using System;
using System.Text;
using System.Text.RegularExpressions;
using System.Collections.Generic;
using System.IO;
using System.Linq;

namespace Lab4.ChainedWords
{
    static class TaskUtils
    {
        private static MatchCollection MatchByWords(string text, string punctuation)
        {
            string pattern = string.Format(@"[^{0}\n]+", Regex.Escape(punctuation));
            return Regex.Matches(text, pattern, RegexOptions.IgnoreCase);
        }

        private static MatchCollection MatchByIntegers(string text)
        {
            return Regex.Matches(text, @"\d+");
        }

        public static List<Tuple<int, string>> FindChains(string text, string punctuation)
        {
            List<Tuple<int, string>> chains = new List<Tuple<int, string>>();

            bool startedChain = false;
            int chainStart = 0;

            MatchCollection matches = MatchByWords(text, punctuation);
            for (int i = 1; i < matches.Count; i++)
            {
                Match prevMatch = matches[i-1];
                Match match = matches[i];
                bool matchesCriteria = prevMatch.Value.ToLowerInvariant().Last() == match.Value.ToLowerInvariant().First();

                if (matchesCriteria && !startedChain)
                {
                    startedChain = true;
                    chainStart = prevMatch.Index;
                }
                else if (!matchesCriteria && startedChain)
                {
                    startedChain = false;
                    int line = text.Substring(0, chainStart).Count(c => c == '\n')+1;
                    string chain = text.Substring(chainStart, match.Index-chainStart).TrimEnd('\n');
                    chains.Add(new Tuple<int, string>(line, chain));
                }
            }

            // Ensure that last chain gets added to list
            if (startedChain)
            {
                int line = text.Substring(0, chainStart).Count(c => c == '\n')+1;
                string chain = text.Substring(chainStart).TrimEnd('\n');
                chains.Add(new Tuple<int, string>(line, chain));
            }

            return chains;
        }

        public static List<int> FindIntegers(string text)
        {
            List<int> integers = new List<int>();

            MatchCollection matches = MatchByIntegers(text);
            foreach (Match match in matches)
            {
                integers.Add(int.Parse(match.Value));
            }

            return integers;
        }

        public static Tuple<int, string> FindLongestChain(string text, string punctuation)
        {
            List<Tuple<int, string>> chains = FindChains(text, punctuation);

            if (chains.Count == 0)
            {
                return null;
            }

            Tuple<int, string> longestChain = chains[0];
            foreach (var pair in chains)
            {
                if (pair.Item2.Length > longestChain.Item2.Length)
                {
                    longestChain = pair;
                }
            }

            return longestChain;
        }

        public static void ProcessChains(string inputFile, string outputFile, string punctuation)
        {
            string text = File.ReadAllText(inputFile, Encoding.UTF8);
            Tuple<int, string> longestChain = FindLongestChain(text, punctuation);
            List<int> integers = FindIntegers(text);

            using (StreamWriter writer = new StreamWriter(outputFile))
            {
                if (longestChain != null)
                {
                    writer.WriteLine("Ilgiausia žodžių grandinė {0} eilutėje: {1}", longestChain.Item1, longestChain.Item2);
                }
                else
                {
                    writer.WriteLine("Nėra žodžių grandinių.");
                }

                writer.WriteLine("Yra {0} žodžiai sudaryti iš skaitmenų. Jų suma: {1}", integers.Count, integers.Sum());
            }
        }

        public static void ProcessAligned(string input, string ouput, string punctuation)
        {
        }
    }
}