"""Exercise the connection state machine with a scripted serial peer."""

import queue
import sys
import types
import unittest
from unittest.mock import patch

from controller.link import Link


class HandshakeTests(unittest.TestCase):
    def run_peer(self, malformed=False):
        events = queue.Queue()
        link = Link("COM7", events)
        packets = []
        # Replay actual device ACK + CONNECT_INFO, then a link-complete ACK.
        # Peer data sequence 0x1d is independent of our outbound sequence 1.
        info = (
            bytes.fromhex("00 bb 01 1d 00 01 02 20")
            if malformed
            else bytes.fromhex("00 bb 01 1d 00 0b 02 10 01 34 30 04 01 02 04 05 01 b0")
        )
        reads = iter(
            (bytes.fromhex("00 bb 00 01 00 00 01"), info, bytes.fromhex("00 bb 00 02 00 00 02"))
        )

        class Peer:
            def __enter__(self):
                return self

            def __exit__(self, *args):
                pass

            def write(self, data):
                packets.append(data)
                return len(data)

            def read(self, size):
                try:
                    return next(reads)
                except StopIteration:
                    link.stop()
                    return b""

        with patch.dict(
            sys.modules, {"serial": types.SimpleNamespace(Serial=lambda *a, **k: Peer())}
        ):
            link.run()
        return packets, list(events.queue)

    def test_waits_for_peer_before_ready(self):
        packets, events = self.run_peer()
        self.assertEqual([p[6:-1] for p in packets], [b"\x01", b"\x04"])
        self.assertEqual(packets[1], bytes.fromhex("00 bb 01 02 00 01 04 08"))
        self.assertEqual(sum(kind == "ready" for kind, _ in events), 1)
        self.assertFalse(any(kind == "error" for kind, _ in events))

    def test_malformed_info_never_enables_controls(self):
        packets, events = self.run_peer(malformed=True)
        self.assertEqual(len(packets), 1)
        self.assertFalse(any(kind == "ready" for kind, _ in events))
        self.assertTrue(any(kind == "error" for kind, _ in events))