Download today's apod image

apod.rb

#!/usr/bin/env ruby

require 'fileutils'
require 'open-uri'

def get_links
  image_urls = []
  # Download latest page
  puts "Downloading #{$apod_url}"
  open($apod_url) do |stream|
    stream.each do |line|
      if line =~ %r[href="(image/.*)"]
        image_urls << "#{$apod_url}/#{$1}"
      end
    end
  end
  image_urls
end

def get_image(url)
  image_name = File.join($basedir, File.basename(url))

  if File.file? image_name
    puts "#{image_name} already on disk, not downloading"
  else
    begin
      image = nil
      puts "Downloading #{url}"
      open(url) { |stream| image = stream.read }

      # Save image
      puts "Saving #{url} as #{image_name}"
      File.open(image_name, "w") { |f| f.write image }
    rescue SocketError => e
      puts e
    end
  end
end

# Prep file structure
$basedir = "#{ENV['HOME']}/Pictures"
if not File.directory? $basedir
  FileUtils.mkdir $basedir
end

$apod_url = "http://apod.nasa.gov/apod"

image_urls = get_links

unless image_urls.length > 0
  $stderr.puts "Could not find image url in current page, bailing out."
  exit
end

image_urls.each do |image_url|
  get_image(image_url)
end