using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.IO.Pipes;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using System.Threading.Tasks;
using NUnit.Framework;
using System.Drawing;
namespace CodeRetreatConwaysGameLife
{
    class Game
    {
        private readonly ImmutableHashSet<Point> aliveCells;

        public Game()
            : this(ImmutableHashSet<Point>.Empty)
        {
        }

        private Game(ImmutableHashSet<Point> aliveCells)
        {
            this.aliveCells = aliveCells;
        }

        public static Game Stick()
        {
            return new Game()
                .SetCellAlive(2, 2)
                .SetCellAlive(2, 3)
                .SetCellAlive(2, 4)
                ;
        }


        private Game SetCellAlive(int x, int y)
        {
            return SetCellAlive(new Point(x, y));
        }

        public static IEnumerable<Point> GetNeighbours(Point cell)
        {
            return
                from dx in new int[] { -1, 0, 1 }
                from dy in new int[] { -1, 0, 1 }
                where Math.Abs(dx) + Math.Abs(dy) != 0
                select new Point(cell.X + dx, cell.Y + dy);
        }

        public IEnumerable<Point> GetAliveNeighbours(Point cell)
        {
            return GetNeighbours(cell).Where(IsAlive);
        }

        public bool IsAlive(Point cell)
        {
            return aliveCells.Contains(cell);
        }

        public Game SetCellAlive(Point cell)
        {
            return new Game(aliveCells.Add(cell));
        }

        public Game NextStep()
        {
            return new Game(GetNextGeneration());
        }

        private ImmutableHashSet<Point> GetNextGeneration()
        {
            return aliveCells.SelectMany(GetNeighbours)
                .Where(WillBeAlive)
                .ToImmutableHashSet();
        }

        private bool WillBeAlive(Point cell)
        {
            var count = GetAliveNeighbours(cell).Count();
            return (IsAlive(cell) && count == 2) || count == 3;
        }

        public override string ToString()
        {
            return String.Join("\n",

                Enumerable.Range(0, 10)
                .Select(y =>
                    String.Join("", Enumerable.Range(0, 10)
                        .Select(x => IsAlive(new Point(x, y)) ? "*" : " ")
                        )));
        }
    }
}