#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <time.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include "list.h"
#include <sys/time.h>
#include <sys/select.h>

#define LISTENING_PORT 1337
#define LISTENING_GROUP "224.0.0.42"
#define BUFLEN 512

main(int argc) {
  struct sockaddr_in addr, tcpaddr;
  int addrlen, tcpaddrlen, sock, tcpsock, cnt, maxfd, res, tcpport, newsock;
  struct ip_mreq mreq;
  char message[BUFLEN];
  fd_set rset;
  List sockets;
  Position pos;

  //create the multicast udp socket to use
  sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);

  //throw error when the multicast socket couldn't be opened
  if(sock<0) {
    perror("Socket couldn't be opened");
    exit(1);
  }

  //create the tcp communication socket to use
  tcpsock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

  //throw error when the multicast socket couldn't be opened
  if(tcpsock<0) {
    perror("TCP socket couldn't be opened");
    exit(1);
  }

  //fill string with zeros
  bzero((char *)&tcpaddr, sizeof(tcpaddr));
  //set the socket-family to ipv4 protocolfamily
  tcpaddr.sin_family = AF_INET;
  //enter the address of the host we're running on into the struct
  tcpaddr.sin_addr.s_addr = htonl(INADDR_ANY);
  //calculate the size of the address
  tcpaddrlen = sizeof(tcpaddr);

  //fill string with zeros
  bzero((char *)&addr, sizeof(addr));
  //set the socket-family to ipv4 protocolfamily
  addr.sin_family = AF_INET;
  //enter the address of the host we're running on into the struct
  addr.sin_addr.s_addr = htonl(INADDR_ANY);
  //calculate the size of the address
  addrlen = sizeof(addr);
  //enter the port to listen on into the struct
  addr.sin_port = htons(LISTENING_PORT);

  //bind the tcp communication socket to the address used
  if(bind(tcpsock, (struct sockaddr *)&tcpaddr, sizeof(tcpaddr))<0) {
    perror("Couldn't bind the multicast socket");
    exit(1);
  }

  //start to listen on that socket
  if(listen(tcpsock,10)<0) {
    perror("Couldn't listen on that socket");
    exit(1);
  }

  //bind the multicast socket to the address used
  if(bind(sock, (struct sockaddr *)&addr, sizeof(addr))<0) {
    perror("Couldn't bind the multicast socket");
    exit(1);
  }

  //get the assigned port for the tcp communication socket
  if(getsockname(tcpsock, (struct sockaddr *)&tcpaddr, &tcpaddrlen)<0) {
    perror("Couldn't get the socketname");
    exit(1);
  }
  tcpport = tcpaddr.sin_port;
  printf("The TCP communication socket port is: %d\n",tcpport);

  //create the linked list to save the sockets
  sockets = MakeEmpty(NULL);
  pos = Header(sockets);
  Insert(sock, sockets, pos);
  Insert(tcpsock, sockets, pos);

  //set the address of the multicast group that we want to listen to
  mreq.imr_multiaddr.s_addr = inet_addr(LISTENING_GROUP);
  //set the address on which we will try to join the multicast group to the interface
  mreq.imr_interface.s_addr = htonl(INADDR_ANY);

  //request to join the multicast group to the interface
  if(setsockopt(sock, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq))<0) {
    perror("Couldn't set the socket options for mreq");
    exit(1);
  }

  //start to listen to clients searching for the server through the multicast group
  while(1) {
    FD_ZERO(&rset);
    pos = Header(sockets);
    maxfd = 0;
    do {
      pos = Advance(pos);
      FD_SET(Retrieve(pos),&rset);
      if(Retrieve(pos)>maxfd)
        maxfd = Retrieve(pos);
      printf("pos is: %d\n",Retrieve(pos));
    } while(!IsLast(pos, sockets));
    printf("Going to make a select() call\n");
    printf("%d is maxfd\n",maxfd);
    res = select(maxfd+1,&rset,NULL,NULL,NULL);
    if(res<=0) {
      perror("Error while selecting a socket");
      exit(1);
    }
    printf("Made the select() call\n");
    if(FD_ISSET(sock,&rset)) {
      //try to receive a message sent to the multicast group including the information of who sent it
      cnt = recvfrom(sock, message, sizeof(message)-1, 0, (struct sockaddr *)&addr, &addrlen);

      //if there is an error reading from the socket, terminate
      //else if the result is 0, there was no message to read, break the loop and try again
      if(cnt<0) {
        perror("Error while trying to receive a message from the socket");
        exit(1);
      } else if(cnt==0) {
        break;
      }
      message[cnt] = '\0';
      printf("%s",message);
      bzero(message, sizeof(message));
      sprintf(message, "discovery_reply %d\n",tcpport);
      if(sendto(sock,message,BUFLEN,0,(struct sockaddr *)&addr,addrlen)<0) {
        perror("Couldn't answer multicast request");
        exit(1);
      }
    }
    if(FD_ISSET(tcpsock,&rset)) {
      printf("Accepting new connection");
      newsock = accept(tcpsock,(struct sockaddr *)&tcpaddr, &tcpaddrlen);
      if(newsock<0) {
        perror("Couldn't create new socket");
        exit(1);
      }
      Insert(newsock, sockets, pos);
    }
    pos = Header(sockets);
    while(!IsLast(pos, sockets)){
      pos = Advance(pos);
      if((Retrieve(pos)!=sock)&&(Retrieve(pos)!=tcpsock)) {
        if(FD_ISSET(Retrieve(pos),&rset)) {
          cnt = recvfrom(Retrieve(pos), message, sizeof(message)-1, 0, (struct sockaddr *)&addr, &addrlen);
          if(cnt<0) {
            perror("Error while trying to receive a message from the socket");
            exit(1);
          }
          message[cnt] = '\0';
          printf("%s",message);
        }
      }
    }
  }
}