"""Tests for lat/probe/lat_probe.py — validated against a captured real frame."""
import os
import sys
import unittest

HERE = os.path.dirname(os.path.abspath(__file__))
sys.path.insert(0, HERE)
import lat_probe as lp  # noqa: E402

# LAT payload of vt-session.pcap frame 15 (terminal -> host): flags=0x02 (Master,
# type=Run), nbr_slots=1, dst_cir=0x0001, src_cir=0x5460, seq=5, ack=6,
# slot: dst=1 src=1 byte_count=1 credits=0 type=Data_a data='a'
CAPTURED_PAYLOAD = bytes.fromhex("02010100605 405060101010061".replace(" ", ""))


class BuildTest(unittest.TestCase):
    def test_matches_the_captured_frame(self):
        f = lp.build_run(lp.VT1200_MAC, "2c:16:db:a0:e7:b1", 1,
                         [(1, 1, 1, 0, 0, b"\x61")],
                         dst_cir=1, src_cir=0x5460, seq=5, ack=6)
        self.assertEqual(len(f), 60)
        self.assertEqual(f[14:14 + len(CAPTURED_PAYLOAD)], CAPTURED_PAYLOAD)

    def test_parse_roundtrip(self):
        f = lp.build_run(lp.VT1200_MAC, "2c:16:db:a0:e7:b1", 255,
                         [(1, 1, 4, 0, 0, b"AAAA")])
        p = lp.parse_frame(f)
        self.assertEqual(p["nbr_slots"], 255)
        self.assertEqual(p["type"], 0)
        self.assertTrue(p["master"])
        self.assertEqual(p["slots"][0][5], b"AAAA")

    def test_malformed_count_is_written_verbatim(self):
        # the whole point: claim 255 slots while carrying one
        f = lp.build_run(lp.VT1200_MAC, "2c:16:db:a0:e7:b1", 255,
                         [(1, 1, 1, 0, 0, b"z")])
        self.assertEqual(f[15], 255)     # LAT+1


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