
/*******************************************************************************
* Used NCrystal_sample as basis for creating a Union process that can use the  *
* NCrystal library.                                                            *
* Changes by Mads Bertelsen, 13/8 2020.                                        *
*******************************************************************************/

/******************************************************************************/
/* The original code contained the following license/copyright statement:     */
/******************************************************************************/
/*                                                                            */
/*  This file is part of NCrystal (see https://mctools.github.io/ncrystal/)   */
/*                                                                            */
/*  Copyright 2015-2019 NCrystal developers                                   */
/*                                                                            */
/*  Licensed under the Apache License, Version 2.0 (the "License");           */
/*  you may not use this file except in compliance with the License.          */
/*  You may obtain a copy of the License at                                   */
/*                                                                            */
/*      http://www.apache.org/licenses/LICENSE-2.0                            */
/*                                                                            */
/*  Unless required by applicable law or agreed to in writing, software       */
/*  distributed under the License is distributed on an "AS IS" BASIS,         */
/*  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  */
/*  See the License for the specific language governing permissions and       */
/*  limitations under the License.                                            */
/*                                                                            */
/******************************************************************************/
/*******************************************************************************
*
*  McStas, neutron ray-tracing package
*  Copyright(C) 2007 Risoe National Laboratory.
*
* %I
* Written by: NCrystal developers, converted to a Union component by Mads Bertelsen
* Date: 20.08.15
* Version: $Revision: 0.1 $
* Origin: NCrystal Developers (European Spallation Source ERIC and DTU Nutech)
*
*
* %D
*
* This process uses the NCrystal library as a Union process, see user documentation
*  for the NCrystal_sample.comp component for more information. The process only
*  uses the physics, as the Union components has a separate geometry system.
*  Absorption is also handled by Union, so any absorption output from NCrystal
*  is ignored.
*
* Part of the Union components, a set of components that work together and thus
*  sperates geometry and physics within McStas.
* The use of this component requires other components to be used.
*
* 1) One specifies a number of processes using process components like this one
* 2) These are gathered into material definitions using Union_make_material
* 3) Geometries are placed using Union_box / Union_cylinder, assigned a material
* 4) A Union_master component placed after all of the above
*
* Only in step 4 will any simulation happen, and per default all geometries
*  defined before the master, but after the previous will be simulated here.
*
* There is a dedicated manual available for the Union_components
*
*
* Original header text for NCrystal_sample.comp:
* McStas sample component for the NCrystal scattering library. Find more
* information at <a href="https://github.com/mctools/ncrystal/wiki">the NCrystal
* wiki</a>. In particular, browse the available datafiles at <a
* href="https://github.com/mctools/ncrystal/wiki/Data-library">Data-library</a>
* and read about format of the configuration string expected in the "cfg"
* parameter at <a href="https://github.com/mctools/ncrystal/wiki/Using-NCrystal">Using-NCrystal</a>.
*
* <p/>NCrystal is available under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache 2.0 license</a>. Depending
* on the configuration choices, optional NCrystal modules under different
* licenses might be enabled - see <a
* href="https://github.com/mctools/ncrystal/wiki/About">About</a> for more
* details.
*
* Algorithm:
* Described elsewhere
*
* %P
* INPUT PARAMETERS:
* cfg:               [str]    NCrystal material configuration string (details <a href="https://github.com/mctools/ncrystal/wiki/Using-NCrystal">on this page</a>).
* packing_factor:    [1]      Material packing factor
* interact_fraction: [1]      How large a part of the scattering events should use this process 0-1 (sum of all processes in material = 1)
*
* CALCULATED PARAMETERS:
* NCrystal_storage          // Storage used to communicate with the probability and scattering function
*
* %L
*
* %E
******************************************************************************/

DEFINE COMPONENT NCrystal_process // Remember to change the name of process here

SETTING PARAMETERS(string cfg = "", packing_factor=1, interact_fraction=-1, string init="init")
DEPENDENCY "-Wl,-rpath,CMD(ncrystal-config --show libdir) -Wl,CMD(ncrystal-config --show libpath) -ICMD(ncrystal-config --show includedir)"

SHARE
%{
#ifndef Union
#error "The Union_init component must be included before this NCrystal_process component"
#endif

#include "NCrystal/ncrystal.h"
#include "stdio.h"
#include "stdlib.h"
#ifndef NCMCERR2
  /* consistent/convenient error reporting */
#  define NCMCERR2(compname,msg) do { fprintf(stderr, "\nNCrystal: %s: ERROR: %s\n\n", compname, msg); exit(1); } while (0)
#endif

  static int ncsample_reported_version_union = 0;

