#!/usr/bin/env python3
# Serial monitor for ESP32. Optionally pulses RTS/DTR to reset the device
# so we capture boot output. Prefixes each line with elapsed seconds.
import serial, sys, time, argparse

def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("--port",    default="/dev/ttyUSB0")
    ap.add_argument("--baud",    type=int, default=115200)
    ap.add_argument("--seconds", type=int, default=20)
    ap.add_argument("--reset",   action="store_true",
                    help="Pulse RTS/DTR to reset the ESP32 before reading")
    ap.add_argument("--timestamp", action="store_true",
                    help="Prefix each line with elapsed seconds since boot")
    args = ap.parse_args()

    try:
        s = serial.Serial(args.port, args.baud, timeout=0.2,
                          rtscts=False, dsrdtr=False)
    except Exception as e:
        print(f"[open-fail] {e}", flush=True)
        sys.exit(2)

    if args.reset:
        s.setDTR(False)
        s.setRTS(True)
        time.sleep(0.1)
        s.setRTS(False)
        s.reset_input_buffer()

    t0 = time.time()
    end = t0 + args.seconds
    buf = b""
    while time.time() < end:
        chunk = s.read(512)
        if chunk:
            buf += chunk
            while b"\n" in buf:
                line, buf = buf.split(b"\n", 1)
                text = line.decode("utf-8", errors="replace").rstrip("\r")
                if args.timestamp:
                    sys.stdout.write(f"[{time.time()-t0:5.1f}s] {text}\n")
                else:
                    sys.stdout.write(text + "\n")
                sys.stdout.flush()
    if buf:
        text = buf.decode("utf-8", errors="replace")
        if args.timestamp:
            sys.stdout.write(f"[{time.time()-t0:5.1f}s] {text}\n")
        else:
            sys.stdout.write(text)
        sys.stdout.flush()
    s.close()

if __name__ == "__main__":
    main()