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: download.go
    path of file: ./repos/sliver/client/command/filesystem
    
    the code of the file until where you have to start completion: package filesystem

/*
	Sliver Implant Framework
	Copyright (C) 2019  Bishop Fox

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/

import (
	"context"
	"fmt"
	"os"
	"path/filepath"
	"regexp"
	"runtime"
	"strings"
	"time"

	"github.com/bishopfox/sliver/client/command/loot"
	"github.com/bishopfox/sliver/client/console"
	"github.com/bishopfox/sliver/protobuf/clientpb"
	"github.com/bishopfox/sliver/protobuf/sliverpb"
	"github.com/bishopfox/sliver/util/encoders"
	"github.com/spf13/cobra"
	"google.golang.org/protobuf/proto"
	"gopkg.in/AlecAivazis/survey.v1"
)

func DownloadCmd(cmd *cobra.Command, con *console.SliverClient, args []string) {
	session, beacon := con.ActiveTarget.GetInteractive()
	if session == nil && beacon == nil {
		return
	}

	remotePath := args[0]
	recurse, _ := cmd.Flags().GetBool("recurse")

	ctrl := make(chan bool)
	con.SpinUntil(fmt.Sprintf("Downloading %s ...", remotePath), ctrl)
	download, err := con.Rpc.Download(context.Background(), &sliverpb.DownloadReq{
		Request:          con.ActiveTarget.Request(cmd),
		Path:             remotePath,
		Recurse:          recurse,
		RestrictedToFile: false,
	})
	ctrl <- true
	<-ctrl
	if err != nil {
		con.PrintErrorf("%s\n", err)
		return
	}
	if download.Response != nil && download.Response.Async {
		con.AddBeaconCallback(download.Response.TaskID, func(task *clientpb.BeaconTask) {
			err = proto.Unmarshal(task.Response, download)
			if err != nil {
				con.PrintErrorf("Failed to decode response %s\n", err)
				return
			}
			HandleDownloadResponse(download, cmd, args, con)
		})
		con.PrintAsyncResponse(download.Response)
	} else {
		HandleDownloadResponse(download, cmd, args, con)
	}
}

func prettifyDownloadName(path string) string {
	nonAlphaNumericRegex, err := regexp.Compile("[^a-zA-Z0-9]+")
	if err != nil {
		// Well, we tried.
		return path
	}

	pathNoSeparators := strings.ReplaceAll(path, "\\", "_")
	pathNoSeparators = strings.ReplaceAll(pathNoSeparators, "/", "_")

	filteredString := nonAlphaNumericRegex.ReplaceAllString(pathNoSeparators, "_")

	// Collapse multiple underscores into one
	multipleUnderscoreRegex, err := regexp.Compile("_{2,}")
	if err != nil {
		return filteredString
	}

	filteredString = multipleUnderscoreRegex.ReplaceAllString(filteredString, "_")

	// If there is an underscore at the front of the filename, strip that off
	if strings.H
    
func HandleDownloadResponse(download *sliverpb.Download, cmd *cobra.Command, args []string, con *console.SliverClient) {
	var err error
	if download.Response != nil && download.Response.Err != "" {
		con.PrintErrorf("%s\n", download.Response.Err)
		return
	}

	if download.Encoder == "gzip" {
		download.Data, err = new(encoders.Gzip).Decode(download.Data)
		if err != nil {
			con.PrintErrorf("Decoding failed %s", err)
		}
	}

	remotePath := args[0]
	var localPath string
	if len(args) == 1 {
		localPath = "."
	} else {
		localPath = args[1]
	}
	saveLoot, _ := cmd.Flags().GetBool("loot")

	if download.ReadFiles == 0 {
		// No files downloaded successfully.
		con.PrintErrorf("No files downloaded from the implant - check permissions, path, and / or filters.\n")
		return
	}

	if saveLoot {
		lootName, _ := cmd.Flags().GetString("name")
		// Hand off to the loot package to take care of looting
		fType, _ := cmd.Flags().GetString("file-type")
		fileType := loot.ValidateLootFileType(fType, download.Data)
		loot.LootDownload(download, lootName, fileType, cmd, con)
	} else {
		fileName := filepath.Base(remotePath)
		dst, err := filepath.Abs(localPath)
		if err != nil {
			con.PrintErrorf("%s\n", err)
			return
		}

		fi, err := os.Stat(dst)
		if err != nil && !os.IsNotExist(err) {
			con.PrintErrorf("%s\n", err)
			return
		}
		if err == nil && fi.IsDir() {
			if download.IsDir {
				// Come up with a good file name - filters might make the filename ugly
				session, beacon := con.ActiveTarget.Get()
				implantName := ""
				if session != nil {
					implantName = session.Name
				} else if beacon != nil {
					implantName = beacon.Name
				}

				fileName = fmt.Sprintf("%s_download_%s_%d.tar.gz", filepath.Base(implantName), filepath.Base(prettifyDownloadName(remotePath)), time.Now().Unix())
			}
			if runtime.GOOS == "windows" {
				// Windows has a file path length of 260 characters
				// +1 for the path separator before the file name
				if len(dst)+len(fileName)+1 > 260 {
					// Make an effort to shorten the file name. If this does not work, the operator will have to find somewhere else to put the file
					fileName = fmt.Sprintf("down_%d.tar.gz", time.Now().Unix())
				}
			}
			dst = filepath.Join(dst, fileName)
		}

		// Add an extension to a directory download if one is not provided.
		if download.IsDir && (!strings.HasSuffix(dst, ".tgz") && !strings.HasSuffix(dst, ".tar.gz")) {
			dst += ".tar.gz"
		}

		if _, err := os.Stat(dst); err == nil {
			overwrite := false
			prompt := &survey.Confirm{Message: "Overwrite local file?"}
			survey.AskOne(prompt, &overwrite, nil)
			if !overwrite {
				return
			}
		}

		dstFile, err := os.Create(dst)
		if err != nil {
			con.PrintErrorf("Failed to open local file %s: %s\n", dst, err)
			return
		}
		defer dstFile.Close()
		n, err := dstFile.Write(download.Data)
		if err != nil {
			con.PrintErrorf("Failed to write data %v\n", err)
		} else {
			var readFilesText string
			var unreadFilesText string

			if download.ReadFiles == 1 {
				readFilesText = "file"
			} else {
				readFilesText = "files"
			}

			if download.UnreadableFiles == 1 {
				unreadFilesText = "file"
			} else {
				unreadFilesText = "files"
			}

			con.PrintInfof("Wrote %d bytes (%d %s successfully, %d %s unsuccessfully) to %s\n",
				n,
				download.ReadFiles,
				readFilesText,
				download.UnreadableFiles,
				unreadFilesText,
				dstFile.Name())
		}
	}
}