using System.Collections.Generic;
using System;

namespace TextAnalysis
{
    static class SentencesParserTask
    {
        public static List<List<string>> ParseSentences(string text)
        {
            var sentencesList = new List<List<string>>();

            List<string> sentences = new List<string>();
            FillSentences(sentences,text);

            for (int i = 0; i < sentences.Count; i++)
            {
                sentences[i] = sentences[i].Trim();
                List<string> words = new List<string>();
				DivideByWords(words,sentences[i]);

                if (words.Count > 0)
                    sentencesList.Add(words);
            }

            return sentencesList;
        }

		public static void DivideByWords(List<string> words, string sentence)
		{
			string wordTemp = "";
            for (int j = 0; j < sentence.Length; j++)//foreach simbol
            {
                 if (char.IsLetter(sentence[j]) || sentence[j] == '\'')
                 {
                    wordTemp += sentence[j];
                 }
                 else
                 {
                     if (wordTemp != "")
                     {
                        words.Add(wordTemp.ToLower());
                        wordTemp = "";
                     }
                 }
            }
			if (wordTemp != "")
            {
                words.Add(wordTemp.ToLower());
            }
		}

		public static void FillSentences(List<string> sentences, string text)
		{
			string part = "";
            string separators = ".!?;:()";
            for (int i = 0; i < text.Length; i++)
            {
                if (separators.IndexOf(text[i]) == -1)
                {
                    part += text[i];
                }
                else
                {
                    if (part != "")
                    {
                        sentences.Add(part.ToLower());
                        part = "";
                    }
                }
            }
            if (part != "")
            {
                sentences.Add(part.ToLower());
                part = "";
            }
		}
    }
}