using System;
using System.Collections.Generic;

namespace TextAnalysis
{
    static class SentencesParserTask
    {
        public static List<string> SplitSentenceIntoWords(string sentence)
        {
            var words = sentence.Split(' ', '^');
            var wordList = new List<String>();
            foreach (string word in words)
            {
                var clearWord = word;
                bool wordIsClear = false;
                for (var i = 0; i < clearWord.Length; i++)
                {
                    if (!char.IsLetter(clearWord[i]) && clearWord[i] != '\'')
                    {
                        clearWord = clearWord.Remove(i, 1);
                        i--;
                        while (!char.IsLetter(clearWord[0]))
                        {
                            clearWord = clearWord.Remove(0, 1);
                        }
                        wordList.Add(clearWord.ToLower());
                        wordIsClear = true;
                    }
                }
                if (!wordIsClear)
                {
                    wordList.Add(word);
                }
            }
            return wordList;
        }
        public static List<List<string>> ParseSentences(string text)
        {
            var sentencesList = new List<List<string>>();
            var sentences = text.Split('.', '!', '?', ';', ':', '(', ')');
            foreach (string sentence in sentences)
            {
                if (!sentence.Equals(""))
                sentencesList.Add(SplitSentenceIntoWords(sentence));
            }
            return sentencesList;
        }
    }
}