Powershell script to backup Asana

Get-AsanaBackup.ps1

<#
  .SYNOPSIS
  Creates a backup of Asana projects

  .DESCRIPTION
  The script will get all Asana projects and writes the projects, tasks, and comments in XML format as a backup.
  
  .PARAMETER FilePath
  The file to which the backup will be written.

  .PARAMETER Key
  An Asana Personal Access Token that has rights to the data.

  .EXAMPLE
  Get-AsanaBackup -FilePath c:\temp\asana.xml -Key 'abcdefg'
  
  This will save the backup to c:\temp\asana.xml

  .EXAMPLE
  Get-AsanaBackup -FilePath c:\temp\asana.xml -Key 'abcdefg' -Verbose
  
  Enabling verbose output will display status on how the backup is proceeding.
#>
[CmdletBinding()]
param(
	[Parameter(Mandatory=$true,ValueFromPipeline=$true)]
	[ValidateScript({Test-Path $(Split-Path $_ -Parent) -PathType 'Container'})] 
	[string] $FilePath,

	[Parameter(Mandatory=$true,ValueFromPipeline=$false)]	
	[string] $Key
	)

function Get-Asana($url, $apikey)
{
	$baseurl = "https://app.asana.com/api/1.0/"		
	$fullUrl = $baseurl + $url
    $authorization = "Authorization: Bearer " + $apikey
    $fastAPI = 'Asana-Fast-Api: true'
	
	$request = [System.Net.WebRequest]::Create($fullUrl)
	$request.Headers.Add($authorization)
	$request.Headers.Add($fastAPI)
	
	try
	{
		$response = $request.GetResponse()
		if ($response -ne $null)
		{
			$StreamReader = New-Object System.IO.StreamReader $response.GetResponseStream() 
			$json = $StreamReader.ReadToEnd()
			ConvertFrom-Json -InputObject $json
		}
	}
	catch 
	{
		# Likely a time out.  Sleep and re-try but first let people know.
		$message = $_.Exception.Message
		write-error "Exception $message"
		write-error $url
		start-sleep -seconds 1
		Get-Asana $url $apikey
	}
	
}

function StripInvalidXmlCharacters([string] $str)
{
    $invalidXmlCharactersRegex = [Regex] "[^\u0009\u000a\u000d\u0020-\ufffd]|([\ud800-\udbff](?![\udc00-\udfff]))|((?<![\ud800-\udbff])[\udc00-\udfff])"
    $invalidXmlCharactersRegex.Replace($str, "")
}
 
function EscapeInvalidXmlCharacters([string] $str)
{
    $invalidXmlCharactersRegex = [Regex] "[^\u0009\u000a\u000d\u0020-\ufffd]|([\ud800-\udbff](?![\udc00-\udfff]))|((?<![\ud800-\udbff])[\udc00-\udfff])"
    $invalidXmlCharactersRegex.Replace($str, {CharToUnicodeSequence($args[0].Value)})
}
 
function CharToUnicodeSequence([char] $symbol)
{
    "\u$(([int] $symbol).ToString("x4"))"
}

function ConvertTo-XMLString($object)
{		
	$string = $object | convertto-xml -Depth 30 -NoTypeInformation -As String
	$string -replace '<.xml version="1.0".>',''
}

# Tell .Net what the current directory is so the next call will work with relative paths
[System.IO.Directory]::SetCurrentDirectory(((Get-Location -PSProvider FileSystem).ProviderPath))  

$stream = [System.IO.StreamWriter] $FilePath
if ($stream -eq $null)
{	
    write-error "$FilePath stream returned null.  Aborting."
	return	# Something went wrong.  The exception should have displayed.
}
if (-not $stream.BaseStream.CanWrite)
{	
    write-error "$FilePath stream cannot be written to.  Aborting."
	return	# Something went wrong.  The exception should have displayed.
}

# Tell .Net to use TLS 1.2
[System.Net.ServicePointManager]::SecurityProtocol = [System.Net.SecurityProtocolType]::Tls12

$stream.WriteLine('<projects>')
$projects = Get-Asana 'projects' $Key
$projects.data | ForEach-Object {
	$stream.WriteLine('<project>')
	# each has an id and a name
	$id = $_.id
	$projectName = $_.name
	Write-Verbose "Project $projectName"
	
	$details = Get-Asana "projects/$id`?opt_expand=owner" $Key
	$stream.WriteLine($(ConvertTo-XMLString $details))
	
	$stream.WriteLine('<sections>')
	$sections = Get-Asana "projects/$id/sections" $Key
	if ($sections -ne $null)
	{
		$stream.WriteLine($(convertto-xmlstring $sections))
	}
	$stream.WriteLine('</sections>')

	$stream.WriteLine('<tasks>')
	$tasks = Get-Asana "projects/$id/tasks" $Key
	$tasks.data | ForEach-Object {
		$stream.WriteLine("`n<task>")
		$tid = $_.id
		$tname = $_.name
		Write-Verbose "    Task $tname"
		$task = Get-Asana "tasks/$tid" $Key
		if ($task -ne $null) 
		{
			$stream.WriteLine($(convertto-xmlstring $task))
		}
		
		$stream.WriteLine("<comments>")
		$stories = Get-Asana "tasks/$tid/stories" $Key
		if ($stories -ne $null)
		{
			foreach ($story in $stories.data)
			{
				$story.text = EscapeInvalidXmlCharacters $story.text
			}
			$stream.WriteLine($(convertto-xmlstring $stories))
		}
		$stream.WriteLine('</comments>')
		
		$stream.WriteLine('</task>')
	}
	$stream.WriteLine('</tasks>')
	$stream.WriteLine('</project>')
}
$stream.WriteLine('</projects>')
$stream.Close()