  //Keep all instance-specific parameters on a few structs:
  typedef struct {
    double density_factor;
    double inv_density_factor;
    ncrystal_scatter_t scat;
    ncrystal_process_t proc_scat, proc_abs;
    int proc_scat_isoriented;
    int absmode;
  } ncrystalsample_t_union;

#ifndef NCMCERR
  /* more convenient form (only works in TRACE section, not in SHARE functions) */
#  define NCMCERR(msg) NCMCERR2(NAME_CURRENT_COMP,msg)
#endif

// Very important to add a pointer to this struct in the union-lib.c file
struct NCrystal_physics_storage_struct{
    // Variables that needs to be transfered between any of the following places:
    // The initialize in this component
    // The function for calculating my
    // The function for calculating scattering
    
    // Avoid duplicates of output parameters and setting parameters in naming
    ncrystalsample_t_union stored_params;
    double ncrystal_convfact_vsq2ekin;
    double ncrystal_convfact_ekin2vsq;
};

// Function for calculating my, the inverse penetration depth (for only this scattering process).
// The input for this function and its order may not be changed, but the names may be updated.
int NCrystal_physics_my(double *my, double *k_initial, union data_transfer_union data_transfer, struct focus_data_struct *focus_data, _class_particle *_particle) {
    // *k_initial is a pointer to a simple vector with 3 doubles, k[0], k[1], k[2] which describes the wavevector
    double k_mag = sqrt(k_initial[0]*k_initial[0] + k_initial[1]*k_initial[1] + k_initial[2]*k_initial[2]);
    
    // Normalized direction dir[3]
    double dir[3];
    dir[0] = k_initial[0]/k_mag;
    dir[1] = k_initial[1]/k_mag;
    dir[2] = k_initial[2]/k_mag;
    
    // Kinetic energy
    double vsq2ekin = data_transfer.pointer_to_a_NCrystal_physics_storage_struct->ncrystal_convfact_vsq2ekin;
    
    double ekin = vsq2ekin*K2V*k_mag*K2V*k_mag;
    
    double xsect_scat = 0.0;
    // Call NCrystal library, xsect_scat is updated
    ncrystal_crosssection(data_transfer.pointer_to_a_NCrystal_physics_storage_struct->stored_params.proc_scat, ekin, (const double(*)[3])&dir, &xsect_scat);

    double density_factor = data_transfer.pointer_to_a_NCrystal_physics_storage_struct->stored_params.density_factor;
    // Convert xsect_scat to inverse penetration depth
    *my = xsect_scat / density_factor;
    
    return 1;
};

// Function that provides description of a basic scattering event.
// Do not change the function signature
 int NCrystal_physics_scattering(double *k_final, double *k_initial, double *weight, union data_transfer_union data_transfer, struct focus_data_struct *focus_data, _class_particle *_particle) {

    // Magnitude of given wavevector
    double k_mag = sqrt(k_initial[0]*k_initial[0] + k_initial[1]*k_initial[1] + k_initial[2]*k_initial[2]);
    
    // Normalized direction dir[3]
    double dir[3], dirout[3];
    dir[0] = k_initial[0]/k_mag;
    dir[1] = k_initial[1]/k_mag;
    dir[2] = k_initial[2]/k_mag;
    
    double vsq2ekin = data_transfer.pointer_to_a_NCrystal_physics_storage_struct->ncrystal_convfact_vsq2ekin;
    double ekin, delta_ekin, v2, absv;
    
    ekin = vsq2ekin*K2V*k_mag*K2V*k_mag;
    delta_ekin = 0.0;
    // Call NCrystal library, dirout and delta_ekin is updated
    ncrystal_genscatter(data_transfer.pointer_to_a_NCrystal_physics_storage_struct->stored_params.scat, ekin, (const double(*)[3])&dir, &dirout, &delta_ekin);
    
    if (delta_ekin) {
      ekin += delta_ekin;
      if (ekin<=0) {
        //not expected to happen much, but an interaction could in principle bring the neutron to rest.
        return 0; // Eqivalent to ABSORB
      }
      v2 = data_transfer.pointer_to_a_NCrystal_physics_storage_struct->ncrystal_convfact_ekin2vsq * ekin;
      absv = sqrt(v2);
      k_mag = absv*V2K;
    }
    
    k_final[0] = dirout[0]*k_mag;
    k_final[1] = dirout[1]*k_mag;
    k_final[2] = dirout[2]*k_mag;
    
    // A pointer to k_final is returned, and the wavevector will be set to k_final after a scattering event
    return 1; // return 1 is sucess, return 0 is failure, and the ray will be absorbed.
              // failure should not happen, as this function will only be called when
              // the cross section for the current k_initial is above zero.
    
