"""Tests for tools/ptr_constants.py.

The VT1200 firmware stores TMS34010 *bit* addresses: a 32-bit value P refers to
physical byte P >> 3.  ptr_constants.scan() finds those constants in an
address-ordered image and resolves where they point.
"""
import os
import struct
import sys
import unittest

HERE = os.path.dirname(os.path.abspath(__file__))
sys.path.insert(0, os.path.join(HERE, "tools"))

import ptr_constants

ROM_BASE = 0x07E40000


class ScanSyntheticTest(unittest.TestCase):
    def test_finds_string_pointer(self):
        img = bytearray(0x1000)
        img[0x100:0x100 + 11] = b"HELLO WORLD"
        ptr = (ROM_BASE + 0x100) << 3           # bit address of the string
        struct.pack_into("<I", img, 0x10, ptr)
        hits = list(ptr_constants.scan(bytes(img)))
        self.assertIn((0x10, ptr, 0x100, "string"), hits)

    def test_ignores_values_that_do_not_resolve(self):
        self.assertEqual(list(ptr_constants.scan(b"\xff" * 0x100)), [])


class ClassifyTest(unittest.TestCase):
    def test_printable_run_is_a_string(self):
        img = b"\x00" * 8 + b"ABCDEFGH"
        self.assertEqual(ptr_constants.classify(img, 8), "string")

    def test_non_printable_is_other(self):
        img = b"\x00" * 16
        self.assertEqual(ptr_constants.classify(img, 8), "other")

    def test_out_of_range_returns_none(self):
        self.assertIsNone(ptr_constants.classify(b"\x00\x01", 99))


class RealImageTest(unittest.TestCase):
    def test_known_pointer_resolves_to_its_string(self):
        path = os.path.join(HERE, "vt1200_v21.bin")
        if not os.path.exists(path):
            self.skipTest("image not built")
        with open(path, "rb") as fh:
            img = fh.read()
        by_value = {v: (off, tgt, kind) for off, v, tgt, kind in ptr_constants.scan(img)}
        self.assertIn(0x3F816ED8, by_value)
        off, tgt, kind = by_value[0x3F816ED8]
        self.assertEqual(tgt, 0xC2DDB)
        self.assertEqual(kind, "string")
        self.assertEqual(img[tgt:tgt + 15], b"Messages re-xmt")


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