You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: proxystatus.go
    path of file: ./repos/istio/istioctl/pkg/proxystatus
    
    the code of the file until where you have to start completion: // Copyright Istio Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package proxystatus

import (
	"context"
	"fmt"
	"io"
	"os"

	discovery "github.com/envoyproxy/go-control-plane/envoy/service/discovery/v3"
	"github.com/spf13/cobra"

	"istio.io/istio/istioctl/pkg/cli"
	"istio.io/istio/istioctl/pkg/clioptions"
	"istio.io/istio/istioctl/pkg/completion"
	"istio.io/istio/istioctl/pkg/multixds"
	"istio.io/istio/istioctl/pkg/util/ambient"
	"istio.io/istio/istioctl/pkg/writer/compare"
	"istio.io/istio/istioctl/pkg/writer/pilot"
	pilotxds "istio.io/istio/pilot/pkg/xds"
	"istio.io/istio/pkg/log"
)

var configDumpFile string

func readConfigFile(filename string) ([]byte, error) {
	file := os.Stdin
	if filename != "-" {
		var err error
		file, err = os.Open(filename)
		if err != nil {
			return nil, err
		}
	}
	defer func() {
		if err := file.Close(); err != nil {
			log.Errorf("failed to close %s: %s", filename, err)
		}
	}()
	data, err := io.ReadAll(file)
	if err != nil {
		return nil, err
	}
	return data, nil
}

func StableXdsStatusCommand(ctx cli.Context) *cobra.Command {
	cmd := XdsStatusCommand(ctx)
	unstableFlags := []string{"xds-via-agents", "xds-via-agents-limit"}
	cmd.PreRunE = func(cmd *cobra.Command, args []string) error {
		for _, flag := range unstableFlags {
			if cmd.PersistentFlags().Changed(flag) {
				return fmt.Errorf("--%s is experimental. Use `istioctl experimental ps --%s`", flag, flag)
			}
		}
		return nil
	}
	for _, flag := range unstableFlags {
		_ = cmd.PersistentFlags().MarkHidden(flag)
	}
	return cmd
}

func XdsStatusCommand(ctx cli.Context) *cobra.Command {
	var opts clioptions.ControlPlaneOptions
	var centralOpts clioptions.CentralControlPlaneOptions
	var multiXdsOpts multixds.Options

	statusCmd := &cobra.Command{
		Use:   "proxy-status [<type>/]<name>[.<namespace>]",
		Short: "Retrieves the synchronization status of each Envoy in the mesh",
		Long: `
Retrieves last sent and last acknowledged xDS sync from Istiod to each Envoy in the mesh
`,
		Example: `  # Retrieve sync status for all Envoys in a mesh
  istioctl proxy-status

  # Retrieve sync status for Envoys in a specific namespace
  istioctl proxy-status --namespace foo

  # Retrieve sync diff for a single Envoy and Istiod
  istioctl proxy-status istio-egressga
    
func XdsStatusCommand(ctx cli.Context) *cobra.Command {
	var opts clioptions.ControlPlaneOptions
	var centralOpts clioptions.CentralControlPlaneOptions
	var multiXdsOpts multixds.Options

	statusCmd := &cobra.Command{
		Use:   "proxy-status [<type>/]<name>[.<namespace>]",
		Short: "Retrieves the synchronization status of each Envoy in the mesh",
		Long: `
Retrieves last sent and last acknowledged xDS sync from Istiod to each Envoy in the mesh
`,
		Example: `  # Retrieve sync status for all Envoys in a mesh
  istioctl proxy-status

  # Retrieve sync status for Envoys in a specific namespace
  istioctl proxy-status --namespace foo

  # Retrieve sync diff for a single Envoy and Istiod
  istioctl proxy-status istio-egressgateway-59585c5b9c-ndc59.istio-system

  # SECURITY OPTIONS

  # Retrieve proxy status information directly from the control plane, using token security
  # (This is the usual way to get the proxy-status with an out-of-cluster control plane.)
  istioctl ps --xds-address istio.cloudprovider.example.com:15012

