using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using MarkovGrams.Utilities;

namespace MarkovGrams
{
	public enum Mode
	{
		None,
		Help,
		NGrams,
		Markov,
		WeightedMarkov
	}

	class MainClass
	{
		public static int Main(string[] args)
		{
			Mode operationMode = Mode.None;
			GenerationMode generationMode = GenerationMode.CharacterLevel;
			List<string> extras = new List<string>();
			StreamReader wordlistSource = new StreamReader(Console.OpenStandardInput());
			int order = 3, length = 8, count = 10;
			bool splitOnWhitespace = true,
				ngramsUnique = true,
				convertLowercase = false,
				startOnUppercase = false;
			for (int i = 0; i < args.Length; i++)
			{
				if (!args[i].StartsWith("-"))
				{
					extras.Add(args[i]);
					continue;
				}

				switch (args[i].TrimStart("-".ToCharArray()))
				{
					case "wordlist":
						wordlistSource = new StreamReader(args[++i]);
						break;
					case "order":
						order = int.Parse(args[++i]);
						break;
					case "length":
						length = int.Parse(args[++i]);
						break;
					case "count":
						count = int.Parse(args[++i]);
						break;
					case "no-split":
						splitOnWhitespace = false;
						break;
					case "no-unique":
						ngramsUnique = false;
						break;
					case "lowercase":
						convertLowercase = true;
						break;
					case "start-uppercase":
						startOnUppercase = true;
						break;
					case "words":
						generationMode = GenerationMode.WordLevel;
						splitOnWhitespace = false;
						break;
					case "help":
						operationMode = Mode.Help;
						break;
					default:
						Console.Error.WriteLine($"Error: Unknown option '{args[i]}'.");
						return 1;
				}
			}

			if(operationMode != Mode.Help && extras.Count > 0)
				operationMode = (Mode)Enum.Parse(typeof(Mode), extras.ShiftAt(0).Replace("markov-w", "weightedmarkov"), true);


			// ------------------------------------------------------------------------------------------

			IEnumerable<string> words = wordlistSource.ReadAllLines().SelectMany((string word) => {
				word = word.Trim();
				if (convertLowercase)
					word = word.ToLower();
				if (splitOnWhitespace)
					return word.Split(' ');
				return new string[] { word.Trim() };
			});

			switch (operationMode)
			{
				case Mode.Markov:
					Stopwatch utimer = Stopwatch.StartNew();
					UnweightedMarkovChain unweightedChain = new UnweightedMarkovChain(
						NGrams.GenerateFlat(words, order, generationMode),
						generationMode
					);
					unweightedChain.StartOnUppercase = startOnUppercase;

					for (int i = 0; i < count; i++)
						Console.WriteLine(unweightedChain.Generate(length));
					Console.Error.WriteLine($"{count} words in {utimer.ElapsedMilliseconds}ms");
					break;

				case Mode.WeightedMarkov:
					Stopwatch wtimer = Stopwatch.StartNew();
					WeightedMarkovChain weightedChain = new WeightedMarkovChain(
						NGrams.GenerateWeighted(words, order, generationMode),
						generationMode
					);
					weightedChain.StartOnUppercase = startOnUppercase;

					for (int i = 0; i < count; i++)
						Console.WriteLine(weightedChain.Generate(length));
					Console.Error.WriteLine($"{count} words in {wtimer.ElapsedMilliseconds}ms");
					break;

				case Mode.NGrams:
					foreach (string ngram in NGrams.GenerateFlat(words, order, generationMode, ngramsUnique))
						Console.WriteLine(ngram);

					break;

				case Mode.Help:
				default:
					Console.WriteLine("Usage:");
					Console.WriteLine("    ./MarkovGrams.exe <mode> [options]");
					Console.WriteLine();
					Console.WriteLine("Available modes:");
					Console.WriteLine("    markov:");
					Console.WriteLine("        Generate new words using an unweighted markov chain.");
					Console.WriteLine("    markov-w:");
					Console.WriteLine("        Generate new words using a weighted markov chain.");
					Console.WriteLine("    ngrams:");
					Console.WriteLine("        Generate raw unique n-grams");
					Console.WriteLine();
					Console.WriteLine("Available options:");
					Console.WriteLine("    --help                  Show this message");
					Console.WriteLine("    --wordlist {filename}   Read the wordlist from the specified filename instead of stdin");
					Console.WriteLine("    --order {number}        Use the specified order when generating n-grams (default: 3)");
					Console.WriteLine("    --length {number}       The target length of word to generate (Not available in ngrams mode; instead specifies the number of words to generate with --words)");
					Console.WriteLine("    --count {number}        The number of words to generate (Not valid in ngrams mode)");
					Console.WriteLine("    --words                 Generate ngrams on word-level instead of character-level (Applies to all modes; implies --no-split)");
					Console.WriteLine("    --no-split              Don't split input words on whitespace - treat each line as a single word");
					Console.WriteLine("    --lowercase             Convert the input to lowercase before processing");
					Console.WriteLine("    --start-uppercase       Start the generating a word only with n-grams that start with a capital letter");
					Console.WriteLine("    --no-unique             Don't remove duplicates from the list of ngrams (Only valid in ngrams mode)");
					Console.WriteLine("Type just ./MarkovGrams.exe <mode> to see mode-specific help.");
					return 1;
			}

			return 0;
		}
	}
}