aoc_omni/ruby/2016/11/problem.rb

class Column
  attr_reader :floors, :items, :elevator, :history

  def self.for(lines)
    floors = lines.each_with_index.map { |line, index| Floor.for line, index + 1 }
    items = floors.map(&:items).flatten
    elevator = 1
    new floors, items, elevator
  end

  def initialize(floors, items, elevator, history=[])
    @floors = floors
    @items = items
    @elevator = elevator
    @history = history
  end

  def to_s
    @to_s ||= floors.reverse.map do |floor|
      floor_num = "F#{floor.number}"
      elevator_indicator = elevator == floor.number ? "E  " : ".  "
      item_string = items.map do |item|
        floor.has_item?(item) ? item.abbr : ".  "
      end.join(" ")
      "#{floor_num} #{elevator_indicator} #{item_string}"
    end.join("\n")
  end

  def valid?
    floors.all? &:valid?
  end

  def repeat?
    history.include? to_s
  end

  def apply(move)
    from_floor = floors.find { |floor| move.from == floor.number }
    to_floor = floors.find { |floor| move.to == floor.number }
    other_floors = floors.find_all { |floor| ![move.from, move.to].include?(floor.number) }
    new_from_floor = Floor.new(from_floor.items - move.with, from_floor.number)
    new_to_floor = Floor.new(to_floor.items + move.with, to_floor.number)

    self.class.new [new_from_floor, new_to_floor, *other_floors].sort_by(&:number), items, move.to, self.history + [to_s]
  end

  def complete?
    (items - floors.last.items).empty?
  end

  def current_floor
    floors.find { |floor| elevator == floor.number }
  end

  def generate_moves
    current_floor.generate_moves
  end

  def next_states
    generate_moves.map { |move| apply(move) }.select(&:valid?).reject(&:repeat?)
  end
end

class Floor
  attr_reader :items, :number

  def initialize(items, number)
    @items = items
    @number = number
  end

  def self.for(line, number)
    strings = line.gsub(" and", "").gsub(",", "").gsub(".", "").split(" a ")[1..]
    new strings.map { |string| Item.for string }, number
  end

  def has_item?(item)
    items.include? item
  end

  def valid?
    items.all? { |item| item.valid_on? self }
  end

  def generators
    items.select &:generator?
  end

  def microchips
    items.select &:microchip?
  end

  def has_matching_generator?(element)
    generators.any? { |gen| gen.is_element? element }
  end

  def generate_moves
    [*one_item_moves, *two_item_moves]
  end

  def one_item_moves
    [*one_item_up_moves, *one_item_down_moves]
  end

  def one_item_up_moves
    return [] if number == 4

    items.map do |item|
      Move.new number, number + 1, [item]
    end
  end

  def one_item_down_moves
    return [] if number == 1

    items.map do |item|
      Move.new number, number - 1, [item]
    end
  end

  def two_item_moves
    [*two_item_up_moves, *two_item_down_moves]
  end

  def two_item_up_moves
    return [] if number == 4

    items.each_with_index.map do |item_one, i1|
      items.each_with_index.map do |item_two, i2|
        next if item_one == item_two
        next if i1 < i2
        Move.new number, number + 1, [item_one, item_two]
      end
    end.flatten.compact
  end

  def two_item_down_moves
    return [] if number == 1

    items.each_with_index.map do |item_one, i1|
      items.each_with_index.map do |item_two, i2|
        next if item_one == item_two
        next if i1 < i2
        Move.new number, number - 1, [item_one, item_two]
      end
    end.flatten.compact
  end
end

class Item
  attr_reader :element

  def initialize(element)
    @element = element
  end

  def self.for(string)
    case string.split[1]
    when "microchip"
      Microchip.new string.split[0].split("-")[0]
    when "generator"
      Generator.new string.split[0]
    end
  end

  def element_abbr
    element[0..1].upcase
  end

  def abbr
    "#{element_abbr}#{object_abbr}"
  end

  def generator?
    false
  end

  def microchip?
    false
  end

  def is_element?(other_element)
    element == other_element
  end
end

class Microchip < Item
  def object_abbr
    "M"
  end

  def valid_on?(floor)
    floor.has_matching_generator?(element) || floor.generators.empty?
  end

  def microchip?
    true
  end

  def to_s
    @to_s ||= "#{element} microchip"
  end
end

class Generator < Item
  def object_abbr
    "G"
  end

  def valid_on?(_)
    true
  end

  def generator?
    true
  end

  def to_s
    @to_s ||= "#{element} generator"
  end
end

class Move
  attr_reader :from, :to, :with

  def initialize(from, to, with)
    @from = from
    @to = to
    @with = with
  end

  def to_s
    "From #{from} to #{to} with #{with.map(&:to_s)}"
  end
end

input = STDIN.read.chomp
lines = input.split("\n")
column = Column.for(lines)

states = [column]
until states.any?(&:complete?)
  states = states.map(&:next_states).flatten.uniq(&:to_s)
  puts "next"
end
part_1 = states.find(&:complete?).history.count
puts "Part 1: #{part_1}"