refactering gtin

lib/jancode/gtin.rb

@@ -7,8 +7,29 @@ def initialize(company_prefix = nil, item_code = nil)
       @item_code = item_code
     end
 
+    def check_digit
+      validation
+      val = ((sum_even_numbers * 3) + sum_odd_numbers).to_s[-1].to_i
+      val == 0 ? 0 : 10 - val
+    end
+
     def create
       [@company_prefix, @item_code, check_digit].join
     end
+
+    private
+    def sum_even_numbers
+      code = code_array.reverse
+      (0..(code.size - 1)).step(2).inject(0){|i,n| i += code[n].to_i}
+    end
+
+    def sum_odd_numbers
+      code = code_array.reverse
+      (1..(code.size - 1)).step(2).inject(0){|i,n| i += code[n].to_i}
+    end
+
+    def code_array
+      [@company_prefix, @item_code].join.chars
+    end
   end
 end

lib/jancode/gtin13.rb

@@ -1,11 +1,20 @@
 module Jancode
   class GTIN13 < GTIN
-    def check_digit
-      code = [@company_prefix, @item_code].join.chars.map{|n| n.to_i}
-      even = (1..(code.size - 1)).step(2).inject(0){|i,n| i += code[n] * 3}
-      odd = (0..(code.size - 1)).step(2).inject(0){|i,n| i += code[n]}
-      val = (even + odd).to_s[-1].to_i
-      val == 0 ? 0 : 10 - val
+    def validation
+      valid_company_prefix @company_prefix
+      valid_item_code @item_code
+      raise "Is not 12 characters Item Code and GS1 Company Prefix to suit" if code_array.size != 12
+    end
+
+    private
+    def valid_company_prefix(company_prefix)
+      raise "GS1 Company Prefix is not String" unless company_prefix.is_a? String
+      raise "GS1 Company Prefix is not 7 or 9 characters" if company_prefix.size != 7 && company_prefix.size != 9
+    end
+
+    def valid_item_code(item_code)
+      raise "Item Code is not String" unless item_code.is_a? String
+      raise "Item Code is not 5 or 3 characters" if item_code.size != 3 && item_code.size != 5
     end
   end
 end

lib/jancode/gtin8.rb

@@ -1,11 +1,20 @@
 module Jancode
   class GTIN8 < GTIN
-    def check_digit
-      code = [@company_prefix, @item_code].join.chars.map{|n| n.to_i}
-      even = (0..(code.size - 1)).step(2).inject(0){|i,n| i += code[n] * 3}
-      odd = (1..(code.size - 1)).step(2).inject(0){|i,n| i += code[n]}
-      val = (even + odd).to_s[-1].to_i
-      val == 0 ? 0 : 10 - val
+    def validation
+      valid_company_prefix @company_prefix
+      valid_item_code @item_code
+      raise "Is not 7 characters Item Code and GS1 Company Prefix to suit" if code_array.size != 7
+    end
+
+    private
+    def valid_company_prefix(company_prefix)
+      raise "GS1 Company Prefix is not String" unless company_prefix.is_a? String
+      raise "GS1 Company Prefix is not 6 characters" if company_prefix.size != 6
+    end
+
+    def valid_item_code(item_code)
+      raise "Item Code is not String" unless item_code.is_a? String
+      raise "Item Code is not 1 characters" if item_code.size != 1
     end
   end
 end