Weekly Challenges - Robot Simulator

simulator.rb

# Robots can: turn left, turn right, or advance
class Robot
  attr_reader :bearing

  def initialize
    @bearing = :north
    @x = 0
    @y = 0
  end

  def orient(direction)
    raise ArgumentError unless [:north, :south, :east, :west].include? direction
    @bearing = direction
  end

  def coordinates
    [@x, @y]
  end

  def turn_right
    directions = { north: :east, east: :south, south: :west, west: :north }
    @bearing = directions[bearing]
  end

  def turn_left
    directions = { north: :west, west: :south, south: :east, east: :north }
    @bearing = directions[bearing]
  end

  def at(x, y)
    @x = x
    @y = y
  end

  def advance
    value = { north: 1, east: 1, south: -1, west: -1 }[bearing]
    [:east, :west].include?(bearing) ? @x += value : @y += value
  end
end

# Place Robots on a grid and simulate their movements
# based on a string of commands.
class Simulator
  def instructions(command)
    commands = { 'L' => :turn_left, 'R' => :turn_right, 'A' => :advance }
    command.chars.map { |letter| commands[letter] }
  end

  def place(robot, options = {})
    robot.orient(options[:direction])
    robot.at(options[:x], options[:y])
  end

  def evaluate(robot, command)
    instructions(command).each do |method|
      robot.send(method)
    end
  end
end