/*******************************************************************************
*
* McStas, neutron ray-tracing package
*         Copyright (C) 1997-2008, All rights reserved
*         Risoe National Laboratory, Roskilde, Denmark
*         Institut Laue Langevin, Grenoble, France
*
* Component: SasView_lamellar_hg_stack_caille
*
* %Identification
* Written by: Jose Robledo
* Based on sasmodels from SasView
* Origin: FZJ / DTU / ESS DMSC
*
*
* SasView lamellar_hg_stack_caille model component as sample description.
*
* %Description
*
* SasView_lamellar_hg_stack_caille component, generated from lamellar_hg_stack_caille.c in sasmodels.
*
* Example: 
*  SasView_lamellar_hg_stack_caille(length_tail, length_head, Nlayers, d_spacing, Caille_parameter, sld, sld_head, sld_solvent, 
*     model_scale=1.0, model_abs=0.0, xwidth=0.01, yheight=0.01, zdepth=0.005, R=0, 
*     int target_index=1, target_x=0, target_y=0, target_z=1,
*     focus_xw=0.5, focus_yh=0.5, focus_aw=0, focus_ah=0, focus_r=0, 
*     pd_length_tail=0.0, pd_length_head=0.0)
*
* %Parameters
* INPUT PARAMETERS:
* length_tail: [Ang] ([0, inf]) Tail thickness.
* length_head: [Ang] ([0, inf]) head thickness.
* Nlayers: [] ([1, inf]) Number of layers.
* d_spacing: [Ang] ([0.0, inf]) lamellar d-spacing of Caille S(Q).
* Caille_parameter: [] ([0.0, 0.8]) Caille parameter.
* sld: [1e-6/Ang^2] ([-inf, inf]) Tail scattering length density.
* sld_head: [1e-6/Ang^2] ([-inf, inf]) Head scattering length density.
* sld_solvent: [1e-6/Ang^2] ([-inf, inf]) Solvent scattering length density.
* Optional parameters:
* model_abs: [ ] Absorption cross section density at 2200 m/s.
* model_scale: [ ] Global scale factor for scattering kernel. For systems without inter-particle interference, the form factors can be related to the scattering intensity by the particle volume fraction.
* xwidth: [m] ([-inf, inf]) Horiz. dimension of sample, as a width.
* yheight: [m] ([-inf, inf]) vert . dimension of sample, as a height for cylinder/box
* zdepth: [m] ([-inf, inf]) depth of sample
* R: [m] Outer radius of sample in (x,z) plane for cylinder/sphere.
* target_x: [m] relative focus target position.
* target_y: [m] relative focus target position.
* target_z: [m] relative focus target position.
* target_index: [ ] Relative index of component to focus at, e.g. next is +1.
* focus_xw: [m] horiz. dimension of a rectangular area.
* focus_yh: [m], vert. dimension of a rectangular area.
* focus_aw: [deg], horiz. angular dimension of a rectangular area.
* focus_ah: [deg], vert. angular dimension of a rectangular area.
* focus_r: [m] case of circular focusing, focusing radius.
* pd_length_tail: [] (0,inf) defined as (dx/x), where x is de mean value and dx the standard devition of the variable.
* pd_length_head: [] (0,inf) defined as (dx/x), where x is de mean value and dx the standard devition of the variable
*
* %Link
* %End
*******************************************************************************/
DEFINE COMPONENT SasView_lamellar_hg_stack_caille

SETTING PARAMETERS (
        length_tail=10,
        length_head=2,
        Nlayers=30,
        d_spacing=40.0,
        Caille_parameter=0.001,
        sld=0.4,
        sld_head=2.0,
        sld_solvent=6,
        model_scale=1.0,
        model_abs=0.0,
        xwidth=0.01,
        yheight=0.01,
        zdepth=0.005,
        R=0,
        target_x=0,
        target_y=0,
        target_z=1,
        int target_index=1,
        focus_xw=0.5,
        focus_yh=0.5,
        focus_aw=0,
        focus_ah=0,
        focus_r=0,
        pd_length_tail=0.0,
        pd_length_head=0.0)


SHARE %{
%include "sas_kernel_header.c"

/* BEGIN Required header for SASmodel lamellar_hg_stack_caille */
#define HAS_Iq

#ifndef SAS_HAVE_lamellar_hg_stack_caille
#define SAS_HAVE_lamellar_hg_stack_caille

