PowerShell-PSDscResources/DscResources/CommonResourceHelper.psm1

<#
    .SYNOPSIS
        Tests if the current machine is a Nano server.
#>
function Test-IsNanoServer
{
    [OutputType([System.Boolean])]
    [CmdletBinding()]
    param ()

    $serverLevelsRegKey = 'HKLM:\Software\Microsoft\Windows NT\CurrentVersion\Server\ServerLevels'

    if (Test-Path -Path $serverLevelsRegKey)
    {
        $serverLevels = Get-ItemProperty -Path $serverLevelsRegKey

        if ($serverLevels.NanoServer -eq 1)
        {
            $isNanoServer = $true
        }
        else
        {
            $isNanoServer = $false
        }
    }
    else
    {
        $isNanoServer = $false
    }

    return $isNanoServer
}

<#
    .SYNOPSIS
        Tests whether or not the command with the specified name exists.

    .PARAMETER Name
        The name of the command to test for.
#>
function Test-CommandExists
{
    [OutputType([System.Boolean])]
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [System.String]
        $Name
    )

    $command = Get-Command -Name $Name -ErrorAction 'SilentlyContinue'
    return ($null -ne $command)
}

<#
    .SYNOPSIS
        Creates and throws an invalid argument exception.

    .PARAMETER Message
        The message explaining why this error is being thrown.

    .PARAMETER ArgumentName
        The name of the invalid argument that is causing this error to be thrown.
#>
function New-InvalidArgumentException
{
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [System.String]
        $Message,

        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [System.String]
        $ArgumentName
    )

    $argumentException = New-Object -TypeName 'ArgumentException' `
        -ArgumentList @($Message, $ArgumentName)
    $newObjectParams = @{
        TypeName     = 'System.Management.Automation.ErrorRecord'
        ArgumentList = @($argumentException, $ArgumentName, 'InvalidArgument', $null)
    }
    $errorRecord = New-Object @newObjectParams

    throw $errorRecord
}

<#
    .SYNOPSIS
        Creates and throws an invalid operation exception.

    .PARAMETER Message
        The message explaining why this error is being thrown.

    .PARAMETER ErrorRecord
        The error record containing the exception that is causing this terminating
        error.
#>
function New-InvalidOperationException
{
    [CmdletBinding()]
    param
    (
        [Parameter()]
        [ValidateNotNullOrEmpty()]
        [System.String]
        $Message,

        [Parameter()]
        [ValidateNotNull()]
        [System.Management.Automation.ErrorRecord]
        $ErrorRecord
    )

    if ($null -eq $Message)
    {
        $invalidOperationException = New-Object -TypeName 'InvalidOperationException'
    }
    elseif ($null -eq $ErrorRecord)
    {
        $invalidOperationException = New-Object -TypeName 'InvalidOperationException' `
            -ArgumentList @( $Message )
    }
    else
    {
        $invalidOperationException = New-Object -TypeName 'InvalidOperationException' `
            -ArgumentList @( $Message, $ErrorRecord.Exception )
    }

    $newObjectParams = @{
        TypeName     = 'System.Management.Automation.ErrorRecord'
        ArgumentList = @( $invalidOperationException.ToString(), 'MachineStateIncorrect', 'InvalidOperation', $null )
    }

    $errorRecordToThrow = New-Object @newObjectParams
    throw $errorRecordToThrow
}

<#
    .SYNOPSIS
        Retrieves the localized string data based on the machine's culture.
        Falls back to en-US strings if the machine's culture is not supported.

    .PARAMETER ResourceName
        The name of the resource as it appears before '.strings.psd1' of the localized
        string file.
        For example:
            For WindowsOptionalFeature: MSFT_WindowsOptionalFeature
            For Service: MSFT_ServiceResource
            For Registry: MSFT_RegistryResource
#>
function Get-LocalizedData
{
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [System.String]
        $ResourceName
    )

    $resourceDirectory = Join-Path -Path $PSScriptRoot -ChildPath $ResourceName
    $localizedStringFileLocation = Join-Path -Path $resourceDirectory -ChildPath $PSUICulture

    if (-not (Test-Path -Path $localizedStringFileLocation))
    {
        # Fallback to en-US
        $localizedStringFileLocation = Join-Path -Path $resourceDirectory -ChildPath 'en-US'
    }

    Import-LocalizedData `
        -BindingVariable 'localizedData' `
        -FileName "$ResourceName.strings.psd1" `
        -BaseDirectory $localizedStringFileLocation

    return $localizedData
}

Export-ModuleMember -Function @( 'Test-IsNanoServer', 'New-InvalidArgumentException',
    'New-InvalidOperationException', 'Get-LocalizedData' )