import can
import pytest

from lingkong_motor_service.config import Settings
from lingkong_motor_service.protocol import build_open_loop_frame
from lingkong_motor_service.transport import (
    CanTransportError,
    DisabledCanTransport,
    PythonCanTransport,
)


class StubBus:
    def __init__(self) -> None:
        self.messages: list[can.Message] = []
        self.timeouts: list[float | None] = []
        self.shutdown_count = 0
        self.received_messages: list[can.Message] = []

    def send(self, message: can.Message, timeout: float | None = None) -> None:
        self.messages.append(message)
        self.timeouts.append(timeout)

    def shutdown(self) -> None:
        self.shutdown_count += 1

    def recv(self, timeout: float | None = None) -> can.Message | None:
        del timeout
        if not self.received_messages:
            return None
        return self.received_messages.pop(0)


def test_canalystii_configuration_and_standard_frame(monkeypatch: pytest.MonkeyPatch) -> None:
    captured: dict[str, object] = {}
    bus = StubBus()

    def open_bus(**kwargs: object) -> StubBus:
        captured.update(kwargs)
        return bus

    monkeypatch.setattr(can, "Bus", open_bus)
    transport = PythonCanTransport(Settings(hardware_enabled=True, can_channel=1, can_device=2))

    try:
        transport.send(build_open_loop_frame({1: 400, 2: -400}))

        assert captured == {
            "interface": "canalystii",
            "channel": 1,
            "device": 2,
            "bitrate": 1_000_000,
            "rx_queue_size": 256,
            "receive_own_messages": False,
        }
        assert bus.timeouts == [None]
        assert len(bus.messages) == 1
        assert bus.messages[0].arbitration_id == 0x280
        assert bus.messages[0].is_extended_id is False
        assert bytes(bus.messages[0].data) == bytes.fromhex("90 01 70 FE 00 00 00 00")
    finally:
        transport.shutdown()


def test_disabled_transport_fails_closed() -> None:
    with pytest.raises(CanTransportError, match="hardware access is disabled"):
        DisabledCanTransport().send(build_open_loop_frame({1: 0}))


def test_canalystii_can_wait_for_the_hardware_tx_queue(
    monkeypatch: pytest.MonkeyPatch,
) -> None:
    bus = StubBus()
    monkeypatch.setattr(can, "Bus", lambda **kwargs: bus)
    transport = PythonCanTransport(Settings(hardware_enabled=True))

    try:
        transport.send(
            build_open_loop_frame({}),
            tx_queue_timeout_s=0.1,
        )

        assert bus.timeouts == [0.1]
    finally:
        transport.shutdown()


def test_shutdown_is_idempotent_and_send_after_shutdown_fails(
    monkeypatch: pytest.MonkeyPatch,
) -> None:
    bus = StubBus()
    monkeypatch.setattr(can, "Bus", lambda **kwargs: bus)
    transport = PythonCanTransport(Settings(hardware_enabled=True))

    transport.shutdown()
    transport.shutdown()

    assert transport.is_open is False
    assert bus.shutdown_count == 1
    with pytest.raises(CanTransportError, match="CAN transport is closed"):
        transport.send(build_open_loop_frame({1: 0}))


def test_canalystii_receives_standard_status_frame(monkeypatch: pytest.MonkeyPatch) -> None:
    bus = StubBus()
    bus.received_messages.append(
        can.Message(
            arbitration_id=0x141,
            is_extended_id=False,
            data=bytes.fromhex("9C 4F 64 00 0A 00 34 12"),
        )
    )
    monkeypatch.setattr(can, "Bus", lambda **kwargs: bus)
    transport = PythonCanTransport(Settings(hardware_enabled=True))

    try:
        frame = transport.receive(timeout_s=0.01)

        assert frame is not None
        assert frame.arbitration_id == 0x141
        assert frame.data == bytes.fromhex("9C 4F 64 00 0A 00 34 12")
    finally:
        transport.shutdown()