osem/app/controllers/admin/tracks_controller.rb

module Admin
  class TracksController < Admin::BaseController
    load_and_authorize_resource :conference, find_by: :short_title
    load_and_authorize_resource :program, through: :conference, singleton: true
    load_and_authorize_resource through: :program

    def index; end

    def show
      respond_to do |format|
        format.html { render }
        format.json { render json: @conference.tracks.to_json }
      end
    end

    def new
      @track = @program.tracks.new(color: @conference.next_color_for_collection(:tracks))
    end

    def create
      @track = @program.tracks.new(track_params)
      if @track.save
        redirect_to admin_conference_program_tracks_path(conference_id: @conference.short_title),
                    notice: 'Track successfully created.'
      else
        flash[:error] = "Creating Track failed: #{@track.errors.full_messages.join('. ')}."
        render :new
      end
    end

    def edit; end

    def update
      if @track.update_attributes(track_params)
        redirect_to admin_conference_program_tracks_path(conference_id: @conference.short_title),
                    notice: 'Track successfully updated.'
      else
        flash[:error] = "Track update failed: #{@track.errors.full_messages.join('. ')}."
        render :edit
      end
    end

    def destroy
      if @track.destroy
        redirect_to admin_conference_program_tracks_path(conference_id: @conference.short_title),
                    notice: 'Track successfully deleted.'
      else
        redirect_to admin_conference_program_tracks_path(conference_id: @conference.short_title),
                    error: "Track couldn't be deleted. #{@track.errors.full_messages.join('. ')}."
      end
    end

    private

    def track_params
      params.require(:track).permit(:name, :description, :color)
    end
  end
end