#include <complex.h>
#include <pfft.h>

int main(int argc, char **argv)
{
  int np[2];
  ptrdiff_t n[3], N[3];
  ptrdiff_t alloc_local;
  ptrdiff_t local_ni[3], local_i_start[3];
  ptrdiff_t local_no[3], local_o_start[3];
  double err, *in, *out;
  pfft_plan plan_forw=NULL, plan_back=NULL;
  MPI_Comm comm_cart_2d;
  pfft_r2r_kind kinds_forw[3], kinds_back[3];
  
  /* Set size of FFT and process mesh */
  n[0] = 29; n[1] = 27; n[2] = 31;
  np[0] = 2; np[1] = 2;
  
  /* Set FFTW kinds of 1d R2R trafos */
  kinds_forw[0] = PFFT_REDFT00; kinds_back[0] = PFFT_REDFT00;
  kinds_forw[1] = PFFT_REDFT01; kinds_back[1] = PFFT_REDFT10;
  kinds_forw[2] = PFFT_RODFT00; kinds_back[2] = PFFT_RODFT00;

  /* Set logical DFT sizes corresponding to FFTW manual:
   * for REDFT00 N=2*(n-1), for RODFT00 N=2*(n+1), otherwise N=2*n */
  N[0] = 2*(n[0]-1);
  N[1] = 2*n[1];
  N[2] = 2*(n[2]+1); 

  /* Initialize MPI and PFFT */
  MPI_Init(&argc, &argv);
  pfft_init();

  /* Create two-dimensional process grid of size np[0] x np[1], if possible */
  if( pfft_create_procmesh_2d(MPI_COMM_WORLD, np[0], np[1], &comm_cart_2d) ){
    pfft_fprintf(MPI_COMM_WORLD, stderr, "Error: This test file only works with %d processes.\n", np[0]*np[1]);
    MPI_Finalize();
    return 1;
  }
  
  /* Get parameters of data distribution */
  alloc_local = pfft_local_size_r2r_3d(n, comm_cart_2d, PFFT_TRANSPOSED_OUT,
      local_ni, local_i_start, local_no, local_o_start);

  /* Allocate memory */
  in  = pfft_alloc_real(alloc_local);
  out = pfft_alloc_real(alloc_local);

  /* Plan parallel forward FFT */
  plan_forw = pfft_plan_r2r_3d(
      n, in, out, comm_cart_2d, kinds_forw, PFFT_TRANSPOSED_OUT| PFFT_MEASURE| PFFT_DESTROY_INPUT);
 
  /* Plan parallel backward FFT */
  plan_back = pfft_plan_r2r_3d(
      n, out, in, comm_cart_2d, kinds_back, PFFT_TRANSPOSED_IN| PFFT_MEASURE| PFFT_DESTROY_INPUT);

  /* Initialize input with random numbers */
  pfft_init_input_real_3d(n, local_ni, local_i_start,
      in);

  int myrank, size;
  MPI_Comm_rank(MPI_COMM_WORLD, &myrank);
  MPI_Comm_size(MPI_COMM_WORLD, &size);

//  for(int t=0; t<size; t++){
//    if(t == myrank){  
//      int m=0;
//      for(int k0=0; k0<local_ni[0]; k0++)
//        for(int k1=0; k1<local_ni[1]; k1++){
//          for(int k2=0; k2<local_ni[2]; k2++, m++)
//            printf("in[%d, %d, %d] = %.2f\t", k0+local_i_start[0], k1+local_i_start[1], k2+local_i_start[2], in[m]);
//          printf("\n");
//        }
//    }
//    fflush(stderr);
//    MPI_Barrier(MPI_COMM_WORLD);
//  }

  /* execute parallel forward FFT */
  pfft_execute(plan_forw);

  /* clear the old input */
  pfft_clear_input_real_3d(n, local_ni, local_i_start,
      in);
  

//  for(int t=0; t<size; t++){
//    if(t == myrank){  
//      int m=0;
//      for(int k1=0; k1<local_no[1]; k1++)
//        for(int k2=0; k2<local_no[2]; k2++){
//          for(int k0=0; k0<local_no[0]; k0++, m++)
//            printf("out[%d, %d, %d] = %.2f\t", k0+local_o_start[0], k1+local_o_start[1], k2+local_o_start[2], out[m]);
//          printf("\n");
//        }
//    }
//    fflush(stderr);
//    MPI_Barrier(MPI_COMM_WORLD);
//  }

  /* execute parallel backward FFT */
  pfft_execute(plan_back);
  
  /* Scale data */
  for(ptrdiff_t l=0; l < local_ni[0] * local_ni[1] * local_ni[2]; l++)
    in[l] /= (N[0]*N[1]*N[2]);

  /* Print error of back transformed data */
  MPI_Barrier(MPI_COMM_WORLD);
  err = pfft_check_output_real_3d(n, local_ni, local_i_start, in, comm_cart_2d);
  pfft_printf(comm_cart_2d, "Error after one forward and backward trafo of size n=(%td, %td, %td):\n", n[0], n[1], n[2]); 
  pfft_printf(comm_cart_2d, "maxerror = %6.2e;\n", err);

  /* free mem and finalize */
  pfft_destroy_plan(plan_forw);
  pfft_destroy_plan(plan_back);
  MPI_Comm_free(&comm_cart_2d);
  pfft_free(in); pfft_free(out);
  MPI_Finalize();
  return 0;
}