#to specify target string, change 'Pool.new("Chunky Bacon")' at the bottom of the file


class Pool
  attr_accessor :candidates

  def initialize(perfect = "hello world")
    @candidates = (1..8).map{Candidate.new(perfect.downcase.split(""))}
  end

  def evolve!
    @candidates = @candidates.sort_by{|c| c.fitness}.reverse
    size = @candidates.size
    #merge two low-indexed items and merge them
    @candidates = @candidates.map do
      #square root distribution
      a = (size / 2 - 1) - Math.sqrt(rand((size/2)**2)).to_i
      b = (size / 2 - 1) - Math.sqrt(rand((size/2)**2)).to_i
      parent_a = @candidates[a]
      parent_b = @candidates[b]
      parent_a.merge_with(parent_b)
    end
    @candidates = @candidates.sort_by{|c| c.fitness}.reverse
    puts candidates.map{|c| c.value.join}.join("  |  ")
    sleep 0.03
  end

  def average_fitness
    sum_total = @candidates.inject(0){|sum, candy| sum += candy.fitness}
    return sum_total.to_f/@candidates.size
  end

  def evolve_until_solution
    count = 0
    until @candidates.first.solved?
      count += 1
      self.evolve!
    end
    #puts "Found correct solution after #{count} iterations!"
    return count
  end

end



class Candidate
  attr_accessor :value
  attr_accessor :perfect

  def initialize(perfect)
    @perfect = perfect
    @value = (1..@perfect.size).map{(('a'..'z').to_a << ' ')[rand(27)]}
  end

  def fitness
    fit = 0
    @value.each_with_index do |character, i|
      fit += 1 if character == @perfect[i]
    end
    return fit
  end

  def solved?
    self.fitness == @perfect.size
  end

  def merge_with(candidate)
    child = Candidate.new(@perfect)
    @value.each_with_index do |parent_a, i|
      parent_b = candidate.value[i]
      child.value[i] = (rand(2) == 0 ? parent_a : parent_b)
    end
    child.mutate!
    return child
  end

  def mutate!
    mutation_probability = 0.15 / Math.sqrt(@perfect.size)
    @value = @value.map do |character|
      if rand < mutation_probability
        (('a'..'z').to_a << ' ')[rand(27)]
      else
        character
      end
    end
    return self
  end
end



@p = Pool.new("Chunky Bacon")
@p.candidates.each{|c| print c.value.join + " | "}
puts ""
@p.evolve_until_solution
#total_iterations = 0
#3.times do
#  total_iterations += Pool.new.evolve_until_solution
#end

#puts "Average iterations = #{total_iterations/10.0}"