$vCenterServer = Read-Host -Prompt 'Enter the FQDN of the vCenter Server you want to connect to (ex. vcenter.domain.com)'
Try {
    Connect-VIServer -Server $vCenterServer -ErrorAction Stop | Out-Null
} Catch {
    Write-Host -ForegroundColor Red -BackgroundColor Black "Could not connect to the vCenter Server [$vCenterServer]." `n
    Exit
}

while ($True) {
    ### Prompt the user for the cluster name within that vCenter Server
    $ClusterName = Read-Host -Prompt 'Enter the full name of the cluster you want to work with (ex. ProdCluster01)'

    ### Get information about all hosts in the defined cluster
    $vmHosts = Get-Cluster -Name $ClusterName | Get-VMHost | Sort-Object

    $cont = ""
    $contR = ""
    Do {
        ### Ask the user what step to perform
        Write-Host `n
        Write-Host "Please enter a task to perform on each host in the cluster:"
        Write-Host "1.) Add parameter"
        Write-Host "2.) Add Another parameter"
        Write-Host "3.) Next Cluster"
        Write-Host "4.) Exit" `n
        $choice = Read-Host

        ### Perform a particular task based on user input
        Switch ($choice) {
            ### If task #1 is chosen, add parameter to /etc/hosts
            1 {
                Write-Host -ForegroundColor Yellow `n "Retrieving current /etc/hosts file from $esxihost"
                ForEach ($vmHost in $vmHosts) {
                    #Connectivity Information
                    $Username = "root" # ESXi Username
                    $Password = Read-Host -Prompt 'ESXi Password'

                    #New Host Entry
                    $addIP = Read-Host -Prompt ' New Entry IP'
                    $addHostname = Read-Host -Prompt ' New Entry Hostname'
                    $addAlias = Read-Host -Prompt ' New Entry Alias'

                    ### Create authorization string and store in $head
                    $auth = [System.Convert]::ToBase64String([System.Text.Encoding]::UTF8.GetBytes($Username + ":" + $Password))
                    $head = @{"Authorization" = "Basic $auth" }

                    # Request current hosts file
                    Write-Host "Retrieving current /etc/hosts file from $esxihost" -ForegroundColor Green
                    $requesthostsfile = Invoke-WebRequest -Uri https://$esxihost/host/hosts -Method GET -ContentType "text/plain" -Headers $head

                    if ( $requesthostsfile.StatusCode -ne "200" ) {
                        Write-Host "Unable to retrieve current /etc/hosts file from $esxihost" -ForegroundColor Red
                        Exit
                    }

                    # Add new line to hosts file with $addIP and $addHostname and $addAlias
                    $newhostsfile = $requesthostsfile.Content
                    $newhostsfile += "`n$addIP`t$addHostname`t$addAlias"

                    Write-Host "Contents of new /etc/hosts" -ForegroundColor Green
                    Write-Host "-------------------------------------------------------"
                    Write-Host $newhostsfile
                    Write-Host "-------------------------------------------------------"

                    # Put the new hosts file on the host
                    Write-Host "Putting new /etc/hosts file on $esxihost"
                    $puthostsfile = Invoke-WebRequest -Uri https://$vmHost.domain.bankanet.com.tr/host/hosts -Method PUT -ContentType "text/plain" -Headers $head -Body $newhostsfile

                    if ( $puthostsfile.StatusCode -ne "200" ) {
                        Write-Host "Unable to put new /etc/hosts file on $esxihost" -ForegroundColor Red
                        Exit
                    }
                    Write-Host "Done!" -ForegroundColor Green
                }
                $cont = $True
            }
            ### If task #2 is chosen, Add Another Entry
            2 {
                Write-Host -ForegroundColor Yellow `n "Retrieving current /etc/hosts file from $esxihost"
                ForEach ($vmHost in $vmHosts) {
                    #New Host Entry
                    $addanotherIP = Read-Host -Prompt ' New Entry IP'
                    $addanotherHostname = Read-Host -Prompt ' New Entry Hostname'
                    $addanotherAlias = Read-Host -Prompt ' New Entry Alias'
                }

                # Request current hosts file
                Write-Host "Retrieving current /etc/hosts file from $esxihost" -ForegroundColor Green
                $requesthostsfile = Invoke-WebRequest -Uri https://$esxihost/host/hosts -Method GET -ContentType "text/plain" -Headers $head

                if ( $requesthostsfile.StatusCode -ne "200" ) {
                    Write-Host "Unable to retrieve current /etc/hosts file from $esxihost" -ForegroundColor Red
                    Exit
                }

                # Add new line to hosts file with $addIP and $addHostname and $addAlias
                $newhostsfile = $requesthostsfile.Content
                $newhostsfile += "`n$anotheraddIP`t$addanotherHostname`t$addanotherAlias"

                Write-Host "Contents of new /etc/hosts" -ForegroundColor Green
                Write-Host "-------------------------------------------------------"
                Write-Host $newhostsfile
                Write-Host "-------------------------------------------------------"


                # Put the new hosts file on the host
                Write-Host "Putting new /etc/hosts file on $esxihost"
                $puthostsfile = Invoke-WebRequest -Uri https://$vmHost.domain.bankanet.com.tr/host/hosts -Method PUT -ContentType "text/plain" -Headers $head -Body $newhostsfile

                if ( $puthostsfile.StatusCode -ne "200" ) {
                    Write-Host "Unable to put new /etc/hosts file on $esxihost" -ForegroundColor Red
                    Exit
                }
                $cont = $True
            }
            ### If task #3 is chosen, next cluster
            3 {
                Write-Host "Next Cluster..."
                $cont = $false
                $contR = $false
            }
            ### If task #4 is chosen, exit the script
            4 {
                Write-Host "Exiting..."
                $cont = $false
                $contR = $True
            }

            ### If user enters anything other than 1-4, input is invalid and ask question again
            default {
                Write-Host -ForegroundColor Red ">>> Invalid input. Please select option 1-4."
                $cont = $true
                $contR = $false
            }
        }
        ### Loop through the script until task #4 (Exit) is chosen
    } While ($cont)

    if ($contR) {
        break
    }
}