// ==================================================================
// Author: Jean-Michel Richer
// Email: jean-michel.richer@univ-angers.fr
// Date: Aug 2020
// Last modified: September 2026
// Purpose: Demonstrate basic send functionality, send array of float
// from master (rank=0) to slave (rank=1)
// ==================================================================
// Don't forget to launch with
//
// mpirun -n 2 bin/ezmpi_send_and_recv.exe
//
// ==================================================================
#include <unistd.h>
#include <unistd.h>  // for sleep

#include <cstdlib>
#include <iostream>
#include <numeric>
using namespace std;
#include "ezmpi.hpp"
using namespace ez::mpi;

/**
 * run master and slaves
 */
void run(int argc, char* argv[]) {
    // data to send
    vector<int> vec;
    int vec_size;

    // create process here so that it will be destroyed
    // at the end of the procedure
    Process process(argc, argv);
    process.log(true);

    if (process.is_master()) {
        // ----------------------------------------------------------
        // Code for the master
        // ----------------------------------------------------------

        // set remote cpu identifier that will communicate with master
        process.remote(1);

        vec_size = 10;
        vec.resize(vec_size);
        iota(vec.begin(), vec.end(), 1);

        process << vec << endl;

        // send vector to slave1
        process.send(vec);

        // wait for slave1 to compute and send back sum
        float result = 0;
        process.recv(result);

        process << "- result is " << result << " for length=" << vec_size;
        process << ", expected=" << (vec_size * (vec_size + 1)) / 2 << endl;

    } else if (process.is_slave(1)) {
        // ----------------------------------------------------------
        // Code for the first slave
        // ----------------------------------------------------------

        // tells to Process to send data to master processor
        process.remote(0);

        // process of id 1 will receive the vector and compute the sum

        // we receive the vector
        process.recv(vec);

        process << "- receive vector " << vec << endl;

        // 3- compute sum
        float sum = std::accumulate(vec.begin(), vec.end(), 0);

        // 4- send back result
        process.send(sum);

    } else {
        // ----------------------------------------------------------
        // Code for the other processes: don't do anything
        // ----------------------------------------------------------

        process << "- is idle" << endl;
    }

    process.logs(cout);
}

/**
 * main function
 *
 */
int main(int argc, char** argv) {
    srand(time(nullptr));

    // call a function that contains the code for the master and
    // the slaves in order to avoid problems of initialization and
    // finalization of processes
    run(argc, argv);

    exit(EXIT_SUCCESS);
}