//go:build windows

package runtime

import (
	"encoding/base64"
	"encoding/json"
	"fmt"
	"io"
	"os"
	"os/exec"
	"path/filepath"
	"sort"
	"strconv"
	"strings"
	"sync"
	"syscall"
	"time"
	"unicode/utf16"
	"unsafe"

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

const managedProcessHelperFlag = "--run-managed-process-helper"

func configureManagedProcessCommand(cmd *exec.Cmd) {
	// Run may itself be launched by a service or task scheduler job that
	// terminates its process tree on shutdown. The helper is the durable
	// owner of the game process, so ask Windows to keep it outside that job.
	// The helper itself does not need a console: its stdout/stderr are already
	// durable files. CREATE_NEW_CONSOLE creates a second hidden conhost in a
	// non-interactive Task Scheduler session and prevents the child pseudo
	// console from initializing on Windows Server.
	cmd.SysProcAttr = &syscall.SysProcAttr{CreationFlags: windows.CREATE_NO_WINDOW | windows.CREATE_BREAKAWAY_FROM_JOB, HideWindow: true}
}

// Windows console output is collected by a child helper that owns the
// pseudo-console. The helper inherits the durable stdout/stderr files, so it
// remains attached to the supervised process when Run itself is updated or
// restarted. The new Run instance resumes tailing those files by offset.
type windowsFileManagedProcess struct {
	cmd              *exec.Cmd
	helperExecutable string
	targetPID        int
}

type managedProcessHelperSpec struct {
	Command       ProcessCommand `json:"command"`
	StopEventName string         `json:"stopEventName,omitempty"`
	StdoutPath    string         `json:"stdoutPath,omitempty"`
	StderrPath    string         `json:"stderrPath,omitempty"`
	PIDPath       string         `json:"pidPath,omitempty"`
}

func startManagedProcess(command ProcessCommand, files managedProcessFiles, stopEventName string) (managedProcess, error) {
	pidPath := files.stdout.Name() + ".pid"
	_ = os.Remove(pidPath)
	body, err := json.Marshal(managedProcessHelperSpec{Command: command, StopEventName: stopEventName, StdoutPath: files.stdout.Name(), StderrPath: files.stderr.Name(), PIDPath: pidPath})
	if err != nil {
		return nil, fmt.Errorf("encode managed process helper spec: %w", err)
	}
	payload := base64.RawURLEncoding.EncodeToString(body)
	executable, err := os.Executable()
	if err != nil {
		return nil, fmt.Errorf("resolve Run executable for managed process helper: %w", err)
	}
	helperExecutable, err := prepareManagedProcessHelperExecutable(executable, files.stdout.Name())
	if err != nil {
		return nil, fmt.Errorf("prepare managed process helper executable: %w", err)
	}
	cmd := exec.Command(helperExecutable, managedProcessHelperFlag, payload)
	cmd.Stdout = files.stdout
	cmd.Stderr = files.stderr
	configureManagedProcessCommand(cmd)
	if err := cmd.Start(); err != nil {
		_ = os.Remove(helperExecutable)
		return nil, err
	}
	targetPID := cmd.Process.Pid
	deadline := time.Now().Add(2 * time.Second)
	for time.Now().Before(deadline) {
		if body, readErr := os.ReadFile(pidPath); readErr == nil {
			if parsed, parseErr := strconv.Atoi(strings.TrimSpace(string(body))); parseErr == nil && parsed > 0 {
				targetPID = parsed
				break
			}
		}
		time.Sleep(10 * time.Millisecond)
	}
	return &windowsFileManagedProcess{cmd: cmd, helperExecutable: helperExecutable, targetPID: targetPID}, nil
}

func prepareManagedProcessHelperExecutable(executable, outputPath string) (string, error) {
	directory := filepath.Dir(outputPath)
	if err := os.MkdirAll(directory, 0o700); err != nil {
		return "", err
	}
	temporary, err := os.CreateTemp(directory, ".run-managed-helper-*.exe")
	if err != nil {
		return "", err
	}
	helper := temporary.Name()
	if err := temporary.Close(); err != nil {
		_ = os.Remove(helper)
		return "", err
	}
	if err := os.Remove(helper); err != nil {
		return "", err
	}
	if err := copyExecutable(executable, helper); err != nil {
		_ = os.Remove(helper)
		return "", err
	}
	return helper, nil
}

