require 'debug'

class RotationDecoder
  def initialize(file_path)
    @file_path = file_path
    @mapping = {
      'L' => :-,
      'R' => :+
    }
  end

  def decode(debug: false)
    code = 0
    current_num = 50
    puts "The dial starts by pointing at #{current_num}" if debug
    File.readlines(@file_path, chomp: true).map do |line|
      next if line.nil? || line.empty?
      direction, *number_arr = line.split('')
      number = Integer(number_arr.join)

      full_rotations = number / 100
      rest = number - full_rotations * 100

      raw_num = current_num.send(@mapping[direction], rest)

      # include 100 since that does not pass *through* zero but becomes exactly zero.
      passes_zero = 0

      if current_num != 0
        passes_zero = (0 <= raw_num && raw_num <= 100)  ? 0 : 1
      end

      current_num = raw_num % 100
      print "The dial is rotaded #{line} to point at #{current_num}" if debug
      print "; during this rotation, it points at 0 #{full_rotations + passes_zero} times" if debug && full_rotations + passes_zero > 0
      print "\n" if debug

      code += full_rotations + passes_zero
      code += 1 if current_num == 0
    end

    code
  end
end

if ARGV[0].nil? || ARGV[0].empty?
  puts "Usage: ruby part2.rb <file_name> [debug]"
  exit 1
end

debug = (ARGV[1] == "debug")
rd = RotationDecoder.new(ARGV[0])
puts "The code is: #{rd.decode(debug:)}"