#line 1 "lamellar_hg_stack_caille"
/*	LamellarCailleHG kernel - allows for name changes of passed parameters ...
    Maths identical to LamellarCaille apart from the line for P(Q)
*/

static double
Iq_lamellar_hg_stack_caille(double qval,
   double length_tail,
   double length_head,
   double fp_Nlayers,
   double dd,
   double Cp,
   double tail_sld,
   double head_sld,
   double solvent_sld)
{
  int Nlayers = (int)(fp_Nlayers+0.5);    //cast to an integer for the loop
  double inten,Pq,Sq,alpha,temp,t2;
  //double dQ, dQDefault, t1, t3;
  // from wikipedia 0.577215664901532860606512090082402431042159335
  const double Euler = 0.577215664901533;   // Euler's constant, increased sig figs for new models Feb 2015
  //dQDefault = 0.0;    //[=] 1/A, q-resolution, default value
  //dQ = dQDefault; // REMOVED UNUSED dQ calculations for new models Feb 2015

  Pq = (head_sld-solvent_sld)*(sin(qval*(length_head+length_tail))-sin(qval*length_tail))
       + (tail_sld-solvent_sld)*sin(qval*length_tail);
  Pq *= Pq;
  Pq *= 4.0/(qval*qval);

  Sq = 0.0;
  for(int ii=1; ii < Nlayers; ii++) {
    temp = 0.0;
    alpha = Cp/4.0/M_PI/M_PI*(log(M_PI*ii) + Euler);
    //t1 = 2.0*dQ*dQ*dd*dd*alpha;
    t2 = 2.0*qval*qval*dd*dd*alpha;
    //t3 = dQ*dQ*dd*dd*ii*ii;

    temp = 1.0-(double)ii/(double)Nlayers;
    //temp *= cos(dd*qval*ii/(1.0+t1));
    temp *= cos(dd*qval*ii);
    //if (temp < 0) printf("q=%g: ii=%d, cos(dd*q*ii)=cos(%g) < 0\n",qval,ii,dd*qval*ii);
    //temp *= exp(-1.0*(t2 + t3)/(2.0*(1.0+t1)) );
    temp *= exp(-t2/2.0);
    //temp /= sqrt(1.0+t1);

    Sq += temp;
  }

  Sq *= 2.0;
  Sq += 1.0;

  //if (Sq < 0) printf("q=%g: S(q) =%g\n", qval, Sq);

  inten = 2.0*M_PI*Pq*Sq/(dd*qval*qval);

  inten *= 1.0e-04;   // 1/A to 1/cm
  return inten;
}


#endif // SAS_HAVE_lamellar_hg_stack_caille



/* END Required header for SASmodel lamellar_hg_stack_caille */
%}
    DECLARE
%{
  double shape;
  double my_a_v;
%}

INITIALIZE
%{
shape=-1;  /* -1:no shape, 0:cyl, 1:box, 2:sphere  */
if (xwidth && yheight && zdepth)
    shape=1;
  else if (R > 0 && yheight)
    shape=0;
  else if (R > 0 && !yheight)
    shape=2;
  if (shape < 0)
    exit(fprintf(stderr, "SasView_model: %s: sample has invalid dimensions.\n"
                         "ERROR     Please check parameter values.\n", NAME_CURRENT_COMP));

  /* now compute target coords if a component index is supplied */
  if (!target_index && !target_x && !target_y && !target_z) target_index=1;
  if (target_index)
  {
    Coords ToTarget;
    ToTarget = coords_sub(POS_A_COMP_INDEX(INDEX_CURRENT_COMP+target_index),POS_A_CURRENT_COMP);
    ToTarget = rot_apply(ROT_A_CURRENT_COMP, ToTarget);
    coords_get(ToTarget, &target_x, &target_y, &target_z);
  }

  if (!(target_x || target_y || target_z)) {
    printf("SasView_model: %s: The target is not defined. Using direct beam (Z-axis).\n",
      NAME_CURRENT_COMP);
    target_z=1;
  }

  my_a_v = model_abs*2200*100; /* Is not yet divided by v. 100: Convert barns -> fm^2 */

%}


TRACE
%{
  double t0, t1, v, l_full, l, l_1, dt, d_phi, my_s;
  double aim_x=0, aim_y=0, aim_z=1, axis_x, axis_y, axis_z;
  double arg, tmp_vx, tmp_vy, tmp_vz, vout_x, vout_y, vout_z;
  double f, solid_angle, vx_i, vy_i, vz_i, q, qx, qy, qz;
  char intersect=0;