func (process *windowsFileManagedProcess) PID() int {
	return process.cmd.Process.Pid
}

func (process *windowsFileManagedProcess) TargetPID() int {
	if process.targetPID > 0 {
		return process.targetPID
	}
	return process.PID()
}

func (process *windowsFileManagedProcess) Wait() (int, error) {
	err := process.cmd.Wait()
	if process.helperExecutable != "" {
		_ = os.Remove(process.helperExecutable)
	}
	if process.cmd.ProcessState == nil {
		return -1, err
	}
	return process.cmd.ProcessState.ExitCode(), err
}

func (process *windowsFileManagedProcess) Kill() error {
	return process.cmd.Process.Kill()
}

// RunManagedProcessHelper is invoked by the same executable in a detached
// child process. It is deliberately not a worker mode and does not register
// with Platform.
func RunManagedProcessHelper(args []string) (bool, int) {
	if len(args) < 3 || args[1] != managedProcessHelperFlag {
		return false, 0
	}
	body, err := base64.RawURLEncoding.DecodeString(args[2])
	if err != nil {
		fmt.Fprintf(os.Stderr, "invalid managed process helper payload: %v\n", err)
		return true, 2
	}
	var spec managedProcessHelperSpec
	if err := json.Unmarshal(body, &spec); err != nil || len(spec.Command.Args) == 0 {
		if err == nil {
			err = fmt.Errorf("managed process command is empty")
		}
		fmt.Fprintf(os.Stderr, "invalid managed process helper spec: %v\n", err)
		return true, 2
	}
	code, err := runManagedProcessHelper(spec)
	if err != nil {
		fmt.Fprintf(os.Stderr, "managed process helper failed: %v\n", err)
		if code == 0 {
			code = 1
		}
	}
	return true, code
}

func runManagedProcessHelper(spec managedProcessHelperSpec) (int, error) {
	defer scheduleManagedProcessHelperCleanup()
	stdout, closeStdout, err := openManagedProcessOutput(spec.StdoutPath, os.Stdout)
	if err != nil {
		return 1, fmt.Errorf("open managed process stdout: %w", err)
	}
	defer closeStdout()
	stderr, closeStderr, err := openManagedProcessOutput(spec.StderrPath, os.Stderr)
	if err != nil {
		return 1, fmt.Errorf("open managed process stderr: %w", err)
	}
	defer closeStderr()
	command := spec.Command
	stopEventName := spec.StopEventName
	// The plugin-declared pipes mode uses ordinary inherited handles. The
	// durable output files are attached directly to the child process, so this
	// path remains valid when Run itself is updated or restarted. Console mode
	// is deliberately kept separate for applications that switch from
	// redirected handles to a Windows console after startup.
	if command.OutputMode != "console" {
		return runManagedProcessWithPipes(command, stopEventName, spec.PIDPath, stdout, stderr)
	}
	return runManagedProcessWithPseudoConsole(command, stopEventName, spec.PIDPath, stdout, stderr)
}

func scheduleManagedProcessHelperCleanup() {
	executable, err := os.Executable()
	if err != nil || strings.TrimSpace(executable) == "" {
		return
	}
	commandLine := "ping 127.0.0.1 -n 2 >nul & del /f /q " + quoteWindowsCommandArg(executable)
	cleanup := exec.Command("cmd.exe", "/d", "/c", commandLine)
	cleanup.Stdout = io.Discard
	cleanup.Stderr = io.Discard
	configureManagedProcessCommand(cleanup)
	_ = cleanup.Start()
}

func openManagedProcessOutput(path string, fallback *os.File) (io.Writer, func(), error) {
	if strings.TrimSpace(path) == "" {
		return fallback, func() {}, nil
	}
	file, err := os.OpenFile(path, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0o600)
	if err != nil {
		return nil, nil, err
	}
	return file, func() { _ = file.Close() }, nil
}

