param (
    [string]$vCenterServer,
    [string]$Username,
    [string]$Password,
    [string]$LastVM,
    [switch]$DryRun,  # Add a DryRun switch
    [switch]$Help  # Add a Help switch
)

# Script Information
Write-Host "VMware Emergency Shutdown Script - Paul Mataruso (paulmataruso@dhitechnical.com) v0.1"
Write-Host "-----------------------------------------------------------------------------------------"

# Display help message
if ($Help) {
    Write-Host "Shutdown VMs PowerCLI Script"
    Write-Host "----------------------------------------------------"
    Write-Host "This script connects to a vCenter server and shuts down all running VMs."
    Write-Host "VMs with VMware Tools installed will be gracefully shut down, others will be powered off."
    Write-Host "You can specify a VM that should be shut down last using the -LastVM parameter."
    Write-Host "If no last VM is specified, you will be prompted to select one."
    Write-Host ""
    Write-Host "Usage:"
    Write-Host "  .\script.ps1 -vCenterServer <vCenter> -Username <User> -Password <Pass> [-LastVM <VMName>] [-DryRun] [-Help]"
    Write-Host ""
    Write-Host "Options:"
    Write-Host "  -vCenterServer   Specify the vCenter server hostname or IP."
    Write-Host "  -Username        Specify the vCenter login username."
    Write-Host "  -Password        Specify the vCenter login password."
    Write-Host "  -LastVM          Specify the last VM to be shut down. If omitted, you will be prompted to select one."
    Write-Host "  -DryRun          Simulate the shutdown process without making changes."
    Write-Host "  -Help            Show this help message."
    exit
}

# Import VMware PowerCLI module
if (-not (Get-Module -ListAvailable -Name VMware.PowerCLI)) {
    Write-Host "VMware PowerCLI module is not installed. Installing..."
    Install-Module -Name VMware.PowerCLI -Scope CurrentUser -Force -SkipPublisherCheck
}

# Connect to vCenter
Write-Host "Connecting to vCenter: $vCenterServer"
$securePassword = ConvertTo-SecureString $Password -AsPlainText -Force
$cred = New-Object System.Management.Automation.PSCredential ($Username, $securePassword)
Connect-VIServer -Server $vCenterServer -Credential $cred

# Get all running VMs
$runningVMs = Get-VM | Where-Object { $_.PowerState -eq "PoweredOn" }

# Prompt for last VM if not provided
if (-not $LastVM) {
    Write-Host "Select the last VM to shut down:"
    $vmList = $runningVMs | Select-Object -ExpandProperty Name
    for ($i = 0; $i -lt $vmList.Count; $i++) {
        Write-Host "[$i] $($vmList[$i])"
    }
    $selection = Read-Host "Enter the number corresponding to the VM"
    if ($selection -match "^\d+$" -and [int]$selection -ge 0 -and [int]$selection -lt $vmList.Count) {
        $LastVM = $vmList[[int]$selection]
    } else {
        Write-Host "Invalid selection. Exiting."
        exit
    }
}

# Separate the last VM
$LastVMInstance = $runningVMs | Where-Object { $_.Name -eq $LastVM }
$otherVMs = $runningVMs | Where-Object { $_.Name -ne $LastVM }

foreach ($vm in $otherVMs) {
    Write-Host "Processing VM: $($vm.Name)"
    if ($vm.ExtensionData.Guest.ToolsStatus -eq "toolsOk") {
        Write-Host "[DryRun] Would shut down $($vm.Name) gracefully..."
        if (-not $DryRun) {
            Shutdown-VMGuest -VM $vm -Confirm:$false
        }
    } else {
        Write-Host "[DryRun] Would force power off $($vm.Name)..."
        if (-not $DryRun) {
            Stop-VM -VM $vm -Confirm:$false -Kill
        }
    }
}

# Shutdown last specified VM
if ($LastVMInstance) {
    Write-Host "[DryRun] Would shut down last VM: $($LastVMInstance.Name) last..."
    if (-not $DryRun) {
        if ($LastVMInstance.ExtensionData.Guest.ToolsStatus -eq "toolsOk") {
            Shutdown-VMGuest -VM $LastVMInstance -Confirm:$false
        } else {
            Stop-VM -VM $LastVMInstance -Confirm:$false -Kill
        }
    }
}

Write-Host "All VMs processed. Disconnecting from vCenter."
Disconnect-VIServer -Server $vCenterServer -Confirm:$false

#.\vmshut.ps1 -vCenterServer "vcenter7.dhitechnical.com" -Username "administrator@vsphere.local" -Password "Gx180d132!23456"