"""Tests for the pure parts of Tools/shadow_gap.py."""

import os
import sys

_TOOLS = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
sys.path.insert(0, _TOOLS)
for _sub in ("review", "gen", "unreal", "blender", "input"):
    sys.path.insert(0, os.path.join(_TOOLS, _sub))


import os
import sys
import unittest

from PIL import Image

sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
import shadow_gap as sg  # noqa: E402


def synthetic(object_bottom, shadow_top, size=(80, 120), background=(200, 200, 196)):
    """A grey frame with a dark block (object) and a dark strip (shadow) below it."""
    image = Image.new("RGB", size, background)
    pixels = image.load()
    for y in range(20, object_bottom):
        for x in range(30, 50):
            pixels[x, y] = (18, 18, 20)          # object: far darker than the surface
    for y in range(shadow_top, min(size[1] - 2, shadow_top + 12)):
        for x in range(30, 50):
            # shadow: a darkened version of the surface, as a real shadow is
            pixels[x, y] = (140, 140, 138)
    return image


class MeasureTests(unittest.TestCase):
    def test_contact_reads_as_contact(self):
        image = synthetic(object_bottom=60, shadow_top=61)
        image.save("/tmp/gigline-shadow-contact.png")
        result = sg.measure("/tmp/gigline-shadow-contact.png", (0.2, 0.05, 0.8, 0.95))
        self.assertEqual(result["verdict"], "contact")
        self.assertLessEqual(result["gap_px"], 2)

    def test_a_gap_reads_as_floating(self):
        image = synthetic(object_bottom=60, shadow_top=100)
        image.save("/tmp/gigline-shadow-float.png")
        result = sg.measure("/tmp/gigline-shadow-float.png", (0.2, 0.05, 0.8, 0.95))
        self.assertEqual(result["verdict"], "floating")
        self.assertGreater(result["gap_px"], result["object_height_px"] * 0.12)

    def test_empty_box_reports_an_error(self):
        image = Image.new("RGB", (40, 40), (200, 200, 200))
        image.save("/tmp/gigline-shadow-empty.png")
        result = sg.measure("/tmp/gigline-shadow-empty.png", (0.1, 0.1, 0.9, 0.9))
        self.assertIn("error", result)


class BorderTests(unittest.TestCase):
    def test_border_median_is_the_frame_colour(self):
        image = Image.new("RGB", (40, 40), (180, 190, 200))
        self.assertEqual(sg.border_median(image), (180, 190, 200))


if __name__ == "__main__":
    unittest.main()