Get APOD archive

# Where you want to store the pictures
$DownloadPath = "/home/allywilson/Pictures/wallpapers"

# The Astronomy Picture of the Day base URL
$apod = "https://apod.nasa.gov/apod"

# Let's get the archive page as it has all the links to the picture pages
$ArchivePixPage = Invoke-WebRequest -Uri "$($apod)/archivepix.html"

#Let's filter through all the links on the page and get the ones that begin with "ap" and end with ".html"
$ArchivePixPageLinks = $ArchivePixPage.Links.href | Where-Object {$_ -like "ap*.html"}

# While $i does not equal the number of links to ap*.html stay in this loop.
$i = 0
while ($i -lt $ArchivePixPageLinks.Count){

    # Let's get the JPG link within the ap*.html page
    #  This line of code is also longer than 120 chars which goes against my aesthetics :-(
    #  But, I don't want to sacrifice readability and invoke my code-golf past.
    $picLinkRef = ((Invoke-WebRequest -uri "$($apod)/$($ArchivePixPageLinks[$i])").Links | Where-Object {$_.href -like "image/*.jpg"}).href

    # Wait, what if there's more than 1 *.jpg link? Declaring [0] ruins single strings, so this is a bit of a hack.
    if ($picLinkRef -gt 0){

        # For every *.jpg link we find, we loop through it (these are more common than I expected).
        Foreach ($ref in $picLinkRef){

            # Let's see if we already have this file, if we do skip it (helpful if you got bored and killed script).
            if (!(Test-Path "$DownloadPath/$(($ref -split '/')[-1])")){

                # Let's download the pic and say where we are in the loop.
                "Downloading number $($i) of $(($ArchivePixPageLinks).count)...$(($ref -split '/')[-1])"
                Invoke-WebRequest -Uri "$($apod)/$($ref)" -OutFile "$($DownloadPath)/$(($ref -split '/')[-1])"

                # Please don't remove the below, I don't want to kill APOD web servers.
                Start-Sleep 2
            }
        }
    }

    # Increment $i so we're not stuck in a forever loop.
    $i++
}