    // There is access to the data_transfer from within the scattering function
    // In this case the only variable is my, but it could be read by:
    // double my = data_transfer.pointer_to_a_NCrystal_physics_storage_struct->my_scattering;
    // One can assume that if the scattering function is running, the my fuction was
    //  executed just before and for the same k_initial.
#ifndef PROCESS_DETECTOR
    #define PROCESS_DETECTOR dummy
#endif

#ifndef PROCESS_NCRYSTAL_DETECTOR
    #define PROCESS_NCRYSTAL_DETECTOR dummy
#endif
};

%}

DECLARE
%{
// Declare for this component, to do calculations on the input / store in the transported data
struct NCrystal_physics_storage_struct NCrystal_storage; // Replace NCrystal with your own name here

// Variables needed in initialize of this function.

// Needed for transport to the main component, will be the same for all processes
struct global_process_element_struct global_process_element;
struct scattering_process_struct This_process;

double NCrystal_convfact_ekin2vsq;
double NCrystal_convfact_vsq2ekin;

ncrystalsample_t_union params;

// These lines help with future error correction, and tell other Union components
//  that at least one process have been defined.
#ifndef PROCESS_DETECTOR
    // Obsolete
	//struct pointer_to_global_process_list global_process_list = {0,NULL};
	#define PROCESS_DETECTOR dummy
#endif
%}

INITIALIZE
%{
  // Initialize done in the component
  //Print NCrystal version + sanity check setup.
  if ( NCRYSTAL_VERSION != ncrystal_version() ) {
    NCMCERR("Inconsistency detected between included ncrystal.h and linked NCrystal library!");
  }
  if (ncsample_reported_version_union != ncrystal_version()) {
    if (ncsample_reported_version_union) {
      NCMCERR("Inconsistent NCrystal library versions detected - this should normally not be possible!");
    }
    ncsample_reported_version_union = ncrystal_version();
    printf( "NCrystal: McStas Union process component(s) are using version %s of the NCrystal library.\n", ncrystal_version_str());
  }

  //The following conversion factors might look slightly odd. They reflect the
  //fact that the various conversion factors used in McStas and NCrystal are not
  //completely consistent among each other (TODO: Follow up on this with McStas
  //developers!). Also McStas's V2K*K2V is not exactly 1. All in all, this can
  //give issues when a McStas user is trying to set up a narrow beam very
  //precisely in an instrument file, attempting to carefully hit a certain
  //narrow Bragg reflection in this NCrystal component. We can not completely
  //work around all issues here, but for now, we assume that the user is
  //carefully setting up things by specifying the wavelength to some source
  //component. That wavelength is then converted to the McStas state pars
  //(vx,vy,vz) via K2V. We thus here first use 1/K2V (and *not* V2K) to convert
  //back to a wavelength, and then we use NCrystal's conversion constants to
  //convert the resulting wavelength to kinetic energy needed for NCrystal's
  //interfaces.

  // 0.0253302959105844428609698658024319097260896937 is 1/(4*pi^2)
  NCrystal_convfact_vsq2ekin = ncrystal_wl2ekin(1.0) * 0.0253302959105844428609698658024319097260896937 / ( K2V*K2V );
  NCrystal_convfact_ekin2vsq = 1.0 / NCrystal_convfact_vsq2ekin;

  //for our sanity, zero-initialise all instance-specific data:
  memset(&params,0,sizeof(params));

  /* Make sure NCrystal use the McStas RNG (ok if more than one component instance does this): */
#ifndef rand01
  /* Tell NCrystal to use the rand01 function provided by McStas: */
  ncrystal_setrandgen(rand01);
#else
  /* rand01 is actually a macro not an actual C-function (most likely defined as */
  /* _rand01(_particle->randstate) for OPENACC purposes), which we can not       */
  /* register with NCrystal. As a workaround we tell NCrystal to use its own RNG */
  /* algorithm, with merely the seed provided by McStas:                         */
  ncrystal_setbuiltinrandgen_withseed( mcseed );
#endif

  /* access powder packingfactor (nb: always 1.0 for non-powders): */
  // Union change: multiplying by Union packing_factor
  double packingfactor = ncrystal_decodecfg_packfact(cfg)*packing_factor;

  /* access crystal structure to get number density (natoms/volume): */
  ncrystal_info_t info = ncrystal_create_info(cfg);
  
  // Depending on the version of NCrystal, the number density is retrieved in
  // two different ways. The preprocessor is used to switch between the two
  // methods depending on the NCRYSTAL_VERSION
  #if NCRYSTAL_VERSION  >= 1099001
      double numberdensity = ncrystal_info_getnumberdensity(info);
      if( numberdensity <= 0.0 )
        NCMCERR("Number density information is unavailable in the loaded NCrystal Info");
      ncrystal_unref(&info);

