require 'set'

@p1 = []
@p2 = []

input = File.readlines("day22.txt").collect(&:chomp).each do |line|
    next if line.empty?
    next @deck = @p1 if line == "Player 1:"
    next @deck = @p2 if line == "Player 2:"
    @deck << line.to_i
end

def play_combat(p1, p2)
    until p1.empty? || p2.empty?
        p1_draw, p2_draw = p1.shift, p2.shift
        if p1_draw > p2_draw
            p1 += [p1_draw, p2_draw]
        else
            p2 += [p2_draw, p1_draw]
        end
    end

    return p2.empty? ? p1 : p2
end

def play_recursive_combat(p1, p2, recursive = false)
    rounds = Set.new
    until p1.empty? || p2.empty?
        this_round = [p1, p2].hash
        return [:p1, p1] if rounds.include?(this_round)
        rounds << this_round
        p1_draw, p2_draw = p1.shift, p2.shift
        result =
            if p1.size >= p1_draw && p2.size >= p2_draw
                play_recursive_combat(p1.take(p1_draw),
                                      p2.take(p2_draw),
                                      true).first
            else
                p1_draw > p2_draw ? :p1 : :p2
            end
        if result == :p1
            p1 += [p1_draw, p2_draw]
        else
            p2 += [p2_draw, p1_draw]
        end
    end

    return p2.empty? ? [:p1, p1] : [:p2, p2]
end

def calculate_score(deck)
    return score = deck.reverse.collect.with_index do |card, idx|
        card * (idx + 1)
    end.sum
end

t1 = Time.now.utc

puts format("Part One: %<score>s (%<time>s seconds)",
            score: calculate_score(play_combat(@p1.dup, @p2.dup)),
            time: Time.now.utc - t1)

t2 = Time.now.utc

puts format("Part Two: %<score>s (%<time>s seconds)",
            score: calculate_score(play_recursive_combat(@p1.dup, @p2.dup).last),
            time: Time.now.utc - t2)