using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.Net.Sockets;

namespace Alert
{
    class Program
    {
        static void Main(string[] args)
        {
            const int DEFAULT_TCP_PORT = 12121;

            if (args.Length < 4 || args.Length>6)
            {
                Console.WriteLine("Syntax : Alert <Kind> <Localisation> <Product> <Quantity> [<server> [<port>]]");
                return;
            }
            try
            {
                string kind, localisation, product, quantity, server, message;
                int port;
                TcpClient client;
                NetworkStream stream;

                kind = args[0];
                localisation = args[1];
                product = args[2];
                quantity = args[3];
                if (args.Length == 5)
                {
                    server = args[4];
                    port = DEFAULT_TCP_PORT;
                }
                else if (args.Length == 6)
                {
                    server = args[4];
                    if (!int.TryParse(args[5], out port))
                    {
                        Console.WriteLine("Error port must be a number !");
                        return;
                    }
                }
                else
                {
                    server = "localhost";
                    port = DEFAULT_TCP_PORT;
                }

                client = new TcpClient();

                client.Connect(server, port);
                stream = client.GetStream();

                if (stream.CanWrite)
                {
                    // a message alert is 256 bytes length
                    // structure of message alert is :
                    // [0,63] : kind
                    // [64,127] : localisation
                    // [128,191] : product
                    // [192,255] : quantity
                    message = Pad(kind) + Pad(localisation) + Pad(product) + Pad(quantity);
                    Byte[] sendBytes = ASCIIEncoding.ASCII.GetBytes(message);
                    stream.Write(sendBytes, 0, sendBytes.Length);
                    stream.Close();
                    stream.Dispose();
                }
                client.Close();
            }
            catch (Exception ex)
            {
                Console.WriteLine("Error sending alert !\n" + ex.ToString());
                return;
            }
        }

        static string Pad(string input)
        {
            if (input.Length > 64)
                return input.Substring(0, 64);

            return input + new string(' ', 64 - input.Length);
        }
    }
}