Journeys

journeys.rb

class Robot
  MOVES = {
    L: 'move_left',
    R: 'move_right',
    F: 'move_forward'
  }

  DIRECTIONS = ['N', 'E', 'S', 'W']

  def initialize position
    @coordinates = position.split(' ')[0, 2].map(&:to_i)
    @direction = position.split(' ')[2]
  end

  def move moves
    moves.split('').each do |move|
      self.send(MOVES[move.to_sym])
    end
  end

  def move_right
    index = (DIRECTIONS.find_index(@direction) + 1) % DIRECTIONS.count
    @direction = DIRECTIONS[index]
  end

  def move_left
    index = (DIRECTIONS.find_index(@direction) - 1) % DIRECTIONS.count
    @direction = DIRECTIONS[index]
  end

  def move_forward
    case @direction
    when 'N'
      @coordinates = [@coordinates[0], @coordinates[1] + 1]
    when 'E'
      @coordinates = [@coordinates[0] + 1, @coordinates[1]]
    when 'S'
      @coordinates = [@coordinates[0], @coordinates[1] - 1]
    when 'W'
      @coordinates = [@coordinates[0] - 1, @coordinates[1]]
    end
  end

  def position
    [@coordinates.flatten, @direction].join(' ')
  end
end

inputs = []
File.open('journeys.txt', 'r') do |file|
  file.each_line do |line|
    inputs << line.gsub("\n", "")
  end
end
inputs.delete("")

inputs.each_slice(3).each do |slice|
  wallee = Robot.new(slice[0])
  wallee.move(slice[1])
  puts "Actual: #{wallee.position}"
  puts "Expected: #{slice[2]}"
  puts wallee.position == slice[2]
end