from __future__ import annotations

import sys
import signal
from pathlib import Path
from types import ModuleType, SimpleNamespace
from typing import Any

from yolo_webui.config import MlflowConfig, TrainingConfig
from yolo_webui.trainer import TrainingEvent, TrainingRunner


class FakeProcess:
    def __init__(self) -> None:
        self.signals: list[int] = []
        self.terminate_calls = 0
        self.kill_calls = 0

    def send_signal(self, signum: int) -> None:
        self.signals.append(signum)

    def terminate(self) -> None:
        self.terminate_calls += 1

    def kill(self) -> None:
        self.kill_calls += 1

    def poll(self) -> None:
        return None


def test_runner_wires_yolo_callbacks_and_returns_output(
    monkeypatch: Any, tmp_path: Path
) -> None:
    settings_updates: list[dict[str, bool]] = []
    constructed: list[tuple[str, str]] = []
    train_arguments: list[dict[str, Any]] = []

    class FakeSettings:
        def update(self, values: dict[str, bool]) -> None:
            settings_updates.append(values)

    class FakeYOLO:
        def __init__(self, model: str, task: str) -> None:
            constructed.append((model, task))
            self.callbacks: dict[str, list[Any]] = {}
            self.trainer = SimpleNamespace(
                args=SimpleNamespace(epochs=2),
                epoch=0,
                metrics={},
                fitness=0.0,
                best_fitness=0.0,
                stop=False,
                save_dir=tmp_path / "run",
            )

        def add_callback(self, name: str, callback: Any) -> None:
            self.callbacks.setdefault(name, []).append(callback)

        def run_callbacks(self, name: str) -> None:
            for callback in self.callbacks.get(name, []):
                callback(self.trainer)

        def train(self, **kwargs: Any) -> None:
            train_arguments.append(kwargs)
            self.run_callbacks("on_train_start")
            for epoch in range(2):
                self.trainer.epoch = epoch
                self.trainer.metrics = {"metrics/mAP50": 0.5 + epoch / 10}
                self.trainer.fitness = 0.5 + epoch / 10
                self.trainer.best_fitness = self.trainer.fitness
                self.run_callbacks("on_fit_epoch_end")
            self.run_callbacks("on_train_end")

    fake_ultralytics = ModuleType("ultralytics")
    fake_ultralytics.YOLO = FakeYOLO  # type: ignore[attr-defined]
    fake_ultralytics.settings = FakeSettings()  # type: ignore[attr-defined]
    fake_trainers = ModuleType("yolo_webui.ultralytics_trainers")

    class FakeTrainer:
        pass

    fake_trainers.trainer_for_task = lambda _task: FakeTrainer  # type: ignore[attr-defined]
    monkeypatch.setitem(sys.modules, "ultralytics", fake_ultralytics)
    monkeypatch.setitem(sys.modules, "yolo_webui.ultralytics_trainers", fake_trainers)

    config = TrainingConfig(
        dataset="dataset.yaml",
        model="model.pt",
        task="pose",
        epochs=2,
        mlflow=MlflowConfig(enabled=False),
    )
    events: list[TrainingEvent] = []

    output = TrainingRunner().train(config, events.append)

    assert output == tmp_path / "run"
    assert constructed == [("models/model.pt", "pose")]
    assert settings_updates == [{"mlflow": False}]
    assert train_arguments[0]["data"] == "dataset.yaml"
    assert train_arguments[0]["verbose"] is True
    assert train_arguments[0]["trainer"] is FakeTrainer
    assert [event.kind for event in events] == ["info", "started", "epoch", "epoch", "success"]
    assert "mAP50=0.5" in events[2].message
    assert "mAP50=0.6" in events[3].message


def test_final_checkpoint_validation_is_not_reported_as_an_extra_epoch() -> None:
    events: list[TrainingEvent] = []
    trainer = SimpleNamespace(
        args=SimpleNamespace(epochs=1),
        epoch=1,
        metrics={"metrics/mAP50": 0.75},
        validator=SimpleNamespace(training=False),
    )

    TrainingRunner()._on_epoch_end(events.append)(trainer)

    assert events == []


def test_prepare_run_clears_previous_stop_request() -> None:
    runner = TrainingRunner()
    runner.request_stop()
    assert runner.stop_requested is True

    runner.prepare_run()

    assert runner.stop_requested is False


def test_early_stop_is_delivered_after_subprocess_ready() -> None:
    runner = TrainingRunner()
    process = FakeProcess()
    runner.request_stop()

    runner.set_subprocess(process, ready=False)
    assert process.signals == []

    runner.mark_subprocess_ready()

    assert process.signals == [signal.SIGTERM]
    assert process.terminate_calls == 0
    runner.clear_subprocess()


def test_ready_subprocess_receives_cooperative_signal_not_terminate() -> None:
    runner = TrainingRunner()
    process = FakeProcess()
    runner.set_subprocess(process, ready=True)

    runner.request_stop()

    assert process.signals == [signal.SIGTERM]
    assert process.terminate_calls == 0
    runner.clear_subprocess()