func runManagedProcessWithPipes(command ProcessCommand, stopEventName string, pidPath string, stdout io.Writer, stderr io.Writer) (int, error) {
	if len(command.Args) == 0 {
		return 1, fmt.Errorf("managed process command is empty")
	}
	application := command.Args[0]
	if strings.EqualFold(application, "cmd.exe") {
		if comspec := os.Getenv("ComSpec"); comspec != "" {
			application = comspec
		}
	}
	cmd := exec.Command(application, command.Args[1:]...)
	cmd.Dir = command.WorkDir
	cmd.Env = os.Environ()
	for key, value := range command.Env {
		cmd.Env = append(cmd.Env, key+"="+value)
	}
	cmd.Stdout = stdout
	cmd.Stderr = stderr
	configureManagedProcessCommand(cmd)
	if err := cmd.Start(); err != nil {
		return 1, fmt.Errorf("start managed process with pipes: %w", err)
	}
	if err := writeManagedProcessPID(pidPath, cmd.Process.Pid); err != nil {
		_ = cmd.Process.Kill()
		_ = cmd.Wait()
		return 1, fmt.Errorf("persist managed process pid: %w", err)
	}

	processHandle, err := windows.OpenProcess(windows.PROCESS_SET_QUOTA|windows.PROCESS_TERMINATE|windows.PROCESS_QUERY_LIMITED_INFORMATION, false, uint32(cmd.Process.Pid))
	if err != nil {
		_ = cmd.Process.Kill()
		_ = cmd.Wait()
		return 1, fmt.Errorf("open managed process handle: %w", err)
	}
	job, err := createManagedProcessJob(processHandle)
	_ = windows.CloseHandle(processHandle)
	if err != nil {
		_ = cmd.Process.Kill()
		_ = cmd.Wait()
		return 1, err
	}
	defer windows.CloseHandle(job)
	stopCleanup, err := watchManagedProcessStop(job, stopEventName)
	if err != nil {
		_ = windows.TerminateJobObject(job, 1)
		_ = cmd.Wait()
		return 1, err
	}
	defer stopCleanup()

	waitErr := cmd.Wait()
	if cmd.ProcessState == nil {
		if waitErr != nil {
			return 1, waitErr
		}
		return 1, fmt.Errorf("managed process has no exit state")
	}
	exitCode := cmd.ProcessState.ExitCode()
	if waitErr != nil {
		// exec.Cmd returns *exec.ExitError for a normal non-zero exit. Return
		// the actual code without treating it as an internal supervisor error;
		// the outer helper will propagate the code to the durable supervisor.
		if _, ok := waitErr.(*exec.ExitError); !ok {
			return 1, waitErr
		}
	}
	if exitCode > 255 {
		return 1, fmt.Errorf("managed process exited with code %d", exitCode)
	}
	return exitCode, nil
}

func writeManagedProcessPID(path string, pid int) error {
	if strings.TrimSpace(path) == "" || pid <= 0 {
		return nil
	}
	temporary := path + ".tmp"
	if err := os.WriteFile(temporary, []byte(strconv.Itoa(pid)+"\n"), 0o600); err != nil {
		return err
	}
	if err := os.Rename(temporary, path); err != nil {
		_ = os.Remove(temporary)
		return err
	}
	return nil
}

type synchronizedOutputWriter struct {
	mu sync.Mutex
	w  io.Writer
}

func (writer *synchronizedOutputWriter) Write(body []byte) (int, error) {
	writer.mu.Lock()
	defer writer.mu.Unlock()
	return writer.w.Write(body)
}

func runManagedProcessWithPseudoConsole(command ProcessCommand, stopEventName string, pidPath string, stdout io.Writer, stderr io.Writer) (int, error) {
	// Direct console executables use a pseudo-console so programs that require
	// a console handle still have a bounded, hidden console surface. This is
	// also used for plugin-declared console capture around a Windows shell.
	inputRead, inputWrite, err := createPseudoConsolePipe()
	if err != nil {
		return 1, fmt.Errorf("create pseudo-console input pipe: %w", err)
	}
	outputRead, outputWrite, err := createPseudoConsolePipe()
	if err != nil {
		closePseudoConsoleHandles(inputRead, inputWrite)
		return 1, fmt.Errorf("create pseudo-console output pipe: %w", err)
	}

	var console windows.Handle
	if err := windows.CreatePseudoConsole(windows.Coord{X: 160, Y: 50}, inputRead, outputWrite, 0, &console); err != nil {
		closePseudoConsoleHandles(inputRead, inputWrite, outputRead, outputWrite)
		return 1, fmt.Errorf("create pseudo-console: %w", err)
	}
	_ = windows.CloseHandle(inputRead)
	_ = windows.CloseHandle(outputWrite)

