class Bundler::SimilarityDetector

def levenshtein_distance(this, that, ins = 2, del = 2, sub = 1)
  # ins, del, sub are weighted costs
  return nil if this.nil?
  return nil if that.nil?
  dm = [] # distance matrix
  # Initialize first row values
  dm[0] = (0..this.length).collect {|i| i * ins }
  fill = [0] * (this.length - 1)
  # Initialize first column values
  (1..that.length).each do |i|
    dm[i] = [i * del, fill.flatten]
  end
  # populate matrix
  (1..that.length).each do |i|
    (1..this.length).each do |j|
      # critical comparison
      dm[i][j] = [
        dm[i - 1][j - 1] + (this[j - 1] == that[i - 1] ? 0 : sub),
        dm[i][j - 1] + ins,
        dm[i - 1][j] + del
      ].min
    end
  end
  # The last value in matrix is the Levenshtein distance between the strings
  dm[that.length][this.length]
end