rover.rb

class RoversController
  attr_accessor :grid, :rovers
  def initialize(x, y)
    @rovers = []
  end

  def add_rover(x, y, direction)
    @rovers << Rover.new({x: x.to_i, y: y.to_i}, direction)
  end

  def execute_instructions(instructions)
    rover = @rovers.last
    instructions.each do |action|
      case action
      when 'L'
        rover.rotate_left
      when 'R'
        rover.rotate_right
      when 'M'
        rover.move
      end
    end
  end
end

class Rover
  attr_accessor :direction, :position
  def initialize(position, direction)
    @direction = direction
    @position = position
  end

  def rotate_left
    case @direction
    when 'N'
      @direction = 'W'
    when 'E'
      @direction = 'N'
    when 'S'
      @direction = 'E'
    when 'W'
      @direction = 'S'
    end
  end

  def rotate_right
    case @direction
    when 'N'
      @direction = 'E'
    when 'E'
      @direction = 'S'
    when 'S'
      @direction = 'W'
    when 'W'
      @direction = 'N'
    end
  end

  def move
    case direction
    when 'N'
      @position[:y] += 1
    when 'E'
      @position[:x] += 1
    when 'S'
      @position[:y] -= 1
    when 'W'
      @position[:x] -= 1
    end
  end
end

file = File.new(ARGV.first)
input = file.map(&:chomp)
plateau_size = input.shift.split

rc = RoversController.new(plateau_size.first, plateau_size.last)

input.each_slice(2) do |rl, ri|
  location = rl.split
  instructions = ri.split('')
  rc.add_rover(location[0], location[1], location[2])
  rc.execute_instructions(instructions)
end

rc.rovers.each do |rover|
  puts "#{rover.position[:x]} #{rover.position[:y]} #{rover.direction}"
end

rover_input.txt

5 5
1 2 N
LMLMLMLMM
3 3 E
MMRMMRMRRM