using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;

namespace MyTcpListener
{
    public partial class Form1 : Form
    {
        TcpListener server = null;
        int gNo = 0;
        bool fOK = true;
        Int32 port;
        IPAddress localAddr;
        Byte[] bytes = new Byte[256];
        String data = null;
        TcpClient client;
        NetworkStream stream;

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            button1.Enabled = true;
            button2.Enabled = false;
            button3.Enabled = false;
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            if (fOK) { TimeP(); }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            port = Convert.ToInt32(textBox1.Text); 
            IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
            localAddr = ipHostInfo.AddressList[0];
            server = new TcpListener(localAddr, port);
            
            gNo = 1;
            button1.Enabled = false;
            button2.Enabled = true;
        }

        private void button2_Click(object sender, EventArgs e)
        {
            gNo = 0;
            server.Stop();
            client.Close();
            client = null;
            button1.Enabled = true;
            button2.Enabled = false;
            button3.Enabled = false;
        }

        private void button3_Click(object sender, EventArgs e)
        {
            byte[] msg = System.Text.Encoding.ASCII.GetBytes(textBox2.Text + "\r\n");
            stream.Write(msg, 0, msg.Length);
            gNo = 3;  
        }

        void TimeP()
        {
            fOK = false;
            switch (gNo)
            {
                case 1:
                    textBox3.AppendText("接続待ち\r\n");
                    textBox3.AppendText("接続待ちで強制終了する場合は、タスクマネージャーを使用してください！！\r\n");
                    server.Start();
                    client = server.AcceptTcpClient();
                    textBox3.AppendText("接続完了\r\n");
                    stream = client.GetStream();
                    gNo = 3;
                    button3.Enabled = true;
                    break;
                case 3:
                    if (stream.DataAvailable)
                    {
                        int i = stream.Read(bytes, 0, bytes.Length);
                        if (i != 0)
                        {
                            data = System.Text.Encoding.ASCII.GetString(bytes, 0, i);
                            textBox3.AppendText(data);
                        }
                    }
                    break;
                default:
                    break;
            }
            fOK = true;
        }
    }
}