easy-going-rails/lib/formatters/ansi_wrapper.rb

# AnsiWrapper cares about Ansi Colour Code \e[...
class AnsiWrapper
  TAB_TO_SPACES = 2
  ANSI_REGEX = /\e\[[0-9;]*m/ # TODO: support for \x1b and \033
  ANSI_RESET = "\e[0m".freeze

  def self.wrap(text, length, prefix = '', continuation = prefix)
    if visible_length(prefix) != visible_length(continuation)
      raise "continuation <#{continuation.inspect}> should have the same length as prefix <#{prefix.inspect}>"
    end
    return unless text

    text = text.gsub("\t", ' ' * TAB_TO_SPACES)

    lines = split_text_to_lines(text, length - visible_length(prefix))
    lines = inject_continuation_and_ansi_colors_to_lines(lines, prefix, continuation)
    lines.join("\n")
  end

  private_class_method def self.inject_continuation_and_ansi_colors_to_lines(lines, prefix, continuation)
    last_ansi = ''
    lines.each_with_index.map do |line, index|
      current = index.zero? ? prefix : continuation
      current += last_ansi unless last_ansi.empty? || last_ansi == ANSI_RESET
      current += line

      last_ansi = scan_for_actual_ansi(line, last_ansi)

      current += ANSI_RESET if last_ansi.empty? || last_ansi != ANSI_RESET
      current
    end
  end

  private_class_method def self.scan_for_actual_ansi(line, last_ansi)
    line.scan(ANSI_REGEX).each do |match|
      ansi_code = match.to_s
      if ansi_code == ANSI_RESET
        last_ansi = ANSI_RESET
      else
        last_ansi += ansi_code
      end
    end
    last_ansi
  end

  private_class_method def self.split_text_to_lines(text, length)
    lines = text.split("\n")
    sublines = lines.map do |line|
      visible_length(line) > length ? visible_split(line, length) : [line]
    end
    sublines.flatten
  end

  private_class_method def self.visible_length(line)
    raise 'line should not contain carriage return character!' if line.match "\n"

    ansi_code_length = line.scan(ANSI_REGEX).map(&:length).sum
    line.length - ansi_code_length
  end

  # TODO: might be refactored with less complexity
  private_class_method def self.visible_split(line, length, stack = '') # rubocop:disable Metrics/AbcSize,Metrics/MethodLength
    before, ansi_code, after = line.partition(ANSI_REGEX)
    stack_length = visible_length(stack)
    visible_length = before.length + stack_length
    if visible_length == length
      ["#{stack}#{before}#{ansi_code}"] + visible_split(after, length)
    elsif visible_length > length
      first_line = stack + before[0...length - stack_length]
      tail = before[length - stack_length..] + ansi_code + after
      [first_line] + visible_split(tail, length)
    elsif ansi_code.length.positive?
      visible_split(after, length, "#{stack}#{before}#{ansi_code}")
    else
      ["#{stack}#{before}#{ansi_code}"]
    end
  end
end