module Typus

  module Format

    protected

    def generate_html

      items_count = @resource.count(:joins => @joins, :conditions => @conditions)
      items_per_page = @resource.typus_options_for(:per_page)

      @pager = ::Paginator.new(items_count, items_per_page) do |offset, per_page|
        data(:limit => per_page, :offset => offset)
      end

      @items = @pager.page(params[:page])

    end

    #--
    # TODO: Find in batches only works properly if it's used on
    #       models, not controllers, so in this action does nothing.
    #       We should find a way to be able to process data.
    #++
    def generate_csv

      fields = @resource.typus_fields_for(:csv)

      require 'csv'
      if CSV.const_defined?(:Reader)
        # Old CSV version so we enable faster CSV.
        begin
          require 'fastercsv'
        rescue Exception => error
          raise error.message
        end
        csv = FasterCSV
      else
        csv = CSV
      end

      filename = Rails.root.join("tmp", "export-#{@resource.to_resource}-#{Time.now.utc.to_s(:number)}.csv")

      options = { :conditions => @conditions, :batch_size => 1000 }

      csv.open(filename, 'w', :col_sep => ';') do |csv|
        csv << fields.keys
        @resource.find_in_batches(options) do |records|
          records.each do |record|
            csv << fields.map do |key, value|
                     case value
                     when :transversal
                       a, b = key.split(".")
                       record.send(a).send(b)
                     when :belongs_to
                       record.send(key).to_label
                     else
                       record.send(key)
                     end
                   end
          end
        end
      end

      send_file filename

    end

    def generate_json; export(:json); end
    def generate_xml; export(:xml); end

    def export(format)
      fields = @resource.typus_fields_for(format).collect { |i| i.first }
      methods = fields - @resource.column_names
      except = @resource.column_names - fields
      render format => data.send("to_#{format}", :methods => methods, :except => except)
    end

    def data(*args)
      eager_loading = @resource.reflect_on_all_associations(:belongs_to).map { |i| i.name }
      options = { :joins => @joins, :conditions => @conditions, :order => @order, :include => eager_loading }
      options.merge!(args.extract_options!)
      @resource.all(options)
    end

  end

end