USING: arrays io.encodings.utf8 io.files kernel math math.parser
math.unicode math.vectors prettyprint sequences splitting
strings vectors ;
IN: aoc.5

: parse-crates ( strings -- crates ) flip [ last 32 ≠ ] filter [ [ 32 ≠ ] filter >vector ] map ;
: parse-instructions ( strings -- instrs ) [ " " split [ dec> ] map sift { 0 1 1 } v- ] map ;
: input ( -- instrs crates ) "~/factor/aoc/5/5.in" utf8 file-lines { "" } split first2 swap
    [ parse-instructions ] [ parse-crates ] bi* ;

:: amend ( seq n quote: ( elt -- ... newelt ) -- ... seq ) n seq nth quote call n seq set-nth seq ; inline
: destructure-nth ( crates len  n -- crates' list ) swap [ cut ]         curry amend swap ;
: prepend-nth     ( crates list n -- crates'      ) swap [ swap append ] curry amend      ;
: pick-up  ( crates    {n,from,to} -- crates' up ) first2 destructure-nth ;
: put-down ( crates up {n,from,to} -- crates'    ) last prepend-nth ;
:: crane ( fn -- str ) input [ [ pick-up fn call ] keep put-down ] reduce [ first ] map >string ; inline
: part1 ( -- str ) [ reverse ] crane ;
: part2 ( -- str ) [         ] crane ;

: solve ( -- ) part2 part1 . . ;