colorize console output, for rails logs

colorize.rb

#!/usr/bin/env ruby -w

# SETUP:
#   Copy this file to your $PATH
#   cp colorize.rb ~/colorize (or symlink)
#   chmod +x ~/bin/colorize
#
# USAGE:
#   tail -f log/development.log | colorize
#   rails server | colorize
#
# COLORS:
#   https://misc.flogisoft.com/bash/tip_colors_and_formatting

class String
  FOREGROUND_COLORS = {
    black: 30,
    blue:  34,
    yellow: 33,
    cyan: 36,
    green: 32,
    magenta: 35,
    red: 31,
    white: 37
  }

  BACKGROUND_COLORS = {
    black: 40,
    blue:  44,
    yellow: 43,
    cyan: 46,
    green: 42,
    magenta: 45,
    red: 41,
    white: 107
  }

  BACKGROUND_COLORS.each do |color, code|
    define_method(color) do |fore_color = nil, prefix = ''|
      foreground = fore_color ? "#{FOREGROUND_COLORS[fore_color]};" : ''
      "\e[#{foreground}#{code}m#{prefix}#{self.gsub("\n", "")}\033[0m"
    end
  end
end

STDIN.each do |line|
  puts case line
  when /(Processing by)/
    line.green(:black)
  when /(Completed 200 OK)/
    line.black(:green, '√ ')
  when /(\sRendered\s)/
    line.cyan(:black)
  when /(Error)/
    line.red
  when /\[INFO/i
    line.yellow
  else
    line
  end
end