tui.rb

# manages your string in terminal, each call to rendr will clear the old string
# and print the new one
# Extracted from
# https://github.com/arlimus/inquirer.rb/blob/master/lib/inquirer/utils/iohelper.rb
module Buffer
  extend self

  CARRIAGE_RETURN = "\r".freeze
  LINE_UP = "\e[A".freeze
  CLEAR_LINE = "\e[0K".freeze
  CHAR_LEFT = "\e[D".freeze
  CHAR_RIGHT = "\e[C".freeze

  def render(string)
    clear
    @rendered = string.to_s
    print @rendered
  end

  def clear
    n = @rendered.to_s.scan(/\n/).length
    print CARRIAGE_RETURN + (LINE_UP + CLEAR_LINE) * n + CLEAR_LINE
  end

  module_function :render
  module_function :clear
end

class Row < Array
  def to_s
    map(&:to_s).join + "\n"
  end
end

class ProgressBar
  # https://en.wikipedia.org/wiki/Code_page_437
  BACKGROUND = "\u2591".freeze
  FOREGROUND = "\u2593".freeze

  attr_accessor :width, :value

  def initialize(width, value = 0)
    @width = width
    @value = value
  end

  def background_width
    width - value >= 0 ? width - value : 0
  end

  def foreground_width
    [width, value].min
  end

  def to_s
    FOREGROUND * foreground_width + BACKGROUND * background_width
  end
end

# ====================================
bar = ProgressBar.new(20, 0)
output = Row.new(["Hello World...", bar])

Buffer.render output
sleep 2
output[0] = "This changed, and will change in 2 second"
sleep 2

10.times do
  bar.value += 2
  Buffer.render output
  sleep(1)
end