box-o-sand/ruby-sockets/marco-polo/server.rb

require 'eventmachine'
require 'sequel'

class MarcoPolo
  attr_reader :locations, :db

  def initialize
    @pool_range = 0..99
    # I'm not using this (yet?) ... but don't want to forget how I did it
    # @pool = [].tap do |board|
    #   @pool_range.each do |y|
    #     board << [].tap do |row|
    #       @pool_range.each do |x|
    #         row << "#{y}-#{x}"
    #       end
    #     end
    #   end
    # end
    @db = Sequel.connect("postgres://#{ENV['USER']}@localhost/marco_polo",
                         :max_connections => 10)
    unless @db.table_exists?(:locations)
      @db.create_table :locations do
        primary_key :id
        String :client
        DateTime :timestamp
        Integer :x
        Integer :y
        constraint(:in_the_pool, 'x > -1 and x < 100 and y > -1 and y < 100')
      end
    end
    @locations = @db[:locations]
    puts "LET GAME BEGIN NOW"
  end

  def polo(client, x, y)
    @locations.insert(:client => client, :x => x, :y => y,
                      :timestamp => Time.now)
    nextloc(x, y)
  end

  def marco(client = nil)
    if client
      @locations.where(:client => client).order_by(:timestamp.desc).first
    else
      @locations.order_by(:timestamp.desc).first
    end
  end

  private
  def nextloc(x, y)
    # we allow exiting the pool as long as you get back in on the opposite side
    # a la pac man
    move_x, move_y = rand(-2..2), rand(-2..2)
    new_x = x + move_x
    new_x = 100 + new_x if new_x <= -1
    new_y = y + move_y
    new_y = 100 + new_y if new_y <= -1
    [
      new_x > 99 ? new_x % 100 : new_x,
      new_y > 99 ? new_y % 100 : new_y
    ]
  end
end

class MarcoPoloServer < EventMachine::Connection
  class << self
    attr_accessor :game
  end

  def receive_data(data)
    parts = data.to_s.split
    case parts.first
    when 'polo'
      client, x, y = parts[1,4]
      newloc = self.class.game.polo(client, x.to_i, y.to_i)
      send_data("#{newloc.first} #{newloc.last}\n")
    when 'marco'
      if loc = self.class.game.marco(parts[1])
        send_data("polo #{loc[:client]} #{loc[:x]} #{loc[:y]}\n")
      else
        send_data("polo NULL 0 0\n")
      end
    else
      send_data("#{parts.first}???\n")
    end
  rescue => e
    STDERR.puts("#{e.class.name} #{e.message}: #{e.backtrace.join("\n")}")
  end
end

def main
  MarcoPoloServer.game = MarcoPolo.new
  EventMachine.run do
    host, port = '0.0.0.0', 22000
    EventMachine.start_server(host, port, MarcoPoloServer)
    puts "Listening on #{host}:#{port}"
  end
end

if $0 == __FILE__
  main
end