extracts census document parser to a module

lib/document_parser.rb

@@ -0,0 +1,60 @@
+module DocumentParser
+
+  def get_document_number_variants(document_type, document_number)
+    # Delete all non-alphanumerics
+    document_number = document_number.to_s.gsub(/[^0-9A-Za-z]/i, '')
+    variants = []
+
+    if is_dni?(document_type)
+      document_number, letter = split_letter_from(document_number)
+      number_variants = get_number_variants_with_leading_zeroes_from(document_number)
+      letter_variants = get_letter_variants(number_variants, letter)
+
+      variants += number_variants
+      variants += letter_variants
+    else # if not a DNI, just use the document_number, with no variants
+      variants << document_number
+    end
+
+    variants
+  end
+
+  def split_letter_from(document_number)
+    letter = document_number.last
+    if letter[/[A-Za-z]/] == letter
+      document_number = document_number[0..-2]
+    else
+      letter = nil
+    end
+    return document_number, letter
+  end
+
+  # if the number has less digits than it should, pad with zeros to the left and add each variant to the list
+  # For example, if the initial document_number is 1234, and digits=8, the result is
+  # ['1234', '01234', '001234', '0001234']
+  def get_number_variants_with_leading_zeroes_from(document_number, digits=8)
+    document_number = document_number.to_s.last(digits) # Keep only the last x digits
+    document_number = document_number.gsub(/^0+/, '')   # Removes leading zeros
+
+    variants = []
+    variants << document_number unless document_number.blank?
+    while document_number.size < digits
+      document_number = "0#{document_number}"
+      variants << document_number
+    end
+    variants
+  end
+
+  # Generates uppercase and lowercase variants of a series of numbers, if the letter is present
+  # If number_variants == ['1234', '01234'] & letter == 'A', the result is
+  # ['1234a', '1234A', '01234a', '01234A']
+  def get_letter_variants(number_variants, letter)
+    variants = []
+    if letter.present? then
+      number_variants.each do |number|
+        variants << number + letter.downcase << number + letter.upcase
+      end
+    end
+    variants
+  end
+end