"""固件工具测试 — 以原始镜像为黄金样本（app/ 只读）。"""
import zlib
from pathlib import Path

import pytest

from tools import fw

SAMPLE = Path(__file__).parent.parent / "app" / "firmware-PP_da14585_4.2_CH.img"


@pytest.fixture
def sample():
    return SAMPLE.read_bytes()


class TestParse:
    def test_header_fields(self, sample):
        info = fw.parse_image(sample)
        assert info["magic"] == 0x7051  # 'pQ'
        assert info["flags"] == 0x01AA
        assert info["body_size"] == len(sample) - 64
        assert info["crc_stored"] == zlib.crc32(sample[64:]) & 0xFFFFFFFF

    def test_crc_valid(self, sample):
        assert fw.parse_image(sample)["crc_valid"] is True

    def test_vector_table(self, sample):
        info = fw.parse_image(sample)
        assert info["initial_sp"] == 0x07FD2B58
        assert info["reset_handler"] == 0x07FC0525
        assert info["load_base"] == 0x07FC0000

    def test_bad_magic_rejected(self):
        with pytest.raises(ValueError):
            fw.parse_image(b"\x00" * 128)

    def test_bad_crc_reported(self, sample):
        corrupted = bytearray(sample)
        corrupted[100] ^= 0xFF
        assert fw.parse_image(bytes(corrupted))["crc_valid"] is False


class TestPack:
    def test_repack_roundtrip_byte_identical(self, sample):
        """解包→重打包 == 原文件（字节级）"""
        body = fw.unpack_body(sample)
        assert fw.pack_image(body, flags=0x01AA) == sample

    def test_pack_computes_crc(self):
        body = b"\x58\x2b\xfd\x07" + b"\x00" * 100
        img = fw.pack_image(body)
        info = fw.parse_image(img)
        assert info["crc_valid"] is True
        assert info["body_size"] == len(body)

    def test_patch_and_repack(self, sample):
        """修改体→重打包→CRC 更新且可解析"""
        body = bytearray(fw.unpack_body(sample))
        body[0x1000] ^= 0xAA
        img = fw.pack_image(bytes(body))
        info = fw.parse_image(img)
        assert info["crc_valid"] is True
        assert img != sample