"""Port selection and error explanation, using a fake reader library."""

import types

import pytest

import rdm_card_reader.reader as reader_module
from rdm_card_reader.card import CANDIDATE_PORTS
from rdm_card_reader.reader import explain_error, list_ports, open_reader


class FakeBaseReader:
    """Stands in for rdm6300.BaseReader; records the port it was built with."""

    fail_on = ()

    def __init__(self, port, heartbeat_interval=0.5):
        if port in type(self).fail_on:
            raise OSError("could not open port {}".format(port))
        self.port = port
        self.heartbeat_interval = heartbeat_interval
        self.started = False
        self.closed = False

    def start(self):
        self.started = True

    def close(self):
        self.closed = True


@pytest.fixture
def fake_library(monkeypatch):
    module = types.SimpleNamespace(BaseReader=FakeBaseReader)
    monkeypatch.setattr(reader_module, "rdm6300", module)
    return module


@pytest.fixture(autouse=True)
def restore_library():
    original = reader_module.rdm6300
    yield
    reader_module.rdm6300 = original


def test_default_port_order_matches_the_workstation_app():
    assert CANDIDATE_PORTS == (
        "/dev/ttyS0", "/dev/ttyAMA0", "/dev/ttyUSB0", "/dev/ttyACM0",
    )


def test_first_working_port_wins(fake_library):
    FakeBaseReader.fail_on = ("/dev/ttyS0", "/dev/ttyAMA0")
    reader = open_reader(lambda event: None,
                         ports=["/dev/ttyS0", "/dev/ttyAMA0", "/dev/ttyUSB0"])
    assert reader is not None
    assert reader.port == "/dev/ttyUSB0"


def test_returns_none_when_no_port_works(fake_library):
    FakeBaseReader.fail_on = ("/dev/ttyS0", "/dev/ttyAMA0")
    assert open_reader(lambda event: None,
                       ports=["/dev/ttyS0", "/dev/ttyAMA0"]) is None


def test_failures_are_reported_with_the_port(fake_library):
    FakeBaseReader.fail_on = ("/dev/ttyS0",)
    seen = []
    open_reader(lambda event: None, ports=["/dev/ttyS0"],
                on_error=lambda port, message: seen.append((port, message)))
    assert seen and seen[0][0] == "/dev/ttyS0"


def test_heartbeat_interval_is_passed_through(fake_library):
    FakeBaseReader.fail_on = ()
    reader = open_reader(lambda event: None, ports=["/dev/ttyS0"],
                         heartbeat_interval=1.5)
    assert reader.heartbeat_interval == 1.5


def test_heartbeat_none_disables_removal_detection(fake_library):
    FakeBaseReader.fail_on = ()
    reader = open_reader(lambda event: None, ports=["/dev/ttyS0"],
                         heartbeat_interval=None)
    assert reader.heartbeat_interval is None


def test_events_are_forwarded_to_the_callback(fake_library):
    FakeBaseReader.fail_on = ()
    received = []
    reader = open_reader(received.append, ports=["/dev/ttyS0"])

    class Card:
        value = 7
        checksum = 1
        type = 15
        is_valid = True

    reader.card_inserted(Card())
    assert len(received) == 1
    assert received[0].value == 7
    assert received[0].event == "card_inserted"


def test_card_removed_with_none_is_ignored(fake_library):
    FakeBaseReader.fail_on = ()
    received = []
    reader = open_reader(received.append, ports=["/dev/ttyS0"])
    reader.card_removed(None)
    assert received == []


def test_invalid_card_is_forwarded(fake_library):
    FakeBaseReader.fail_on = ()
    received = []
    reader = open_reader(received.append, ports=["/dev/ttyS0"])

    class Card:
        value = 1
        checksum = 2
        type = 15
        is_valid = False

    reader.invalid_card(Card())
    assert received[0].event == "invalid_card"


def test_missing_library_raises(monkeypatch):
    monkeypatch.setattr(reader_module, "rdm6300", None)
    with pytest.raises(reader_module.ReaderUnavailable):
        open_reader(lambda event: None)


@pytest.mark.parametrize(
    "message,expected_fragment",
    [
        ("[Errno 13] Permission denied: '/dev/ttyS0'", "dialout"),
        ("could not open port /dev/nope", "device not found"),
        ("something else", "something else"),
    ],
)
def test_explain_error(message, expected_fragment):
    assert expected_fragment in explain_error("/dev/ttyS0", message)


def test_list_ports_shape():
    info = list_ports()
    assert set(info) == {"candidates", "detected"}
    assert [port for port, _ in info["candidates"]] == list(CANDIDATE_PORTS)