module Gem::Text

def clean_text(text)
  text.gsub(/[\000-\b\v-\f\016-\037\177]/, ".".freeze)
end

def format_text(text, wrap, indent=0)
  result = []
  work = clean_text(text)
  while work.length > wrap do
    if work =~ /^(.{0,#{wrap}})[ \n]/
      result << $1.rstrip
      work.slice!(0, $&.length)
    else
      result << work.slice!(0, wrap)
    end
  end
  result << work if work.length.nonzero?
  result.join("\n").gsub(/^/, " " * indent)
end

def levenshtein_distance(str1, str2)
  s = str1
  t = str2
  n = s.length
  m = t.length
  return m if (0 == n)
  return n if (0 == m)
  d = (0..m).to_a
  x = nil
  str1.each_char.each_with_index do |char1,i|
    e = i + 1
    str2.each_char.each_with_index do |char2,j|
      cost = (char1 == char2) ? 0 : 1
      x = min3(
           d[j + 1] + 1, # insertion
           e + 1,      # deletion
           d[j] + cost # substitution
         )
      d[j] = e
      e = x
    end
    d[m] = x
  end
  return x
end

def min3(a, b, c) # :nodoc:
  if a < b && a < c
    a
  elsif b < c
    b
  else
    c
  end
end

def truncate_text(text, description, max_length = 100_000)
  raise ArgumentError, "max_length must be positive" unless max_length > 0
  return text if text.size <= max_length
  "Truncating #{description} to #{max_length.to_s.reverse.gsub(/...(?=.)/,'\&,').reverse} characters:\n" + text[0, max_length]
end