batteryNotify.rb

#!/usr/bin/env ruby
#
# Send a notification using gnomes notification system
#
def notify(title, text)
  `notify-send "#{title}" "#{text}"`
end

#
# Returns the integer value of a file
#
def getFileInt(file)
  if File.exist?(file)
    return File.read(file).to_i
  else
    return nil
  end
end


#
# Gets the current battery level
#
def getBatteryPercentage()
  return getFileInt("/sys/class/power_supply/BAT0/capacity")
end


#
# Notifies the user about the current battery level
#
def notifyBatteryLevel(level = nil)
  if level == nil
    level = getBatteryPercentage();
  end
  notify("Battery Level", level.to_s + "%")
end

#
# Sends out a notification, if the
#
def notifyIfDifference(difference = 10, tmpFile = "/tmp/battery_level")
  puts "Checking for difference of more than " + difference.to_s;
  level = getBatteryPercentage();
  oldLevel = getFileInt(tmpFile);
  if oldLevel == nil || level - 10 > oldLevel || level + 10 < oldLevel
    notifyBatteryLevel(level);
    File.open(tmpFile, "w") do |file|
      file.puts(level)
    end
  end
end

#
# Prints the current usage to the user
#
def info()
  msg = "Usage: ./battery_notify.rb ACTION

  ACTIONS:
    - notify: Sends a notification with the current battery load
    - check: Only sends a notification on full steps";
  puts msg;
  notify("battery_notify", msg);
end

#
# Main logic block
#
if ARGV.length > 0
  if ARGV[0] == "notify"
    notifyBatteryLevel();
  elsif ARGV[0] == "check"
    if ARGV.length > 1
      level = ARGV[1];
    else
      level = 10;
    end
    notifyIfDifference(level);
  else
    info();
  end
else
  info();
end