"""甄 AI 客服独立更新器；仅依赖 Python 标准库，打包为单文件 EXE。"""

from __future__ import annotations

import argparse
import ctypes
import hashlib
import json
import os
import subprocess
import time
from pathlib import Path


def _sha256(path: Path) -> str:
    digest = hashlib.sha256()
    with path.open("rb") as source:
        for chunk in iter(lambda: source.read(1024 * 1024), b""):
            digest.update(chunk)
    return digest.hexdigest()


def _process_running(pid: int) -> bool:
    if pid <= 0:
        return False
    if os.name == "nt":
        process_query_limited_information = 0x1000
        handle = ctypes.windll.kernel32.OpenProcess(
            process_query_limited_information, False, pid
        )
        if not handle:
            return False
        ctypes.windll.kernel32.CloseHandle(handle)
        return True
    try:
        os.kill(pid, 0)
        return True
    except OSError:
        return False


def _write_result(path: Path, payload: dict) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    temporary = path.with_suffix(path.suffix + ".tmp")
    temporary.write_text(json.dumps(payload, ensure_ascii=False, indent=2), encoding="utf-8")
    os.replace(temporary, path)


def _wait_for_parent(pid: int, timeout: int = 120) -> None:
    deadline = time.monotonic() + timeout
    while _process_running(pid):
        if time.monotonic() >= deadline:
            raise RuntimeError("主程序在 120 秒内没有退出")
        time.sleep(0.25)


def _start_available_version(install_dir: Path, preferred: Path | None = None) -> bool:
    """启动指定新版本；失败时回退到安装目录中最近的可执行旧版本。"""

    candidates = []
    if preferred is not None:
        candidates.append(preferred)
    try:
        discovered = sorted(
            install_dir.glob("ZhenAI-WeCom-Assistant-v*.exe"),
            key=lambda item: item.stat().st_mtime,
            reverse=True,
        )
    except OSError:
        discovered = []
    candidates.extend(item for item in discovered if item not in candidates)
    for candidate in candidates:
        if not candidate.is_file():
            continue
        try:
            subprocess.Popen([str(candidate)], cwd=install_dir, close_fds=True)
            return True
        except OSError:
            continue
    return False


def main() -> int:
    parser = argparse.ArgumentParser(description="甄 AI 客服独立更新器")
    parser.add_argument("--installer", required=True)
    parser.add_argument("--parent-pid", type=int, required=True)
    parser.add_argument("--install-dir", required=True)
    parser.add_argument("--target-version", required=True)
    parser.add_argument("--result-file", required=True)
    parser.add_argument("--expected-sha256", default="")
    parser.add_argument("--from-version", default="")
    args = parser.parse_args()

    installer = Path(args.installer).resolve()
    install_dir = Path(args.install_dir).resolve()
    result_file = Path(args.result_file).resolve()
    result = {
        "target_version": args.target_version,
        "from_version": args.from_version,
        "status": "failed",
        "error": "",
        "updated_at": time.strftime("%Y-%m-%d %H:%M:%S"),
    }
    try:
        _wait_for_parent(args.parent_pid)
        if not installer.is_file():
            raise RuntimeError("升级安装包不存在")
        if args.expected_sha256 and _sha256(installer) != args.expected_sha256.lower():
            raise RuntimeError("安装前 SHA256 复核失败")
        completed = subprocess.run(
            [str(installer), "/S"],
            timeout=600,
            creationflags=getattr(subprocess, "CREATE_NO_WINDOW", 0),
        )
        if completed.returncode != 0:
            raise RuntimeError(f"静默安装失败，退出码 {completed.returncode}")
        target = install_dir / f"ZhenAI-WeCom-Assistant-v{args.target_version}.exe"
        if not target.is_file():
            raise RuntimeError("安装完成但没有找到新版本主程序")
        result["status"] = "installed"
        _write_result(result_file, result)
        if not _start_available_version(install_dir, target):
            raise RuntimeError("安装成功，但无法启动新版本主程序")
        return 0
    except Exception as exc:
        result["error"] = str(exc)[:1000]
        _write_result(result_file, result)
        _start_available_version(install_dir)
        return 1


if __name__ == "__main__":
    raise SystemExit(main())