/*
 * Copyright (C) by Argonne National Laboratory
 *     See COPYRIGHT in top-level directory
 */

#include "mpi.h"
#include <stdio.h>
#include "mpitest.h"

#define MAX_PROCESSES 10

int main(int argc, char **argv)
{
    int rank, size, i, j, iter;
    int table[MAX_PROCESSES][MAX_PROCESSES];
    int errors = 0;
    int participants;
    int displs[MAX_PROCESSES];
    int recv_counts[MAX_PROCESSES];

    MPI_Request *reqs;
    MPI_Info info;

    MTest_Init(&argc, &argv);
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    MPI_Comm_size(MPI_COMM_WORLD, &size);

    MPI_Info_create(&info);

    /* A maximum of MAX_PROCESSES processes can participate */
    if (size > MAX_PROCESSES)
        participants = MAX_PROCESSES;
    else
        participants = size;
    /* while (MAX_PROCESSES % participants) participants--; */
    if (MAX_PROCESSES % participants) {
        fprintf(stderr, "Number of processors must divide %d\n", MAX_PROCESSES);
        MPI_Abort(MPI_COMM_WORLD, 1);
    }
    reqs = (MPI_Request *) malloc(participants * sizeof(MPI_Request));
    if ((rank < participants)) {
        if (!reqs) {
            fprintf(stderr, "Cannot allocate request handle array\n");
            MPI_Abort(MPI_COMM_WORLD, 1);
        }

        /* Determine what rows are my responsibility */
        int block_size = MAX_PROCESSES / participants;
        int begin_row = rank * block_size;
        int end_row = (rank + 1) * block_size;
        int send_count = block_size * MAX_PROCESSES;

        /* Fill in the displacements and recv_counts */
        for (i = 0; i < participants; i++) {
            displs[i] = i * block_size * MAX_PROCESSES;
            recv_counts[i] = send_count;
        }

        for (i = 0; i < participants; i++) {
            void *sendbuf = (i == rank ? MPI_IN_PLACE : &table[begin_row][0]);
            MPI_Gatherv_init(sendbuf, send_count, MPI_INT, &table[0][0], recv_counts, displs,
                             MPI_INT, i, MPI_COMM_WORLD, info, &reqs[i]);
        }

        for (iter = 0; iter < 10; iter++) {
            /* Paint my rows my color */
            for (i = begin_row; i < end_row; i++)
                for (j = 0; j < MAX_PROCESSES; j++)
                    table[i][j] = rank + 10;

            /* Gather everybody's result together - sort of like an */
            /* inefficient allgather */
            for (i = 0; i < participants; i++) {
                MPI_Start(&reqs[i]);
                MPI_Wait(&reqs[i], MPI_STATUS_IGNORE);
            }

            /* Everybody should have the same table now.
             *
             * The entries are:
             * Table[i][j] = (i/block_size) + 10;
             */
            for (i = 0; i < MAX_PROCESSES; i++)
                if ((table[i][0] - table[i][MAX_PROCESSES - 1] != 0))
                    errors++;
            for (i = 0; i < MAX_PROCESSES; i++) {
                for (j = 0; j < MAX_PROCESSES; j++) {
                    if (table[i][j] != (i / block_size) + 10)
                        errors++;
                }
            }
            if (errors) {
                /* Print out table if there are any errors */
                for (i = 0; i < MAX_PROCESSES; i++) {
                    printf("\n");
                    for (j = 0; j < MAX_PROCESSES; j++)
                        printf("  %d", table[i][j]);
                }
                printf("\n");
            }

        }

        for (i = 0; i < participants; i++) {
            MPI_Request_free(&reqs[i]);
        }
    }

    free(reqs);
    MPI_Info_free(&info);

    MTest_Finalize(errors);
    return MTestReturnValue(errors);
}
