osem/app/controllers/admin/difficulty_levels_controller.rb

module Admin
  class DifficultyLevelsController < Admin::BaseController
    load_and_authorize_resource :conference, find_by: :short_title
    load_and_authorize_resource :difficulty_level, through: :conference

    def index
      authorize! :index, DifficultyLevel.new(conference_id: @conference.id)
    end

    def edit; end

    def new
      @difficulty_level = @conference.difficulty_levels.new
    end

    def create
      @difficulty_level = @conference.difficulty_levels.new(difficulty_level_params)
      if @difficulty_level.save
        redirect_to(admin_conference_difficulty_levels_path(conference_id: @conference.short_title),
                    notice: 'Difficulty level successfully created.')
      else
        flash[:error] = "Creating difficulty level failed: #{@difficulty_level.errors.full_messages.join('. ')}."
        render :new
      end
    end

    def update
      if @difficulty_level.update_attributes(difficulty_level_params)
        redirect_to(admin_conference_difficulty_levels_path(
                    conference_id: @conference.short_title),
                    notice: 'Difficulty level successfully updated.')
      else
        flash[:error] = "Update difficulty level failed: #{@difficulty_level.errors.full_messages.join('. ')}."
        render :edit
      end
    end

    def destroy
      if @difficulty_level.destroy
        redirect_to(admin_conference_difficulty_levels_path(conference_id: @conference.short_title),
                    notice: 'Difficulty level successfully deleted.')
      else
        redirect_to(admin_conference_difficulty_levels_path(conference_id: @conference.short_title),
                    error: 'Deleting difficulty level type failed! ' \
                    "#{@difficulty_level.errors.full_messages.join('. ')}.")
      end
    end

    private

    def difficulty_level_params
      params[:difficulty_level]
    end
  end
end