#lang curly-fn racket

(require "scripts/aoc.rkt")

;; solution for day 21

(define (part1 input)
  ; (define edges
  ;   (for/fold ([edges '()]) ([line (in-list input)])
  ;     (match-define (cons ingreds allergs) line)
  ;     (append edges (for*/list ([i (in-list ingreds)] [a (in-list allergs)])
  ;                     (list i a)))))
  ; (define G (undirected-graph edges))
  ;(define matching (maximum-bipartite-matching G))
  (define all-ingreds (for/fold ([all (set)]) ([line (in-list input)])
                        (set-union all (list->set (car line)))))
  (define all-allergs (for/fold ([all (set)]) ([line (in-list input)])
                        (set-union all (list->set (cdr line)))))
  (define tainted (mutable-set))
  (for ([allerg (in-set all-allergs)])
    (define necessary (for/fold ([necessary all-ingreds]) ([line (in-list input)] #:when (member allerg (cdr line)))
                        (set-intersect necessary (list->set (car line)))))
    (set-union! tainted necessary))
  (define untainted (set-subtract all-ingreds tainted))
  (for*/sum ([line (in-list input)] [ingred (in-list (car line))])
    (if (set-member? untainted ingred) 1 0)))

(define (part2 input)
  (define all-ingreds (for/fold ([all (set)]) ([line (in-list input)])
                        (set-union all (list->set (car line)))))
  (define all-allergs (for/fold ([all (set)]) ([line (in-list input)])
                        (set-union all (list->set (cdr line)))))
  (define tainted (mutable-set))
  (for ([allerg (in-set all-allergs)])
    (define necessary (for/fold ([necessary all-ingreds]) ([line (in-list input)] #:when (member allerg (cdr line)))
                        (set-intersect necessary (list->set (car line)))))
    (set-union! tainted necessary))

  (define tainthash (for/hash ([a (in-set all-allergs)])
                      (values a (for/fold ([is all-ingreds]) ([line (in-list input)] #:when (member a (cdr line)))
                                  (set-intersect is (list->set (filter #{set-member? tainted %} (car line))))))))
  (define edges (for*/list ([k (in-list (hash-keys tainthash))]
                            [v (in-set (hash-ref tainthash k))])
                  (list k v)))

  (pretty-write edges)
  (define G (undirected-graph edges))
  (define matching (maximum-bipartite-matching G))
  (displayln matching)
  (define mhash (for/hash ([item (in-list matching)]) (values (first item) (second item))))
  (displayln mhash)
  (define by-allergs (sort (hash-keys mhash) string<?))
  (string-join
    (for/list ([key (in-list by-allergs)])
      (hash-ref mhash key))
    ",")

  )

; (part2 (parse "test"))
; (error "not shonks")

;; parse input file
(define (parse fname)
  (define lines (file->lines fname))
  (for/list ([line (in-list lines)])
    (match line
      [(pregexp #px"^([^\\(]+) \\(contains ([^\\)]+)\\)+"
                (list _ p1 p2))
       (define ingredients (string-split p1 " "))
       (define allergens (string-split p2 ", "))
       (cons ingredients allergens)]
      [_ (error "not shonks" line)])))

(module+ test
  (require rackunit)
  ;; tests here
  (displayln "no tests :("))

(module+ main
  (define input (parse "inputs/21"))
  (answer 21 1 (time (part1 input)))
  (answer 21 2 (time (part2 input)))
  (displayln "meow"))