#!/usr/bin/env python3
"""Headless Unix PTY smoke: real terminal handoff, child Ctrl+C and IDE resume.
Run after cargo build -p tb-ide: python3 tests/support/ide-execution-pty.py
"""
import fcntl
import os
from pathlib import Path
import select
import signal
import struct
import subprocess
import tempfile
import termios
import time

binary = Path(__file__).resolve().parents[2] / 'target/debug/tb'


def exercise(abort=False, file_shell=False):
    with tempfile.TemporaryDirectory(prefix='tb-pty-') as directory:
        source = Path(directory) / 'main.bas'
        command = "printf '\\nWAITING_CHILD\\n'; exec sleep 30" if abort else "printf '\\nSHELL_PROOF\\n'; exit 7"
        source.write_text(f'PRINT SHELL("{command}")\nSTOP\nPRINT "CONTINUED"\nEND\n')
        master, slave = os.openpty()
        original = termios.tcgetattr(slave)
        fcntl.ioctl(slave, termios.TIOCSWINSZ, struct.pack('HHHH', 30, 100, 0, 0))
        pid = os.fork()
        if pid == 0:
            os.setsid()
            fcntl.ioctl(slave, termios.TIOCSCTTY, 0)
            for fd in (0, 1, 2):
                os.dup2(slave, fd)
            os.close(master)
            os.close(slave)
            os.environ['TERM'] = 'xterm-256color'
            os.environ['XDG_CONFIG_HOME'] = directory
            # Keep the controlling terminal alive while checking restoration.
            signal.signal(signal.SIGINT, lambda *_: None)
            result = subprocess.run([str(binary), str(source)], check=False)
            restored = termios.tcgetattr(0) == original
            os._exit(result.returncode if restored else 99)
        transcript = bytearray()
        reaped = False

        def until(marker, start=0):
            deadline = time.monotonic() + 10
            while marker not in transcript[start:]:
                assert time.monotonic() < deadline, (marker, bytes(transcript[-2000:]))
                if select.select([master], [], [], .1)[0]:
                    transcript.extend(os.read(master, 65536))

        try:
            until(b'?1049h')
            start = len(transcript)
            if file_shell:
                os.write(master, b'\x1bfh')  # File -> Shell
                until(b'?1049l', start)
                os.write(master, b"printf '\\nFILE_SHELL_PROOF\\n'; exit\n")
                until(b'\r\nFILE_SHELL_PROOF\r\n', start)
                until(b'?1049h', start)
            else:
                os.write(master, b'\x1b[15~')  # F5
                until(b'\r\nWAITING_CHILD\r\n' if abort else b'\r\nSHELL_PROOF\r\n', start)
                if abort:
                    os.write(master, b'\x03')  # cooked terminal SIGINT to child + IDE
                until(b'Paused', start)
                start = len(transcript)
                os.write(master, b'\x1b[15~')
                until(b'Ended', start)
            start = len(transcript)
            os.write(master, b'\x1b[1;3S')  # Alt+F4
            until(b'Ungespeicherte', start)  # standalone BAS has an unsaved project manifest
            os.write(master, b'\x1b[C\x1b[C\r')  # discard temporary project
            deadline = time.monotonic() + 10
            while True:
                child, status = os.waitpid(pid, os.WNOHANG)
                if child:
                    reaped = True
                    assert os.waitstatus_to_exitcode(status) == 0
                    break
                assert time.monotonic() < deadline, bytes(transcript[-1000:])
                if select.select([master], [], [], .05)[0]:
                    transcript.extend(os.read(master, 65536))
            assert transcript.count(b'?1049h') >= 2
            assert transcript.count(b'?1049l') >= 2
        finally:
            if not reaped:
                os.killpg(pid, signal.SIGKILL)
                os.waitpid(pid, 0)
            os.close(master)
            os.close(slave)


for kwargs in ({}, {'abort': True}, {'file_shell': True}):
    exercise(**kwargs)
    print('PASS', kwargs or {'shell_exit': 7})