#include "mat_mul.h"

#include <cstdio>
#include <cstdlib>
#include <mpi.h>
#include "util.h"

static float *A, *B, *C;
static int M, N, K;
static int num_threads;
static int mpi_rank, mpi_world_size;
static  int rows[4] = {0,};
static  int offset[4] = {0,};

#define TILEM  32 
#define TILEK  16 
#define TILEN  2048

static void mat_mul_omp() {
  int start = 0;
  int end = rows[mpi_rank];

  // TODO: parallelize & optimize matrix multiplication
  // Use num_threads per node
#pragma omp parallel for num_threads(num_threads) schedule(dynamic)
  for (int ii = start; ii < end; ii += TILEM) {
    for (int kk = 0; kk < K; kk += TILEK) {
      for (int jj = 0; jj < N; jj += TILEN) {
        int ek = kk + TILEK < K ? (kk + TILEK) : K;
        int em = ii + TILEM < M ? (ii + TILEM) : M;
        int en = jj + TILEN < N ? (jj + TILEN) : N;
        for (int i = ii; i < em ; ++i) {
          for (int k = kk; k < ek; ++k) {
            for (int j = jj; j < en; ++j) {
              C[i * N + j] += A[i * K + k] * B[k * N + j];
            } // for j
          } // for kk
        } // for i
      } // for jj
    } // for kk
  } // for ii
}

void mat_mul(float *_A, float *_B, float *_C, int _M, int _N, int _K,
             int _num_threads, int _mpi_rank, int _mpi_world_size) {
  A = _A, B = _B, C = _C;
  M = _M, N = _N, K = _K;
  num_threads = _num_threads, mpi_rank = _mpi_rank,
  mpi_world_size = _mpi_world_size;
  MPI_Request request;
  MPI_Status status;

  // TODO: parallelize & optimize matrix multiplication on multi-node
  // You must allocate & initialize A, B, C for non-root processes

  int num_row = M / mpi_world_size;

  for (int i = 0 ; i < mpi_world_size ; i++) {
    rows[i] = (i == mpi_world_size - 1) ? (M - (num_row * (mpi_world_size - 1))): num_row;
  } 

  for (int i = 0 ; i < mpi_world_size - 1 ; i++) {
    offset[i + 1] = offset[i] + rows[i];
  }

  if (mpi_rank != 0) {
    M = rows[mpi_rank];
    alloc_mat(&A, rows[mpi_rank], K);
    alloc_mat(&B, K, N);
    alloc_mat(&C, rows[mpi_rank], N);
  }

  MPI_Bcast(B, K * N, MPI_FLOAT, 0, MPI_COMM_WORLD);
  if (mpi_rank == 0) {
    for (int i = 1 ; i < mpi_world_size ; i++)
      MPI_Isend(&A[offset[i] * K], rows[i] * K, MPI_FLOAT, i, 0, MPI_COMM_WORLD, &request);
  } else {
      MPI_Recv(A, rows[mpi_rank] * K , MPI_FLOAT, 0, 0, MPI_COMM_WORLD, &status);
  }

  mat_mul_omp();

  if (mpi_rank == 0) {
    for (int i = 1 ; i < mpi_world_size ; i++) {
      MPI_Recv(&C[offset[i] * N], rows[i] * N , MPI_FLOAT, i, 0, MPI_COMM_WORLD, &status);
    }
  } else {
    MPI_Isend(C, rows[mpi_rank] * N, MPI_FLOAT, 0, 0, MPI_COMM_WORLD, &request);
  }
}