aoc/AdventOfCode/Program.cs

using AdventOfCode.Contracts;
using Mono.Options;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;

namespace AdventOfCode
{
    class Program
    {
        private static bool Help { get; set; }
        private static bool BigBoi { get; set; }
        private static List<int> Year { get; set; } = new List<int>();
        private static List<int> Day { get; set; } = new List<int>();

        private static void Main(string[] args)
        {
            OptionSet options = new OptionSet()
            {
                { "h|?|help", "Prints this help message and exits", s => Help = s != null },
                { "y|year=", "The year of the challenge", (int s) => Year.Add(s) },
                { "d|day=", "The day(s) of the challenge. Accepts multiple (-d 1, -day=2)", (int s) =>  Day.Add(s) },
                { "b|BigBoi",  "Tells the program if it should run the BigBoi input", s => BigBoi = s != null}
            };

            try
            {
                options.Parse(args);
            }
            catch (OptionException e)
            {
                Error(e.Message);
                Exit();

                return;
            }

            if (Help)
            {
                Console.WriteLine("Usage: dotnet ./AoC.dll [OPTIONS]");
                Console.WriteLine("If no options are provided, all years and days will be run.");
                Console.WriteLine("If only a year is provided, all days from that year will be run.");
                Console.WriteLine("If only a day is provided, the provided day from all years will be run.");
                options.WriteOptionDescriptions(Console.Out);
                return;
            }

            if (!Day.Any() && (Day.Min() < 0 || Day.Max() > 25))
            {
                Error("Days must be between 1 and 25.");

                return;
            }

            var days = GetDays();

            if (Day.Any())
            {
                days = days.Where(d => Day.Contains(d.DayNumber));
            }

            if (Year.Any())
            {
                days = days.Where(d => Year.Contains(d.Year));
            }

            foreach (Day d in days)
            {
                d.Execute(BigBoi);
                d.Write();
            }

            Exit();
        }

        private static void Error(string e)
        {
            Console.Write("Advent of Code:");
            Console.WriteLine(e);
            Console.WriteLine("Try AdventOfCode --help for more information");
        }

        private static void Exit()
        {
            Console.WriteLine("Press any key to exit.");
            Console.ReadKey();
        }

        private static IEnumerable<Day> GetDays() =>
            Assembly.GetExecutingAssembly()
            .GetTypes()
            .Where(t => t.BaseType == typeof(Day))
            .Select(t => (Day)Activator.CreateInstance(t))
            .OrderBy(t => t.Year)
            .ThenBy(t => t.DayNumber);
    }
}