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

using BlubbFish.Utils;

namespace BroadcastReciever {
  class Program {
    private readonly IPAddress s_mcastAddress;
    private readonly Int32 s_mcastPort;
    private Socket s_mcastSocket;
    private MulticastOption s_mcastOption;

    public Program(String[] args) {
      CmdArgs.Instance.SetArguments(new Dictionary<String, CmdArgs.VaildArguments>() { 
        { "adapter", new CmdArgs.VaildArguments(CmdArgs.ArgLength.Touple, true) },
        { "multicast", new CmdArgs.VaildArguments(CmdArgs.ArgLength.Touple, false, "224.0.24.1") }
      }, args);
      if(!CmdArgs.Instance.HasAllRequiredArguments()) {
        Console.Error.WriteLine(CmdArgs.Instance.GetUsageList("BroadcastReciever.exe"));
        _ = Console.ReadLine();
        return;
      }

      this.s_mcastAddress = IPAddress.Parse(CmdArgs.Instance.GetArgumentData("multicast"));
      this.s_mcastPort = 11000;

      // Start a multicast group.
      this.StartMulticast();

      // Display MulticastOption properties.
      this.MulticastOptionProperties();

      // Receive broadcast messages.
      this.ReceiveBroadcastMessages();
    }

    private void StartMulticast() {
      try {
        this.s_mcastSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);

        IPAddress localIPAddr = IPAddress.Parse(CmdArgs.Instance.GetArgumentData("adapter"));

        //IPAddress localIP = IPAddress.Any;
        EndPoint localEP = new IPEndPoint(localIPAddr, this.s_mcastPort);

        this.s_mcastSocket.Bind(localEP);


        // Define a MulticastOption object specifying the multicast group
        // address and the local IPAddress.
        // The multicast group address is the same as the address used by the server.
        this.s_mcastOption = new MulticastOption(this.s_mcastAddress, localIPAddr);

        this.s_mcastSocket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.AddMembership, this.s_mcastOption);
      } catch(Exception e) {
        Console.WriteLine(e.ToString());
        _ = Console.ReadLine();
        return;
      }
    }

    private void MulticastOptionProperties() {
      Console.WriteLine("Current multicast group is: " + this.s_mcastOption.Group);
      Console.WriteLine("Current multicast local address is: " + this.s_mcastOption.LocalAddress);
    }

    private void ReceiveBroadcastMessages() {
      Boolean done = false;
      Byte[] bytes = new Byte[100];
      IPEndPoint groupEP = new(this.s_mcastAddress, this.s_mcastPort);
      EndPoint remoteEP = new IPEndPoint(IPAddress.Any, 0);

      try {
        Console.WriteLine("Waiting for multicast packets.......");
        Console.WriteLine("Enter ^C to terminate.");
        while(!done) {
          Int32 length = this.s_mcastSocket.ReceiveFrom(bytes, ref remoteEP);
          Console.WriteLine("Received broadcast from \"{0}\" [{1}]: {2}", groupEP.ToString(), length, Encoding.ASCII.GetString(bytes, 0, bytes.Length));
        }

        this.s_mcastSocket.Close();
      } catch(Exception e) {
        Console.WriteLine(e.ToString());
        _ = Console.ReadLine();
        return;
      }
    }


    static void Main(String[] args) => _ = new Program(args);
  }
}