A simple progress bar script to load directly in ruby

progress_bar.rb

# @example Usage
#   require 'open-uri'
#   eval(open('https://gist.githubusercontent.com/thomet/474bd082e15705fdba2906a9f4ca360a/raw/5ed83ff172a408601232d5306cf214ba3bd75775/progress_bar.rb') {|f| f.read })
#
#   progress_bar(1_000) do
#     # do something
#   end
#
#   > Progress [======================================================== 56.90 % \ (~43 seconds)

def progress_bar(iteration_count, &block)
  spinner = ['\\', '|', '/', '-']
  current_spinner = 0
  progress = 'Progress ['
  time_history = []
  last_percentage = 0
  print progress

  iteration_count.times do |i|
    time = Time.now
    block.call
    needed = Time.now - time

    time_history << needed
    time_history = time_history.last(20)
    time_average = time_history.inject{ |sum, el| sum + el }.to_f / time_history.size

    j = i + 1

    total_time = time_average * iteration_count
    left_time = total_time - (j * time_average)

    denominator = iteration_count/100.0
    current_percentage = (j / denominator).to_i
    progress << "=" if last_percentage < current_percentage
    last_percentage = current_percentage
    
    print "\r"
    printable = "#{progress} #{'%.2f' % (j / denominator)} %"
    if iteration_count > j
      formatted_left = if left_time < 60
        "#{left_time.round} seconds"
      else
        "#{(left_time/60).round} Minutes"
      end
      print  "#{printable} #{spinner[current_spinner]} (~#{formatted_left})"
    else
      print  "#{printable}]"
    end
    # force the output to appear immediately when using print
    # by default when \n is printed to the standard output, the buffer is flushed. 
    $stdout.flush
    
    current_spinner += 1
    current_spinner = 0 if current_spinner >= spinner.length
  end
  puts "\nDone!"
end