DSCResources/MSFT_OpticalDiskDriveLetter/MSFT_OpticalDiskDriveLetter.psm1

$modulePath = Join-Path -Path (Split-Path -Path (Split-Path -Path $PSScriptRoot -Parent) -Parent) -ChildPath 'Modules'

# Import the Storage Common Module.
Import-Module -Name (Join-Path -Path $modulePath `
        -ChildPath (Join-Path -Path 'StorageDsc.Common' `
            -ChildPath 'StorageDsc.Common.psm1'))

# Import Localization Strings.
$script:localizedData = Get-LocalizedData -ResourceName 'MSFT_OpticalDiskDriveLetter'

<#
    .SYNOPSIS
        This helper function returns a hashtable containing the current
        drive letter assigned to the optical disk in the system matching
        the disk number.
 
        If the drive exists but is not mounted to a drive letter then
        the DriveLetter will be empty, but the DeviceId will contain the
        DeviceId representing the optical disk.
 
        If there are no optical disks found in the system an exception
        will be thrown.
 
    .PARAMETER DiskId
        Specifies the optical disk number for the disk to return the drive
        letter of.
 
    .NOTES
        The Caption and DeviceID properties are checked to avoid
        mounted ISO images in Windows 2012+ and Windows 10. The
        device ID is required because a CD/DVD in a Hyper-V virtual
        machine has the same caption as a mounted ISO.
 
        Example DeviceID for a virtual drive in a Hyper-V VM - SCSI\CDROM&VEN_MSFT&PROD_VIRTUAL_DVD-ROM\000006
        Example DeviceID for a mounted ISO in a Hyper-V VM - SCSI\CDROM&VEN_MSFT&PROD_VIRTUAL_DVD-ROM\2&1F4ADFFE&0&000002
#>

function Get-OpticalDiskDriveLetter
{
    [CmdletBinding()]
    [OutputType([System.Collections.Hashtable])]
    param
    (
        [Parameter(Mandatory = $true)]
        [System.String]
        $DiskId
    )

    $driveLetter = $null

    Write-Verbose -Message ( @(
            "$($MyInvocation.MyCommand): "
            $($script:localizedData.UsingGetCimInstanceToFetchDriveLetter -f $DiskId)
        ) -join '' )

    # Get the optical disk matching the Id
    $opticalDisks = Get-CimInstance -ClassName Win32_CDROMDrive |
        Where-Object -FilterScript {
        -not (
            $_.Caption -eq 'Microsoft Virtual DVD-ROM' -and
            ($_.DeviceID.Split('\')[-1]).Length -gt 10
        )
    }

    $deviceId = ''

    if ($opticalDisks)
    {
        <#
            To behave in a similar fashion to the other xStorage resources the
            DiskId represents the number of the optical disk in the system.
            However as these are returned as an array of 0..x elements then
            subtract one from the DiskId to get the actual optical disk number
            that is required.
        #>

        $opticalDisk = $opticalDisks[$DiskId - 1]

        if ($opticalDisk)
        {
            try
            {
                # Make sure the current DriveLetter is an actual drive letter
                $driveLetter = Assert-DriveLetterValid -DriveLetter $opticalDisk.Drive -Colon
            }
            catch
            {
                # Optical drive exists but is not mounted to a drive letter
                $driveLetter = ''

                Write-Verbose -Message ( @(
                        "$($MyInvocation.MyCommand): "
                        $($script:localizedData.OpticalDiskNotAssignedDriveLetter -f $DiskId)
                    ) -join '' )
            }
            $deviceId = $opticalDisk.Drive
        }
    }

    if ($null -eq $driveLetter)
    {
        New-InvalidArgumentException `
            -Message ($script:localizedData.NoOpticalDiskDriveError -f $DiskId) `
            -ArgumentName 'DiskId'
    }

    return @{
        DriveLetter = $driveLetter
        DeviceId    = $deviceId
    }
}

<#
    .SYNOPSIS
        Returns the current drive letter assigned to the optical disk.
 
