using System.Text;

namespace Task2
{
    public class Task2
    {
        public static Tuple<Encoding?, Encoding?> ParseArgs(string[] args)
        {
            var inputEncoding = Encoding.GetEncoding(args[1]);
            var outputEncoding = Encoding.GetEncoding(args[2]);
            return new Tuple<Encoding?, Encoding?>(inputEncoding, outputEncoding);
        }

        public static String ReadFile(string filename, Encoding encoding)
        {
            var text = File.ReadAllText(filename, encoding);
            return text;
        }

        public static String Convert(String lines, Tuple<Encoding, Encoding> encodings)
        {
            Encoding inputEncoding = encodings.Item1;
            Encoding outputEncoding = encodings.Item2;

            byte[] inputBytes = inputEncoding.GetBytes(lines);
            byte[] outputBytes = Encoding.Convert(inputEncoding, outputEncoding, inputBytes);
            char[] outputChars = new char[outputEncoding.GetCharCount(outputBytes, 0, outputBytes.Length)];
            outputEncoding.GetChars(outputBytes, 0, outputBytes.Length, outputChars, 0);
            string outputString = new string(outputChars);
            Console.WriteLine("Original string: {0}", lines);
            Console.WriteLine("Сonverted string: {0}", outputString);
            return outputString;
        }

        public static void FileOutput(string filename, String lines, Encoding encoding)
        {
            File.WriteAllText(filename, lines, encoding);
        }

        public static void FileOutputNoEncoding(string filename, String lines)
        {
            File.WriteAllText(filename, lines);
        }
        public static void Main(string[] args)
        {
            Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
            var encodings = ParseArgs(args);
            var lines = ReadFile(args[0], encodings.Item1);
            if (encodings.Item1.Equals(Encoding.GetEncoding("windows-1251")))
            {
                var converted = Convert(lines, encodings);
                FileOutputNoEncoding(args[0], lines);
            }

            else FileOutput(args[0], lines, encodings.Item2);
        }
    }
}