#!/usr/bin/env python3
import argparse
import glob
import sys
import time

try:
    import serial
except ImportError:
    print("need pyserial:  sudo apt install python3-serial  (or pip3 install pyserial)")
    sys.exit(1)


def list_ports():
    ports = sorted(glob.glob("/dev/ttyUSB*") + glob.glob("/dev/ttyACM*") + glob.glob("/dev/ttyS*"))
    for p in ports:
        print(p)
    if not ports:
        print("no serial ports found")
    return ports


def open_port(name, baud):
    sp = serial.Serial(None, baud, bytesize=8, parity="N", stopbits=1, timeout=0.3)
    sp.port = name
    sp.open()
    return sp


def drain(sp, seconds):
    deadline = time.time() + seconds
    buf = b""
    while time.time() < deadline:
        chunk = sp.read(256)
        if chunk:
            buf += chunk
    return buf


def show(buf):
    if not buf:
        return "(no bytes)"
    text = buf.decode("ascii", "replace").replace("\n", "\\n").replace("\r", "\\r")
    hexs = " ".join(f"{b:02X}" for b in buf)
    return f"ascii[{text}]  hex[{hexs}]"


def main():
    ap = argparse.ArgumentParser(description="RS485 bus test tool for LPC verification")
    ap.add_argument("-l", "--list", action="store_true", help="list serial ports")
    ap.add_argument("-p", "--port", default="/dev/ttyUSB0")
    ap.add_argument("-b", "--baud", type=int, default=9600)
    ap.add_argument("-s", "--send", help='text to send, \\n \\r escaped')
    ap.add_argument("-w", "--listen", type=float, default=0, help="seconds to listen after send")
    ap.add_argument("-i", "--interactive", action="store_true", help="read line from stdin, send, show reply")
    args = ap.parse_args()

    if args.list:
        list_ports()
        return

    sp = open_port(args.port, args.baud)
    print(f"opened {args.port} @ {args.baud} 8N1, Ctrl+C to exit")
    try:
        if args.send:
            payload = args.send.replace("\\n", "\n").replace("\\r", "\r").encode("ascii")
            sp.write(payload)
            sp.flush()
            print(f"TX: {payload!r}")
        if args.interactive:
            while True:
                line = input("TX> ")
                if not line:
                    continue
                sp.write((line + "\n").encode("ascii"))
                sp.flush()
                print("RX:", show(drain(sp, 0.3)))
        if args.listen > 0:
            print("RX:", show(drain(sp, args.listen)))
    finally:
        sp.close()


if __name__ == "__main__":
    main()