"""Synthetic structural tests only; no OEM image or ARM execution is used."""

import hashlib
import importlib.util
from pathlib import Path
import unittest
from unittest.mock import patch


ROOT = Path(__file__).resolve().parents[2]
PATH = ROOT / "navigation/archived/v038/patch_nav_vehicle_speed_source.py"
SPEC = importlib.util.spec_from_file_location("archived_speed_patch", PATH)
MODULE = importlib.util.module_from_spec(SPEC)
SPEC.loader.exec_module(MODULE)


class ArchivedSpeedPatchTests(unittest.TestCase):
    def fixture(self):
        settings = dict(
            SETTER_OFFSET=16,
            SETTER_CONTINUE=20,
            CAVE_OFFSET=64,
            CAVE_SIZE=60,
            DISPLAY_CALL_SITES=(160, 168, 176, 184, 192),
            CONVERT_SPEED=256,
            SAFETY_CALL_SITE=200,
        )
        image = bytearray(320)
        image[16:20] = MODULE.SETTER_ORIGINAL
        for site in settings["DISPLAY_CALL_SITES"] + (settings["SAFETY_CALL_SITE"],):
            image[site:site + 4] = MODULE.encode_thumb_branch(site, 256, link=True)
        settings["SOURCE_SHA256"] = hashlib.sha256(image).hexdigest()
        return bytes(image), settings

    def test_unknown_original_is_rejected(self):
        with self.assertRaisesRegex(ValueError, "unknown source"):
            MODULE.patch_image(b"synthetic-not-a-library")

    def test_thumb_alignment_and_range_are_checked(self):
        self.assertEqual(MODULE.encode_thumb_branch(0x1000, 0x1004), b"\x00\xf0\x00\xb8")
        with self.assertRaisesRegex(ValueError, "halfword"):
            MODULE.encode_thumb_branch(0x1000, 0x1005)
        with self.assertRaisesRegex(ValueError, "out of range"):
            MODULE.encode_thumb_branch(0x1000, 0x2001004)

    def test_only_declared_windows_change(self):
        original, settings = self.fixture()
        with patch.multiple(MODULE, **settings):
            result = MODULE.patch_image(original)
        allowed = set(range(16, 20)) | set(range(64, 124))
        changed = {i for i, (a, b) in enumerate(zip(original, result)) if a != b}
        self.assertTrue(changed)
        self.assertLessEqual(changed, allowed)
        self.assertEqual(len(result), len(original))
        for site in settings["DISPLAY_CALL_SITES"] + (settings["SAFETY_CALL_SITE"],):
            self.assertEqual(result[site:site + 4], original[site:site + 4])

    def test_occupied_cave_is_rejected_even_with_matching_hash(self):
        original, settings = self.fixture()
        bad = bytearray(original)
        bad[64] = 1
        settings["SOURCE_SHA256"] = hashlib.sha256(bad).hexdigest()
        with patch.multiple(MODULE, **settings):
            with self.assertRaisesRegex(ValueError, "code cave"):
                MODULE.patch_image(bytes(bad))

    def test_changed_safety_call_is_rejected(self):
        original, settings = self.fixture()
        bad = bytearray(original)
        bad[200] ^= 1
        settings["SOURCE_SHA256"] = hashlib.sha256(bad).hexdigest()
        with patch.multiple(MODULE, **settings):
            with self.assertRaisesRegex(ValueError, "overspeed"):
                MODULE.patch_image(bytes(bad))


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