module RestfulScaffold

  def self.included(controller)
    controller.extend ClassMethods
  end

  module ClassMethods
    def rest_methods_for(table_name, *args)
      module_eval do
        after_filter :standard_respond_to, :only => [ :index, :show, :new ]
        after_filter :set_friendly_instance_variable

        # if table_name == :people; return People
        define_method :model_class do
          table_name.to_s.classify.constantize
        end

        # if table_name == :people; return "person"
        define_method :friendly_model_var_name do
          table_name.to_s.singularize
        end

        # if table_name == :people; return "people"
        define_method :friendly_model_var_name_plural do
          table_name.to_s
        end

        define_method :set_friendly_instance_variable do
          if defined?(@model)
            instance_variable_set("@#{friendly_model_var_name}", @model)
          elsif defined?(@models)
            instance_variable_set("@#{friendly_model_var_name_plural}", @models)
          end
        end

        # if table_name == :people, return result of people_path
        define_method :friendly_model_index_path do
          eval "#{table_name}_path"
        end

        include RestMethods
      end
    end
  end

  module RestMethods
    def index
      @models = model_class.find(:all)
    end

    def show
      @model = model_class.find(params[:id])
    end

    def new
      @model = model_class.new
    end

    def edit
      @model = model_class.find(params[:id])
    end

    def create
      @model = model_class.new(params[friendly_model_var_name])
      respond_to do |format|
        if @model.save
          flash[:notice] = "#{friendly_model_var_name.humanize} was successfully updated."
          format.html { redirect_to(self.instance_variable_get("@#{singular}")) }
          format.xml  { head :ok }
          format.json { render :json => @model.to_json }
        else
          format.html { render :action => "edit" }
          format.xml  { render :xml => @model.errors, :status => :unprocessable_entity }
          format.json { render :json => @model, :status => :unprocessable_entity }
        end
      end
    end

    def update
      @model = model_class.find(params[:id])
      respond_to do |format|
        if @model.update_attributes(params[friendly_model_var_name])
          flash[:notice] = "#{friendly_model_var_name.humanize} was successfully updated."
          format.html { redirect_to(@model) }
          format.xml  { head :ok }
          format.json { render :json => @model.to_json }
        else
          format.html { render :action => "edit" }
          format.xml  { render :xml => @model.errors, :status => :unprocessable_entity }
          format.json { render :json => @model, :status => :unprocessable_entity }
        end
      end
    end

    def destroy
      @model = model_class.find(params[:id])
      @model.destroy
      respond_to do |format|
        format.html { redirect_to( friendly_model_index_path ) }
        format.xml  { head :ok }
        format.json { head :ok }
      end
    end

    private

    def standard_respond_to
      respond_to do |format|
        format.html
        format.xml  { render :xml  => @model }
        format.json { render :json => @model }
      end
    end
  end
end

# Automatically include it so we only have to use the
# macro-style declaration to get the restful goodness
class ActionController::Base
  include RestfulScaffold
end