"""Rendering the red highlight, and leaving the cached diagram untouched."""

import cv2
import numpy as np
import pytest

from spareparts import config, index_db, lookup, overlay

pytestmark = pytest.mark.skipif(
    not config.DB_PATH.exists(), reason="run `python -m spareparts.build_index` first"
)


@pytest.fixture(scope="module")
def worm():
    conn = index_db.connect()
    try:
        part = lookup.find_part(conn, "30642")
    finally:
        conn.close()
    return part, part.occurrences[0]


def _red_pixels(image_bgr):
    b, g, r = image_bgr[:, :, 0], image_bgr[:, :, 1], image_bgr[:, :, 2]
    return (r > 180) & (g < 80) & (b < 80)


def test_load_diagram_reads_the_cached_png(worm):
    _, occurrence = worm
    image = overlay.load_diagram(occurrence.png_path)
    assert image.shape[:2] == (occurrence.img_h, occurrence.img_w)


def test_load_diagram_raises_on_a_missing_file(tmp_path):
    with pytest.raises(FileNotFoundError):
        overlay.load_diagram(tmp_path / "absent.png")


def test_annotation_does_not_modify_the_cached_image_on_disk(worm):
    part, occurrence = worm
    before = occurrence.png_path.read_bytes()
    image = overlay.load_diagram(occurrence.png_path)
    overlay.annotate(image, occurrence.highlights, part.part_no)
    assert occurrence.png_path.read_bytes() == before


def test_annotation_does_not_modify_the_array_passed_in(worm):
    part, occurrence = worm
    image = overlay.load_diagram(occurrence.png_path)
    original = image.copy()
    annotated = overlay.annotate(image, occurrence.highlights, part.part_no)
    assert np.array_equal(image, original), "the source array was drawn on"
    assert not np.array_equal(annotated, original), "nothing was drawn"


def test_red_rectangle_lands_on_the_stored_box(worm):
    part, occurrence = worm
    x0, y0, x1, y1 = occurrence.highlights[0].component_box
    image = overlay.load_diagram(occurrence.png_path)
    annotated = overlay.annotate(
        image, occurrence.highlights, part.part_no, show_callout_box=False
    )
    red = _red_pixels(annotated)

    # Red appears along each edge of the stored box...
    margin = 8
    assert red[max(0, y0 - margin) : y0 + margin, x0:x1].any(), "no top edge"
    assert red[y1 - margin : y1 + margin, x0:x1].any(), "no bottom edge"
    assert red[y0:y1, max(0, x0 - margin) : x0 + margin].any(), "no left edge"
    assert red[y0:y1, x1 - margin : x1 + margin].any(), "no right edge"

    # ...and nowhere far away from it, apart from the caption above the box.
    outside = red.copy()
    outside[max(0, y0 - 140) : y1 + margin, max(0, x0 - margin) : x1 + margin] = False
    assert outside.sum() < 50, "red drawn well outside the stored box"


def test_caption_shows_the_part_number(worm):
    """The number is drawn on a white plate near the box, not left implicit."""
    part, occurrence = worm
    x0, y0, _, _ = occurrence.highlights[0].component_box
    image = overlay.load_diagram(occurrence.png_path)
    annotated = overlay.annotate(image, occurrence.highlights, part.part_no)
    plate = annotated[max(0, y0 - 130) : y0, max(0, x0 - 10) : x0 + 400]
    # A white plate with red text on it.
    assert (plate == 255).all(axis=2).sum() > 500
    assert _red_pixels(plate).any()


def test_every_instance_is_boxed_and_numbered():
    """74506 is drawn four times on page 34; all four must be highlighted."""
    conn = index_db.connect()
    try:
        part = lookup.find_part(conn, "74506")
    finally:
        conn.close()
    occurrence = next(o for o in part.occurrences if o.pdf_page == 34)
    image = overlay.load_diagram(occurrence.png_path)
    annotated = overlay.annotate(
        image, occurrence.highlights, part.part_no, show_callout_box=False
    )
    red = _red_pixels(annotated)
    for highlight in occurrence.highlights:
        x0, y0, x1, y1 = highlight.component_box
        assert red[y0 : y1 + 1, x0 : x1 + 1].any(), f"instance at {highlight.component_box}"


def test_missing_component_box_is_skipped_not_crashed(worm):
    part, occurrence = worm
    blank = lookup.Highlight(
        instance=0, label_box=(10, 10, 100, 40), component_box=None,
        method="none", confidence=0.0, note="",
    )
    image = overlay.load_diagram(occurrence.png_path)
    annotated = overlay.annotate(image, [blank], part.part_no)
    assert annotated.shape == image.shape


def test_box_outside_the_image_is_clipped(worm):
    part, occurrence = worm
    huge = lookup.Highlight(
        instance=0, label_box=(0, 0, 50, 20),
        component_box=(-500, -500, occurrence.img_w + 999, occurrence.img_h + 999),
        method="leader", confidence=1.0, note="",
    )
    image = overlay.load_diagram(occurrence.png_path)
    annotated = overlay.annotate(image, [huge], part.part_no)
    assert annotated.shape == image.shape


def test_encode_png_round_trips(worm):
    part, occurrence = worm
    image = overlay.load_diagram(occurrence.png_path)
    data = overlay.encode_png(overlay.annotate(image, occurrence.highlights, part.part_no))
    assert data[:8] == b"\x89PNG\r\n\x1a\n"
    decoded = cv2.imdecode(np.frombuffer(data, np.uint8), cv2.IMREAD_COLOR)
    assert decoded.shape == image.shape