//go:build windows

// 进程树强杀(编程方式, Windows API)——2026-10-09 起替代原 taskkill /F /T 命令行兜底
// (产品红线: 系统操作禁拼 cmd 命令字符串)。
package process

import (
	"fmt"
	"unsafe"

	"golang.org/x/sys/windows"
)

// killProcessTree 按 PID 定向结束进程及其全部后代:
// Toolhelp32 快照枚举全进程父子关系 → 收集后代(防父子环) → 逐个 OpenProcess+TerminateProcess。
func killProcessTree(root uint32) error {
	parentOf, err := snapshotParentMap()
	if err != nil {
		return err
	}
	var pids []uint32
	visited := map[uint32]bool{}
	var visit func(pid uint32)
	visit = func(pid uint32) {
		if visited[pid] {
			return
		}
		visited[pid] = true
		pids = append(pids, pid)
		for child, parent := range parentOf {
			if parent == pid {
				visit(child)
			}
		}
	}
	visit(root)

	var firstErr error
	for _, pid := range pids {
		h, err := windows.OpenProcess(windows.PROCESS_TERMINATE, false, pid)
		if err != nil {
			if firstErr == nil {
				firstErr = fmt.Errorf("pid=%d OpenProcess: %w", pid, err)
			}
			continue
		}
		if err := windows.TerminateProcess(h, 1); err != nil {
			if firstErr == nil {
				firstErr = fmt.Errorf("pid=%d TerminateProcess: %w", pid, err)
			}
		}
		_ = windows.CloseHandle(h)
	}
	return firstErr
}

// snapshotParentMap 全进程快照: pid → 父 pid。
func snapshotParentMap() (map[uint32]uint32, error) {
	snap, err := windows.CreateToolhelp32Snapshot(windows.TH32CS_SNAPPROCESS, 0)
	if err != nil {
		return nil, fmt.Errorf("CreateToolhelp32Snapshot: %w", err)
	}
	defer windows.CloseHandle(snap)

	parentOf := map[uint32]uint32{}
	var pe windows.ProcessEntry32
	pe.Size = uint32(unsafe.Sizeof(pe))
	if err := windows.Process32First(snap, &pe); err != nil {
		return nil, fmt.Errorf("Process32First: %w", err)
	}
	for {
		parentOf[pe.ProcessID] = pe.ParentProcessID
		if err := windows.Process32Next(snap, &pe); err != nil {
			break
		}
	}
	return parentOf, nil
}