#!/usr/bin/env ruby

require_relative '../common'

class Day07 < Day
  class Tree
    attr_reader :tree

    def self.parse(input)
      input.each_with_object(Tree.new) do |command, tree|
        if command.start_with?('$ ')
          cmd, directory = command.match(/\A\$ (cd|ls) ?([A-Za-z\/.]*)\z/).captures
          tree.cd directory if cmd == "cd"
        else
          if command.start_with?('dir ')
            tree.directory command.split.last
          else
            size, file = command.match(/\A([0-9]+) (.+)\z/).captures
            tree.file file, size
          end
        end
      end
    end

    def initialize
      @current_directory = []
      @tree = {}
    end

    def cd(directory)
      if directory == ".."
        @current_directory.pop
      else
        @current_directory << directory
        if @tree.dig(*@current_directory).nil?
          @current_directory.inject(@tree) do |tree, directory|
            tree[directory] = {} if tree[directory].nil?
            tree[directory]
          end
        end
      end
    end

    def directory(name)
      @tree.dig(*@current_directory)[name] = {}
    end

    def file(name, size)
      @tree.dig(*@current_directory)[name] = size.to_i
    end

    def sizes(directory = ["/"])
      @tree.dig(*directory).each_with_object({directory.join('/') => 0}) do |(name, content), res|
        if content.is_a?(Hash)
          res.merge!(sizes(directory + [name]))
          res[directory.join('/')] += res[(directory + [name]).join('/')]
        else
          res[directory.join('/')] += content
        end
      end
    end
  end
  def part1
    Tree.parse(stdin).sizes.values.select { |v| v <= 100000 }.sum
  end

  def part2
    Tree.parse(stdin).sizes.values.select { |v| v >= 8381165 }.min
  end
end

Day07.run