advent of code day19

day19.rb

class Maze
  attr_accessor :data

  def initialize(stdin)
    self.data = []
    stdin.each_line do |line|
      data.push(line.chomp.split(''))
    end
  end

  def row(i)
    data[i]
  end

  def val_at(point)
    data[point.y][point.x] || ' '
  end
end

class Point
  attr_accessor :x, :y, :game
  def initialize(game, x, y)
    self.x = x
    self.y = y
    self.game = game
  end

  def valid_move?
    game.val_at(self) != ' '
  end

  def empty?
    game.val_at(self) == ' '
  end

  def letter?
    game.val_at(self) =~ /[A-Z]/
  end

  def val
    game.val_at(self)
  end
end

class Game
  attr_accessor :maze, :pos, :dir, :letters, :steps

  def val_at(pos) maze.val_at(pos) end

  def initialize
    self.maze = Maze.new(ARGF)
    self.steps = 1
    self.pos  = find_start_position
    self.dir  = find_direction
    self.letters = []
  end

  def up()    Point.new(self, pos.x, pos.y - 1) end
  def down()  Point.new(self, pos.x, pos.y + 1) end
  def left()  Point.new(self, pos.x - 1, pos.y) end
  def right() Point.new(self, pos.x + 1, pos.y) end

  def find_start_position
    x = maze.row(0).find_index { |val| val && val != ' ' }
    y = 0
    Point.new(self, x, y)
  end

  def find_direction
    [
      dir != method(:up)    && method(:down),
      dir != method(:down)  && method(:up),
      dir != method(:left)  && method(:right),
      dir != method(:right) && method(:left)
    ].find { |d| d && d.call.valid_move? }
  end

  def step
    next_sqr = dir.call
    if next_sqr.valid_move?
      self.pos = dir.call
      letters << next_sqr.val if next_sqr.letter?
      self.steps += 1
      return
    end

    # hit a wall
    self.dir = find_direction

    unless dir
      puts "Found: #{letters}. Took #{steps} steps"
      raise 'Game Over' unless dir
    end
  end
end

g = Game.new
loop {
  g.step
}