#include <iostream>
#include <mpi.h>
#include <string>


void master();
void slave();

int main(int argc, char* argv[]){

  int myid;
  int numprocs;
  int namelen;
  char processor_name[MPI_MAX_PROCESSOR_NAME];
  int headnode=0;



  std::string sharedmemorylocation;


  std::string proc_name_str;
  MPI_Init(&argc,&argv);        MPI_Comm_size(MPI_COMM_WORLD,&numprocs);
  MPI_Comm_rank(MPI_COMM_WORLD,&myid);
  MPI_Get_processor_name(processor_name,&namelen);
  proc_name_str = processor_name;

  if (myid == 0){
  master();
  }
  else{
  slave();
  }
  MPI_Finalize();

}

void master(){
  int numprocs;
  int rank;

  int myid;
  MPI_Comm_rank(MPI_COMM_WORLD,&myid);
  MPI_Status status;

 
  /* Find out how many processes there are in the default
     communicator */
  MPI_Comm_size(MPI_COMM_WORLD, &numprocs);
        
  std::cout << "I am master on process: " << myid << "\n";


  std::cout << "Creating a vector to broadcast to other cores.\n";
  

  int numbytes;
  std::cout << "Enter the number of bytes to send: ";
  std::cin >> numbytes;

  std::string to_send_str = "";

  for (int i = 0; i < numbytes; ++i){

    to_send_str.append("a");
  }

  //  std::cout << to_send_str << "\n";
  
  char* to_send = (char*)(to_send_str.c_str());

  int vectorlengths[1] = {0};
  
  vectorlengths[0] = to_send_str.size();

  std::cout << "vectorlengths[0] = " << vectorlengths[0] << "\n";


  // send the length of the string to be sent ahead of time to the other nodes
  // otherwise they won't be able to get the information correctly
  // as when the data is received, size of the vector being passed is needed

  MPI_Bcast(&vectorlengths,1, MPI_INT,0, MPI_COMM_WORLD);
  MPI_Bcast(&to_send[0], to_send_str.size(), MPI_CHAR, 0, MPI_COMM_WORLD);


  return;
}

void slave(){

  int numrocs;
  int rank;
  int myid;        
  MPI_Comm_rank(MPI_COMM_WORLD,&myid);
  MPI_Status status;

  std::cout << "I am a slave on process: " << myid << "\n";

  int vectorlengths[1] = {0};
  
  MPI_Bcast(&vectorlengths, 1, MPI_INT, 0, MPI_COMM_WORLD);

  
  //  std::cout << "vectorlengths[0] = " << vectorlengths[0] << "\n";
  
  char sent_chars[vectorlengths[0]];
  


  MPI_Bcast(&sent_chars, vectorlengths[0], MPI_CHAR, 0, MPI_COMM_WORLD);
  
  //  std::cout << "Sent a char array of size: " << vectorlengths[0] 
  //	    << "\nYay!\n";

  
  if (myid == 1){
  std::cout << "Sent the following character array: \n";
  std::cout << sent_chars << "\n" << "which is of size: ";
  
  std::cout << "vectorlengths[0] = " << vectorlengths[0] << "\n";
  }
  return;
}