#!/usr/bin/env ruby

require_relative '../common'

class Integer
  def bitwise_complement
    self ^ 65535
  end
end

class Day07 < Day
  def part1
    wires = input.each_with_object({}) do |row, hash|
      instruction, wire = row.split(' -> ')
      hash[wire] = Instruction.new(instruction)
    end

    wires.map { |wire, instruction| [wire, instruction.signal(wires)] }.sort.to_h.fetch('a')
  end

  def part2
    wires = input.each_with_object({}) do |row, hash|
      instruction, wire = row.split(' -> ')
      hash[wire] = Instruction.new(instruction)
    end

    a_signal = wires.map { |wire, instruction| [wire, instruction.signal(wires)] }.sort.to_h.fetch('a')

    wires = input.each_with_object({}) do |row, hash|
      instruction, wire = row.split(' -> ')
      hash[wire] = Instruction.new(instruction)
    end
    wires['b'] = Instruction.new(a_signal.to_s)

    wires.map { |wire, instruction| [wire, instruction.signal(wires)] }.sort.to_h.fetch('a')
  end

  class Instruction
    def initialize(text)
      @text = text
      @not, @first, @operation, @second = text.match(
        /\A((?<not>NOT) )?(?<first>[a-z0-9]+)( (?<operation>AND|OR|LSHIFT|RSHIFT) (?<second>[a-z0-9]+))?\z/
      ).captures
      @signal = nil
    end

    def signal(wires)
      @signal ||= process(wires)
    end

    private

    def process(wires)
      return process_wire(@first, wires).bitwise_complement if @not
      return process_wire(@first, wires) if @operation.nil?

      case @operation
      when "AND"
        process_wire(@first, wires) & process_wire(@second, wires)
      when "OR"
        process_wire(@first, wires) | process_wire(@second, wires)
      when "LSHIFT"
        process_wire(@first, wires) << process_wire(@second, wires)
      when "RSHIFT"
        process_wire(@first, wires) >> process_wire(@second, wires)
      end
    end

    def process_wire(value, wires)
      return value.to_i if value.match?(/\A[0-9]+\z/)
      wires[value].signal(wires)
    end
  end
end

Day07.run