using System;

using System.Net.Http;

using System.Linq;

​

// Get data

var response = await new HttpClient().GetStringAsync("https://tompafireadventofcode.free.beeceptor.com/day2"); 

​

var instructions = response.Split(Environment.NewLine).Select(line => {

    var actionAndValue = line.Split(" ");

    return new { action = actionAndValue.First(), val = int.Parse(actionAndValue.Last()) };

});

​

// Step 1

​

var steps = instructions.Select<dynamic, Func<Position, Position>>(instr => {

    return instr.action switch

    {

            "forward" => (pos) => pos with { Horizontal = pos.Horizontal + instr.val },

            "up" => (pos) => pos with { Vertical = pos.Vertical - instr.val },

            "down" => (pos) => pos with { Vertical = pos.Vertical + instr.val },

            _ => (pos) => pos

    };

}).ToList();

​

var position = new Position(0, 0);

steps.ForEach(step => position = step(position));

​

Console.WriteLine($"{position.Horizontal}, {position.Vertical}");

Console.WriteLine(position.Horizontal * position.Vertical);

​

​

// Step 2

​

var steps2 = instructions.Select<dynamic, Func<Position, Position>>(instr => {

    return instr.action switch

    {

            "forward" => (pos) => pos with { Horizontal = pos.Horizontal + instr.val, Vertical = pos.Vertical + (pos.Aim.GetValueOrDefault() * instr.val) },

            "up" => (pos) => pos with { Aim = pos.Aim - instr.val },

            "down" => (pos) => pos with { Aim = pos.Aim + instr.val },

            _ => (pos) => pos

    };

}).ToList();

​

var position2 = new Position(0, 0, 0);

steps2.ForEach(step => position2 = step(position2));

​

Console.WriteLine($"{position2.Horizontal}, {position2.Vertical}, {position2.Aim}");

Console.WriteLine(position2.Horizontal * position2.Vertical);

​

​

public record Position(int Horizontal, int Vertical, int? Aim = null);

​