using System;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;
namespace Searchers
{
    public class Searcher
    {
        public static bool IsExist(string fileName)
        {
            string errorMessage = "The file: " + fileName + " could not be found! Please enter a valid file name!";

            if (!File.Exists(fileName))
            {
                Console.WriteLine(errorMessage);
                return false;
            }
            else
            {
                return true;
            }

        }
        public static int GetWordsCount(string file)
        {
            var result = file.Split(' ').ToList();
            return result.Count;

        }
        public static int GetSymbolsCount(string file)
        {
            var counter = 0;
            for (int i = 0; i < file.Length; i++)
            {
                counter++;
            }
            return counter;
        }
        public static void WriteOutput(string fileName)
        {
            var readOnlyFile = File.ReadAllText(fileName);
            Console.WriteLine("===============================");
            Console.WriteLine(readOnlyFile);
            Console.WriteLine("===============================");
            Console.WriteLine("The file contains " + GetSymbolsCount(readOnlyFile) + " symbols");
            Console.WriteLine("The file contains ~ " + GetWordsCount(readOnlyFile) + " words");

            Console.WriteLine("Type a word to search");

            String searchInput = Console.ReadLine();
            ImplementLogic(searchInput, fileName);

            }

        public static void ImplementLogic(string searchInput, string filename)
        {
            while (searchInput != "!!exit")
            {
                String pattern = "\\b";
                pattern += searchInput;
                pattern += "\\b";
                int count = Regex.Matches(File.ReadAllText(filename),
                    pattern,
                    RegexOptions.IgnoreCase).Count;
                // IgnoreCase = ignore case sens

                if (count == 1)
                {
                    Console.WriteLine($"The word \"{searchInput}\" has been found {count} time.");
                }
                else
                {
                    Console.WriteLine($"The word \"{searchInput}\" has been found {count} times.");
                }
                Console.WriteLine("Search a new word, or type !!exit");

                searchInput = Console.ReadLine();
            }

        }

        public static void Result()
        {
            // To search dinamically, just ask for a file:
            Console.WriteLine("Enter a file to search. Example: words.txt");

            String fileName = Console.ReadLine().Trim();

            if (IsExist(fileName))
            {
                WriteOutput(fileName);
            }
            else
            {
                while (!IsExist(fileName))
                {
                    fileName = Console.ReadLine();

                }
                if (IsExist(fileName))
                {
                    WriteOutput(fileName);
                }
            }
        }

        public static void Main()
        {
            Result();
        }
    }
}