#!/usr/bin/env python3
# testTwoMachines.py - run two copies of the patched game, each with its own SwiftLink, and cross
# connect their serial lines so whatever one transmits the other receives.
#
#   python3 testTwoMachines.py <disk.d64>
#
# VICE's -rsdev1 "host:port" makes the emulator the TCP *client*, so the two instances cannot be
# pointed at each other directly.  A relay in this script accepts both connections and forwards bytes
# between them - a null modem cable made of sockets.  It also logs every byte in both directions,
# which is what makes the exchange observable.
import os
import select
import socket
import sys
import threading
import time

sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
from viceHarness import ViceSession, aciaArgs, pickFreePort, readByte, SCRATCH

SHOTS = os.path.join(os.path.dirname(os.path.abspath(__file__)), "shots")


class NullModemRelay:
    def __init__(self):
        self.port = pickFreePort()
        self.listener = socket.socket()
        self.listener.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        self.listener.bind(("127.0.0.1", self.port))
        self.listener.listen(4)
        self.conns = []
        self.log = [bytearray(), bytearray()]
        self.running = True
        threading.Thread(target=self.serve, daemon=True).start()

    def serve(self):
        self.listener.settimeout(0.5)
        while self.running:
            readable = list(self.conns)
            if len(self.conns) < 2:
                try:
                    conn, _ = self.listener.accept()
                    conn.setblocking(False)
                    self.conns.append(conn)
                    print(f"[relay] connection {len(self.conns)}", flush=True)
                    continue
                except socket.timeout:
                    pass
                except OSError:
                    return
            if not readable:
                time.sleep(0.1)
                continue
            ready, _, _ = select.select(readable, [], [], 0.2)
            for conn in ready:
                try:
                    chunk = conn.recv(4096)
                except OSError:
                    chunk = b""
                if not chunk:
                    continue
                index = self.conns.index(conn)
                self.log[index] += chunk
                for other in self.conns:
                    if other is not conn:
                        try:
                            other.sendall(chunk)
                        except OSError:
                            pass

    def stop(self):
        self.running = False
        try:
            self.listener.close()
        except OSError:
            pass
        for conn in self.conns:
            try:
                conn.close()
            except OSError:
                pass


def pickModemOpponent(session, tag, answerKey):
    # Options menu: the highlighted row lives in $91D5, row 0 = COMPETE WITH MODEM OPPONENT.  Fire
    # picks it; the game then asks A/O (answer or originate) and then for space before it opens the
    # link, so keep offering both until the ACIA command register stops reading back zero.
    for _ in range(4):
        session.enterMonitor()
        row = readByte(session, 0x91D5)
        session.sock.sendall(b"x\n")
        session.recv(3)
        print(f"[{tag}] menu row = {row}", flush=True)
        if row == 0:
            break
        session.hold("KP_8", 250)
        time.sleep(0.8)
    session.hold("KP_0", 300)
    time.sleep(2)
    return answerKey


def answerModemPrompts(session, tag, answerKey):
    # aciaCommandShadow ($E5BE) is zero until configureUserPortLines has programmed the 6551, so it
    # is the cheapest "is the link open yet" test there is.
    for attempt in range(24):
        session.hold(answerKey, 250)
        session.hold("space", 250)
        time.sleep(1.5)
        session.enterMonitor()
        shadow = readByte(session, 0xE5BE)
        session.sock.sendall(b"x\n")
        session.recv(2)
        if shadow:
            print(f"[{tag}] link opened after {attempt + 1} attempt(s), "
                  f"command register = ${shadow:02X}", flush=True)
            return True
    print(f"[{tag}] link never opened", flush=True)
    return False


def forceCarrier(session, tag):
    # C= + C toggles carrierOverrideFlags ($E04A) bit 6, which makes the driver believe DCD is up.
    # Two machines on a direct cable have no carrier signal, so without this they sit in the Hayes
    # dialogue for ever.  VICE maps the Commodore key to left Ctrl.
    for _ in range(4):
        session.key("ctrl+c")
        time.sleep(1)
        session.enterMonitor()
        flags = readByte(session, 0xE04A)
        phase = readByte(session, 0xE040)
        session.sock.sendall(b"x\n")
        session.recv(2)
        print(f"[{tag}] carrierOverrideFlags = {flags}, connectionPhase = {phase}", flush=True)
        if flags:
            return True
    return False


def main():
    disk = os.path.abspath(sys.argv[1])
    os.makedirs(SHOTS, exist_ok=True)
    relay = NullModemRelay()
    print(f"relay on 127.0.0.1:{relay.port}", flush=True)
    args = aciaArgs(rsDevAddress=f"127.0.0.1:{relay.port}", baud=2400)
    a = ViceSession(disk, f"{SCRATCH}/two.a.vice.log", args, label="A")
    b = ViceSession(disk, f"{SCRATCH}/two.b.vice.log", args, label="B")
    try:
        a.connect()
        b.connect()
        a.bootPastLoader()
        b.bootPastLoader()
        a.findWindow()
        b.findWindow()
        a.focus()
        b.focus()
        time.sleep(8)
        a.shot(f"{SHOTS}/two01aMenu.png")
        b.shot(f"{SHOTS}/two01bMenu.png")

        # A answers, B originates - the two halves of the Hayes dialogue the driver expects.
        pickModemOpponent(a, "A", "a")
        pickModemOpponent(b, "B", "o")
        answerModemPrompts(a, "A", "a")
        answerModemPrompts(b, "B", "o")
        time.sleep(10)
        a.shot(f"{SHOTS}/two02aLinkOpen.png")
        b.shot(f"{SHOTS}/two02bLinkOpen.png")
        report(relay)

        # There is no carrier on a null modem cable, so tell both drivers to pretend there is one.
        forceCarrier(a, "A")
        forceCarrier(b, "B")
        time.sleep(20)
        a.shot(f"{SHOTS}/two03aCarrierForced.png")
        b.shot(f"{SHOTS}/two03bCarrierForced.png")
        report(relay)

        for session, tag in ((a, "A"), (b, "B")):
            session.enterMonitor()
            session.mon("m e030 e047")
            session.mon("m e5b8 e5bf")
            session.mon("m de00 de03")
            session.sock.sendall(b"x\n")
            session.recv(3)
        time.sleep(30)
        a.shot(f"{SHOTS}/two04aLater.png")
        b.shot(f"{SHOTS}/two04bLater.png")
        report(relay)
    finally:
        a.close()
        b.close()
        time.sleep(1)
        relay.stop()
        report(relay)


def report(relay):
    for i, buf in enumerate(relay.log):
        name = "AB"[i] if i < 2 else str(i)
        print(f"[relay] from {name}: {len(buf)} bytes: {bytes(buf[-120:])!r}", flush=True)


if __name__ == "__main__":
    main()