#!/usr/bin/env ruby

# What can I say? I like the word reify.

vars = {}
nets = []

class Var
  def initialize(name)
    @name = name
    @value = nil
  end

  attr_reader :name, :value

  def reified?
    !@value.nil?
  end

  def try_reify_numeric!
    if @name =~ /\A\d+\Z/
      @value = @name.to_i
    end
  end

  def reify!(value)
    @value = value
  end

  def reify_negative!
    @value = 65536 + @value if @value < 0
  end

  def reset!
    @value = nil
  end
end

class Net
  def initialize(left, op, right, out)
    @left = left
    @op = op
    @right = right
    @out = out
    @reified = false
  end

  def reified?
    @reified
  end

  def reifiable?
    return false unless @left.nil? || @left.reified?
    return false unless @right.reified?
    return true
  end

  def reify!
    case @op
    when nil
      @out.reify!(@right.value)
    when "NOT"
      @out.reify!(~@right.value)
    when "AND"
      @out.reify!(@left.value & @right.value)
    when "OR"
      @out.reify!(@left.value | @right.value)
    when "LSHIFT"
      @out.reify!(@left.value << @right.value)
    when "RSHIFT"
      @out.reify!(@left.value >> @right.value)
    end

    @reified = true
  end

  def reset!
    @reified = false
  end
end

File.readlines("day7.input").map(&:strip).each do |line|
  input, output = line.split(" -> ")
  input = input.split

  vars[output] = Var.new(output) if vars[output].nil?
  output = vars[output]

  case input.length
  when 1
    vars[input[0]] = Var.new(input[0]) if vars[input[0]].nil?
    nets << Net.new(nil, nil, vars[input[0]], output)
  when 2
    vars[input[1]] = Var.new(input[1]) if vars[input[1]].nil?
    nets << Net.new(nil, input[0], vars[input[1]], output)
  when 3
    vars[input[0]] = Var.new(input[0]) if vars[input[0]].nil?
    vars[input[2]] = Var.new(input[2]) if vars[input[2]].nil?
    nets << Net.new(vars[input[0]], input[1], vars[input[2]], output)
  end
end

# Part 1
vars.values.each(&:try_reify_numeric!)

until nets.all?(&:reified?)
  nets.each do |net|
    net.reify! if net.reifiable?
  end
end

vars.values.each(&:reify_negative!)

part1 = vars["a"].value
puts "Part 1: #{part1}"

# Part 2
vars.values.each(&:reset!)
nets.each(&:reset!)

vars.values.each(&:try_reify_numeric!)

until nets.all?(&:reified?)
  nets.each do |net|
    vars["b"].reify!(part1)
    net.reify! if net.reifiable?
  end
end

vars.values.each(&:reify_negative!)

part2 = vars["a"].value
puts "Part 2: #{part2}"