Add-WebTransform.ps1

Add-WebTransform -ProjectPath "WebApplication1.csproj" -Environment "Dev"
Add-WebTransform -ProjectPath "WebApplication1.csproj" -Environment "Live"
Add-WebTransform -ProjectPath "WebApplication1.csproj" -Environment "PreLive"
Add-WebTransform -ProjectPath "WebApplication1.csproj" -Environment "Staging"

function Add-WebTransform() {

    Param(
        $ProjectPath = "WebApplication1.csproj",
        $Environment = "Dev"
    )

    # TODO Add some param guards

    $webTransformFile = ".\Web.$Environment.config"

    if ( -not (Test-Path $webTransformFile ))
    {
        $content = 

    '<?xml version="1.0" encoding="utf-8" ?>
<configuration xmlns:xdt="http://schemas.microsoft.com/XML-Document-Transform">
</configuration>'

       $content | out-file -FilePath $webTransformFile 
    }

    $csprojFile = get-content -path  $ProjectPath

    if ($csprojFile -notmatch "^.*<Content.*Web\.Dev\.config.*$") 
    {
        $csprojIncludeWebConfig = '<Content Include="Web.config" />'
        $csprojIncludeTransform = "`t<Content Include=`"Web.$Environment.config`">`n`t`t<DependentUpon>Web.config</DependentUpon>`n`t</Content>"
    
        $csprojFileUpdated = $csprojFile -replace $csprojIncludeWebConfig, "$csprojIncludeWebConfig`n $csprojIncludeTransform"

        set-content -Path $ProjectPath -Value $csprojFileUpdated
    }
}