#include "common.h"

#define INPUTFILE "assignment1.in"

int maximum(int n, int *arrNumbers);

int main(int argc, char *argv[]) {
    int numProcesses, numRank;
    MPI_Status status;

    MPI_Init(&argc, &argv);
    MPI_Comm_size(MPI_COMM_WORLD, &numProcesses);
    MPI_Comm_rank(MPI_COMM_WORLD, &numRank);

    int *arrNumbers, *arrBlockIndices, *arrBlockSizes;
    int sizeBufferTotal, sizeBufferUsed = 0;

    if (numRank == 0) {

        // To avoid aggresive buffer growth at the beggining of the sequence
        sizeBufferTotal = INIT_BUFFER_SIZE;
        // Allocate enough memory for initial buffer
        arrNumbers = my_malloc(sizeBufferTotal * sizeof(int));
        // Open the file with input data
        FILE *ptrFile = my_fopen(INPUTFILE, "r");

        // Read lines of numbers until an EOF or a character is read
        int numNumber;
        while (fscanf(ptrFile, "%d", &numNumber) == 1) {
            // Grow buffer when needed
            arrNumbers = buffer_grow(arrNumbers, sizeBufferUsed, &sizeBufferTotal);
            // Store the number in memory
            arrNumbers[sizeBufferUsed++] = numNumber;
        }

        fclose(ptrFile);

        check_parallel_worth(numProcesses, sizeBufferUsed, 2);
        
        spread_evenly(numProcesses, sizeBufferUsed, 1, &arrBlockIndices, &arrBlockSizes);

    }

    MPI_Bcast(&sizeBufferTotal, 1, MPI_INT, 0, MPI_COMM_WORLD);
    int *arrSlice = my_malloc(sizeBufferTotal * sizeof(int));
    MPI_Scatterv(arrNumbers, arrBlockSizes, arrBlockIndices, MPI_INT, arrSlice, sizeBufferTotal, MPI_INT, 0, MPI_COMM_WORLD);

    int arrBlockData[NUM_CODES];
    MPI_Recv(arrBlockData, NUM_CODES, MPI_INT, 0, 1, MPI_COMM_WORLD, &status);
    //for (int i = 0; i < arrBlockData[CODE_SIZE];  i++) {
        //printf("rank %d: m[%d] = %d\n", numRank, i, arrSlice[i]);
    //}  
    
    int numMaximum = maximum(arrBlockData[CODE_SIZE], arrSlice);
    //printf("max in %d is %d\n", numRank, numMaximum); 
    int *arrMaximums;
    if (numRank == 0) {
        arrMaximums = my_malloc(numProcesses * sizeof(int));
    }

    MPI_Gather(&numMaximum, 1, MPI_INT, arrMaximums, 1, MPI_INT, 0, MPI_COMM_WORLD);

    MPI_Barrier(MPI_COMM_WORLD);
    if (numRank == 0) {
        //for (int i = 0; i < numProcesses; i++) {
            //printf("arrMaximums[%d] = %d\n", i, arrMaximums[i]);
        //}
        printf("The maximum from file %s is %d.\n", INPUTFILE, maximum(numProcesses, arrMaximums));
    }


    MPI_Finalize();
    return (0);
}

int maximum(int n, int *arrNumbers) {
    int value = INT_MIN;                  
    for (int i = 0; i < n; i++) {   
        if (value < arrNumbers[i]) {
            value = arrNumbers[i];  
        }                           
    }                               
    return value;                   
}