	attributes, err := windows.NewProcThreadAttributeList(1)
	if err != nil {
		windows.ClosePseudoConsole(console)
		closePseudoConsoleHandles(inputWrite, outputRead)
		return 1, fmt.Errorf("create pseudo-console process attributes: %w", err)
	}
	defer attributes.Delete()
	// PROC_THREAD_ATTRIBUTE_PSEUDOCONSOLE expects the HPCON handle value as
	// lpValue, not the address of the local variable that stores the handle.
	if err := attributes.Update(windows.PROC_THREAD_ATTRIBUTE_PSEUDOCONSOLE, unsafe.Pointer(uintptr(console)), unsafe.Sizeof(console)); err != nil {
		windows.ClosePseudoConsole(console)
		closePseudoConsoleHandles(inputWrite, outputRead)
		return 1, fmt.Errorf("configure pseudo-console process attributes: %w", err)
	}

	applicationPath := command.Args[0]
	commandIsCmd := strings.EqualFold(applicationPath, "cmd.exe")
	if commandIsCmd {
		applicationPath = os.Getenv("ComSpec")
		if applicationPath == "" {
			applicationPath = `C:\Windows\System32\cmd.exe`
		}
	}
	// CreateProcess receives both an application name and a command line.
	// Keep the command-line program name identical to the resolved application
	// name; cmd.exe can fail with STATUS_DLL_INIT_FAILED when the former is
	// left as the short name while the latter is an absolute path.
	commandArgs := append([]string(nil), command.Args...)
	commandArgs[0] = applicationPath
	commandLine, err := windows.UTF16FromString(windows.ComposeCommandLine(commandArgs))
	if err != nil {
		windows.ClosePseudoConsole(console)
		closePseudoConsoleHandles(inputWrite, outputRead)
		return 1, fmt.Errorf("encode managed process command: %w", err)
	}
	var applicationName *uint16
	if !commandIsCmd && strings.ContainsAny(applicationPath, `:\`) {
		applicationName, err = windows.UTF16PtrFromString(applicationPath)
		if err != nil {
			windows.ClosePseudoConsole(console)
			closePseudoConsoleHandles(inputWrite, outputRead)
			return 1, fmt.Errorf("encode managed process executable: %w", err)
		}
	}
	environment, err := managedProcessEnvironment(command.Env)
	if err != nil {
		windows.ClosePseudoConsole(console)
		closePseudoConsoleHandles(inputWrite, outputRead)
		return 1, fmt.Errorf("encode managed process environment: %w", err)
	}
	var workDir *uint16
	if command.WorkDir != "" {
		workDir, err = windows.UTF16PtrFromString(command.WorkDir)
		if err != nil {
			windows.ClosePseudoConsole(console)
			closePseudoConsoleHandles(inputWrite, outputRead)
			return 1, fmt.Errorf("encode managed process working directory: %w", err)
		}
	}

	// A pseudo-console supplies the child's console surface itself; do not
	// combine it with STARTF_USESHOWWINDOW, which makes cmd.exe fail during
	// initialization on some non-interactive Windows Server sessions.
	startup := &windows.StartupInfoEx{StartupInfo: windows.StartupInfo{Cb: uint32(unsafe.Sizeof(windows.StartupInfoEx{}))}, ProcThreadAttributeList: attributes.List()}
	var processInfo windows.ProcessInformation
	// The helper has already detached from any parent job. A second
	// CREATE_BREAKAWAY_FROM_JOB on the pseudo-console client is rejected by
	// some Windows Server builds during console initialization and surfaces as
	// STATUS_DLL_INIT_FAILED from the otherwise valid child process.
	if err := windows.CreateProcess(applicationName, &commandLine[0], nil, nil, false, windows.CREATE_UNICODE_ENVIRONMENT|windows.EXTENDED_STARTUPINFO_PRESENT, environment, workDir, &startup.StartupInfo, &processInfo); err != nil {
		windows.ClosePseudoConsole(console)
		closePseudoConsoleHandles(inputWrite, outputRead)
		return 1, fmt.Errorf("start managed process in pseudo-console: %w", err)
	}
	_ = windows.CloseHandle(processInfo.Thread)
	_ = windows.CloseHandle(inputWrite)
	if err := writeManagedProcessPID(pidPath, int(processInfo.ProcessId)); err != nil {
		_ = windows.TerminateProcess(processInfo.Process, 1)
		_ = windows.CloseHandle(processInfo.Process)
		windows.ClosePseudoConsole(console)
		_ = windows.CloseHandle(outputRead)
		return 1, fmt.Errorf("persist managed process pid: %w", err)
	}

