using System.Collections.Generic;
using System;

namespace TextAnalysis
{
    static class FrequencyAnalysisTask
    {


        public static Dictionary<string, string> GetDictWithGramm(List<List<string>> text)
        {
            var result = new Dictionary<string, string>();
            for (int j = 0; j < text.Count; j++)
            {
                var sentence = text[j];
                for (int i = 0; i < sentence.Count - 1; i++)
                {
                    var keyB = sentence[i];
                    if (result.ContainsKey(keyB))
                    {
                        result[keyB] += " " + sentence[i + 1];
                    }
                    else
                    {
                        result[keyB] = sentence[i + 1];
                    }
                }
                for (int i = 0; i < sentence.Count - 2; i++)
                {
                    var keyT = sentence[i] + " " + sentence[i + 1];
                    if (result.ContainsKey(keyT))
                    {
                        result[keyT] += " " + sentence[i + 2];
                    }
                    else
                        result[keyT] = sentence[i + 2];
                }
            }
            return result;
        }

        public static Dictionary<string, string> GetMostFrequentNextWords(List<List<string>> text)
        {
            var result = GetDictWithGramm(text);
            var keys = new List<string>();
            foreach (var key in result)
                keys.Add(key.Key);
            for (int i = 0; i < keys.Count; i++)
            {
                string key = keys[i];
                var words = result[key].Split();
                var dictWAndF = new Dictionary<string, int>();
                for (int j = 0; j < words.Length; j++)
                {
                    string word = words[j];
                    if (!dictWAndF.ContainsKey(word)) dictWAndF[word] = 0;
                    dictWAndF[word]= dictWAndF[word]+1;
                }
                result[key] = GetContinue(dictWAndF);
            }
            return result;
        }

        public static string GetContinue(Dictionary<string, int> dict)
        {
            var i = 0;
            string continueW = "";
            foreach (var item in dict)
            {
                if (item.Value > i)
                {
                    i = item.Value;
                    continueW = item.Key;
                }
                else
                {
                    if ((item.Value == i) && (String.CompareOrdinal(continueW, item.Key) > 0))
                    {
                        continueW = item.Key;
                        i = item.Value;
                    }
                }
            }
            return continueW;
        }
    }
}