#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <thread>
void accept_print(int sockfd);
void print_by_tid(std::string c)
{
   std::cout<<std::this_thread::get_id() << ": " << c << std::endl;
}
void print_by_tid(std::string c, unsigned int s) {
      std::cout<<std::this_thread::get_id() << ": " << c << "\t" << s <<std::endl;

}

int main(int argc, char *argv[])
{
   int portno;
   struct sockaddr_in serv_addr;

   /* First call to socket() function */
   int sockfd = socket(AF_INET, SOCK_STREAM, 0);  //返回文件描述符

   if (sockfd < 0)
   {
      perror("ERROR opening socket");
      exit(1);
   }

   /* Initialize socket structure */
   bzero((char *)&serv_addr, sizeof(serv_addr));
   portno = 5001;

   serv_addr.sin_family = AF_INET;
   serv_addr.sin_addr.s_addr = INADDR_ANY;
   serv_addr.sin_port = htons(portno);

   /* Now bind the host address using bind() call.*/
   if (bind(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
   {
      perror("ERROR on binding");
      exit(1);
   }

   /* Now start listening for the clients, here process will
      * go in sleep mode and will wait for the incoming connection
   */

   listen(sockfd, 5);

   int read_fd_count = 1;

      struct timeval timeout;
      timeout.tv_sec = 20;
      timeout.tv_usec = 0;
      fd_set temp_hs;
      FD_ZERO(&temp_hs);
      FD_SET(sockfd, &temp_hs);

      int num_ready = select(FD_SETSIZE, &temp_hs, nullptr, nullptr, &timeout);
      if (num_ready < 0)
      {
         perror("error in select()");
      }
      else if (num_ready == 0)
      {
         print_by_tid("timeout\n");
      }
      else
      {
         for (int i = 0; i < read_fd_count; i++)
            if (FD_ISSET(sockfd, &temp_hs))
            {
               print_by_tid("fd %d is ready for reading", sockfd);
               accept_print(sockfd);
            }
            else
            {
               print_by_tid("fd %d is not ready for reading though select is wake up", sockfd);
            }
            
      }

}

void accept_print(int sockfd)
{
   int cli_addr;
   unsigned int clilen = sizeof(cli_addr);
   /* Accept actual connection from the client */
   print_by_tid("accepting socket");
   int newsockfd = accept(sockfd, (struct sockaddr *)&cli_addr, &clilen);
   print_by_tid("accepted socket");
   if (newsockfd < 0)
   {
      perror("ERROR on accept");
      exit(1);
   }
   char buffer[256];

   /* If connection is established then start communicating */
   bzero(buffer, 256);
   int n = read(newsockfd, buffer, 3);
   printf("received bytes: %s", buffer);
   n = read(newsockfd, buffer, 252);
   printf("received bytes: %s", buffer+4);

   if (n < 0)
   {
      perror("ERROR reading from socket");
      exit(1);
   }
   std::string s = std::string("Here is the message: ").append(buffer);
   print_by_tid(s);

   /* Write a response to the client */
   //n = write(newsockfd, "I got your message", 18);

   if (n < 0)
   {
      perror("ERROR writing to socket");
      exit(1);
   }
}