	job, err := createManagedProcessJob(processInfo.Process)
	if err != nil {
		_ = windows.TerminateProcess(processInfo.Process, 1)
		_ = windows.CloseHandle(processInfo.Process)
		windows.ClosePseudoConsole(console)
		_ = windows.CloseHandle(outputRead)
		return 1, err
	}
	defer windows.CloseHandle(job)
	stopCleanup, err := watchManagedProcessStop(job, stopEventName)
	if err != nil {
		_ = windows.TerminateJobObject(job, 1)
		windows.ClosePseudoConsole(console)
		_ = windows.CloseHandle(processInfo.Process)
		return 1, err
	}
	defer stopCleanup()

	outputFile := os.NewFile(uintptr(outputRead), "run-pseudo-console-output")
	if outputFile == nil {
		_ = windows.TerminateProcess(processInfo.Process, 1)
		_ = windows.CloseHandle(processInfo.Process)
		windows.ClosePseudoConsole(console)
		return 1, fmt.Errorf("open pseudo-console output")
	}
	outputDone := make(chan struct{})
	outputWriter := &synchronizedOutputWriter{w: stdout}
	go func() {
		_, _ = io.Copy(outputWriter, outputFile)
		close(outputDone)
	}()

	_, waitErr := windows.WaitForSingleObject(processInfo.Process, windows.INFINITE)
	var exitCode uint32
	if waitErr == nil {
		waitErr = windows.GetExitCodeProcess(processInfo.Process, &exitCode)
	}
	windows.ClosePseudoConsole(console)
	<-outputDone
	_ = outputFile.Close()
	_ = windows.CloseHandle(processInfo.Process)
	if waitErr != nil {
		return 1, waitErr
	}
	if exitCode > 255 {
		return 1, fmt.Errorf("managed process exited with code %d", exitCode)
	}
	return int(exitCode), nil
}

func runManagedShellWithPipes(command ProcessCommand, stopEventName string, stdout io.Writer, stderr io.Writer) (int, error) {
	inputRead, inputWrite, err := createPseudoConsolePipe()
	if err != nil {
		return 1, fmt.Errorf("create managed shell input pipe: %w", err)
	}
	stdoutRead, stdoutWrite, err := createPseudoConsolePipe()
	if err != nil {
		closePseudoConsoleHandles(inputRead, inputWrite)
		return 1, fmt.Errorf("create managed shell stdout pipe: %w", err)
	}
	stderrRead, stderrWrite, err := createPseudoConsolePipe()
	if err != nil {
		closePseudoConsoleHandles(inputRead, inputWrite, stdoutRead, stdoutWrite)
		return 1, fmt.Errorf("create managed shell stderr pipe: %w", err)
	}
	closeOnError := func() {
		closePseudoConsoleHandles(inputRead, inputWrite, stdoutRead, stdoutWrite, stderrRead, stderrWrite)
	}
	if err := windows.SetHandleInformation(stdoutRead, windows.HANDLE_FLAG_INHERIT, 0); err != nil {
		closeOnError()
		return 1, fmt.Errorf("make managed shell stdout pipe private: %w", err)
	}
	if err := windows.SetHandleInformation(stderrRead, windows.HANDLE_FLAG_INHERIT, 0); err != nil {
		closeOnError()
		return 1, fmt.Errorf("make managed shell stderr pipe private: %w", err)
	}

