DSCResources/DSC_xScriptResource/DSC_xScriptResource.psm1

$errorActionPreference = 'Stop'
Set-StrictMode -Version 'Latest'

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

# Import the shared modules
Import-Module -Name (Join-Path -Path $modulePath `
    -ChildPath (Join-Path -Path 'xPSDesiredStateConfiguration.Common' `
        -ChildPath 'xPSDesiredStateConfiguration.Common.psm1'))

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

<#
    .SYNOPSIS
        Runs the given get script.
        Should return a hashtable.
 
    .PARAMETER GetScript
        A string that can be used to create a PowerShell script block that retrieves the
        current state of the resource.
 
    .PARAMETER SetScript
        Not used in Get-TargetResource.
 
    .PARAMETER TestScript
        Not used in Get-TargetResource.
 
    .PARAMETER Credential
        The credential of the user account to run the script under if needed.
#>

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

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

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

        [Parameter()]
        [ValidateNotNull()]
        [System.Management.Automation.PSCredential]
        [System.Management.Automation.Credential()]
        $Credential
    )

    Write-Verbose -Message $script:localizedData.GetTargetResourceStartVerboseMessage

    $invokeScriptParameters = @{
        ScriptBlock = [System.Management.Automation.ScriptBlock]::Create($GetScript)
    }

    if ($PSBoundParameters.ContainsKey('Credential'))
    {
        $invokeScriptParameters['Credential'] = $Credential
    }

    $invokeScriptResult = Invoke-Script @invokeScriptParameters

    if ($invokeScriptResult -is [System.Management.Automation.ErrorRecord])
    {
        New-InvalidOperationException -Message $script:localizedData.GetScriptThrewError -ErrorRecord $invokeScriptResult
    }

    $invokeScriptResultAsHashTable = $invokeScriptResult -as [System.Collections.Hashtable]

    if ($null -eq $invokeScriptResultAsHashTable)
    {
        New-InvalidArgumentException -ArgumentName 'TestScript' -Message $script:localizedData.GetScriptDidNotReturnHashtable
    }

    Write-Verbose -Message $script:localizedData.GetTargetResourceEndVerboseMessage

    return $invokeScriptResultAsHashTable
}

<#
    .SYNOPSIS
        Runs the given set script.
        Should not return.
 
    .PARAMETER GetScript
        Not used in Set-TargetResource.
 
    .PARAMETER SetScript
        A string that can be used to create a PowerShell script block that sets the resource
        to the desired state.
 
    .PARAMETER TestScript
        Not used in Set-TargetResource.
 
    .PARAMETER Credential
        The credential of the user account to run the script under if needed.
#>

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

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

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

        [Parameter()]
        [ValidateNotNull()]
        [System.Management.Automation.PSCredential]
        [System.Management.Automation.Credential()]
        $Credential
    )

    Write-Verbose -Message $script:localizedData.SetTargetResourceStartVerboseMessage

    $invokeScriptParameters = @{
        ScriptBlock = [System.Management.Automation.ScriptBlock]::Create($SetScript)
    }

    if ($PSBoundParameters.ContainsKey('Credential'))
    {
        $invokeScriptParameters['Credential'] = $Credential
    }

    $invokeScriptResult = Invoke-Script @invokeScriptParameters

    if ($invokeScriptResult -is [System.Management.Automation.ErrorRecord])
    {
        New-InvalidOperationException -Message $script:localizedData.SetScriptThrewError -ErrorRecord $invokeScriptResult
    }

    Write-Verbose -Message $script:localizedData.SetTargetResourceEndVerboseMessage
}

<#
    .SYNOPSIS
        Runs the given test script.
        Should return true if the resource is in the desired state and false otherwise.
 
    .PARAMETER GetScript
        Not used in Test-TargetResource.
 
    .PARAMETER SetScript
        Not used in Test-TargetResource.
 
    .PARAMETER TestScript
        A string that can be used to create a PowerShell script block that validates whether
        or not the resource is in the desired state.
 
    .PARAMETER Credential
        The credential of the user account to run the script under if needed.
#>

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

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

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

        [Parameter()]
        [ValidateNotNull()]
        [System.Management.Automation.PSCredential]
        [System.Management.Automation.Credential()]
        $Credential
    )

    Write-Verbose -Message $script:localizedData.TestTargetResourceStartVerboseMessage

    $invokeScriptParameters = @{
        ScriptBlock = [System.Management.Automation.ScriptBlock]::Create($TestScript)
    }

    if ($PSBoundParameters.ContainsKey('Credential'))
    {
        $invokeScriptParameters['Credential'] = $Credential
    }

    $invokeScriptResult = Invoke-Script @invokeScriptParameters

    # If the script is returing multiple objects, then we consider the last object to be the result of the script execution.
    if ($invokeScriptResult -is [System.Object[]] -and $invokeScriptResult.Count -gt 0)
    {
        $invokeScriptResult = $invokeScriptResult[$invokeScriptResult.Count - 1]
    }

    if ($invokeScriptResult -is [System.Management.Automation.ErrorRecord])
    {
        New-InvalidOperationException -Message $script:localizedData.TestScriptThrewError -ErrorRecord $invokeScriptResult
    }

    if ($null -eq $invokeScriptResult -or -not ($invokeScriptResult -is [System.Boolean]))
    {
        New-InvalidArgumentException -ArgumentName 'TestScript' -Message $script:localizedData.TestScriptDidNotReturnBoolean
    }

    Write-Verbose -Message $script:localizedData.TestTargetResourceEndVerboseMessage

    return $invokeScriptResult
}

<#
    .SYNOPSIS
        Invokes the given script block.
 
        The output of the script will be returned unless the script throws an error.
        If the script throws an error, the ErrorRecord will be returned rather than thrown.
 
    .PARAMETER ScriptBlock
        The script block to invoke.
 
    .PARAMETER Credential
        The credential to run the script under if needed.
#>

function Invoke-Script
{
    [OutputType([System.Object])]
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory = $true)]
        [System.Management.Automation.ScriptBlock]
        $ScriptBlock,

        [Parameter()]
        [ValidateNotNull()]
        [System.Management.Automation.PSCredential]
        [System.Management.Automation.Credential()]
        $Credential
    )

    $scriptResult = $null

    try
    {
        Write-Verbose -Message ($script:localizedData.ExecutingScriptMessage -f $ScriptBlock)

        if ($null -ne $Credential)
        {
            $scriptResult = Invoke-Command -ScriptBlock $ScriptBlock -Credential $Credential -ComputerName .
        }
        else
        {
            $scriptResult = & $ScriptBlock
        }
    }
    catch
    {
        # Surfacing the error thrown by the execution of the script
        $scriptResult = $_
    }

    return $scriptResult
}