largest_prime

require 'pry'

num = 13195

class FindLargestPrimeFactor

  def initialize(num)
    @num = num
  end

  def run
    @factors = find_factors(@num)
    @prime_factors = find_prime_factors(@factors)
    largest_prime(@prime_factors)
  end

  def find_factors(num)
    i = 1
    num_factors = []
    (num-1).times do |n|
      if num%i==0
        num_factors << i
      end
      i+=1
    end
    num_factors
  end

  # find all the prime factors
  def find_prime_factors(num_factors)
    prime_factors = []
    num_factors.each do |num|
      i = 1
      factors = []
      (num).times do |n|
        if num%i==0
          factors << i
        end
        i+=1
      end
      if factors.count == 2
        prime_factors << num
      end
    end
    prime_factors
  end

  # find the largest prime number
  def largest_prime(prime_factors)
    prime_factors.sort.last
  end
end
binding.pry