	applicationPath := os.Getenv("ComSpec")
	if applicationPath == "" {
		applicationPath = `C:\Windows\System32\cmd.exe`
	}
	commandArgs := append([]string(nil), command.Args...)
	commandArgs[0] = applicationPath
	commandLine, err := windows.UTF16FromString(windows.ComposeCommandLine(commandArgs))
	if err != nil {
		closeOnError()
		return 1, fmt.Errorf("encode managed shell command: %w", err)
	}
	applicationName, err := windows.UTF16PtrFromString(applicationPath)
	if err != nil {
		closeOnError()
		return 1, fmt.Errorf("encode managed shell executable: %w", err)
	}
	environment, err := managedProcessEnvironment(command.Env)
	if err != nil {
		closeOnError()
		return 1, fmt.Errorf("encode managed shell environment: %w", err)
	}
	var workDir *uint16
	if command.WorkDir != "" {
		workDir, err = windows.UTF16PtrFromString(command.WorkDir)
		if err != nil {
			closeOnError()
			return 1, fmt.Errorf("encode managed shell working directory: %w", err)
		}
	}
	startup := &windows.StartupInfo{Cb: uint32(unsafe.Sizeof(windows.StartupInfo{})), Flags: windows.STARTF_USESTDHANDLES | windows.STARTF_USESHOWWINDOW, ShowWindow: windows.SW_HIDE, StdInput: inputRead, StdOutput: stdoutWrite, StdErr: stderrWrite}
	var processInfo windows.ProcessInformation
	if err := windows.CreateProcess(applicationName, &commandLine[0], nil, nil, true, windows.CREATE_BREAKAWAY_FROM_JOB|windows.CREATE_NO_WINDOW|windows.CREATE_UNICODE_ENVIRONMENT, environment, workDir, startup, &processInfo); err != nil {
		closeOnError()
		return 1, fmt.Errorf("start managed shell: %w", err)
	}
	_ = windows.CloseHandle(processInfo.Thread)
	closePseudoConsoleHandles(inputRead, inputWrite, stdoutWrite, stderrWrite)

	job, err := createManagedProcessJob(processInfo.Process)
	if err != nil {
		_ = windows.TerminateProcess(processInfo.Process, 1)
		_ = windows.CloseHandle(processInfo.Process)
		closePseudoConsoleHandles(stdoutRead, stderrRead)
		return 1, err
	}
	defer windows.CloseHandle(job)
	stopCleanup, err := watchManagedProcessStop(job, stopEventName)
	if err != nil {
		_ = windows.TerminateJobObject(job, 1)
		_ = windows.CloseHandle(processInfo.Process)
		return 1, err
	}
	defer stopCleanup()
	stdoutFile := os.NewFile(uintptr(stdoutRead), "run-managed-shell-stdout")
	stderrFile := os.NewFile(uintptr(stderrRead), "run-managed-shell-stderr")
	if stdoutFile == nil || stderrFile == nil {
		if stdoutFile != nil {
			_ = stdoutFile.Close()
		}
		if stderrFile != nil {
			_ = stderrFile.Close()
		}
		_ = windows.TerminateProcess(processInfo.Process, 1)
		_ = windows.CloseHandle(processInfo.Process)
		return 1, fmt.Errorf("open managed shell output pipes")
	}
	outputDone := make(chan struct{})
	outputWriter := &synchronizedOutputWriter{w: stdout}
	go func() {
		_, _ = io.Copy(outputWriter, stdoutFile)
		_ = stdoutFile.Close()
		close(outputDone)
	}()
	errorDone := make(chan struct{})
	errorWriter := &synchronizedOutputWriter{w: stderr}
	go func() {
		_, _ = io.Copy(errorWriter, stderrFile)
		_ = stderrFile.Close()
		close(errorDone)
	}()

	_, waitErr := windows.WaitForSingleObject(processInfo.Process, windows.INFINITE)
	var exitCode uint32
	if waitErr == nil {
		waitErr = windows.GetExitCodeProcess(processInfo.Process, &exitCode)
	}
	<-outputDone
	<-errorDone
	_ = windows.CloseHandle(processInfo.Process)
	if waitErr != nil {
		return 1, waitErr
	}
	if exitCode > 255 {
		return 1, fmt.Errorf("managed shell exited with code %d", exitCode)
	}
	return int(exitCode), nil
}

func createManagedProcessJob(process windows.Handle) (windows.Handle, error) {
	job, err := windows.CreateJobObject(nil, nil)
	if err != nil {
		return 0, fmt.Errorf("create managed process job: %w", err)
	}
	if err := windows.AssignProcessToJobObject(job, process); err != nil {
		_ = windows.CloseHandle(job)
		return 0, fmt.Errorf("assign managed process to job: %w", err)
	}
	return job, nil
}

