# Rewrited for PowerShell 7 with the help of ChatGPH
param(
    [Parameter(Mandatory)]
    [string]$VMName
)

function ConvertTo-SubnetMask {
    param(
        [string]$PrefixLength
    )

    if ($PrefixLength -notmatch '^\d+$' -or
        [int]$PrefixLength -lt 0 -or
        [int]$PrefixLength -gt 32) {
        return $PrefixLength
    }

    $mask = [uint32]::MaxValue -shl (32 - [int]$PrefixLength)
    $bytes = [BitConverter]::GetBytes($mask)
    [Array]::Reverse($bytes)
    return ($bytes -join '.')
}

$vm = Get-VM -Name $VMName -ErrorAction Stop
if ($vm.State -ne 'Running') {
    Write-Host "VM $VMName is not Running."
    exit 1
}

$ns = "root\virtualization\v2"

# Virtual System Management Service
$vsvms = Get-CimInstance `
    -Namespace $ns `
    -ClassName Msvm_VirtualSystemManagementService

# VM
$vmcs = Get-CimInstance `
    -Namespace $ns `
    -ClassName Msvm_ComputerSystem `
    -Filter "ElementName='$VMName'"

if (-not $vmcs) {
    Write-Host "Error: VM $VMName is missing."
    exit 1
}

# Msvm_ComputerSystem
#   -> Msvm_VirtualSystemSettingData
$vs_settingdata = Get-CimAssociatedInstance `
    -InputObject $vmcs `
    -Association Msvm_SettingsDefineState `
    -ResultClassName Msvm_VirtualSystemSettingData

# Msvm_VirtualSystemSettingData
#   -> Msvm_SyntheticEthernetPortSettingData
$et_settingdata = Get-CimAssociatedInstance `
    -InputObject $vs_settingdata `
    -ResultClassName Msvm_SyntheticEthernetPortSettingData

# Msvm_SyntheticEthernetPortSettingData
#   -> Msvm_GuestNetworkAdapterConfiguration
$vm_netconf = Get-CimAssociatedInstance `
    -InputObject $et_settingdata `
    -Association Msvm_SettingDataComponent `
    -ResultClassName Msvm_GuestNetworkAdapterConfiguration

$yesno = Read-Host "Enable DHCP? (y/n[n])"

if ($yesno.ToLower() -eq "y") {

    $vm_netconf.PSBase.CimInstanceProperties["DHCPEnabled"].Value = $true

}
else {

    $vm_netconf.PSBase.CimInstanceProperties["DHCPEnabled"].Value = $false
    $vm_netconf.PSBase.CimInstanceProperties["IPAddresses"].Value =
        @((Read-Host "Specify static ipv4 address"))

    $vm_netconf.PSBase.CimInstanceProperties["Subnets"].Value =
        @(ConvertTo-SubnetMask((Read-Host "Specify subnetmask")))

    $vm_netconf.PSBase.CimInstanceProperties["DefaultGateways"].Value =
        @((Read-Host "Specify default gateway"))

    $vm_netconf.PSBase.CimInstanceProperties["DNSServers"].Value =
        @((Read-Host "Specify preferred dns server"))
}

# CIMインスタンスを embedded instance 文字列に変換
$cimSerializer =
    [Microsoft.Management.Infrastructure.Serialization.CimSerializer]::Create()

$serialized =
    $cimSerializer.Serialize(
        $vm_netconf,
        [Microsoft.Management.Infrastructure.Serialization.InstanceSerializationOptions]::None
    )

$networkConfiguration =
    [System.Text.Encoding]::Unicode.GetString($serialized)

# 設定をVMへ適用

$ret = Invoke-CimMethod `
    -InputObject $vsvms `
    -MethodName SetGuestNetworkAdapterConfiguration `
    -Arguments @{
        ComputerSystem      = $vmcs
        NetworkConfiguration = @($networkConfiguration)
    }

if ($ret.ReturnValue -ne 0) {
    Write-Host "Error: something went wrong. ReturnValue=$($ret.ReturnValue)"
}
else {
    Write-Host "Success"
    Get-CimInstance -Namespace $ns -ClassName Msvm_GuestNetworkAdapterConfiguration |
  Where { $_.InstanceID -like "*$($vm.vmId)*" }|Select DHCPEnabled,IPAddresses,Subnets,DefaultGateways,DNSServers

}