#+TITLE: TREXIO I/O library
#+SETUPFILE: ../tools/theme.setup
#+INCLUDE: ../tools/lib.org

The [[https://github.com/trex-coe/trexio][TREXIO library]] enables easy and efficient input/output of wave
function parameters. In this section we provide high-level functions
to prepare the context by reading the required data from a TREXIO file.

* Headers                                                          :noexport:
  #+begin_src elisp :noexport :results none
(org-babel-lob-ingest "../tools/lib.org")
#+end_src


  #+begin_src c :tangle (eval c_test) :noweb yes
#include "qmckl.h"
#include <assert.h>
#include <math.h>
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "chbrclf.h"
#include <stdio.h>

int main() {
  qmckl_context context;
  context = qmckl_context_create();
#ifdef HAVE_TREXIO
  #+end_src

  #+begin_src c :tangle (eval c)
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#ifdef HAVE_STDINT_H
#include <stdint.h>
#elif HAVE_INTTYPES_H
#include <inttypes.h>
#endif

#ifdef HAVE_TREXIO
#include <trexio.h>
#endif

#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include <assert.h>
#include <math.h>

#include <stdio.h>

#include "qmckl.h"
#include "qmckl_memory_private_type.h"
#include "qmckl_memory_private_func.h"
  #+end_src
  
* Local functions

  Functions defined in this section are all local: they should not be
  exposed in the API. To identify them, we append ~_X~ to
  their name.
  
  
** Open file
   
   We first define a helper function to open a file by first trying to
   use the TEXT back end, and then the HDF5 back end. If both
   strategies fail, a ~NULL~ pointer is returned. This will allow to
   open only once the file and call multiple small functions to read
   groups of data by passing the ~trexio_t~ handle.
  
   #+begin_src c :tangle (eval c)
#ifdef HAVE_TREXIO
trexio_t* qmckl_trexio_open_X(const char* file_name, qmckl_exit_code* rc)
{
  *rc = QMCKL_SUCCESS;
  trexio_t* file = NULL;

  file = trexio_open(file_name, 'r', TREXIO_TEXT, rc);
  if (file != NULL) return file;

  file = trexio_open(file_name, 'r', TREXIO_HDF5, rc);
  if (file != NULL) return file;
    
  *rc = QMCKL_FAILURE;
  return NULL;
}
#endif
   #+end_src

** Electron
   
   In this section we read all the data into the electron data structure.
  
   #+begin_src c :tangle (eval c)
#ifdef HAVE_TREXIO
qmckl_exit_code
qmckl_trexio_read_electron_X(qmckl_context context, trexio_t* const file) 
{
  // Should not be possible by construction.
  assert (context != (qmckl_context) 0);
  assert (file != NULL);
  
  int rcio = 0;

  int64_t up_num = 0;
  int64_t dn_num = 0;

  rcio = trexio_read_electron_up_num_64(file, &up_num);
  if (rcio != TREXIO_SUCCESS) {
    return qmckl_failwith( context,
                           QMCKL_FAILURE,
                           "trexio_read_electron_up_num",
                           trexio_string_of_error(rcio));
  }

  assert (up_num >= 0);

  rcio = trexio_read_electron_dn_num_64(file, &dn_num);
  if (rcio != TREXIO_SUCCESS) {
    return qmckl_failwith( context,
                           QMCKL_FAILURE,
                           "trexio_read_electron_dn_num",
                           trexio_string_of_error(rcio));
  }
  
  assert (dn_num >= 0);
  
  
  qmckl_exit_code rc;
  rc = qmckl_set_electron_num(context, up_num, dn_num);
  return rc;
}
#endif
   #+end_src

** Nucleus
   
   In this section we read the molecular geometry and nuclear charges.
  
   #+begin_src c :tangle (eval c)
#ifdef HAVE_TREXIO
qmckl_exit_code
qmckl_trexio_read_nucleus_X(qmckl_context context, trexio_t* const file) 
{
  // Should not be possible by construction.
  assert (context != (qmckl_context) 0);
  assert (file != NULL);
  
  qmckl_exit_code rc;
  int rcio = 0;

  // Nucleus num
  int64_t num = 0;

  rcio = trexio_read_nucleus_num_64(file, &num);
  if (rcio != TREXIO_SUCCESS) {
    return qmckl_failwith( context,
                           QMCKL_FAILURE,
                           "trexio_read_nucleus_num",
                           trexio_string_of_error(rcio));
  }
  
  assert (num > 0);
  rc = qmckl_set_nucleus_num(context, num);


  // Nuclear charges
  {
    qmckl_memory_info_struct mem_info = qmckl_memory_info_struct_zero;
    mem_info.size = num * sizeof(double);

    double* nucl_charge = (double*) qmckl_malloc(context, mem_info);

    if (nucl_charge == NULL) {
      return qmckl_failwith( context,
                             QMCKL_ALLOCATION_FAILED,
                             "qmckl_trexio_read_nucleus_X",
                             NULL);
    }

    assert (nucl_charge != NULL);

    rcio = trexio_read_nucleus_charge_64(file, nucl_charge);
    if (rcio != TREXIO_SUCCESS) {
      return qmckl_failwith( context,
                             QMCKL_FAILURE,
                             "trexio_read_nucleus_charge",
                             trexio_string_of_error(rcio));
    }

    rc = qmckl_set_nucleus_charge(context, nucl_charge);

