using System.Text.RegularExpressions;

namespace Sort
{
    public class Sort
    {
        public static bool CheckCommand(string command)
        {
            switch (command)
            {
                case "sort":
                    return true;
                case "Sort":
                    Console.WriteLine("I don't know this command, sorry to say that. Is there a chance you meant 'sort'?");
                    return false;
                default:
                    Console.WriteLine("I don't know this command, sorry to say that. And I have no idea what you meant...");
                    return false;
            }
        }

        public static List<String> ReadFile(string name)
        {
            List<String> lines = new List<String>();
            try
            {
                foreach (string line in File.ReadLines(name))
                {
                    lines.Add(line);
                }
            }
            catch (FileNotFoundException)
            {
                Console.WriteLine("I am so sorry to say, but I cannot find such file (" + name + "). I know this might be very difficult," +
                                  " but please check if you have entered the name correctly. I believe in you.");
            }

            return lines;
        }

        public static async Task Print(bool toFile, List<String> linesArray, string fileName)
        {
            if (toFile)
            {
                await File.WriteAllLinesAsync(fileName, linesArray);
            }
            else
            {
                foreach (var line in linesArray)
                {
                    Console.WriteLine(line);
                }
            }
        }

        public static List<String> SortLines(List<String> lines, bool reverse, bool unique, bool numericSort)
        {
            if (numericSort)
            {
                List<String> nums = new List<string>();
                List<String> other = new List<string>();
                foreach (var line in lines)
                {
                    if (new Regex("^[0-9]*$").IsMatch(line)) nums.Add(line);
                    else other.Add(line);
                }
                nums.Sort();
                if (reverse) nums.Reverse();
                nums.AddRange(other);
                if (unique) nums = nums.Distinct().ToList();
                return nums;
            }
            lines.Sort();
            if (reverse) lines.Reverse();
            if (unique) lines = lines.Distinct().ToList();

            return lines;
        }

        public static void Main(string[] args)
        {
            var command = Console.ReadLine();
            String[] flags = command!.Split(" ");
            if(!CheckCommand(flags[0])) return;

            var fileName = flags[^1];
            var linesArray = ReadFile(fileName);

            bool ignoreCase = false,
                reverse = false,
                unique = false,
                numericSort = false,
                versionSort = false,
                fileOutput = false;
            string outputFileName = "output.txt";
            for (int i = 1; i < flags.Length - 1; i++)
            {
                var flag = flags[i];
                if (flag == "-f" || flag == "--ignore-case") ignoreCase = true;
                else if (flag == "-r" || flag == "--reverse") reverse = true;
                else if (flag == "-u" || flag == "--unique") unique = true;
                else if (flag == "-n" || flag == "--numeric-sort") numericSort = true;
                else if (flag == "-o" || Regex.Match(flag , @"--output=.*").Success)
                {
                    fileOutput = true;
                    if (flag == "-o")
                    {

                            outputFileName = flags[i + 1];
                            i++;
                            if (i == flags.Length - 1)
                            {
                                Console.WriteLine("Hmmm... Seems like you didn't specify the output file name.");
                                return;
                            }

                            Console.WriteLine("Hmmm... Seems like you didn't specify the output file name.");
                            return;
                    }
                    else
                    {
                        outputFileName = flag.Substring(9);
                        if(outputFileName == "")
                        {
                            Console.Write("Hmmm... Seems like you didn't specify the file name.");
                            return;
                        }
                    }
                }
                else
                {
                    Console.WriteLine("Unknown flag: " + flag + ". Maybe try reading the documentation? (just an advise)");
                    return;
                }
            }

            linesArray = SortLines(linesArray, reverse, unique, numericSort);
            Print(fileOutput, linesArray, outputFileName);
        }
    }
}