# Nicked from Brandon Tilly
 # Gist https://gist.github.com/803483
 # Post http://brandontilley.com/2011/01/31/gist-tag-for-jekyll.html
 #
 # Example usage: {% gist 803483 gist_tag.rb %} //embeds a gist for this plugin
 
 require 'digest/md5'
 require 'net/https'
 require 'uri'
 
 module Jekyll
   class GistTag < Liquid::Tag
     def initialize(tag_name, text, token)
       super
       system('mkdir -p .gist_cache')
       @text         = text
       @cache        = true
       @cache_folder = File.expand_path "../.gist_cache", File.dirname(__FILE__)
     end
 
     def render(context)
       return "" unless @text =~ /([\d]*) (.*)/
 
       gist, file = $1.strip, $2.strip
       script_url = "https://gist.github.com/#{gist}.js?file=#{file}"
 
       code       = get_cached_gist(gist, file) || get_gist_from_web(gist, file)
       code       = code.gsub "<", "&lt;"
       string     = "<script src='#{script_url}'></script>"
       string    += "<noscript><pre><code>#{code}</code></pre></noscript>"
       return string
     end
 
     def get_gist_url_for(gist, file)
       "https://gist.github.com/raw/#{gist}/#{file}"
     end
 
     def cache_gist(gist, file, data)
       file = get_cache_file_for gist, file
       File.open(file, "w+") do |f|
         f.write(data)
       end
     end
 
     def get_cached_gist(gist, file)
       return nil if @cache == false
       file = get_cache_file_for gist, file
       return nil unless File.exist?(file)
       return File.new(file).readlines.join
     end
 
     def get_cache_file_for(gist, file)
       gist.gsub! /[^a-zA-Z0-9\-_\.]/, ''
       file.gsub! /[^a-zA-Z0-9\-_\.]/, ''
       md5 = Digest::MD5.hexdigest "#{gist}-#{file}"
       File.join @cache_folder, "#{gist}-#{file}-#{md5}.cache"
     end
 
     def get_gist_from_web(gist, file)
       gist_url          = get_gist_url_for(gist, file)
       raw_uri           = URI.parse(gist_url)
       https             = Net::HTTP.new(raw_uri.host, raw_uri.port)
       https.use_ssl     = true
       https.verify_mode = OpenSSL::SSL::VERIFY_NONE
       request           = Net::HTTP::Get.new(raw_uri.request_uri)
       data              = https.request(request)
       data              = data.body
       cache_gist(gist, file, data) unless @cache == false
       data
     end
   end
 
   class GistTagNoCache < GistTag
     def initialize(tag_name, text, token)
       super
       @cache = false
     end
   end
 end
 
 Liquid::Template.register_tag('gist', Jekyll::GistTag)
 Liquid::Template.register_tag('gistnocache', Jekyll::GistTagNoCache)