module Jekyll
 
   # Extended plugin type that allows the plugin
   # to be called on varous callback methods.
   #
   # Examples:
   # https://github.com/tedkulp/octopress/blob/master/plugins/post_metaweblog.rb
   # https://github.com/tedkulp/octopress/blob/master/plugins/post_twitter.rb
   class PostFilter < Plugin
 
     #Called before post is sent to the converter. Allows
     #you to modify the post object before the converter
     #does it's thing
     def pre_render(post)
     end
 
     #Called after the post is rendered with the converter.
     #Use the post object to modify it's contents before the
     #post is inserted into the template.
     def post_render(post)
     end
 
     #Called after the post is written to the disk.
     #Use the post object to read it's contents to do something
     #after the post is safely written.
     def post_write(post)
     end
   end
 
   # Monkey patch for the Jekyll Site class. For the original class,
   # see: https://github.com/mojombo/jekyll/blob/master/lib/jekyll/site.rb
   class Site
 
     # Instance variable to store the various post_filter
     # plugins that are loaded.
     attr_accessor :post_filters
 
     # Instantiates all of the post_filter plugins. This is basically
     # a duplication of the other loaders in Site#setup.
     def load_post_filters
       self.post_filters = Jekyll::PostFilter.subclasses.select do |c|
         !self.safe || c.safe
       end.map do |c|
         c.new(self.config)
       end
     end
   end
 
   # Monkey patch for the Jekyll Post class. For the original class,
   # see: https://github.com/mojombo/jekyll/blob/master/lib/jekyll/post.rb
   class Post
 
     # Copy the #write method to #old_write, so we can redefine #write
     # method.
     alias_method :old_write, :write
 
     # Write the generated post file to the destination directory. It
     # then calls any post_write methods that may exist.
     #   +dest+ is the String path to the destination dir
     #
     # Returns nothing
     def write(dest)
       old_write(dest)
       post_write if respond_to?(:post_write)
     end
   end
 
   # Monkey patch for the Jekyll Page class. For the original class,
   # see: https://github.com/mojombo/jekyll/blob/master/lib/jekyll/page.rb
   class Page
 
     # Copy the #write method to #old_write, so we can redefine #write
     # method.
     alias_method :old_write, :write
 
     # Write the generated post file to the destination directory. It
     # then calls any post_write methods that may exist.
     #   +dest+ is the String path to the destination dir
     #
     # Returns nothing
     def write(dest)
       old_write(dest)
       post_write if respond_to?(:post_write)
     end
   end
 
   # Monkey patch for the Jekyll Convertible module. For the original class,
   # see: https://github.com/mojombo/jekyll/blob/master/lib/jekyll/convertible.rb
   module Convertible
 
     def is_post?
       self.class.to_s == 'Jekyll::Post'
     end
 
     def is_page?
       self.class.to_s == 'Jekyll::Page'
     end
 
     def is_filterable?
       is_post? or is_page?
     end
 
     # Call the #pre_render methods on all of the loaded
     # post_filter plugins.
     #
     # Returns nothing
     def pre_render
       self.site.load_post_filters unless self.site.post_filters
 
       if self.site.post_filters and is_filterable?
         self.site.post_filters.each do |filter|
           filter.pre_render(self)
         end
       end
     end
 
     # Call the #post_render methods on all of the loaded
     # post_filter plugins.
     #
     # Returns nothing
     def post_render
       if self.site.post_filters and is_filterable?
         self.site.post_filters.each do |filter|
           filter.post_render(self)
         end
       end
     end
 
     # Call the #post_write methods on all of the loaded
     # post_filter plugins.
     #
     # Returns nothing
     def post_write
       if self.site.post_filters and is_filterable?
         self.site.post_filters.each do |filter|
           filter.post_write(self)
         end
       end
     end
 
     # Copy the #transform method to #old_transform, so we can
     # redefine #transform method.
     alias_method :old_transform, :transform
 
     # Transform the contents based on the content type. Then calls the
     # #post_render method if it exists
     #
     # Returns nothing.
     def transform
       old_transform
       post_render if respond_to?(:post_render)
     end
 
     # Copy the #do_layout method to #old_do_layout, so we can
     # redefine #do_layout method.
     alias_method :old_do_layout, :do_layout
 
     # Calls the pre_render method if it exists and then adds any necessary
     # layouts to this convertible document.
     #
     # payload - The site payload Hash.
     # layouts - A Hash of {"name" => "layout"}.
     #
     # Returns nothing.
     def do_layout(payload, layouts)
       pre_render if respond_to?(:pre_render)
       old_do_layout(payload, layouts)
     end
 
     # Returns the full url of the post, including the
     # configured url
     def full_url
       self.site.config['url'] + self.url
     end
   end
 end