    .PARAMETER DiskId
        Specifies the optical disk number for the disk to assign the drive
        letter to.
 
    .PARAMETER DriveLetter
        Specifies the drive letter to assign to the optical disk. Can be a
        single letter, optionally followed by a colon. This value is ignored
        if Ensure is set to Absent.
#>

function Get-TargetResource
{
    [CmdletBinding()]
    [OutputType([System.Collections.Hashtable])]
    param
    (
        [Parameter(Mandatory = $true)]
        [System.String]
        $DiskId,

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

    $ensure = 'Absent'

    # Get the drive letter assigned to the optical disk
    $currentDriveInfo = Get-OpticalDiskDriveLetter -DiskId $DiskId
    $currentDriveLetter = $currentDriveInfo.DriveLetter

    if ([System.String]::IsNullOrWhiteSpace($currentDriveLetter))
    {
        Write-Verbose -Message ( @(
                "$($MyInvocation.MyCommand): "
                $($script:localizedData.OpticalDiskNotAssignedDriveLetter -f $DiskId)
            ) -join '' )
    }
    else
    {
        Write-Verbose -Message ( @(
                "$($MyInvocation.MyCommand): "
                $($script:localizedData.OpticalDiskAssignedDriveLetter -f $DiskId, $DriveLetter)
            ) -join '' )

        $Ensure = 'Present'
    }

    $returnValue += @{
        DiskId      = $DiskId
        DriveLetter = $currentDriveLetter
        Ensure      = $ensure
    }

    return $returnValue
} # Get-TargetResource

<#
    .SYNOPSIS
        Sets the drive letter of an optical disk.
 
    .PARAMETER DiskId
        Specifies the optical disk number for the disk to assign the drive
        letter to.
 
    .PARAMETER DriveLetter
        Specifies the drive letter to assign to the optical disk. Can be a
        single letter, optionally followed by a colon. This value is ignored
        if Ensure is set to Absent.
 
    .PARAMETER Ensure
        Determines whether a drive letter should be assigned to the
        optical disk. Defaults to 'Present'.
#>

function Set-TargetResource
{
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory = $true)]
        [System.String]
        $DiskId,

        [Parameter(Mandatory = $true)]
        [System.String]
        $DriveLetter,

        [Parameter()]
        [ValidateSet('Present', 'Absent')]
        [System.String]
        $Ensure = 'Present'
    )

    # Allow use of drive letter without colon
    $DriveLetter = Assert-DriveLetterValid -DriveLetter $DriveLetter -Colon

    # Get the drive letter assigned to the optical disk
    $currentDriveInfo = Get-OpticalDiskDriveLetter -DiskId $DiskId
    $currentDriveLetter = $currentDriveInfo.DriveLetter

    if ([System.String]::IsNullOrWhiteSpace($currentDriveLetter))
    {
        <#
            If the current drive letter is empty then the volume must be looked up by DeviceId
            The DeviceId in the volume will show as \\?\Volume{bba1802b-e7a1-11e3-824e-806e6f6e6963}\
            So we need to change the currentDriveLetter to match this value when we set the drive letter
        #>

        $deviceId = $currentDriveInfo.DeviceId

        $volume = Get-CimInstance `
            -ClassName Win32_Volume `
            -Filter "DeviceId = '\\\\?\\$deviceId\\'"
    }
    else
    {
        $volume = Get-CimInstance `
            -ClassName Win32_Volume `
            -Filter "DriveLetter = '$currentDriveLetter'"
    }

    # Does the Drive Letter need to be added or removed
    if ($Ensure -eq 'Absent')
    {
        Write-Verbose -Message ( @(
            "$($MyInvocation.MyCommand): "
            $($script:localizedData.AttemptingToRemoveDriveLetter -f $diskId, $currentDriveLetter)
        ) -join '' )

        $volume | Set-CimInstance -Property @{ DriveLetter = $null }
    }
    else
    {
        Write-Verbose -Message ( @(
            "$($MyInvocation.MyCommand): "
            $($script:localizedData.AttemptingToSetDriveLetter -f $diskId, $currentDriveLetter, $DriveLetter)
        ) -join '' )

        $volume | Set-CimInstance -Property @{ DriveLetter = $DriveLetter }
    }
} # Set-TargetResource

<#
    .SYNOPSIS
        Tests the disk letter assigned to an optical disk is correct.
 
