module Jekyll

  # The TagIndex class creates a single tag page for the specified tag.
  class TagIndex < Page

    # Initializes a new TagIndex.
    #
    #  +base+         is the String path to the <source>.
    #  +tag_dir+ is the String path between <source> and the tag folder.
    #  +tag+     is the tag currently being processed.
    def initialize(site, base, tag_dir, tag)
      @site = site
      @base = base
      @dir  = tag_dir
      @name = 'index.html'
      self.process(@name)
      # Read the YAML data from the layout page.
      self.read_yaml(File.join(base, '_layouts'), 'tag_index.html')
      self.data['tag']    = tag
      # Set the title for this page.
      title_prefix             = site.config['tag_title_prefix'] || 'Tag: '
      self.data['title']       = "#{title_prefix}#{tag}"
      # Set the meta-description for this page.
      meta_description_prefix  = site.config['tag_meta_description_prefix'] || 'Tag: '
      self.data['description'] = "#{meta_description_prefix}#{tag}"
    end

  end

  # The tagFeed class creates an Atom feed for the specified tag.
  class TagFeed < Page

    # Initializes a new tagFeed.
    #
    #  +base+         is the String path to the <source>.
    #  +tag_dir+ is the String path between <source> and the tag folder.
    #  +tag+     is the tag currently being processed.
    def initialize(site, base, tag_dir, tag)
      @site = site
      @base = base
      @dir  = tag_dir
      @name = 'atom.xml'
      self.process(@name)
      # Read the YAML data from the layout page.
      self.read_yaml(File.join(base, '_includes/custom'), 'tag_feed.xml')
      self.data['tag']    = tag
      # Set the title for this page.
      title_prefix             = site.config['tag_title_prefix'] || 'Tag: '
      self.data['title']       = "#{title_prefix}#{tag}"
      # Set the meta-description for this page.
      meta_description_prefix  = site.config['tag_meta_description_prefix'] || 'Tag: '
      self.data['description'] = "#{meta_description_prefix}#{tag}"

      # Set the correct feed URL.
      self.data['feed_url'] = "#{tag_dir}/#{name}"
    end

  end

  # The Site class is a built-in Jekyll class with access to global site config information.
  class Site

    # Creates an instance of tagIndex for each tag page, renders it, and
    # writes the output to a file.
    #
    #  +tag_dir+ is the String path to the tag folder.
    #  +tag+     is the tag currently being processed.
    def write_tag_index(tag_dir, tag)
      index = TagIndex.new(self, self.source, tag_dir, tag)
      index.render(self.layouts, site_payload)
      index.write(self.dest)
      # Record the fact that this page has been added, otherwise Site::cleanup will remove it.
      self.pages << index

      # Create an Atom-feed for each index.
      feed = TagFeed.new(self, self.source, tag_dir, tag)
      feed.render(self.layouts, site_payload)
      feed.write(self.dest)
      # Record the fact that this page has been added, otherwise Site::cleanup will remove it.
      self.pages << feed
    end

    # Loops through the list of tag pages and processes each one.
    def write_tag_indexes
      if self.layouts.key? 'tag_index'
        dir = self.config['tag_dir'] || 'tags'
        self.tags.keys.each do |tag|
          self.write_tag_index(File.join(dir, tag.gsub(/_|\P{Word}/, '-').gsub(/-{2,}/, '-').downcase), tag)
        end

      # Throw an exception if the layout couldn't be found.
      else
        throw "No 'tag_index' layout found."
      end
    end

  end


  # Jekyll hook - the generate method is called by jekyll, and generates all of the tag pages.
  class GenerateTags < Generator
    safe true
    priority :low

    def generate(site)
      site.write_tag_indexes
    end

  end


  # Adds some extra filters used during the tag creation process.
  module Filters

    # Outputs a list of tags as comma-separated <a> links. This is used
    # to output the tag list for each post on a tag page.
    #
    #  +tags+ is the list of tags to format.
    #
    # Returns string
    #
    def tag_links(tags)
      dir = @context.registers[:site].config['tag_dir']
      tags = tags.sort!.map do |item|
        "<a class='category' href='/#{dir}/#{item.gsub(/_|\P{Word}/, '-').gsub(/-{2,}/, '-').downcase}/'>#{item}</a>"
      end

      case tags.length
      when 0
        ""
      when 1
        tags[0].to_s
      else
        "#{tags[0...-1].join(', ')}, #{tags[-1]}"
      end
    end