  # Retrieve proxy status information via Kubernetes config, using token security
  # (This is the usual way to get the proxy-status with an in-cluster control plane.)
  istioctl proxy-status

  # Retrieve proxy status information directly from the control plane, using RSA certificate security
  # (Certificates must be obtained before this step.  The --cert-dir flag lets istioctl bypass the Kubernetes API server.)
  istioctl ps --xds-address istio.example.com:15012 --cert-dir ~/.istio-certs

  # Retrieve proxy status information via XDS from specific control plane in multi-control plane in-cluster configuration
  # (Select a specific control plane in an in-cluster canary Istio configuration.)
  istioctl ps --xds-label istio.io/rev=default
`,
		Aliases: []string{"ps"},
		RunE: func(c *cobra.Command, args []string) error {
			kubeClient, err := ctx.CLIClientWithRevision(opts.Revision)
			if err != nil {
				return err
			}
			multiXdsOpts.MessageWriter = c.OutOrStdout()

			if len(args) > 0 {
				podName, ns, err := ctx.InferPodInfoFromTypedResource(args[0], ctx.Namespace())
				if err != nil {
					return err
				}
				if ambient.IsZtunnelPod(kubeClient, podName, ns) {
					_, _ = fmt.Fprintf(c.OutOrStdout(),
						"Sync diff is not available for ztunnel pod %s.%s\n", podName, ns)
					return nil
				}
				var envoyDump []byte
				if configDumpFile != "" {
					envoyDump, err = readConfigFile(configDumpFile)
				} else {
					path := "config_dump"
					envoyDump, err = kubeClient.EnvoyDo(context.TODO(), podName, ns, "GET", path)
				}
				if err != nil {
					return fmt.Errorf("could not contact sidecar: %w", err)
				}

				xdsRequest := discovery.DiscoveryRequest{
					ResourceNames: []string{fmt.Sprintf("%s.%s", podName, ns)},
					TypeUrl:       pilotxds.TypeDebugConfigDump,
				}
				xdsResponses, err := multixds.FirstRequestAndProcessXds(&xdsRequest, centralOpts, ctx.IstioNamespace(), "", "", kubeClient, multiXdsOpts)
				if err != nil {
					return err
				}
				c, err := compare.NewXdsComparator(c.OutOrStdout(), xdsResponses, envoyDump)
				if err != nil {
					return err
				}
				return c.Diff()
			}
			xdsRequest := discovery.DiscoveryRequest{
				TypeUrl: pilotxds.TypeDebugSyncronization,
			}
			xdsResponses, err := multixds.AllRequestAndProcessXds(&xdsRequest, centralOpts, ctx.IstioNamespace(), "", "", kubeClient, multiXdsOpts)
			if err != nil {
				return err
			}
			sw := pilot.XdsStatusWriter{
				Writer:    c.OutOrStdout(),
				Namespace: ctx.Namespace(),
			}
			return sw.PrintAll(xdsResponses)
		},
		ValidArgsFunction: func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
			return completion.ValidPodsNameArgs(cmd, ctx, args, toComplete)
		},
	}

	opts.AttachControlPlaneFlags(statusCmd)
	centralOpts.AttachControlPlaneFlags(statusCmd)
	statusCmd.PersistentFlags().StringVarP(&configDumpFile, "file", "f", "",
		"Envoy config dump JSON file")
	statusCmd.PersistentFlags().BoolVar(&multiXdsOpts.XdsViaAgents, "xds-via-agents", false,
		"Access Istiod via the tap service of each agent")
	statusCmd.PersistentFlags().IntVar(&multiXdsOpts.XdsViaAgentsLimit, "xds-via-agents-limit", 100,
		"Maximum number of pods being visited by istioctl when `xds-via-agent` flag is true."+
			"To iterate all the agent pods without limit, set to 0")

	return statusCmd
}