    .PARAMETER DiskId
        Specifies the optical disk number for the disk to assign the drive
        letter to.
 
    .PARAMETER DriveLetter
        Specifies the drive letter to assign to the optical disk. Can be a
        single letter, optionally followed by a colon. This value is ignored
        if Ensure is set to Absent.
 
    .PARAMETER Ensure
        Determines whether a drive letter should be assigned to the
        optical disk. Defaults to 'Present'.
#>

function Test-TargetResource
{
    [CmdletBinding()]
    [OutputType([System.Boolean])]
    param
    (
        [Parameter(Mandatory = $true)]
        [System.String]
        $DiskId,

        [Parameter(Mandatory = $true)]
        [System.String]
        $DriveLetter,

        [Parameter()]
        [ValidateSet('Present', 'Absent')]
        [System.String]
        $Ensure = 'Present'
    )

    $desiredConfigurationMatch = $true

    # Allow use of drive letter without colon
    $DriveLetter = Assert-DriveLetterValid -DriveLetter $DriveLetter -Colon

    # Get the drive letter assigned to the optical disk
    $currentDriveInfo = Get-OpticalDiskDriveLetter -DiskId $DiskId
    $currentDriveLetter = $currentDriveInfo.DriveLetter

    if ($Ensure -eq 'Absent')
    {
        # The Drive Letter should be absent from the optical disk
        if ([System.String]::IsNullOrWhiteSpace($currentDriveLetter))
        {
            Write-Verbose -Message ( @(
                    "$($MyInvocation.MyCommand): "
                    $($script:localizedData.DriveLetterDoesNotExistAndShouldNot -f $DiskId)
                ) -join '' )
        }
        else
        {
            # The Drive Letter needs to be dismounted
            Write-Verbose -Message ( @(
                    "$($MyInvocation.MyCommand): "
                    $($script:localizedData.DriveLetterExistsButShouldNot -f $DiskId, $currentDriveLetter)
                ) -join '' )

            $desiredConfigurationMatch = $false
        }
    }
    else
    {
        if ($currentDriveLetter -eq $DriveLetter)
        {
            # The optical disk drive letter is already set correctly
            Write-Verbose -Message ( @(
                    "$($MyInvocation.MyCommand): "
                    $($script:localizedData.DriverLetterExistsAndIsCorrect -f $DiskId, $DriveLetter)
                ) -join '' )
        }
        else
        {
            # Is a desired drive letter already assigned to a different drive?
            $existingVolume = Get-CimInstance `
                -ClassName Win32_Volume `
                -Filter "DriveLetter = '$DriveLetter'"

            if ($existingVolume)
            {
                # The desired drive letter is already assigned to another drive - can't proceed
                New-InvalidOperationException `
                    -Message $($script:localizedData.DriveLetterAssignedToAnotherDrive -f $DriveLetter)
            }
            else
            {
                # The optical drive letter needs to be changed
                Write-Verbose -Message ( @(
                        "$($MyInvocation.MyCommand): "
                        $($script:localizedData.DriverLetterExistsAndIsNotCorrect -f $DiskId, $currentDriveLetter, $DriveLetter)
                    ) -join '' )

                $desiredConfigurationMatch = $false
            }
        }
    }

    return $desiredConfigurationMatch
}

Export-ModuleMember -Function *-TargetResource