#!/usr/bin/env python3
"""
Telnet-only tool to toggle DTR/RTS via ser2net admin console.

New sequences (physical levels):
 - restart:  RTS HI -> DTR LO -> DTR HI
 - download: RTS LO -> DTR LO -> DTR HI -> RTS HI

Timing parameters tunable via args (ms). Use admin host/port and connection name (con).
Example:
  python3 helper/remote-serial.py --host 192.168.1.100 --admin-port 7373 --con con1 --action restart -v
"""
import argparse
import socket
import errno
import time
import sys

def send_admin_cmd(host, port, cmd, timeout=1.0, verbose=False):
    if verbose:
        print(f"> {cmd}")
    try:
        with socket.create_connection((host, port), timeout=timeout) as s:
            s.settimeout(timeout)
            try:
                s.sendall(cmd.encode('ascii') + b"\n")
            except Exception as e:
                print(f"ERROR sending command: {e}", file=sys.stderr)
                return None
            # small pause to let server respond
            time.sleep(0.05)
            chunks = []
            while True:
                try:
                    data = s.recv(4096)
                    if not data:
                        break
                    chunks.append(data)
                    # short sleep to allow more data to arrive
                    time.sleep(0.01)
                except socket.timeout:
                    break
                except OSError as e:
                    if getattr(e, 'errno', None) == errno.EWOULDBLOCK:
                        break
                    break
            resp = b"".join(chunks)
            if resp:
                try:
                    txt = resp.decode(errors="ignore")
                except Exception:
                    txt = str(resp)
                if verbose:
                    print(txt.strip())
                return txt
            return ""
    except Exception as e:
        print(f"ERROR: cannot connect to {host}:{port} -> {e}", file=sys.stderr)
        return None

def set_port_control(host, admin_port, con, line, hi_or_lo, timeout, verbose):
    # hi_or_lo must be 'HI' or 'LO'
    cmd = f"setportcontrol {con} {line}{hi_or_lo}"
    return send_admin_cmd(host, admin_port, cmd, timeout=timeout, verbose=verbose)

def run_sequence(host, admin_port, con, seq, timeout, verbose):
    # seq: list of (line, state, sleep_seconds)
    for line, state, sleep_s in seq:
        if verbose:
            print(f"-> {line}{state}  (wait {sleep_s:.3f}s)")
        res = set_port_control(host, admin_port, con, line, state, timeout, verbose)
        # continue even if response is None; user sees errors in stderr
        if sleep_s and sleep_s > 0:
            time.sleep(sleep_s)

def main():
    p = argparse.ArgumentParser(description="ser2net admin: restart / download sequences (explicit HI/LO)")
    p.add_argument("--host", required=True, help="ser2net admin host/ip")
    p.add_argument("--admin-port", type=int, required=True, help="ser2net admin port")
    p.add_argument("--con", required=True, help="ser2net connection name (e.g. con1)")
    p.add_argument("--action", choices=["restart", "download", "bootloader"], default="restart",
                   help="restart or download (bootloader alias)")
    p.add_argument("--pulse-ms", type=float, default=100.0, help="DTR pulse length in milliseconds")
    p.add_argument("--step-delay-ms", type=float, default=20.0, help="short delay between steps in milliseconds")
    p.add_argument("--tail-delay-ms", type=float, default=50.0, help="extra delay after sequence in milliseconds")
    p.add_argument("--timeout", type=float, default=1.0, help="telnet connect/read timeout seconds")
    p.add_argument("-v", "--verbose", action="store_true")
    args = p.parse_args()

    pulse_s = max(0.001, args.pulse_ms / 1000.0)
    step_delay_s = max(0.0, args.step_delay_ms / 1000.0)
    tail_delay_s = max(0.0, args.tail_delay_ms / 1000.0)

    if args.verbose:
        print(f"Admin {args.host}:{args.admin_port}  con={args.con}  action={args.action}")

    # sequences use explicit physical HI/LO as requested
    if args.action == "restart":
        seq = [
            ("RTS", "HI", step_delay_s),   # RTS HI
            ("DTR", "LO", pulse_s),        # DTR LO (pulse start)
            ("DTR", "HI", tail_delay_s),   # DTR HI (pulse end), then tail delay
        ]
    else:  # download / bootloader
        # Ensure known starting state (RESET released), then enter download:
        # 1) ensure DTR=HI (reset released)
        # 2) RTS=LO (IO0 low)
        # 3) DTR=LO -> wait pulse_ms
        # 4) DTR=HI -> small delay
        # 5) RTS=HI -> release IO0 (enter bootloader)
        seq = [
            ("DTR", "HI", step_delay_s),   # ensure reset released
            ("RTS", "LO", step_delay_s),   # RTS LO (IO0 low)
            ("DTR", "LO", pulse_s),        # DTR LO (reset asserted)
            ("DTR", "HI", step_delay_s),   # DTR HI (reset released)
            ("RTS", "HI", tail_delay_s),   # RTS HI (release IO0)
        ]

    run_sequence(args.host, args.admin_port, args.con, seq, args.timeout, args.verbose)

    if args.verbose:
        print("Sequence finished.")

if __name__ == "__main__":
    main()