    qmckl_free(context, nucl_charge);
    nucl_charge = NULL;

    if (rc != QMCKL_SUCCESS) {
      return rc;
    }
  }

  // Nuclear coordinates
  {
    qmckl_memory_info_struct mem_info = qmckl_memory_info_struct_zero;
    mem_info.size = num * 3 * sizeof(double);

    double* nucl_coord = (double*) qmckl_malloc(context, mem_info);

    if (nucl_coord == NULL) {
      return qmckl_failwith( context,
                             QMCKL_ALLOCATION_FAILED,
                             "qmckl_trexio_read_nucleus_X",
                             NULL);
    }

    assert (nucl_coord != NULL);

    rcio = trexio_read_nucleus_coord_64(file, nucl_coord);
    if (rcio != TREXIO_SUCCESS) {
      return qmckl_failwith( context,
                             QMCKL_FAILURE,
                             "trexio_read_nucleus_charge",
                             trexio_string_of_error(rcio));
    }

    rc = qmckl_set_nucleus_coord(context, 'N', nucl_coord);

    qmckl_free(context, nucl_coord);
    nucl_coord = NULL;

    if (rc != QMCKL_SUCCESS) {
      return rc;
    }
  }

  return QMCKL_SUCCESS;
}
#endif
   #+end_src

* Read everything

  #+begin_src c :tangle (eval h_func)
qmckl_exit_code qmckl_trexio_read(const qmckl_context context, const char* file_name);
  #+end_src

  #+begin_src c :tangle (eval c)
qmckl_exit_code
qmckl_trexio_read(const qmckl_context context, const char* file_name)
{
  if (qmckl_context_check(context) == QMCKL_NULL_CONTEXT) {
    return false;
  }

  qmckl_exit_code rc;

#ifdef HAVE_TREXIO
  trexio_t* file = qmckl_trexio_open_X(file_name, &rc);
  if (file == NULL) {
    trexio_close(file);
    return qmckl_failwith( context,
                           QMCKL_INVALID_ARG_2,
                           "qmckl_trexio_read",
                           trexio_string_of_error(rc));
  }

  assert (file != NULL);

  rc = qmckl_trexio_read_electron_X(context, file);
  if (rc != QMCKL_SUCCESS) {
    trexio_close(file);
    return qmckl_failwith( context,
                           QMCKL_FAILURE,
                           "qmckl_trexio_read",
                           "Error reading electron");
  }
  
  rc = qmckl_trexio_read_nucleus_X(context, file);
  if (rc != QMCKL_SUCCESS) {
    trexio_close(file);
    return qmckl_failwith( context,
                           QMCKL_FAILURE,
                           "qmckl_trexio_read",
                           "Error reading nucleus");
  }
  
  trexio_close(file);
  file = NULL;
#else
  
  rc = qmckl_failwith( context,
                       QMCKL_FAILURE,
                       "qmckl_trexio_read",
                       "QMCkl was not compiled without TREXIO");
#endif
  return rc;
}
  #+end_src
  
* Test

  #+begin_src c :tangle (eval c_test)
#ifdef HAVE_TREXIO

qmckl_exit_code rc;
char fname[256];
char message[256];
rc = qmckl_trexio_read(context, "share/qmckl/test_data/chbrclf");
if (rc != QMCKL_SUCCESS) {
  printf("%s\n", qmckl_string_of_error(rc));
  qmckl_get_error(context, &rc, fname, message);
  printf("%s\n", fname);
  printf("%s\n", message);
 }
  
assert ( rc == QMCKL_SUCCESS );

printf("Electrons");
int64_t num;
rc = qmckl_get_electron_up_num(context, &num);
assert (rc == QMCKL_SUCCESS);
assert (num == chbrclf_elec_up_num);
  
rc = qmckl_get_electron_down_num(context, &num);
assert (rc == QMCKL_SUCCESS);
assert (num == chbrclf_elec_dn_num);

rc = qmckl_get_nucleus_num(context, &num);
assert (rc == QMCKL_SUCCESS);
assert (num == chbrclf_nucl_num);

printf("Nuclear charges");
double * charge = (double*) malloc (num * sizeof(double));
rc = qmckl_get_nucleus_charge(context, charge);
assert (rc == QMCKL_SUCCESS);
for (int i=0 ; i<num ; i++) {
  assert (charge[i] == chbrclf_charge[i]);
 }
free(charge);
charge = NULL;

printf("Nuclear coordinates");
double * coord  = (double*) malloc (num * 3 * sizeof(double));
rc = qmckl_get_nucleus_coord(context, 'T', coord);
assert (rc == QMCKL_SUCCESS);
int k=0;
for (int j=0 ; j<3 ; ++j) {
  for (int i=0 ; i<num ; ++i) {
//    printf("%f  %f\n", coord[k], chbrclf_nucl_coord[j][i]);
    assert (coord[k] == chbrclf_nucl_coord[j][i]);
    ++k;
  }
 }
free(coord);
coord = NULL;
  

#endif
  #+end_src

* End of files                                                     :noexport:

*** Test
  #+begin_src c :tangle (eval c_test)
  if (qmckl_context_destroy(context) != QMCKL_SUCCESS)
    return QMCKL_FAILURE;
#endif
  return 0;
}
  #+end_src

# -*- mode: org -*-
# vim: syntax=c