#!/usr/bin/env python3
from __future__ import annotations

import importlib.util
import tempfile
import unittest
from pathlib import Path

from PIL import Image, ImageDraw


MODULE_PATH = Path(__file__).with_name("verify_visual_fidelity.py")
SPEC = importlib.util.spec_from_file_location("verify_visual_fidelity", MODULE_PATH)
assert SPEC is not None and SPEC.loader is not None
VERIFY = importlib.util.module_from_spec(SPEC)
SPEC.loader.exec_module(VERIFY)


class VisualFidelityTests(unittest.TestCase):
    def _image(self, box: tuple[int, int, int, int] | None = None) -> Image.Image:
        image = Image.new("RGB", (200, 100), "white")
        if box is not None:
            ImageDraw.Draw(image).rectangle(box, fill="black")
        return image

    def _contract(self) -> dict:
        return {
            "approved_master": {"aspect": 2.0},
            "runtime_canvas": {"bounds": "auto_centered"},
            "defaults": {
                "analysis_width": 200,
                "aspect_ratio_delta": 0.01,
                "anchor_delta": 0.02,
                "focal_scale_delta": 0.02,
                "occupancy_delta": 0.05,
                "static_region_mean_error": 0.01,
                "dynamic_detection": {
                    "difference_threshold": 0.1,
                    "minimum_component_area_px": 4,
                },
            },
            "regions": [
                {
                    "id": "subject",
                    "mode": "runtime_replacement",
                    "search_bounds": [0.0, 0.0, 1.0, 1.0],
                    "runtime_bounds": [0.2, 0.2, 0.2, 0.4],
                }
            ],
        }

    def _run(self, runtime_box: tuple[int, int, int, int]) -> dict:
        with tempfile.TemporaryDirectory() as directory:
            return VERIFY.run_verification(
                self._image((40, 20, 80, 60)),
                self._image(runtime_box),
                self._image(),
                self._contract(),
                Path(directory),
                Path("approved.png"),
                Path("runtime.png"),
                Path("static.png"),
            )

    def test_matching_rendered_dynamic_bounds_pass(self) -> None:
        report = self._run((40, 20, 80, 60))
        subject = report["checks"][1]
        self.assertEqual("PASS", report["result"])
        self.assertEqual([0.2, 0.2, 0.205, 0.41], subject["runtime_measurement"]["bounds"])
        self.assertIn("declared_runtime_bounds_ignored", subject)

    def test_copied_runtime_bounds_cannot_hide_shifted_pixels(self) -> None:
        report = self._run((110, 30, 180, 80))
        subject = report["checks"][1]
        self.assertEqual("FAIL_VISUAL_FIDELITY", report["result"])
        self.assertEqual([0.55, 0.3, 0.355, 0.51], subject["runtime_measurement"]["bounds"])
        self.assertGreater(subject["anchor_delta"], subject["anchor_tolerance"])
        self.assertGreater(subject["size_delta"], subject["size_tolerance"])


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