# modules/sbx_debug.py - 沙箱崩溃排查的临时调试日志模块（诊断完成后移除）
#
# 双通道日志：
#   1) UDP 发送到独立监控进程（后端死亡前消息已送达，监控进程独立存活）
#   2) 文件追加 .wsl-exp/sbx_debug.log（每行立即落盘，保底冗余）
# 环境变量：
#   SBX_DEBUG=0                关闭全部调试日志
#   SBX_DEBUG_PORT=9956        UDP 监控端口
#   SBX_DEBUG_SWALLOW_CTRL=0   控制台事件不吞掉（记录后恢复默认行为=真实死亡）

from __future__ import annotations

import datetime
import os
import signal
import socket
import threading
import traceback

_ENABLED = os.environ.get("SBX_DEBUG", "1").strip().lower() not in {"0", "false", "no", "off"}
_PORT = int(os.environ.get("SBX_DEBUG_PORT", "8092") or "8092")  # UDP，与后端 TCP 端口不冲突
_SWALLOW = os.environ.get("SBX_DEBUG_SWALLOW_CTRL", "1").strip().lower() not in {"0", "false", "no", "off"}

_LOCK = threading.Lock()
_SOCK = None
_PROBES_INSTALLED = False


def _log_path() -> str:
    try:
        root = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
    except Exception:
        root = os.getcwd()
    d = os.path.join(root, ".wsl-exp")
    try:
        os.makedirs(d, exist_ok=True)
    except Exception:
        pass
    return os.path.join(d, "sbx_debug.log")


def _get_sock():
    global _SOCK
    if _SOCK is None:
        try:
            _SOCK = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        except Exception:
            _SOCK = False
    return _SOCK or None


def sbx_log(event: str, **fields) -> None:
    """写一条调试日志（任何异常都吞掉，绝不影响主流程）。"""
    if not _ENABLED:
        return
    try:
        ts = datetime.datetime.now().strftime("%H:%M:%S.%f")[:-3]
        parts = [f"{k}={fields[k]!r}" for k in sorted(fields)]
        line = f"[{ts}] [pid={os.getpid()}] [th={threading.current_thread().name}] {event}"
        if parts:
            line += " | " + " ".join(parts)
        data = (line + "\n").encode("utf-8", "replace")
        with _LOCK:
            sock = _get_sock()
            if sock is not None:
                try:
                    sock.sendto(data, ("127.0.0.1", _PORT))
                except Exception:
                    pass
            try:
                with open(_log_path(), "a", encoding="utf-8") as f:
                    f.write(line + "\n")
            except Exception:
                pass
    except Exception:
        pass


def sbx_log_stack(event: str, **fields) -> None:
    """写一条带调用堆栈的调试日志。"""
    try:
        stack = "".join(traceback.format_stack(limit=14)[:-2])
    except Exception:
        stack = "<no stack>"
    fields["stack"] = stack
    sbx_log(event, **fields)


def console_pids():
    """返回当前控制台附加的进程 pid 列表（Windows），用于判断子进程是否共享后端控制台。"""
    if os.name != "nt":
        return []
    try:
        import ctypes
        arr = (ctypes.c_ulong * 64)()
        got = ctypes.windll.kernel32.GetConsoleProcessList(arr, 64)
        if not got:
            return []
        return [int(arr[i]) for i in range(min(got, 64))]
    except Exception:
        return ["?"]


def install_ctrl_event_probes(tag: str = "backend") -> None:
    """安装 SIGINT/SIGBREAK 探针：控制台事件到达时先记录日志。

    SBX_DEBUG_SWALLOW_CTRL=1（默认）：记录后吞掉事件，进程存活，可继续观察后续行为；
    =0：记录后恢复原处理器语义（SIGINT→KeyboardInterrupt；SIGBREAK→默认终止）。
    只能在主线程安装，失败静默。
    """
    global _PROBES_INSTALLED
    if not _ENABLED or os.name != "nt" or _PROBES_INSTALLED:
        return
    if threading.current_thread() is not threading.main_thread():
        sbx_log("CTRL-PROBES-SKIPPED", reason="not main thread", tag=tag)
        return

    def _make_handler(sig, name):
        prev = signal.getsignal(sig)

        def _handler(signum, frame):
            sbx_log_stack("CTRL-EVENT-RECEIVED", signal=name, tag=tag, swallowed=_SWALLOW)
            if _SWALLOW:
                return
            if callable(prev):
                prev(signum, frame)
                return
            try:
                signal.signal(sig, signal.SIG_DFL)
                os.kill(os.getpid(), sig)
            except Exception:
                os._exit(128 + int(signum))

        return _handler

    try:
        signal.signal(signal.SIGINT, _make_handler(signal.SIGINT, "SIGINT(CTRL_C)"))
    except Exception:
        pass
    try:
        sigbreak = getattr(signal, "SIGBREAK", None)
        if sigbreak is not None:
            signal.signal(sigbreak, _make_handler(sigbreak, "SIGBREAK(CTRL_BREAK)"))
    except Exception:
        pass
    _PROBES_INSTALLED = True
    sbx_log("CTRL-PROBES-INSTALLED", tag=tag, swallow=_SWALLOW, port=_PORT)