//go:build windows

package main

import (
	"context"
	"os"
	"os/exec"
	"strconv"
	"syscall"
	"time"
	"unsafe"

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

const createNoWindow = 0x08000000

// hideWindow 让子进程完全不显示终端窗口（CREATE_NO_WINDOW + HideWindow）。
func hideWindow(cmd *exec.Cmd) {
	if cmd.SysProcAttr == nil {
		cmd.SysProcAttr = &syscall.SysProcAttr{}
	}
	cmd.SysProcAttr.HideWindow = true
	cmd.SysProcAttr.CreationFlags |= createNoWindow
}

// killTree 强制结束进程树（含 node 派生的子进程），带超时防止卡住。
// taskkill 不可用或超时时，退化为直接终止目标进程。
func killTree(pid int) error {
	if pid <= 0 {
		return nil
	}
	ctx, cancel := context.WithTimeout(context.Background(), 8*time.Second)
	defer cancel()
	cmd := exec.CommandContext(ctx, "taskkill", "/PID", strconv.Itoa(pid), "/T", "/F")
	hideWindow(cmd)
	if err := cmd.Run(); err == nil {
		return nil
	}
	proc, err := os.FindProcess(pid)
	if err != nil {
		return err
	}
	return proc.Kill()
}

// processAlive 判断进程是否仍在运行。
func processAlive(pid int) bool {
	if pid <= 0 {
		return false
	}
	h, err := windows.OpenProcess(windows.PROCESS_QUERY_LIMITED_INFORMATION, false, uint32(pid))
	if err != nil {
		return false
	}
	defer windows.CloseHandle(h)
	var code uint32
	if err := windows.GetExitCodeProcess(h, &code); err != nil {
		return false
	}
	return code == 259 // STILL_ACTIVE
}

var (
	kernel32          = windows.NewLazySystemDLL("kernel32.dll")
	procCreateMutex   = kernel32.NewProc("CreateMutexW")
	procAttachConsole = kernel32.NewProc("AttachConsole")
)

// singleInstance 基于命名互斥体的单实例保护。
type singleInstance struct {
	handle windows.Handle
}

func acquireSingleInstance(name string) (*singleInstance, bool) {
	n, err := windows.UTF16PtrFromString(name)
	if err != nil {
		return nil, true
	}
	h, _, callErr := procCreateMutex.Call(0, 0, uintptr(unsafe.Pointer(n)))
	if h == 0 {
		return nil, true // 创建失败时放行，避免误伤
	}
	if errno, ok := callErr.(syscall.Errno); ok && errno == syscall.ERROR_ALREADY_EXISTS {
		_ = windows.CloseHandle(windows.Handle(h))
		return nil, false
	}
	return &singleInstance{handle: windows.Handle(h)}, true
}

func (s *singleInstance) release() {
	if s != nil && s.handle != 0 {
		_ = windows.CloseHandle(s.handle)
		s.handle = 0
	}
}

// attachConsole 让 windowsgui 子系统程序能输出到调用它的终端（仅 CLI 子命令使用）。
func attachConsole() {
	const attachParentProcess = 0xFFFFFFFF
	ret, _, _ := procAttachConsole.Call(uintptr(attachParentProcess))
	if ret == 0 {
		return
	}
	if f, err := os.OpenFile("CONOUT$", os.O_WRONLY, 0); err == nil {
		os.Stdout = f
		os.Stderr = f
	}
}