require 'initializer' unless defined? ::Rails::Initializer 
require 'action_controller/dispatcher' unless defined? ::ActionController::Dispatcher

module HasManyPolymorphs

=begin rdoc    
Searches for models that use <tt>has_many_polymorphs</tt> or <tt>acts_as_double_polymorphic_join</tt> and makes sure that they get loaded during app initialization. This ensures that helper methods are injected into the target classes. 

Note that you can override DEFAULT_OPTIONS via Rails::Configuration#has_many_polymorphs_options. For example, if you need an application extension to be required before has_many_polymorphs loads your models, add an <tt>after_initialize</tt> block in <tt>config/environment.rb</tt> that appends to the <tt>'requirements'</tt> key:
  Rails::Initializer.run do |config|     
    # your other configuration here
    
    config.after_initialize do
      config.has_many_polymorphs_options['requirements'] << 'lib/my_extension'
    end    
  end
  
=end
  
  MODELS_ROOT = "#{RAILS_ROOT}/app/models/"
  
  DEFAULT_OPTIONS = {
    :file_pattern => "#{MODELS_ROOT}**/*.rb",
    :file_exclusions => ['svn', 'CVS', 'bzr'],
    :methods => ['has_many_polymorphs', 'acts_as_double_polymorphic_join'],
    :requirements => []}
  
  mattr_accessor :options
  @@options = HashWithIndifferentAccess.new(DEFAULT_OPTIONS)      

  
  # Dispatcher callback to load polymorphic relationships from the top down.
  def self.autoload

    _logger_debug "autoload hook invoked"
    
    options[:requirements].each do |requirement|
      _logger_warn "forcing requirement load of #{requirement}"
      require requirement
    end
  
    Dir.glob(options[:file_pattern]).each do |filename|
      next if filename =~ /#{options[:file_exclusions].join("|")}/
      open(filename) do |file|
        if file.grep(/#{options[:methods].join("|")}/).any?
          begin
            modelname = filename[0..-4]
            modelname.slice!(MODELS_ROOT)
            model = modelname.camelize
            _logger_warn "preloading parent model #{model}"
            model.constantize
          rescue Object => e
            _logger_warn "#{model} could not be preloaded: #{e.inspect}"
          end
        end
      end
    end
  end  
    
end

class Rails::Initializer #:nodoc:
  # Make sure it gets loaded in the console, tests, and migrations
  def after_initialize_with_autoload 
    after_initialize_without_autoload
    HasManyPolymorphs.autoload
  end
  alias_method_chain :after_initialize, :autoload 
end

ActionController::Dispatcher.to_prepare(:has_many_polymorphs_autoload) do
  # Make sure it gets loaded in the app
  HasManyPolymorphs.autoload
end