    # Outputs the post.date as formatted html, with hooks for CSS styling.
    #
    #  +date+ is the date object to format as HTML.
    #
    # Returns string
    def date_to_html_string(date)
      result = '<span class="month">' + date.strftime('%b').upcase + '</span> '
      result += date.strftime('<span class="day">%d</span> ')
      result += date.strftime('<span class="year">%Y</span> ')
      result
    end

  end

end

module Jekyll

  class TagCloud < Liquid::Tag

    def initialize(tag_name, markup, tokens)
      @opts = {}
      @opts['bgcolor'] = '#ffffff'
      @opts['tcolor1'] = '#333333'
      @opts['tcolor2'] = '#333333'
      @opts['hicolor'] = '#000000'

      opt_names = ['bgcolor', 'tcolor1', 'tcolor2', 'hicolor']

      opt_names.each do |opt_name|
          if markup.strip =~ /\s*#{opt_name}:(#[0-9a-fA-F]+)/iu
            @opts[opt_name] = $1
            markup = markup.strip.sub(/#{opt_name}:\w+/iu,'')
          end
      end

      opt_names = opt_names[1..3]
      opt_names.each do |opt_name|
          @opts[opt_name] = '0x' + @opts[opt_name][1..8]
      end

      super
    end

    def render(context)
      lists = {}
      max, min = 1, 1
      config = context.registers[:site].config
      tag_dir = config['url'] + config['root'] + config['tag_dir'] + '/'
      tags = context.registers[:site].tags
      tags.keys.sort_by{ |str| str.downcase }.each do |tag|
        count = tags[tag].count
        lists[tag] = count
        max = count if count > max
      end

      bgcolor = @opts['bgcolor']

      bgcolor = @opts['bgcolor']
      tcolor1 = @opts['tcolor1']
      tcolor2 = @opts['tcolor2']
      hicolor = @opts['hicolor']

      html = ''
      html << "<embed type='application/x-shockwave-flash' src='/javascripts/tagcloud.swf'"
      html << "width='100%' height='250' bgcolor='#{bgcolor}' id='tagcloudflash' name='tagcloudflash' quality='high' allowscriptaccess='always'"

      html << 'flashvars="'
      html << "tcolor=#{tcolor1}&amp;tcolor2=#{tcolor2}&amp;hicolor=#{hicolor}&amp;tspeed=100&amp;distr=true&amp;mode=tags&amp;"

      html << 'tagcloud='

      tagcloud = ''
      tagcloud << '<tags>'


      lists.each do | tag, counter |
        url = tag_dir + tag.gsub(/_|\P{Word}/u, '-').gsub(/-{2,}/u, '-').downcase
        style = "font-size: #{10 + (40 * Float(counter)/max)}%"

        tagcloud << "<a href='#{url}' style='#{style}'>#{tag}"
        tagcloud << "</a> "

      end

      tagcloud << '</tags>'

      # tagcloud urlencode
      tagcloud = CGI.escape(tagcloud)

      html << tagcloud
      html << '">'
      html
    end
  end
end

Liquid::Template.register_tag('tag_cloud', Jekyll::TagCloud)

category_dir: blog/categories
tag_dir: blog/tags

<div id="blog-archives" class="category">
{% for post in site.tags[page.tag] %}
{% capture this_year %}{{ post.date | date: "%Y" }}{% endcapture %}
{% unless year == this_year %}
  {% assign year = this_year %}
  <h2>{{ year }}</h2>
{% endunless %}
<article>
  {% include archive_post.html %}
</article>
{% endfor %}
</div>

<p class="meta">
  Tags: {% include post/tags.html %}
</p>

{% capture tag %}{% if post %}{{ post.tags | tag_links | size }}{% else %}{{ page.tags | tag_links | size }}{% endif %}{% endcapture %}
{% unless tag == '0' %}
<span class="categories">
  {% if post %}
    {{ post.tags | tag_links }}
  {% else %}
    {{ page.tags | tag_links }}
  {% endif %}
</span>
{% endunless %}