void Main()
{
	var test = new Markov(2);
	test.ReadFromSource(File.ReadAllText(@"filenamet"));
	test.GenerateText().Dump();
}



public class Markov
{
	public Markov(int length)
	{
		_length = length;
		_keys = new Dictionary<string, List<string>>();
	}

	int _length;
	public Dictionary<string, List<string>> _keys;


	public void ReadFromSource(string source)
	{
		var buffer = new Queue<string>(_length);

		foreach (var word in getWords(source))
		{
			var key = getKey(buffer.Take(_length));
			buffer.CircularAdd(_length, word);

			if (buffer.Count() < _length) continue;

			if (!_keys.ContainsKey(key)) _keys[key] = new List<string>();
			_keys[key].Add(word);
		}
	}

	public string GenerateText()
	{
		var maxLen = 500;
		var sb = new StringBuilder();
		foreach (var word in generate())
		{
			if(maxLen-- <= 0) break;
			sb.Append(word + " ");
		}

		return sb.ToString();
	}

	private IEnumerable<string> generate()
	{
		var rnd = new Random();
		var size = _keys.Count();

		var queue = new Queue<string>(_length);
		var first = _keys.Keys.ElementAt(rnd.Next(size-1));




		while (true)
		{

			if (queue.Count() < _length)
			{
				foreach (var word in first.Split('|'))
				{
					queue.CircularAdd(_length, word);
					yield return word;
				}
			}

			var key = getKey(queue);
			if (_keys.ContainsKey(key))
			{
				var words = _keys[key];
				var index = rnd.Next(words.Count());
				var word = words[index];
				queue.CircularAdd(_length, word);
				yield return word;
			}
			else
			{
				Debug.WriteLine("No key found", getKey(queue));
				queue.Dequeue();
			}
		}

	}



	private string getKey(IEnumerable<string> keys)
	{
		return keys.DefaultIfEmpty().Aggregate((a, b) => $"{a}|{b}");
	}

	private IEnumerable<string> getWords(string source)
	{
		var result = source.Split(" ".ToArray(), StringSplitOptions.RemoveEmptyEntries);
		foreach (var r in result) yield return r;
	}
}

static class Helpers
{
	public static Queue<string> CircularAdd(this Queue <string> queue, int length, string value)
	{
		queue.Enqueue(value);
		while(queue.Count() > length) queue.Dequeue();
		return queue;
	}
}