import serial, sys, time

port = sys.argv[1] if len(sys.argv) > 1 else "COM8"
baud = int(sys.argv[2]) if len(sys.argv) > 2 else 115200
outfile = sys.argv[3] if len(sys.argv) > 3 else "serial_capture.log"

while True:
    try:
        ser = serial.Serial(port, baud, timeout=1)
        print(f"opened {port} @ {baud}", flush=True)
        break
    except Exception as e:
        print(f"open failed: {e}, retry in 2s", flush=True)
        time.sleep(2)

with open(outfile, "ab", buffering=0) as f:
    while True:
        try:
            data = ser.read(4096)
            if data:
                f.write(data)
        except serial.SerialException as e:
            print(f"read error: {e}, reopening...", flush=True)
            time.sleep(2)
            while True:
                try:
                    ser = serial.Serial(port, baud, timeout=1)
                    break
                except Exception:
                    time.sleep(2)