import pytest

from tiny_computer_agent import Element, FakeScreen, Observation
from tiny_computer_agent.demo import fake_desktop, write_fake_desktop
from tiny_computer_agent.observe import ImageScreen
from tiny_computer_agent.perception import (
    DetectorUnavailable, IndexedScreen, OcrDetector, detector_available, make_detector,
)

BOX = [[10, 10], [80, 10], [80, 30], [10, 30]]


class FakeDetector:
    name = "fake"

    def __init__(self, elements=(), error=None):
        self.elements = tuple(elements)
        self.error = error

    def detect(self, image):
        if self.error is not None:
            raise self.error
        return self.elements


def test_low_confidence_boxes_are_dropped():
    assert OcrDetector(min_score=0.9)._to_element(BOX, "Save", 0.5) is None


def test_prose_fragments_and_punctuation_are_not_widgets():
    detector = OcrDetector(max_label_chars=20, min_label_chars=2)
    assert detector._to_element(BOX, "a long sentence that is not a widget", 1.0) is None
    assert detector._to_element(BOX, "S", 1.0) is None
    assert detector._to_element(BOX, " ... ", 1.0) is None
    assert detector._to_element(BOX, " first ", 1.0).label == "first"


def test_a_box_becomes_a_clickable_element():
    element = OcrDetector()._to_element(BOX, "Save", 0.99)
    assert (element.x, element.y, element.width, element.height) == (10, 10, 70, 20)
    assert element.center == (45, 20)


def test_indexed_screen_replaces_elements_with_detected_ones():
    screen = IndexedScreen(
        FakeScreen([(Element("stale"),)]), FakeDetector((Element("Save"), Element("Cancel")))
    )
    observation = screen.capture()
    assert [e.label for e in observation.elements] == ["Save", "Cancel"]
    assert observation.text == "Save Cancel"          # text filled from the index


def test_indexed_screen_keeps_text_from_the_source():
    screen = IndexedScreen(FakeScreen([(Element("x"),)], text="hello"),
                           FakeDetector((Element("Save"),)))
    assert screen.capture().text == "hello"


def test_a_perception_error_does_not_kill_the_run():
    screen = IndexedScreen(FakeScreen([(Element("x"),)]), FakeDetector(error=ValueError("boom")))
    observation = screen.capture()
    assert observation.elements == ()
    assert "perception error" in observation.text


def test_a_missing_engine_is_reported_loudly():
    screen = IndexedScreen(FakeScreen([(Element("x"),)]),
                           FakeDetector(error=DetectorUnavailable("no engine")))
    with pytest.raises(DetectorUnavailable):
        screen.capture()


def test_unknown_detector_names_are_reported():
    available, detail = detector_available("nope")
    assert available is False and "unknown detector" in detail
    with pytest.raises(DetectorUnavailable):
        make_detector("nope")


def test_image_screen_replays_a_still_and_holds_it(tmp_path):
    path = write_fake_desktop(tmp_path / "screen.png")
    screen = ImageScreen(str(path))
    assert screen.capture().frame.size == screen.capture().frame.size
    assert isinstance(screen.capture().text, str)


def test_image_screen_rejects_something_empty():
    with pytest.raises(ValueError):
        ImageScreen([])


def test_the_synthetic_desktop_looks_like_the_intended_screen():
    image = fake_desktop()
    assert image.size == (720, 460)


@pytest.mark.skipif(not detector_available("ocr")[0], reason="no OCR engine installed")  # conftest.require_ocr is the in-test form
def test_real_ocr_reads_a_real_screenshot():
    """The whole point: pixels in, labelled elements with usable coordinates out."""
    elements = OcrDetector().detect(fake_desktop())
    labels = [e.label for e in elements]
    assert len(elements) >= 3, labels
    assert any(e.matches("Save") for e in elements), labels

    save = next(e for e in elements if e.matches("Save"))
    # the Save button is drawn at (200..380, 265..300)
    assert 200 <= save.center[0] <= 380
    assert 260 <= save.center[1] <= 310


@pytest.mark.skipif(not detector_available("ocr")[0], reason="no OCR engine installed")  # conftest.require_ocr is the in-test form
def test_ocr_index_plugs_straight_into_a_click():
    """Label -> pixel resolution on coordinates the detector actually produced."""
    from tiny_computer_agent import Action, resolve_point

    observation = Observation(elements=OcrDetector().detect(fake_desktop()))
    point = resolve_point(Action("click", label="Save"), observation)
    assert point is not None
    assert 200 <= point[0] <= 380