caesar_cipher.rb

# frozen_string_literal: true

def wrap_lower?(char, shifted_char, range)
  range.include?(char) && !range.include?(shifted_char)
end

def wrap_upper?(char, shifted_char, range)
  range.include?(char) && !range.include?(shifted_char)
end

def wrap(char, shifted_char, lowercase_range = 'a'.ord..'z'.ord, uppercase_range = 'A'.ord..'Z'.ord)
  if wrap_lower?(char, shifted_char, lowercase_range)
    'a'.ord + (shifted_char - 'a'.ord) % lowercase_range.size
  elsif wrap_upper?(char, shifted_char, uppercase_range)
    'A'.ord + (shifted_char - 'A'.ord) % uppercase_range.size
  else
    shifted_char
  end
end

def letter?(char)
  char.upcase != char.downcase
end

def caesar_cipher(string, shift)
  string.chars.map do |char|
    if letter?(char)
      wrap(char.ord, char.ord + shift).chr
    else
      char
    end
  end.join
end