Parses an online RSS feed and creates a PDF from it, using the Ruby Prawn library

rss-to-pdf.rb

#!/usr/bin/env ruby
# rss-to-pdf.rb
# Author:   Werner Robitza
# Synopsis: A basic console RSS to PDF writer using the prawn library
# Usage:    rss-to-pdf.rb <url>
#           <url> being the URL of the RSS news feed

require 'open-uri'
require 'nokogiri'
require 'pp'
require 'prawn'
 
def show_usage
  puts "Usage: rss-to-pdf.rb <url>"
  puts "<url> being the URL of the RSS news feed"
  exit
end

# -----------------------------------------------------------------------------

show_usage if ARGV.size != 1

# assign parameters
remote_uri = ARGV[0]

begin
  @doc = Nokogiri::HTML(open(remote_uri))
  @doc.remove_namespaces!
rescue
  puts "Could not open URI, aborting."
  exit
end

# let's find out if this is RSS or Atom
@type = :atom if @doc.root.xpath("body/feed").size == 1
@type = :rss if @doc.root.xpath("body/rss").size == 1


# generate the PDF document
file_name = "#{File.basename(remote_uri)}.pdf"
Prawn::Document.generate file_name do |pdf|
  # print the title
  pdf.font_size(25) do
    title_xpath = "//channel/title" if @type == :rss 
    title_xpath = "//feed/title" if @type == :atom
    pdf.text @doc.xpath(title_xpath).text
  end
  
  # print each item  
  item_xpath = "//channel/item" if @type == :rss
  item_xpath = "//feed/entry" if @type == :atom
  @doc.xpath(item_xpath).each do |item|
    pdf.start_new_page
    pdf.group do
      # heading
      pdf.font_size(18) do
        title = item.xpath("title").text
        link = item.xpath("text()").text.chomp!
        pdf.text "<link href=\"#{link}\">#{title}</link>", :inline_format => true
      end
      # metadata
      pdf.move_down 20
      pdf.text "Published at: ", :style => :bold
      pdf.text item.xpath("pubdate").text if @type == :rss
      pdf.text item.xpath("published").text if @type == :atom
      
      # check for valid image
      image_link = item.xpath("enclosure/@url").text
      unless image_link.empty?
        image_name = File.basename image_link
        unless File.exists?("#{image_name}")
          open("#{image_name}", "wb") do |file|
            file << open(image_link).read
          end  
        end
        pdf.move_down 20
        pdf.image "#{image_name}", :position => :left
      end
    end
    pdf.move_down 20
    pdf.text "Description: ", :style => :bold
    pdf.text item.xpath("description").text.gsub("]]>", "")
    
    if @type == :rss
      pdf.move_down 20
      pdf.text "Content: ", :style => :bold
      pdf.text item.xpath("encoded").text.gsub("]]>", "")
    end
  end
end