$root = 'C:\Users\ben\Documents\documentation\source\'
# initialize the hash
$topicTitles = @{}

# safely open XML files
Function Get-XML ($filePath) {
    $fileContent = New-Object System.Xml.XmlDocument
    # tell it not to get the DTD
    $fileContent.XmlResolver = $null
    Try {
        $fileContent.Load($filePath)
        }
    Catch [system.exception] {
        write-host "Could not open file $filePath"
    }
    $fileContent
}

# list DITA files from the root
Get-Childitem $root -recurse -include *.dita,*.ditamap |
    # ignore OT directories
    where {$_ -notmatch 'out' -and $_ -notmatch 'temp'} |
    ForEach-Object {
        $file = $_
        $fileFull = Join-Path -path $file.directory -childpath $file.name | Resolve-Path
        $fileFull = [string]$fileFull
        $fileRel = $fileFull.Replace($root, '')
        
        $fileContent = Get-XML($fileFull)
        # get the topic or map title
        $title = $fileContent.SelectSingleNode("/*/title | /bookmap/booktitle/mainbooktitle").get_InnerText()
        # add a record to the hash
        $topicTitles.Add($fileRel, $title)
    }
    
    $topicTitles.GetEnumerator() | Sort-Object Name | Format-Table -Autosize | Tee-Object $root\audit.txt