func watchManagedProcessStop(job windows.Handle, name string) (func(), error) {
	if strings.TrimSpace(name) == "" {
		return func() {}, nil
	}
	eventName, err := windows.UTF16PtrFromString(name)
	if err != nil {
		return nil, fmt.Errorf("encode managed process stop event: %w", err)
	}
	event, eventErr := windows.CreateEvent(nil, 1, 0, eventName)
	if eventErr != nil && eventErr != windows.ERROR_ALREADY_EXISTS {
		if event != 0 {
			_ = windows.CloseHandle(event)
		}
		return nil, fmt.Errorf("create managed process stop event: %w", eventErr)
	}
	stop := make(chan struct{})
	done := make(chan struct{})
	go func() {
		defer close(done)
		for {
			select {
			case <-stop:
				return
			default:
			}
			result, waitErr := windows.WaitForSingleObject(event, 100)
			if waitErr != nil {
				return
			}
			if result == windows.WAIT_OBJECT_0 {
				_ = windows.TerminateJobObject(job, 1)
				return
			}
		}
	}()
	return func() {
		close(stop)
		<-done
		_ = windows.CloseHandle(event)
	}, nil
}

func requestManagedProcessStop(identity ProcessIdentity) error {
	if strings.TrimSpace(identity.StopEventName) != "" {
		name, err := windows.UTF16PtrFromString(identity.StopEventName)
		if err != nil {
			return err
		}
		deadline := time.Now().Add(2 * time.Second)
		for time.Now().Before(deadline) {
			event, openErr := windows.OpenEvent(windows.EVENT_MODIFY_STATE|windows.SYNCHRONIZE, false, name)
			if openErr == nil {
				setErr := windows.SetEvent(event)
				_ = windows.CloseHandle(event)
				return setErr
			}
			time.Sleep(25 * time.Millisecond)
		}
	}
	return fmt.Errorf("managed process stop event is unavailable")
}

func forceManagedProcessStop(identity ProcessIdentity) error {
	if err := requestManagedProcessStop(identity); err == nil {
		return nil
	}
	if identity.PID <= 0 {
		return fmt.Errorf("managed process pid is invalid")
	}
	// A recovered process can outlive its helper. In that case no stop-event
	// watcher remains. Target only the persisted process PID here: /T would
	// recursively terminate descendants and can take down a game process that
	// was deliberately kept alive while Run is being restarted or updated.
	command := exec.Command("taskkill.exe", "/PID", strconv.Itoa(identity.PID), "/F")
	command.Stdout = io.Discard
	command.Stderr = io.Discard
	return command.Run()
}

func createPseudoConsolePipe() (windows.Handle, windows.Handle, error) {
	var readHandle, writeHandle windows.Handle
	// ConPTY owns these handles through its internal duplication. Keeping the
	// pipe ends non-inheritable matches the Windows ConPTY contract and avoids
	// leaking the pseudo-console handles into the client process.
	if err := windows.CreatePipe(&readHandle, &writeHandle, nil, 0); err != nil {
		return 0, 0, err
	}
	return readHandle, writeHandle, nil
}

func closePseudoConsoleHandles(handles ...windows.Handle) {
	for _, handle := range handles {
		if handle != 0 && handle != windows.InvalidHandle {
			_ = windows.CloseHandle(handle)
		}
	}
}

func managedProcessEnvironment(values map[string]string) (*uint16, error) {
	if len(values) == 0 {
		// A nil environment tells CreateProcess to inherit the helper's
		// environment. This preserves Windows' special drive-current-directory
		// entries and avoids rebuilding a potentially incomplete environment
		// block for the common case.
		return nil, nil
	}
	environment := make(map[string]string, len(values))
	for _, entry := range os.Environ() {
		keyEnd := strings.IndexByte(entry, '=')
		if strings.HasPrefix(entry, "=") {
			// Windows stores drive current directories as =C:=C:\\...;
			// the first equals sign is part of that variable's name.
			if next := strings.IndexByte(entry[1:], '='); next >= 0 {
				keyEnd = next + 1
			}
		}
		if keyEnd > 0 {
			key := entry[:keyEnd]
			environment[strings.ToUpper(key)] = entry
		}
	}
	for key, value := range values {
		environment[strings.ToUpper(key)] = key + "=" + value
	}
	entries := make([]string, 0, len(environment))
	for _, entry := range environment {
		entries = append(entries, entry)
	}
	sort.Slice(entries, func(i, j int) bool { return strings.ToUpper(entries[i]) < strings.ToUpper(entries[j]) })
	encoded := utf16.Encode([]rune(strings.Join(entries, "\x00") + "\x00\x00"))
	return &encoded[0], nil
}