodeCancelled):
            pool.run(
                "demo",
                "slow",
                "import time\n\n\ndef process(params):\n    time.sleep(30)\n",
                {},
                {},
                "demo.slow",
                timeout=30,
            )
    finally:
        stopper.join()


def test_a_result_that_is_not_json_is_refused(pool):
    with pytest.raises(Exception, match="cannot be sent back as JSON"):
        run(pool, "def process(params):\n    return {'out': {1, 2}}\n")


def test_compiling_reports_where_the_source_is_wrong(pool):
    assert pool.compile("demo", "broken", "def process(params)\n    return {}\n")
    assert pool.compile("demo", "fine", "def process(params):\n    return {}\n") is None


def test_a_node_imports_the_standard_library_not_the_engines_own_modules(pool):
    # The worker script lives in app/flow, which holds queue.py, secrets.py and
    # more; the interpreter would put that directory first on sys.path.
    result = run(
        pool,
        "import queue\nimport secrets\n\n\n"
        "def process(params):\n"
        "    return {'out': [queue.Queue().qsize(), len(secrets.token_hex(4))]}\n",
    )
    assert result == {"out": [0, 8]}


def test_the_engines_secrets_are_not_in_a_workers_environment(pool, monkeypatch):
    monkeypatch.setenv("SECRET_KEY", "not-for-nodes")
    monkeypatch.setenv("POSTGRES_PASSWORD", "not-for-nodes")
    monkeypatch.setenv("FLUKSIO_HARMLESS", "fine")
    # A fresh process, so it is built from the environment set just now.
    pool.respawn_all()

    result = run(
        pool,
        "import os\n\n\n"
        "def process(params):\n"
        "    return {'out': [k for k in ('SECRET_KEY', 'POSTGRES_PASSWORD',\n"
        "                                'FLUKSIO_HARMLESS') if k in os.environ]}\n",
    )
    assert result == {"out": ["FLUKSIO_HARMLESS"]}


def test_a_pool_can_stop_while_a_node_is_running(pool):
    # One slot, taken by a node that will not finish on its own, and a second
    # call queued behind it. The engine's node threads are not daemons, so a
    # wait here is a shutdown that never completes.
    outcomes: list[str] = []

    def call(node: str) -> None:
        try:
            pool.run(
                "demo",
                node,
                "import time\n\n\ndef process(params):\n    time.sleep(60)\n",
                {},
                {},
                f"demo.{node}",
                timeout=60,
            )
            outcomes.append("returned")
        except Exception as exc:
            outcomes.append(type(exc).__name__)

    busy = threading.Thread(target=call, args=("busy",))
    busy.start()
    # Let the first one take the slot, so the second is blocked acquiring it.
    time.sleep(1)
    waiting = threading.Thread(target=call, args=("waiting",))
    waiting.start()
    time.sleep(0.2)

    pool.stop()
    for thread in (busy, waiting):
        thread.join(timeout=10)
        assert not thread.is_alive()
    assert len(outcomes) == 2

    with pytest.raises(Exception, match="shutting down"):
        run(pool, "def process(params):\n    return {'out': 1}\n")


# -----------------------------------------------------------------------------
# Producing values before returning: a generator node
# -----------------------------------------------------------------------------


def test_a_generator_node_publishes_each_yield_and_returns_the_end(pool):
    seen = []
    result = pool.run(
        "demo",
        "train",
        "def process(params):\n"
        "    for step in range(3):\n"
        "        yield {'loss': 1.0 / (step + 1)}\n"
        "    return {'weights': 'w', 'final_loss': 0.25}\n",
        {},
        {},
        "demo.train",
        timeout=5,
        run_id="r1",
        on_event=seen.append,
    )