      //numberdensity is the atomic number density in units of Aa^-3=1e30m^3, and
      //given that we have cross-sections in barn (1e-28m^2) and want to generate
      //distances in meters with -log(R)/(numberdensity*xsect), we get the unit
      //conversion factor of 0.01. We also apply the powder packing factor here (it
      //is guaranteed to be non-zero):
      
      // Union change: In NCrystal_sample density factor is negative for easier sampling,
      //  but as the sampling is performed in the master we use a positive sign for the
      //  density factor as this is more intuitive.
      params.density_factor = 0.01  / ( numberdensity * packingfactor );
      params.inv_density_factor = 1.0/params.density_factor;

  #else
      unsigned cell_sg,cell_atnum;
      double cell_a,cell_b,cell_c,cell_alpha,cell_beta,cell_gamma,cell_volume;
      if(!ncrystal_info_getstructure(info,&cell_sg,&cell_a,&cell_b,&cell_c,&cell_alpha,&cell_beta,&cell_gamma,&cell_volume,&cell_atnum))
        NCMCERR("Structure information is unavailable in the loaded NCrystal Info");
      ncrystal_unref(&info);

      //cell_atnum/cell_volume is the atomic number density in units of
      //Aa^-3=1e30m^3, and given that we have cross-sections in barn (1e-28m^2) and
      //want to generate distances in meters with -log(R)/(numberdensity*xsect), we
      //get the unit conversion factor of 0.01. We also apply the powder packing
      //factor here (it is guaranteed to be non-zero):
      
      // Union change: In NCrystal_sample density factor is negative for easier sampling,
      //  but as the sampling is performed in the master we use a positive sign for the
      //  density factor as this is more intuitive.
      params.density_factor = 0.01 * cell_volume / ( cell_atnum * packingfactor );
      params.inv_density_factor = 1.0/params.density_factor;
  #endif

  //TODO for NC2: The density used here is in principle different from the one
  //used in the Geant4 interface, which is possibly inconsistent when not using
  //.ncmat files (more info at https://github.com/mctools/ncrystal/issues/9).

  //Setup scattering:
  params.scat = ncrystal_create_scatter(cfg);
  params.proc_scat = ncrystal_cast_scat2proc(params.scat);
  params.proc_scat_isoriented = ! ncrystal_isnonoriented(params.proc_scat);
  // It may be possible to get whether or not the physics is isotropic or not from the above
  
  //Setup absorption:
  if (params.absmode) {
    params.proc_abs = ncrystal_cast_abs2proc(ncrystal_create_absorption(cfg));
    if (!ncrystal_isnonoriented(params.proc_abs))
      NCMCERR("Encountered oriented NCAbsorption process which is not currently supported by this component.");
  }
  
  NCrystal_storage.stored_params = params;
  NCrystal_storage.ncrystal_convfact_vsq2ekin = NCrystal_convfact_vsq2ekin;
  NCrystal_storage.ncrystal_convfact_ekin2vsq = NCrystal_convfact_ekin2vsq;
  
  // Need to specify if this process is isotropic
  //This_process.non_isotropic_rot_index = -1; // Yes (powder)
  This_process.non_isotropic_rot_index =  1;  // No (single crystal)
    
  // The type of the process must be saved in the global enum process
  This_process.eProcess = NCrystal;

  // Packing the data into a structure that is transported to the main component
  This_process.data_transfer.pointer_to_a_NCrystal_physics_storage_struct = &NCrystal_storage;
  This_process.probability_for_scattering_function = &NCrystal_physics_my;
  This_process.scattering_function = &NCrystal_physics_scattering;

  // This will be the same for all process's, and can thus be moved to an include.
  sprintf(This_process.name,"%s",NAME_CURRENT_COMP);
  This_process.process_p_interact = interact_fraction;
  rot_copy(This_process.rotation_matrix,ROT_A_CURRENT_COMP);
  sprintf(global_process_element.name,"%s",NAME_CURRENT_COMP);
  global_process_element.component_index = INDEX_CURRENT_COMP;
  global_process_element.p_scattering_process = &This_process;

if (_getcomp_index(init) < 0) {
fprintf(stderr,"NCrystal_process:%s: Error identifying Union_init component, %s is not a known component name.\n",
NAME_CURRENT_COMP, init);
exit(-1);
}

struct pointer_to_global_process_list *global_process_list = COMP_GETPAR3(Union_init, init, global_process_list);
  add_element_to_process_list(global_process_list, global_process_element);
 %}

TRACE
%{
    // Trace should be empty, the simulation is done in Union_master
%}

FINALLY
%{
  ncrystal_unref(&params.scat);
  ncrystal_invalidate(&params.proc_scat);//a cast of params.scat, so just invalidate handle don't unref
  if (params.absmode)
    ncrystal_unref(&params.proc_abs);
%}

END
