using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

namespace _307_intermediate {
	class ScrabbleProblemSolver {

		static void Main(string[] args) {
			string path = (@"../../enable1.txt");
			string[] lines = File.ReadAllLines(path);
			List<string> longestChain = new List<string>();

			var twoLetterWords = lines.Where(l => l.Length == 2);

			foreach (var word in twoLetterWords) {
				List<string> currentChain = RecursiveCheck(word, lines, longestChain, new List<string>());
				if (currentChain.Count > longestChain.Count) {
					longestChain = currentChain;
				}
			}

			if (longestChain.Count == 0) {
				Console.WriteLine("There don't seem to be any words in this file.");
			} else {
				Console.WriteLine("The longest word we can build using this method is {0} characters long.", longestChain.Last().Length);
				Console.WriteLine("It's {0}.", longestChain.Last());
				if (longestChain.Count > 1) {
					Console.WriteLine("Here's the full chain:");
					foreach (var word in longestChain) {
						Console.WriteLine("{0} - {1}", word.Length, word);
					}
				}
			}

			Console.WriteLine("Press Enter to exit.");
			Console.ReadLine();
		}

		static List<string> RecursiveCheck(string word, string[] words, List<string> longestChain, List<string> previousChain) {
			List<string> currentChain = new List<string>(previousChain);
			currentChain.Add(word);
			var longerWords = words.Where(w => w.Contains(word) && w.Length > word.Length).OrderBy(w => w.Length);

			if (longerWords.Count() == 0) {
				return currentChain;
			}
			if (longerWords.Last().Length <= (longestChain.Count - 1)) {
				// no point in continuing to go down this route
				return currentChain;
			}

			List<string> returnChain = new List<string>(currentChain);

			foreach (var longerWord in longerWords.Where(w => w.Length == word.Length + 1)) {
				List<string> newChain = RecursiveCheck(longerWord, longerWords.ToArray(), longestChain, currentChain);
				if (newChain.Count > returnChain.Count) {
					returnChain = newChain;
				}
			}
			return returnChain;
		}

	}
}