Credit Check - Casey Macaulay

credit_check.rb

card_number = "4929735477250543"

valid = false

# Your Luhn Algorithm Here
# From the right most digit [1] moving left, double the value of
# every second digit.

card_reverse = card_number.reverse
card_array = card_reverse.chars

doubled_odds = card_array.map.with_index do |number, index|
  if index.odd?
    (number.to_i) * 2
  else
    number.to_i
  end
end

# If the product of this doubling operation is greater than 9
# then sum the digits of the products

def sum_integers(number_to_integer)
  number_to_integer.map do |digit|
    digit.to_i
  end.reduce(:+)
end

sum_products = doubled_odds.map do |number|
  if number > 9
    sum_integers(number.to_s.chars)
  else
    number
  end
end


### Take the sum of all digits

final_sum = sum_products.reduce(:+)

# # Output

if final_sum % 10 == 0
    ## If it is valid, print "The number is valid!"
  puts "Can you believe it?! The number is valid!"
    true
else
      ## If it is invalid, print "The number is invalid!"
  puts "Whomp, the number is invalid"
    false
    end