-- introducing: let expressions!!!
-- i implemented them yesterday because this was just too annoying otherwise

load "list.quox"
load "string.quox"
load "io.quox"


def0 Line : ★ = List ℕ × List ℕ


-- i still don't have char literals. quox has no idea what "a char" is
def colon = char.from-ℕ 0x3A
def bar   = char.from-ℕ 0x7C

def split-line : ω.String → Line =
  λ line ⇒
  letω line  = snd (string.break (char.eq colon) line);
       pair  = string.break (char.eq bar) line;
       got   = fst pair; want = snd pair;
       got   = list.filter String string.not-null (string.split char.ws? got);
       want  = list.filter String string.not-null (string.split char.ws? want);
       got   = list.tail-or-nil String got;
       want  = list.tail-or-nil String want;
       to-ℕs = list.map String ℕ
         (λ s ⇒ maybe.fold ℕ ℕ 0 (λ n ⇒ n) (string.to-ℕ s)) in
  (to-ℕs got, to-ℕs want)

def mem : ω.ℕ → ω.(List ℕ) → Bool =
  λ n ⇒ list.foldlω ℕ Bool 'false (λ b n' ⇒ bool.or b (nat.eq n n'))

def all-members : ω.(List ℕ) → ω.(List ℕ) → List ℕ =
  λ g w ⇒ list.filter ℕ (λ n ⇒ mem n w) g

def score-from-len : ω.(List ℕ) → ℕ =
  λ xs ⇒
    maybe.foldω (ℕ × List ℕ) ℕ 0
      (λ xxs ⇒ list.foldlω ℕ ℕ 1 (λ c _ ⇒ nat.times 2 c) (snd xxs))
      (list.uncons ℕ xs)

def score : ω.Line → ℕ =
  λ ln ⇒ score-from-len (all-members (fst ln) (snd ln))

def total-score : ω.(List Line) → ℕ =
  list.foldlω Line ℕ 0 (λ n l ⇒ nat.plus n (score l))

#[main]
def main =
  io.bindω String True
    (io.read-fileω "in/day4")
    (λ s ⇒ io.dump ℕ
      (letω lines = string.split (char.eq char.newline) s;
            lines = list.mapω String Line split-line lines in
       total-score lines))