from snapshot_sequence import MAX_SEQUENCE, SequenceCounter, SequenceWindow, is_newer, next_sequence


def test_next_sequence_skips_zero_after_wrap():
    assert next_sequence(0) == 1
    assert next_sequence(1) == 2
    assert next_sequence(MAX_SEQUENCE) == 1


def test_is_newer_is_wrap_safe():
    assert is_newer(1, 0)
    assert is_newer(2, 1)
    assert not is_newer(1, 1)
    assert not is_newer(1, 2)
    assert is_newer(1, MAX_SEQUENCE)
    assert not is_newer(MAX_SEQUENCE, 1)
    assert not is_newer(0, MAX_SEQUENCE)


def test_counter_and_window_enforce_latest_wins():
    counter = SequenceCounter()
    assert counter.current == 0
    assert counter.advance() == 1
    assert counter.advance() == 2
    counter.reset()
    assert counter.advance() == 1

    window = SequenceWindow()
    assert window.accept(1)
    assert not window.accept(1)
    assert window.accept(2)
    assert not window.accept(1)
    window.reset()
    assert window.accept(MAX_SEQUENCE)
    assert window.accept(1)
    assert not window.accept(MAX_SEQUENCE)


def test_invalid_sequence_inputs_are_rejected():
    assert not is_newer(-1, 0)
    assert not is_newer(1, -1)
    assert not is_newer(True, 0)
    assert not is_newer(1, MAX_SEQUENCE + 1)