drone.rb

# Template for an autonomous drone.
#
# Usage: ruby drone.rb LETTER HOSTNAME
#
# The autonomous drone communciates with the drone manager with a set
# of simple commands. Each command is a single line of text sent over
# a TCP socket connection.
#
# Commands sent by the drone:
#
#    name <letter> -- Send the name of the drone to the manager. The
#                     name should be a single character.
#
#                     Example: name X
#
#    position <x> <y> -- Send the current position of the drone. This
#                        command should be sent whenever the drone
#                        changes position. The x and y coordinates
#                        should be between 1 and 15 (inclusive).
#
#                        A drone should not move more than 1 space at
#                        a time (the no teleportation rule), and not
#                        update the position more than about once a
#                        second.
#
#                        Example: position 4 10
#
# The drone should be ready to handle any the the following commands:
#
#    name? -- The drone should respond immendiately with the name
#             command listed above.
#
#             Example: name?
#
#    crash! -- Informs the drone that it has crashed. The drone should
#              immediately shut down and kill its socket connection.
#
#             Example: crash!
#
#    radar <x1>,<y1>;<x2>,<y2>;<x3>,<y3> -- List of positions of all
#              the known objects in the screen. This may be an empty
#              list if the locations of the existing objects is not
#              yet known by the drone manager. Note that the drone's
#              own position (if known) will be included in the list.
#
#             Example: radar 10,3;7,2;5,4

# ---------------------------------------------------------------------
# Some versions of Celluloid want to use sysctl on a Mac to figure out
# the number of CPUs. If you don't have /usr/sbin in your path, then
# leave the following line in to add it automatically. If you are not
# on a Mac, or already have /usr/sbin in your path, then you can
# delete the following line.

ENV['PATH'] = ENV['PATH'] + ":/usr/sbin"

require 'celluloid/io'

class DroneController
  include Celluloid::IO

  def initialize(name, host=nil)
    host = host || 'localhost'
    @name = name
    @x = rand_coord
    @y = rand_coord
    @socket = TCPSocket.new(host, 8090)
    @running = true
    async.run
  end

  def running?
    @running
  end

  def run
    puts "Drone #{@name} flying"
    while running? && line = @socket.gets
      case line
      when /^name\?/
        send_data("name #{@name}")
      when /^crash!/
        puts "Drone #{@name} crashed\n"
        @running = false
      when /^radar/
        # We parse the radar coordinates for you, but don't do
        # anything with them. Here would be an interesting place to
        # put some custom code.
        coords = parse_radar(line)
      end
    end
    @socket.close
  end

  def parse_radar(line)
    line.scan(/(\d+),(\d+)/).map { |x, y|
      [x.to_i, y.to_i]
    }
  end

  def rand_coord
    (1 + rand * 15.0).to_i
  end

  def rand_walk(p)
    result = p + rand(3) - 1
    result = 1 if result < 1
    result = 15 if result > 15
    result
  end

  def move
    @x = rand_walk(@x)
    @y = rand_walk(@y)
    send_data("position #{@x} #{@y}\n")
  end

  def send_data(string)
    @socket.puts(string) if running?
  end
end

if $0 == __FILE__
  name, host = ARGV
  if name.nil?
    puts "Usage: drone.rb NAME [host]"
    exit(1)
  end

  drone = DroneController.new(name, host)

  while drone.running?
    sleep 1.0
    drone.move
  end
end

Gemfile

source 'https://rubygems.org'

gem 'celluloid'
gem 'celluloid-io'