using System.Collections.Generic;
using System.Text;

namespace TextAnalysis
{
    static class SentencesParserTask
    {
        public static List<List<string>> ParseSentences(string text)
        {
            var sentencesList = new List<List<string>>();
            var sentences = text.Split('.', '!', '?', ';', ':', '(', ')');
            foreach (var sentence in sentences)
            {
                var newsentence = "";
                var listOfSentences = new List<string>();
                var result = ParseSentencesIntoWords(sentence);
                if (newsentence.Length > 0)
                    listOfSentences.Add(newsentence.ToLower());
                if (result.Count > 0)
                    sentencesList.Add(result);
            }

            return sentencesList;
        }

        public static List<string> ParseSentencesIntoWords(string sentence)
        {
            var listOfSentences = new List<string>();
            var newsentence = "";
            foreach (var letter in sentence)
            {
                if (char.IsLetter(letter) || letter == '\'')
                {
                    newsentence += letter.ToString();

                }

                else if(newsentence.Length > 0)
                {
                    listOfSentences.Add(newsentence.ToLower());
                    newsentence = "";
                }
            }
            if (newsentence.Length > 0)
                listOfSentences.Add(newsentence.ToLower());

            return listOfSentences;
        }
    }
}