Simple countdown timer script for Mac OS X

timer.rb

#!/usr/bin/env ruby

if ARGV.empty?
  puts 'Usage: timer TIME'
  exit
end

TOKENS = { 's' => 1, 'm' => 60, 'h' => 60 * 60 }

def parse_duration(str)
  time = 0
  str.scan(/(\d+)(\w)/).each do |amount, measure|
    time += amount.to_i * TOKENS[measure] if TOKENS.has_key?(measure)
  end
  return time
end

def format_duration(seconds)
  minutes = seconds / 60
  seconds = seconds % 60
  parts = []
  if minutes > 0
    parts << "#{minutes} minutes"
  end
  if seconds > 0
    parts << "#{seconds} seconds"
  end
  return parts.join(', ')
end


def notify(message)
  system 'osascript', '-e', %[display notification "#{message}" sound name "Ping" with title "Timer"]
end

duration = parse_duration(ARGV.join(' '))

if duration.zero?
  puts 'Specify duration'
  exit 1
end

# Notify when 5% of time is left
wake_time = (duration * 0.05).ceil
if wake_time < duration
  sleep duration - wake_time
  notify(format_duration(wake_time) + ' remaining')
end

# Sleep remaining time
sleep wake_time
notify 'Time is up'