(import std)

(define main

(do io/bind

(<- inp (io/map unwrap! (read-file "inputs/day2.txt")))

(let1 cmds (map parse-cmd (lines inp)))

(display "Part 1:")

(display (show-int (let1 [x y] (exec1 cmds)

(* x y))))

(display "Part 2:")

(display (show-int (let1 [x y _aim] (exec2 cmds)

(* x y))))))

(data Cmd (Forward Int) (Down Int))

(define (parse-cmd line)

(let ((ss (words line))

([s1 ss] (unwrap! (next ss)))

([s2 _] (unwrap! (next ss)))

(val (unwrap! (parse-int s2))))

(match s1

(case "forward" (Forward val))

(case "down" (Down val))

(case "up" (Down (neg val)))

(case _ (panic "unreachable")))))

(define (exec1 cmds)

(define (go [x y])

(fmatch (case (Forward dx) [(+ dx x) y])

(case (Down dy) [x (+ dy y)])))

(foldl go [0 0] cmds))

(define (exec2 cmds)

(define (go [x y aim])

(fmatch (case (Forward dx) [(+ dx x) (+ (* dx aim) y) aim])

(case (Down daim) [x y (+ daim aim)])))

(foldl go [0 0 0] cmds))