#!/usr/bin/env python3
"""pty_baud.py – run a shell behind two baud-rate simulators."""
import os, pty, sys, tty, termios, select, subprocess

BAUD  = sys.argv[1] if len(sys.argv) > 1 else "baud"
SHELL = ["bash", "--norc"]

master, slave = pty.openpty()
shell = subprocess.Popen(SHELL, stdin=slave, stdout=slave, stderr=slave,
                         preexec_fn=os.setsid, close_fds=True)
os.close(slave)

baud_out = subprocess.Popen([BAUD], stdin=subprocess.PIPE,
                            stdout=subprocess.PIPE)
baud_in  = subprocess.Popen([BAUD], stdin=subprocess.PIPE,
                            stdout=subprocess.PIPE)

# ── flatten every endpoint to an int fd ──────────────────────────
fd_term          = sys.stdin.fileno()
fd_baud_in_stdin = baud_in.stdin.fileno()
fd_baud_in_out   = baud_in.stdout.fileno()
fd_baud_out_in   = baud_out.stdin.fileno()
fd_baud_out_out  = baud_out.stdout.fileno()
# master is already an int from openpty()

old = termios.tcgetattr(fd_term)
tty.setraw(fd_term)

def pump(r, w):
    try:
        d = os.read(r, 4096)          # r is already an int
    except OSError:
        return False
    if not d:
        return False
    try:
        os.write(w, d)                # w is already an int
    except OSError:
        return False
    return True

try:
    while True:
        r, _, _ = select.select(
            [fd_term, master, fd_baud_in_out, fd_baud_out_out],
            [], [], 0.01)

        if fd_term          in r: pump(fd_term,          fd_baud_in_stdin)
        if master           in r: pump(master,           fd_baud_out_in)
        if fd_baud_in_out   in r: pump(fd_baud_in_out,   master)
        if fd_baud_out_out  in r: pump(fd_baud_out_out,  fd_term)
except KeyboardInterrupt:
    pass
finally:
    termios.tcsetattr(fd_term, termios.TCSADRAIN, old)
    for p in (shell, baud_in, baud_out):
        try: p.terminate()
        except OSError: pass