Implement formatter

lib/planet_express_express.rb

@@ -5,6 +5,7 @@ require_relative "planet_express_express/constants"
 require_relative "planet_express_express/shipment_reader"
 require_relative "planet_express_express/rules"
 require_relative "planet_express_express/discount_budget"
+require_relative "planet_express_express/formatter"
 
 module PlanetExpressExpress
   class Error < StandardError; end

lib/planet_express_express/formatter.rb

@@ -0,0 +1,17 @@
+module PlanetExpressExpress
+  class Formatter
+    def initialize(io)
+      @io = io
+    end
+
+    def format(shipments)
+      shipments[:all].each do |month|
+        month.each do |shipment|
+          @io.write(
+            "#{shipment[:date].iso8601} #{shipment[:size]} #{shipment[:provider]} #{(shipment[:price] - shipment[:discount]).to_s.rjust(3, "0").insert(-3, ".")} #{shipment[:discount].zero? ? "-" : shipment[:discount].to_s.rjust(3, "0").insert(-3, ".")}\n"
+          )
+        end
+      end
+    end
+  end
+end