A comfortable Channel 9 video download script

ch9downloader.ps1

# channel9 downloader, downloads complete channel9 videos from there rss feeds
#
# Features
#    * Checks for allready downloaded files
#    * use a tempfile to ensure full downloads
#    * gives the download file a name based on the title of the rss entry in the feed
#    * creates a proper directory structure
#    * set the creation und modified date to the date in the rss entry
#
#    by Albert Weinert http://der-albert.com
#
# usage:  ch9downloader.ps1 feedUrl
# example: ch9downloader.ps1 http://channel9.msdn.com/Events/WindowsAzureConf/2012/RSS/mp4high
#
# i'm not a powershell poweruser, if you have suggestion for better scripting, let me know

# your base directory for the downloads, change it to your needs
# the script creates subdirectories based on the rss fedd url
# with the example the download goes to 
# \\DISKSTATION\video\anderes\channel9\Events\WindowsAzureConf\2012

$destinationDirectory  = "\\DISKSTATION\video\anderes\channel9\"


$feedUrl = $Args[0]

$url = New-Object System.Uri($feedUrl)
$overwrite = $false


for ($i=1; $i -le ($url.Segments.Length-3); $i++)
{
    $destinationDirectory = join-path $destinationDirectory $url.Segments[$i] 
}

function DownloadEntries {
 param ([string]$feedUrl) 

 $webClient = New-Object System.Net.WebClient
 $webClient.proxy.credentials=[system.net.credentialcache]::defaultnetworkcredentials
 $feed = [xml]$webClient.DownloadString($feedUrl)

 $progress = 0
 $pagepercent = 0
 $entries = $feed.rss.channel.item.Length

 $invalidChars = [System.IO.Path]::GetInvalidFileNameChars()

 $feed.rss.channel.item | foreach {
    $url = $Null
    
    $name = $_.title
    $url = New-Object System.Uri($_.enclosure.url)
    $extension = [System.IO.Path]::GetExtension($url.Segments[-1])
    $fileName = $name + $extension

    $invalidchars | foreach { $filename = $filename.Replace($_, ' ') }

    $saveFileName = join-path $destinationDirectory $fileName
    $tempFilename = $saveFilename + ".tmp"

    $progress++

    if ((-not $overwrite) -and (Test-Path -path $saveFileName)) 
    {
        write-progress -activity "$fileName already downloaded" -status "$pagepercent% of current feed complete" -percentcomplete $pagepercent
    }
    else 
    {
        write-progress -activity "Downloading $url" -status "$pagepercent% of current feed complete ($progress of $entries)" -percentcomplete $pagepercent
        try {
            $wc = (New-Object System.Net.WebClient)
            $wc.proxy.credentials=[system.net.credentialcache]::defaultnetworkcredentials
            $wc.DownloadFile($url, $tempFilename) 
            if (Test-Path -path $tempFilename)
            {
                rename-item $tempFilename $saveFileName
            }
        } catch [Exception] {
            write-host $_.Exception.GetType().FullName 
            write-host $_.Exception.Message
            write-host $_.Exception.StackTrace
            throw
        }

    }
    $date =  [System.DateTime]::Parse($_.pubDate)
    $file = Get-Item $saveFilename
    $file.LastWriteTime = $date
    $file.CreationTime = $date
    $pagepercent = [Math]::floor(($progress)/$entries*100)
  }
}  

if (!(Test-Path -path $destinationDirectory)) { New-Item $destinationDirectory -type directory }
 
DownloadEntries $feedUrl