Advent of Code 2021 - Day 2

///usr/bin/env jbang "$0" "$@" ; exit $?
//JAVAC_OPTIONS --enable-preview -source 17
//JAVA_OPTIONS --enable-preview

import static java.lang.System.*;

import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.function.Function;
import java.util.stream.Stream;

public class Day2 {

    static record Position(int h, int d, int a) {
        static Position move(Position position, Movement movement) {
            return switch (movement) {
                case Forward f -> new Position(position.h + f.value, position.d, 0);
                case Down d -> new Position(position.h, position.d + d.value, 0);
                case Up u -> new Position(position.h, position.d - u.value, 0);
            };
        }

        static Position aim(Position position, Movement movement) {
            return switch (movement) {
                case Forward f -> new Position(position.h + f.value, position.d + (position.a * f.value), position.a);
                case Down d -> new Position(position.h, position.d, position.a + d.value);
                case Up u -> new Position(position.h, position.d, position.a - u.value);
            };
        }

        static Position combine(Position l, Position r) {
            return new Position(l.h + r.h, l.d + r.d, l.a + r.a);
        }


        int multiplied() { return h * d;}
    };



    static sealed interface Movement permits Forward, Down, Up {
        int value();
    }

    static record Forward(int value) implements Movement {}
    static record Down(int value) implements Movement {}
    static record Up(int value) implements Movement{}


    static Stream<Movement> lines() {
        final Function<String, Movement> mapper = (s) -> {
            final String[] ss = s.split(" ");
            final String direction = ss[0];
            final int value = Integer.parseInt(ss[1]);
            return switch(direction) {
                case "forward" -> new Forward(value);
                case "down" -> new Down(value);
                case "up" -> new Up(value);
                default -> throw new RuntimeException();
            };
        };
        try  {
            return Files.readAllLines(Paths.get("input.txt")).stream().map(mapper);
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        throw new RuntimeException();
    }


    static void part1() {
        final Position pos = lines().reduce(new Position(0, 0, 0), Position::move, Position::combine);
        out.println(pos.multiplied());
    }

    static void part2() {
        final Position pos = lines().reduce(new Position(0, 0, 0), Position::aim, Position::combine);
        out.println(pos.multiplied());
    }

    public static void main(String... args) {
        part1();
        part2();
    }
}