/********************************************************************
  Author:        Dana Vrajitoru, IUSB, CS
  Class:         B424 B524 Parallel Programming
  File name:     process_graph.cc
  Last updated:  October, 2020.
  Description:   The master - worker functions related to the 
                 implementation of the dependency graph problem 
                 in parallel using MPI.
*********************************************************************/

#include "graph.h"
#include "process_graph.h"
#include <mpi.h>
#include <iostream>
using namespace std;
#include <cstdlib>

// Master process: input the graph, sends the information to the
// workers, then calls the dependency function for vertex 0.
void Master(int nr_proc) 
{

    char filename[80];
    Graph gr;
    
    cout << "Enter the graph filename" << endl;
    cin>> filename;
    gr.Read(filename);
    gr.Print();
    if (nr_proc < gr.nr_vertices) {
        cout << "Cannot run the problem on this graph with less than " 
             << gr.nr_vertices << " processes" << endl;
        exit(0);
    }
    gr.Send_outgoing(nr_proc);
    gr.Send_incoming(nr_proc);
    Process_dependency(0, gr.nr_outgoing[0], gr.outgoing[0], 
                       gr.nr_incoming[0], gr.incoming[0]);
}

// Worker process: receives the incoming and outgoing arrays from the
// master and calls the dependency resolution function.
void Worker(int id) 
{
    int nr_in, nr_out, *incoming, *outgoing, tag=0, src=0;
    MPI_Status status;
    MPI_Recv(&nr_out, 1, MPI_INT, src, tag, MPI_COMM_WORLD, &status);
    if (nr_out != 0) {
        outgoing = new int[nr_out];
        MPI_Recv(outgoing, nr_out, MPI_INT, src, tag, MPI_COMM_WORLD, &status);
    }
    MPI_Recv(&nr_in, 1, MPI_INT, src, tag, MPI_COMM_WORLD, &status);
    if (nr_in != 0) {
        incoming = new int[nr_in];
        MPI_Recv(incoming, nr_in, MPI_INT, src, tag, MPI_COMM_WORLD, &status);
    }
    if (nr_in || nr_out) 
        Process_dependency(id, nr_out, outgoing, nr_in, incoming);
}

// The process should first receive a message from all the processes
// in its incoming list, then output a message containing the id, then
// send a message to all the vertices in the outgoing dependency list.
void Process_dependency(int id, int nr_out, int *outgoing, 
                        int nr_in, int *incoming)
{
    // To be completed by the student
}