"""Hardware-free tests for _open_multi_usrp's transient-FX3 retry.

On B200/B210 the `uhd_find_devices` enumeration that runs right before opening
can leave the FX3 USB controller mid-reset, so the first MultiUSRP open fails
with "fx3 is in state 5". _open_multi_usrp retries transient USB states with a
short settle; a non-transient error is re-raised immediately.
"""

from __future__ import annotations

import sys
import types

import pytest


@pytest.fixture
def usrp_mod(monkeypatch):
    """Import the usrp module against a stub `uhd`, with time.sleep neutered."""
    saved_uhd = sys.modules.get("uhd")
    saved_usrp = sys.modules.get("ria_toolkit_oss.sdr.usrp")

    uhd = types.ModuleType("uhd")
    uhd.usrp = types.SimpleNamespace(MultiUSRP=None)  # set per-test
    sys.modules["uhd"] = uhd
    sys.modules.pop("ria_toolkit_oss.sdr.usrp", None)
    import ria_toolkit_oss.sdr.usrp as mod

    monkeypatch.setattr(mod.time, "sleep", lambda *_a, **_k: None)

    yield mod

    for name, m in (("uhd", saved_uhd), ("ria_toolkit_oss.sdr.usrp", saved_usrp)):
        if m is None:
            sys.modules.pop(name, None)
        else:
            sys.modules[name] = m


def _flaky_factory(fail_times, exc):
    """A MultiUSRP stand-in that raises `exc` the first `fail_times` calls."""
    calls = {"n": 0}

    def make(args):
        calls["n"] += 1
        if calls["n"] <= fail_times:
            raise exc
        return f"usrp<{args}>"

    make.calls = calls
    return make


def test_retries_transient_fx3_state_then_succeeds(usrp_mod):
    factory = _flaky_factory(2, RuntimeError("RuntimeError: fx3 is in state 5"))
    usrp_mod.uhd.usrp.MultiUSRP = factory

    out = usrp_mod._open_multi_usrp("name=B210,", attempts=4, settle_s=0)

    assert out == "usrp<name=B210,>"
    assert factory.calls["n"] == 3  # failed twice, third succeeded


def test_gives_up_after_attempts_and_raises_last(usrp_mod):
    factory = _flaky_factory(99, RuntimeError("fx3 is in state 5"))
    usrp_mod.uhd.usrp.MultiUSRP = factory

    with pytest.raises(RuntimeError, match="fx3 is in state 5"):
        usrp_mod._open_multi_usrp("name=B210,", attempts=3, settle_s=0)

    assert factory.calls["n"] == 3  # exactly `attempts` tries, no infinite loop


def test_non_transient_error_is_raised_immediately(usrp_mod):
    factory = _flaky_factory(99, RuntimeError("EnvironmentError: no UHD images"))
    usrp_mod.uhd.usrp.MultiUSRP = factory

    with pytest.raises(RuntimeError, match="no UHD images"):
        usrp_mod._open_multi_usrp("name=B210,", attempts=4, settle_s=0)

    assert factory.calls["n"] == 1  # not retried — fails fast


def test_success_on_first_try_does_not_retry(usrp_mod):
    factory = _flaky_factory(0, RuntimeError("fx3 is in state 5"))
    usrp_mod.uhd.usrp.MultiUSRP = factory

    out = usrp_mod._open_multi_usrp("addr=192.168.10.2,", attempts=4, settle_s=0)

    assert out == "usrp<addr=192.168.10.2,>"
    assert factory.calls["n"] == 1