    # What it returned is the node's output; what it yielded went out as it
    # happened, on the same ports.
    assert result == {"weights": "w", "final_loss": 0.25}
    assert [event["outputs"] for event in seen] == [
        {"loss": 1.0},
        {"loss": 0.5},
        {"loss": 1 / 3},
    ]
    # Every frame says which call it belongs to, so a sweep can tell them apart.
    assert {event["call_id"] for event in seen} == {"r1:demo.train"}


def test_without_a_return_the_last_yield_is_the_result(pool):
    seen = []
    result = pool.run(
        "demo",
        "count",
        "def process(params):\n"
        "    yield {'out': 1}\n"
        "    yield {'out': 2}\n"
        "    yield {'out': 3}\n",
        {},
        {},
        "demo.count",
        timeout=5,
        on_event=seen.append,
    )

    assert result == {"out": 3}
    assert [event["outputs"] for event in seen] == [{"out": 1}, {"out": 2}]


def test_emit_reaches_the_same_ports_from_inside_a_callback(pool):
    # A value produced somewhere a yield cannot reach — inside a framework's
    # callback — is still an output rather than a log.
    seen = []
    result = pool.run(
        "demo",
        "fit",
        "import fluksio\n"
        "def process(params):\n"
        "    def on_epoch(n):\n"
        "        fluksio.emit(loss=1.0 / (n + 1))\n"
        "    for epoch in range(2):\n"
        "        on_epoch(epoch)\n"
        "    return {'done': True}\n",
        {},
        {},
        "demo.fit",
        timeout=5,
        on_event=seen.append,
    )

    assert result == {"done": True}
    assert [event["outputs"] for event in seen] == [{"loss": 1.0}, {"loss": 0.5}]


def test_a_plain_function_still_just_returns(pool):
    seen = []
    assert run(pool, "def process(params):\n    return {'out': 7}\n") == {"out": 7}
    assert seen == []


def test_events_hold_off_the_timeout_but_silence_does_not(pool):
    # The deadline measures silence: a node yielding every 0.05s stays alive
    # well past a 0.3s timeout, which is what a two-hour training needs.
    result = pool.run(
        "demo",
        "slow",
        "import time\n"
        "def process(params):\n"
        "    for step in range(12):\n"
        "        time.sleep(0.05)\n"
        "        yield {'beat': step}\n"
        "    return {'done': True}\n",
        {},
        {},
        "demo.slow",
        timeout=0.3,
        run_id="r2",
        on_event=lambda _event: None,
    )
    assert result == {"done": True}

    with pytest.raises(NodeTimeout):
        pool.run(
            "demo",
            "quiet",
            "import time\ndef process(params):\n    time.sleep(2)\n    return {}\n",
            {},
            {},
            "demo.quiet",
            timeout=0.3,
        )


def test_cancelling_one_run_leaves_the_same_node_in_another_alone(pool):
    # Keyed by (run, node): cancelling a config of a sweep must not kill the
    # rest of it. With one slot the second run is not executing, so the check
    # is that the pool refuses to find it rather than killing the wrong worker.
    started = threading.Event()

    def hold():
        try:
            pool.run(
                "demo",
                "hold",
                "import time\ndef process(params):\n    time.sleep(5)\n    return {}\n",
                {},
                {},
                "demo.hold",
                timeout=10,
                run_id="run-a",
            )
        except Exception:
            pass
        finally:
            started.set()

    thread = threading.Thread(target=hold, daemon=True)
    thread.start()
    time.sleep(0.5)

    assert pool.cancel("demo.hold", run_id="run-b") is False
    assert pool.cancel("demo.hold", run_id="run-a") is True
    started.wait(timeout=5)
    thread.join(timeout=5)


def test_a_node_saves_and_loads_an_artifact(tmp_path):
    # Bytes never travel as a message: the node stores them and returns a
    # reference, which the next node opens.
    store = ArtifactStore(tmp_path / "artifacts")
    pool = PythonWorkerPool(
        python=sys.executable, size=1, env={ARTIFACT_DIR_ENV: str(store.root)}
    )
    pool.start()
    try:
        ref = pool.run(
            "demo",
            "save",
            "import fluksio\n"
            "def process(params):\n"
            "    return {'weights': fluksio.save_artifact(b'x' * 2048, 'w.npz')}\n",
            {},
            {},
            "demo.save",
            timeout=10,
        )["weights"]

        assert ref["size"] == 2048
        assert MessageSpec(name="weights", dtype=DType.ARTIFACT).check(ref) is None
        assert store.path(ref["digest"]) is not None

        loaded = pool.run(
            "demo",
            "load",
            "import fluksio\n"
            "def process(weights, params):\n"
            "    with open(fluksio.load_artifact(weights), 'rb') as f:\n"
            "        return {'size': len(f.read())}\n",
            {"weights": ref},
            {},
            "demo.load",
            timeout=10,
        )
        assert loaded == {"size": 2048}
    finally:
        pool.stop()