#lang racket
(require "../../jj-aoc.rkt"
         threading
         racket/struct)

(struct present (l w h) #:transparent)

(define presents
  (for/list ([size-string (in-lines (open-day 2 2015))])
    (~> size-string (string-split "x") (map string->number _) (apply present _))))

;; part 1
(define (paper-area p)
  (define main-area (~> p struct->list (combinations 2) (map (λ~> (apply * 2 _)) _) (apply + _)))
  (define slack-area (~> p struct->list (sort <) (take 2) (apply * _)))
  (+ main-area slack-area))

(for/sum ([p (in-list presents)]) (paper-area p))

;; part 2
(define (ribbon-length p)
  (define ribbon-around-box (~> p struct->list (sort <) (take 2) (map (λ~> (* 2)) _) (apply + _)))
  (define ribbon-for-bow (~> p struct->list (apply * _)))
  (+ ribbon-around-box ribbon-for-bow))

(for/sum ([p (in-list presents)]) (ribbon-length p))