Add functions for configuration data handling and extend template merging capabilities

Private/Get-ConfigurationDataDictionaryValue.ps1

@@ -0,0 +1,22 @@
+function Get-ConfigurationDataDictionaryValue {
+    [CmdletBinding()]
+    Param(
+        [Parameter(Mandatory=$true)]
+        [System.Collections.IDictionary]
+        $Dictionary,
+
+        [Parameter(Mandatory=$true)]
+        [string]
+        $Key,
+
+        [Parameter(Mandatory=$false)]
+        [AllowNull()]
+        $DefaultValue = $null
+    )
+
+    if(Test-ConfigurationDataDictionaryKey -Dictionary $Dictionary -Key $Key){
+        return $Dictionary[$Key]
+    }
+
+    return $DefaultValue
+}

Private/Get-ConfigurationDataTemplateExtends.ps1

@@ -0,0 +1,31 @@
+function Get-ConfigurationDataTemplateExtends {
+    [CmdletBinding()]
+    Param(
+        [Parameter(Mandatory=$true)]
+        [System.Collections.IDictionary]
+        $ConfigurationData
+    )
+
+    $Extends = $null
+
+    if(Test-ConfigurationDataDictionaryKey -Dictionary $ConfigurationData -Key "Metadata"){
+        $Metadata = Get-ConfigurationDataDictionaryValue -Dictionary $ConfigurationData -Key "Metadata"
+        if($Metadata -is [System.Collections.IDictionary] -and (Test-ConfigurationDataDictionaryKey -Dictionary $Metadata -Key "Extends")){
+            $Extends = Get-ConfigurationDataDictionaryValue -Dictionary $Metadata -Key "Extends"
+        }
+    }
+
+    if($null -eq $Extends -and (Test-ConfigurationDataDictionaryKey -Dictionary $ConfigurationData -Key "Extends")){
+        $Extends = Get-ConfigurationDataDictionaryValue -Dictionary $ConfigurationData -Key "Extends"
+    }
+
+    if($null -eq $Extends){
+        return @()
+    }
+
+    if($Extends -is [System.Array] -and $Extends -isnot [string]){
+        return @($Extends)
+    }
+
+    return @($Extends)
+}

Private/Get-ConfigurationDataTemplateMergeFile.ps1

@@ -0,0 +1,42 @@
+function Get-ConfigurationDataTemplateMergeFile {
+    [CmdletBinding()]
+    Param(
+        [Parameter(Mandatory=$true)]
+        [string]
+        $Path,
+
+        [Parameter(Mandatory=$false)]
+        [hashtable]
+        $Visited = @{}
+    )
+
+    $ResolvedPath = Resolve-ConfigurationDataTemplatePath -Path $Path
+
+    if($Visited.ContainsKey($ResolvedPath)){
+        $Chain = @($Visited.Keys + $ResolvedPath) -join " -> "
+        throw "Circular configuration data template inheritance detected: $Chain"
+    }
+
+    $Visited[$ResolvedPath] = $true
+
+    $ConfigurationData = Import-PowerShellDataFile -Path $ResolvedPath
+    if($ConfigurationData -isnot [System.Collections.IDictionary]){
+        throw "Configuration data template [$ResolvedPath] must contain a hashtable."
+    }
+
+    $Files = @()
+    $BasePath = Split-Path -Path $ResolvedPath -Parent
+    foreach($ParentPath in @(Get-ConfigurationDataTemplateExtends -ConfigurationData $ConfigurationData)){
+        if([string]::IsNullOrWhiteSpace([string]$ParentPath)){
+            continue
+        }
+
+        $ResolvedParentPath = Resolve-ConfigurationDataTemplatePath -Path ([string]$ParentPath) -BasePath $BasePath
+        $Files += @(Get-ConfigurationDataTemplateMergeFile -Path $ResolvedParentPath -Visited $Visited)
+    }
+
+    $Files += $ResolvedPath
+    $Visited.Remove($ResolvedPath)
+
+    return @($Files)
+}

Private/Merge-ConfigurationDataTemplateFile.ps1

@@ -0,0 +1,49 @@
+function Merge-ConfigurationDataTemplateFile {
+    [CmdletBinding()]
+    Param(
+        [Parameter(Mandatory=$true)]
+        [string[]]
+        $Path,
+
+        [Parameter(Mandatory=$false)]
+        [switch]
+        $PassThru
+    )
+
+    $MergeFiles = @()
+    $AddedFiles = @{}
+
+    foreach($Item in $Path){
+        foreach($File in @(Get-ConfigurationDataTemplateMergeFile -Path $Item)){
+            if(-not $AddedFiles.ContainsKey($File)){
+                $MergeFiles += $File
+                $AddedFiles[$File] = $true
+            }
+        }
+    }
+
+    $MergedConfigurationData = $null
+    foreach($File in $MergeFiles){
+        $TemplateData = Import-PowerShellDataFile -Path $File
+        if($null -eq $MergedConfigurationData){
+            $MergedConfigurationData = Copy-ConfigurationDataValue -Value $TemplateData
+            if($MergedConfigurationData -is [System.Collections.IDictionary] -and (Test-ConfigurationDataDictionaryKey -Dictionary $MergedConfigurationData -Key "Metadata")){
+                $MergedConfigurationData.Remove("Metadata")
+            }
+        }else{
+            $MergedConfigurationData = Merge-DSCConfigurationData -Template $MergedConfigurationData -Deployment $TemplateData
+            if($MergedConfigurationData -is [System.Collections.IDictionary] -and (Test-ConfigurationDataDictionaryKey -Dictionary $MergedConfigurationData -Key "Metadata")){
+                $MergedConfigurationData.Remove("Metadata")
+            }
+        }
+    }
+
+    if($PassThru){
+        return [PSCustomObject]@{
+            Files = $MergeFiles
+            ConfigurationData = $MergedConfigurationData
+        }
+    }
+
+    return $MergedConfigurationData
+}

Private/Resolve-ConfigurationDataTemplatePath.ps1

@@ -0,0 +1,24 @@
+function Resolve-ConfigurationDataTemplatePath {
+    [CmdletBinding()]
+    Param(
+        [Parameter(Mandatory=$true)]
+        [string]
+        $Path,
+
+        [Parameter(Mandatory=$false)]
+        [string]
+        $BasePath = (Get-Location).Path
+    )
+
+    $CandidatePath = $Path
+    if(-not [System.IO.Path]::IsPathRooted($CandidatePath)){
+        $CandidatePath = Join-Path -Path $BasePath -ChildPath $CandidatePath
+    }
+
+    $ResolvedPath = Resolve-Path -Path $CandidatePath -ErrorAction SilentlyContinue
+    if($null -eq $ResolvedPath){
+        throw "Configuration data template [$Path] was not found. Base path [$BasePath]."
+    }
+
+    return $ResolvedPath.ProviderPath
+}

Private/Test-ConfigurationDataDictionaryKey.ps1

@@ -0,0 +1,18 @@
+function Test-ConfigurationDataDictionaryKey {
+    [CmdletBinding()]
+    Param(
+        [Parameter(Mandatory=$true)]
+        [System.Collections.IDictionary]
+        $Dictionary,
+
+        [Parameter(Mandatory=$true)]
+        [string]
+        $Key
+    )
+
+    if($Dictionary -is [System.Collections.Specialized.OrderedDictionary]){
+        return $Dictionary.Contains($Key)
+    }
+
+    return $Dictionary.ContainsKey($Key)
+}