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