#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""Offline sample-frame selftest for iec104_master.py RX decode (task-21/m104fix).

Why offline (no bench): the 2026-10-25 big-window leg proved on the wire that the
slave answers an out-of-range C_SE_NC_1 with type=50 and cause byte 0x47 (cot 7 |
PN 0x40) -- two captured events: 51.0 @ 0x8030 and 2.0 @ 0x8034. The old RX path
looked for PN in byte[3] (OA byte, always 0) and did not mask the cause byte, so
such frames decoded as cot=71/pn=False and actcon_of(type, True) could never match
(negative-confirm PN was never asserted on hardware before that window).

These tests pin the FIXED decoder against reconstructed sample frames (identical to
the captured wire bytes: type, vsq=1, cause, oa, ca(LE16), echoed obj ioa3+float4+
qdc1). Pure stdlib, no socket, no hardware.

Known in-house-format limitation (NOT reachable on the wire today, kept visible):
the RBT bit4 lives inside the 6-bit cause field of the in-house 6-byte head, so a
cause value 16..23 would collide with RBT=1. The firmware never sets RBT on TX
(iec104_link.c passes cot_hi=0/0x40 only); proper fix belongs to the standard
COT=2 rework (registry: 104 ASDU head in-house-COT1 compression), not this task.

Usage: python test/host/test_iec104_master_rx.py [-v]
Exit code: 0 = all PASS.
Created 2026-10-25 (lane-d, task-21).
"""
import os
import struct
import sys
import unittest

sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))

import iec104_master as m104  # noqa: E402

CA = m104.CA


def actcon_frame(cause_byte, ioa, val):
    """Rebuild a slave C_SE actcon exactly as iec104_link.c s_cmd_con echoes it."""
    obj = m104.put_ioa(ioa) + struct.pack("<f", val) + bytes([0x00])
    return bytes([m104.T_C_SE_NC_1, 0x01, cause_byte, 0x00,
                  CA & 0xFF, (CA >> 8) & 0xFF]) + obj


class DecodeCot(unittest.TestCase):
    """Pure-cause-byte semantics: wire bytes captured in the 2026-10-25 window."""

    def test_reject_cause_0x47(self):
        # captured x2: "RX I type=50 cot=71" == 7|0x40 pre-fix display
        self.assertEqual(m104.decode_cot(0x47), (7, True))

    def test_accept_cause_0x07(self):
        self.assertEqual(m104.decode_cot(0x07), (7, False))

    def test_reject_frames_carry_expected_values(self):
        f1 = actcon_frame(0x47, 0x8030, 51.0)
        f2 = actcon_frame(0x47, 0x8034, 2.0)
        self.assertEqual(f1[2], 71)
        self.assertEqual(f2[2], 71)
        # cause value survives masking, flags are gone from cot
        self.assertEqual(m104.decode_cot(f1[2]), (7, True))


class EndToEndMatch(unittest.TestCase):
    """decoder output -> events tuple -> actcon_of matcher (what window waits on)."""

    def test_reject_matches_negative_actcon(self):
        f = actcon_frame(0x47, 0x8030, 51.0)
        cot, pn = m104.decode_cot(f[2])
        ev = ("asdu", (f[0], cot, pn, f[6:]))
        self.assertTrue(m104.actcon_of(m104.T_C_SE_NC_1, True)(ev))
        # old wrong decode would build (50, 71, False) and miss:
        legacy = ("asdu", (f[0], f[2], (f[3] & m104.COT_PN) != 0, f[6:]))
        self.assertFalse(m104.actcon_of(m104.T_C_SE_NC_1, True)(legacy))

    def test_positive_still_matches_positive(self):
        f = actcon_frame(0x07, 0x8030, 0.7)
        cot, pn = m104.decode_cot(f[2])
        ev = ("asdu", (f[0], cot, pn, f[6:]))
        self.assertTrue(m104.actcon_of(m104.T_C_SE_NC_1, False)(ev))
        self.assertFalse(m104.actcon_of(m104.T_C_SE_NC_1, True)(ev))

    def test_matcher_none_wants_any_pn(self):
        for cause in (0x07, 0x47):
            cot, pn = m104.decode_cot(cause)
            ev = ("asdu", (50, cot, pn, b""))
            self.assertTrue(m104.actcon_of(m104.T_C_SE_NC_1)(ev))


if __name__ == "__main__":
    unittest.main(verbosity=2)