day7.rb

require 'pry-byebug'
@wires = {}
def is_integer? n
  return n.to_i.to_s == n
end


def first_pass
  File.readlines('input.txt').each do |line|
    line = line.split("->")
    signal = line[0].strip
    wire = line[1].strip
    @wires[wire] = signal
  end
end


def parse wire
  # puts "enter wire #{wire}"
  # binding.pry
  wire = wire.strip
  # we are dealing with an integer
  return wire.to_i if is_integer? wire
  # the gate has a value in our hash
  return @wires[wire] if is_integer? @wires[wire] 
  # the gate has a signal
  signal = @wires[wire]
  tokens = signal.split(" ")
  value = case tokens.count
  when 3
    operator = tokens[1]
    left_operand = tokens[0]
    right_operand = tokens[2]
    case operator
    when "AND"
      parse(left_operand).to_i & parse(right_operand).to_i
    when "OR"
      parse(left_operand).to_i | parse(right_operand).to_i
    when "LSHIFT"
      parse(left_operand).to_i << parse(right_operand).to_i
    when "RSHIFT"
      parse(left_operand).to_i >> parse(right_operand).to_i
    end
  when 2
     ~ parse(tokens[1]).to_i
  else
    puts " store #{tokens[0]}"
    # puts @wires
    @wires[wire] = parse(tokens[0])
  end
  # puts "exit #{wire}"
  value
end


first_pass
# p @wires
gate = 'a'
puts "#{gate} -> #{parse gate}"
# p @wires