Luhn

luhn.rb

@@ -0,0 +1,45 @@
+class Luhn
+  def initialize(num)
+    @number = num
+  end
+  def addends
+    temp_loop = @number
+    @result_chunks = []
+    count = 1
+    while temp_loop > 0
+      digit_chunk = temp_loop % 10
+      if count % 2 == 0
+        check_9 = digit_chunk * 2
+        if check_9 > 9
+          @result_chunks << (check_9 - 9)
+        else
+          @result_chunks << check_9
+        end
+      else
+        @result_chunks << digit_chunk
+      end
+      temp_loop = temp_loop / 10
+      count += 1
+    end
+    @result_chunks.reverse!
+  end
+  def checksum
+    addends
+    @sum_array = @result_chunks.inject(&:+)
+    @sum_array
+  end
+  def valid?
+    checksum
+    if @sum_array % 10 == 0
+      true
+    else
+      false
+    end
+  end
+  def self.create(number)
+    arr = Luhn.new(number).addends
+    new_sum = 0
+    number = number * 10 + (10 - Luhn.new(number * 10).checksum) % 10
+    number
+  end
+end