#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <mpi.h>
#include <fstream>
#include <iostream>


 using namespace std;
int main (int argc, char * argv[])
{
    srand(time(NULL));
    int rank;
    int numProcessors;
    int myNum;
    int B;
    int A;
    int localNum;

    MPI_Init(&argc, &argv);
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    MPI_Comm_size(MPI_COMM_WORLD, &numProcessors);

    int *tab = new int[numProcessors];

    if(rank > 0)
    {
        MPI_Recv(&myNum, 1, MPI_INT, 0, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
    }

    if(rank == 0)
    {
        cout << "Nieposortowana tablica..." << endl;
        myNum = rand();
        cout << "[0]" << myNum << endl;

        for (int i = 1; i < numProcessors; i++) // for all the numbers in the file
        {
            localNum = rand();
            cout << "["<<i<<"] "<< localNum << endl;
            MPI_Send(&localNum, 1, MPI_INT, i, 0, MPI_COMM_WORLD); // broadcast the number to its assigned processor i
        }

        localNum = NULL;
    }

    if (rank %2 == 0)
    {
        A = rank + 1;
        B = rank - 1;
    }
    else
    {
        A = rank - 1;
        B = rank + 1;
    }

    if ((A == -1) || (A==numProcessors))
        A = rank;
    if ((B == -1) || (B == numProcessors))
        B = rank;

    // begin the main sorting loop
    for (int i = 0; i<numProcessors; i++)
    {
        if (i %2 == 0)
        {
            MPI_Sendrecv(&myNum, 1, MPI_INT, B, 8, &localNum, 1, MPI_INT , B, 8, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
        }
        else
        {
            MPI_Sendrecv(&myNum, 1, MPI_INT, A, 9, &localNum, 1, MPI_INT, A, 9, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
        }

        if (i %2 == 0)
        {
            if (rank %2 == 0 && localNum > myNum)
                myNum = localNum;
            if (rank %2 == 1 && localNum < myNum)
                myNum=localNum;

            MPI_Barrier(MPI_Comm MPI_COMM_WORLD);
        }

        else
        {
            if (rank %2 == 0 && localNum < myNum)
                myNum = localNum;
            if (rank %2 == 1 && localNum > myNum)
                myNum=localNum;

            MPI_Barrier(MPI_Comm MPI_COMM_WORLD);
        }

        MPI_Barrier(MPI_Comm MPI_COMM_WORLD);
    }

    if (rank > 0)
        MPI_Send(&myNum, 1, MPI_INT, 0, 5, MPI_COMM_WORLD);
    else if(rank == 0)
    {
        tab[0] = myNum;
        for (int i = 1; i < numProcessors; i++)
        {
            MPI_Recv(&tab[i], 1, MPI_INT, i, 5, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
        }

        std::cout << "Posortowana tablica: \n" << std::endl;
        for (int i = 0; i < numProcessors; i++)
                std::cout << "["<<i<<"] " << tab[i] << std::endl;
    }

    MPI_Finalize();

    free(tab);

    return 0;
}