markdown内のimageタグをlazy load形式に書き換え

gistfile1.rb

require 'tempfile'

post_dir = 'source/_posts'
files = Dir.glob("#{File.expand_path(post_dir)}/*")
files.each do |file|
  p file
  temp = Tempfile::new('temp')
  open(file, 'r') do |f|
    f.each do |line|
      if line.index(/!\[[0-9]+\..+\]/)
        if line.index(/!\[1\..+\]/)
        else
          line.gsub!(/!\[([0-9]+\..+)\]\((\S+).+\)/) do
            "<img alt='#{$1}' data-original='#{$2}'>"
          end
        end
      end
      temp.puts(line)
    end
  end

  temp.close
  temp.open

  open(file, "w") {|f| temp.each {|line| f.puts(line) }}

  temp.close(true)
end