import pytest

from tiny_computer_agent import Element, FakeScreen, Observation


def test_element_center_is_the_middle_of_the_box():
    assert Element("Save", x=320, y=120, width=80, height=24).center == (360, 132)


def test_element_center_falls_back_to_corner_without_size():
    assert Element("dot", x=5, y=7).center == (5, 7)


def test_element_rejects_empty_label():
    with pytest.raises(ValueError, match="non-empty"):
        Element("   ")


def test_element_rejects_negative_geometry():
    with pytest.raises(ValueError, match="non-negative"):
        Element("Save", x=-5)


def test_fake_screen_advances_then_holds_the_last_frame():
    screen = FakeScreen([(Element("A"),), (Element("B"),)])
    assert [e.label for f in range(4) for e in screen.capture().elements] == ["A", "B", "B", "B"]
    assert screen.captures == 4


def test_find_prefers_exact_match_over_substring():
    observation = Observation(elements=(
        Element("Save as"), Element("Save"), Element("Save all"),
    ))
    assert observation.find("Save").label == "Save"       # exact wins
    assert observation.find("save as").label == "Save as"  # case-insensitive
    assert observation.find("ave a").label == "Save as"    # substring fallback
    assert observation.find("Quit") is None


def test_summary_lists_elements_and_truncates():
    observation = Observation(
        index=2,
        elements=tuple(Element(f"button {i}") for i in range(5)),
        text="  Untitled\n  document ",
    )
    summary = observation.summary(max_elements=3)
    assert "step 2" in summary
    assert "Untitled document" in summary          # whitespace collapsed
    assert "button 0" in summary
    assert "and 2 more" in summary


def test_summary_admits_when_there_is_no_index():
    assert "no element index" in Observation().summary()