MODEL_DIR   = File.join(RAILS_ROOT, "app/models")

# Rake task for updating all the popularities of is_popular models
# Usage: rake popularity:update
module Popularity

  # Return a list of the model files. If we have 
  # command line arguments, they're assumed to be either
  # the underscore or CamelCase versions of model names.
  # Otherwise we take all the model files in the 
  # app/models directory.
  def self.get_model_names
    models = ARGV.dup
    models.shift
    
    if models.empty?
      Dir.chdir(MODEL_DIR) do 
        models = Dir["**/*.rb"]
      end
    end
    models
  end

  # We're passed a name of things that might be 
  # ActiveRecord models. If the model matches _popularity
  # and we can find the class and it's a subclass of ActiveRecord::Base
  # and it responds to update_popularities,
  # then run that class's update_popularities method
  def self.update
    self.get_model_names.each do |m|
      class_name = m.sub(/\.rb$/,'')
      popularity_class = class_name.include?("_popularity") ? class_name.gsub("_popularity", "").camelize : nil
      if popularity_class
        klass = popularity_class.split('::').inject(Object){ |klass,part| klass.const_get(part) } rescue nil 
        if klass && klass < ActiveRecord::Base && ! klass.abstract_class? && klass.respond_to?("update_popularities")
          puts "Updating Popularity For #{klass.name}"
          klass.update_popularities
        end
      end
    end
  end
end