vsts-apply-transform.ps1

# This scripts applies an XD transform to a file
#
# For diagnostic the script outputs a diff between the original file and the transformed file.

# FOR MORE INFO ABOUT XDT TRANSFORMS READ HERE 
# https://msdn.microsoft.com/en-us/library/dd465326(v=vs.110).aspx

[CmdletBinding()]
Param(
    <#
        .SYNOPSIS Transform file path
    #>
    [Parameter(Mandatory=$true)]
    [ValidateScript({Test-Path $_})]
    [ValidateNotNullOrEmpty()]
    [string]$transformFilePath,

    <#
        .SYNOPSIS Transform target file path
    #>
    [Parameter(Mandatory=$true)]
    [ValidateScript({Test-Path $_})]
    [ValidateNotNullOrEmpty()]
    [string]$transformTargetFilePath,

    <#
        .SYNOPSIS A directory where command line tools will be downloaded if they do not exist already
    #>
    [Parameter(Mandatory=$false)]
    [ValidateScript({Test-Path $_})]
    [ValidateNotNullOrEmpty()]
    [string]$toolsPath = ([System.IO.Path]::GetFullPath(".\tools")),

    <#
        .SYNOPSIS Whether to print diff between files for diagnostic purpose
    #>
    [Parameter(Mandatory=$false)]
    [bool]$printDiffForDiagnostic = $true
)

$sourceFilePath = $transformTargetFilePath
$dstFilePath = $transformTargetFilePath
$intermediateFilePath = $dstFilePath + ".new"

# Used in case if `nuget.exe` is not available in PATH
$nugetDownloadUrl = "http://nuget.org/nuget.exe"

<#
.SYNOPSIS
    If nuget is not in the toolsPath
    folder then it will be downloaded there.
#>
function Get-Nuget(){
    [cmdletbinding()]
    param(
        $toolsPathDir = ($toolsPath),

        $nugetDownloadUrl = "http://nuget.org/nuget.exe"
    )
    process{
        
        $nugetDestPath = "nuget.exe"
        
        if(!(Get-Command $nugetDestPath -ErrorAction SilentlyContinue)) {
            $nugetDestPath = Join-Path -Path $toolsPathDir -ChildPath nuget.exe
            if(!(Test-Path $nugetDestPath)){
                'Downloading nuget.exe' | Write-Verbose
                # download nuget
                $webclient = New-Object System.Net.WebClient
                $webclient.DownloadFile($nugetDownloadUrl, $nugetDestPath)

                # double check that is was written to disk
                if(!(Test-Path $nugetDestPath)){
                    throw 'unable to download nuget'
                }
            }
        }

        # return the path of the file
        $nugetDestPath
    }
}

function GetTransformXmlExe(){
    [cmdletbinding()]
    param(
        $toolsPathDir = ($toolsPath)
    )
    process {

        if(!(Test-Path $toolsPathDir)){ 
            New-Item -Path $toolsPathDir -ItemType Directory | Out-Null
        }

        $xdtExe = (Get-ChildItem -Path $toolsPathDir -Include 'SlowCheetah.Xdt.exe' -Recurse) | Select-Object -First 1

        if(!$xdtExe){
            'Downloading xdt since it was not found in the toolsPath folder' | Write-Verbose
             # nuget install SlowCheetah.Xdt -Prerelease -OutputDirectory toolsPathDir\
            $cmdArgs = @('install','SlowCheetah.Xdt','-Prerelease','-OutputDirectory',(Resolve-Path $toolsPathDir).ToString())

            'Calling nuget.exe to download SlowCheetah.Xdt with the following args: [{0} {1}]' -f (Get-Nuget -toolsPathDir $toolsPathDir -nugetDownloadUrl $nugetDownloadUrl), ($cmdArgs -join ' ') | Write-Verbose
            &(Get-Nuget -toolsPathDir $toolsPathDir -nugetDownloadUrl $nugetDownloadUrl) $cmdArgs | Out-Null

            $xdtExe = (Get-ChildItem -Path $toolsPathDir -Include 'SlowCheetah.Xdt.exe' -Recurse) | Select-Object -First 1
            # copy the xdt assemlby if the xdt directory is missing it
            $xdtDllExpectedPath = (Join-Path $xdtExe.Directory.FullName 'Microsoft.Web.XmlTransform.dll')
            
            if(!(Test-Path $xdtDllExpectedPath)){
                # copy the xdt.dll next to the slowcheetah .exe
                $xdtDll = (Get-ChildItem -Path $toolsPathDir -Include 'Microsoft.Web.XmlTransform.dll' -Recurse) | Select-Object -First 1

                if(!$xdtDll){ throw 'Microsoft.Web.XmlTransform.dll not found' }

                Copy-Item -Path $xdtDll.Fullname -Destination $xdtDllExpectedPath | Out-Null
            }

        }

        if(!$xdtExe){
            throw ('SlowCheetah.Xdt not found. Expected location: [{0}]' -f $xdtExe)
        }

        $xdtExe
    }
}

function Transform-Xml{
    [cmdletbinding()]
    param(
        [Parameter(
            Mandatory=$true,
            Position=0)]
        $sourceFile,

        [Parameter(
            Mandatory=$true,
            Position=1)]
        $transformFile,

        [Parameter(
            Mandatory=$true,
            Position=2)]
        $destFile,

        $toolsPathDir = ($toolsPath)
    )
    process {
        # slowcheetah.xdt.exe <source file> <transform> <dest file>
        $cmdArgs = @((Resolve-Path $sourceFile).ToString(),
                     (Resolve-Path $transformFile).ToString(),
                     $destFile)

        'Calling slowcheetah.xdt.exe with the args: [{0} {1}]' -f (GetTransformXmlExe), ($cmdArgs -join ' ') | Write-Verbose
        &(GetTransformXmlExe -toolsPathDir $toolsPathDir) $cmdArgs | Out-Null
    }
}

Transform-Xml -sourceFile $sourceFilePath -transformFile $transformFilePath -destFile $intermediateFilePath
$gitLocation = "git"
foreach ($item in @("git", "C:\Program Files\Git\bin\git")) {
    if (Get-Command $item -ErrorAction SilentlyContinue) {
        $gitLocation = $item
        break
    }
}
$output = & $gitLocation diff `"$dstFilePath`" `"$intermediateFilePath`" 2>$null
if ($output.Length -eq 0) {
    Write-Host "The target file at '$dstFilePath' was not changed, apparently transformations did not have any effect"
    Write-Host
} else {
    Write-Host "Changes has been made to the target file '$dstFilePath'"
    Write-Host
    if ($printDiffForDiagnostic) {
        Write-Output $output
        Write-Host
    }
    Copy-Item -Path $intermediateFilePath -Destination $dstFilePath -Force
    Remove-Item $intermediateFilePath
}