# Jekyll category page generator.
 # http://recursive-design.com/projects/jekyll-plugins/
 #
 # Version: 0.1.4 (201101061053)
 #
 # Copyright (c) 2010 Dave Perrett, http://recursive-design.com/
 # Licensed under the MIT license (http://www.opensource.org/licenses/mit-license.php)
 #
 # A generator that creates category pages for jekyll sites.
 #
 # To use it, simply drop this script into the _plugins directory of your Jekyll site. You should
 # also create a file called 'category_index.html' in the _layouts directory of your jekyll site
 # with the following contents (note: you should remove the leading '# ' characters):
 #
 # ================================== COPY BELOW THIS LINE ==================================
 # ---
 # layout: default
 # ---
 #
 # <h1 class="category">{{ page.title }}</h1>
 # <ul class="posts">
 # {% for post in site.categories[page.category] %}
 #     <div>{{ post.date | date_to_html_string }}</div>
 #     <h2><a href="{{ post.url }}">{{ post.title }}</a></h2>
 #     <div class="categories">Filed under {{ post.categories | category_links }}</div>
 # {% endfor %}
 # </ul>
 # ================================== COPY ABOVE THIS LINE ==================================
 #
 # You can alter the _layout_ setting if you wish to use an alternate layout, and obviously you
 # can change the HTML above as you see fit.
 #
 # When you compile your jekyll site, this plugin will loop through the list of categories in your
 # site, and use the layout above to generate a page for each one with a list of links to the
 # individual posts.
 #
 # Included filters :
 # - category_links:      Outputs the list of categories as comma-separated <a> links.
 # - date_to_html_string: Outputs the post.date as formatted html, with hooks for CSS styling.
 #
 # Available _config.yml settings :
 # - category_dir:          The subfolder to build category pages in (default is 'categories').
 # - category_title_prefix: The string used before the category name in the page title (default is
 #                          'Category: ').
 module Jekyll
 
 
   # The CategoryIndex class creates a single category page for the specified category.
   class CategoryIndex < Page
 
     # Initializes a new CategoryIndex.
     #
     #  +base+         is the String path to the <source>.
     #  +category_dir+ is the String path between <source> and the category folder.
     #  +category+     is the category currently being processed.
     def initialize(site, base, category_dir, category)
       @site = site
       @base = base
       @dir  = category_dir
       @name = 'index.html'
       self.process(@name)
       # Read the YAML data from the layout page.
       self.read_yaml(File.join(base, '_layouts'), 'category_index.html')
       self.data['category']    = category
       # Set the title for this page.
       title_prefix             = site.config['category_title_prefix'] || 'Category: '
       self.data['title']       = "#{title_prefix}#{category}"
       # Set the meta-description for this page.
       meta_description_prefix  = site.config['category_meta_description_prefix'] || 'Category: '
       self.data['description'] = "#{meta_description_prefix}#{category}"
     end
 
   end
 
 
   # The Site class is a built-in Jekyll class with access to global site config information.
   class Site
 
     # Creates an instance of CategoryIndex for each category page, renders it, and
     # writes the output to a file.
     #
     #  +category_dir+ is the String path to the category folder.
     #  +category+     is the category currently being processed.
     def write_category_index(category_dir, category)
       index = CategoryIndex.new(self, self.source, category_dir, category)
       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
     end
 
     # Loops through the list of category pages and processes each one.
     def write_category_indexes
       if self.layouts.key? 'category_index'
         dir = self.config['category_dir'] || 'categories'
         self.categories.keys.each do |category|
           self.write_category_index(File.join(dir, category.gsub(/_|\W/, '-')), category)
         end
 
       # Throw an exception if the layout couldn't be found.
       else
         throw "No 'category_index' layout found."
       end
     end
 
   end
 
 
   # Jekyll hook - the generate method is called by jekyll, and generates all of the category pages.
   class GenerateCategories < Generator
     safe true
     priority :low
 
     def generate(site)
       site.write_category_indexes
     end
 
   end
 
 
   # Adds some extra filters used during the category creation process.
   module Filters
 
     # Outputs a list of categories as comma-separated <a> links. This is used
     # to output the category list for each post on a category page.
     #
     #  +categories+ is the list of categories to format.
     #
     # Returns string
     #
     def category_links(categories)
       categories = categories.sort!.map do |item|
         "<a class='category' href='/#{@context.registers[:site].config['category_dir']}/#{item.gsub(/_|\W/, '-')}'/>#{item}</a>"
       end
 
       case categories.length
       when 0
         ""
       when 1
         categories[0].to_s
       else
         "#{categories[0...-1].join(', ')}, #{categories[-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