  /* Intersection neutron trajectory / sample (sample surface) */
  if (shape == 0){
    intersect = cylinder_intersect(&t0, &t1, x, y, z, vx, vy, vz, R, yheight);}
  else if (shape == 1){
    intersect = box_intersect(&t0, &t1, x, y, z, vx, vy, vz, xwidth, yheight, zdepth);}
  else if (shape == 2){
    intersect = sphere_intersect(&t0, &t1, x, y, z, vx, vy, vz, R);}
  if(intersect)
  {
    if(t0 < 0)
      ABSORB;

    /* Neutron enters at t=t0. */
    v = sqrt(vx*vx + vy*vy + vz*vz);
    l_full = v * (t1 - t0);          /* Length of full path through sample */
    dt = rand01()*(t1 - t0) + t0;    /* Time of scattering */
    PROP_DT(dt);                     /* Point of scattering */
    l = v*(dt-t0);                   /* Penetration in sample */

    vx_i=vx;
    vy_i=vy;
    vz_i=vz;
    if ((target_x || target_y || target_z)) {
      aim_x = target_x-x;            /* Vector pointing at target (anal./det.) */
      aim_y = target_y-y;
      aim_z = target_z-z;
    }
    if(focus_aw && focus_ah) {
      randvec_target_rect_angular(&vx, &vy, &vz, &solid_angle,
        aim_x, aim_y, aim_z, focus_aw, focus_ah, ROT_A_CURRENT_COMP);
    } else if(focus_xw && focus_yh) {
      randvec_target_rect(&vx, &vy, &vz, &solid_angle,
        aim_x, aim_y, aim_z, focus_xw, focus_yh, ROT_A_CURRENT_COMP);
    } else {
      randvec_target_circle(&vx, &vy, &vz, &solid_angle, aim_x, aim_y, aim_z, focus_r);
    }
    NORM(vx, vy, vz);
    vx *= v;
    vy *= v;
    vz *= v;
    qx = V2K*(vx_i-vx);
    qy = V2K*(vy_i-vy);
    qz = V2K*(vz_i-vz);
    q = sqrt(qx*qx+qy*qy+qz*qz);
    
    double trace_length_tail=length_tail;
    double trace_length_head=length_head;
    if ( pd_length_tail!=0.0 || pd_length_head!=0.0 ){
    trace_length_tail = (randnorm()*pd_length_tail+1.0)*length_tail;
    trace_length_head = (randnorm()*pd_length_head+1.0)*length_head;
    }

        


    // Sample dependent. Retrieved from SasView./////////////////////
    float Iq_out;
    Iq_out = 1;

    Iq_out = Iq_lamellar_hg_stack_caille(q, trace_length_tail, trace_length_head, Nlayers, d_spacing, Caille_parameter, sld, sld_head, sld_solvent);


    float vol;
    vol = 1;

    // Scale by 1.0E2 [SasView: 1/cm  ->   McStas: 1/m]
    Iq_out = model_scale*Iq_out / vol * 1.0E2;

    l_1 = v*t1;
    p *= l_full*solid_angle/(4*PI)*Iq_out*exp(-my_a_v*(l+l_1)/v);
    SCATTER;
  }
%}

MCDISPLAY
%{

  if (shape == 0) {	/* cylinder */
    circle("xz", 0,  yheight/2.0, 0, R);
    circle("xz", 0, -yheight/2.0, 0, R);
    line(-R, -yheight/2.0, 0, -R, +yheight/2.0, 0);
    line(+R, -yheight/2.0, 0, +R, +yheight/2.0, 0);
    line(0, -yheight/2.0, -R, 0, +yheight/2.0, -R);
    line(0, -yheight/2.0, +R, 0, +yheight/2.0, +R);
  }
  else if (shape == 1) { 	/* box */
    double xmin = -0.5*xwidth;
    double xmax =  0.5*xwidth;
    double ymin = -0.5*yheight;
    double ymax =  0.5*yheight;
    double zmin = -0.5*zdepth;
    double zmax =  0.5*zdepth;
    multiline(5, xmin, ymin, zmin,
                 xmax, ymin, zmin,
                 xmax, ymax, zmin,
                 xmin, ymax, zmin,
                 xmin, ymin, zmin);
    multiline(5, xmin, ymin, zmax,
                 xmax, ymin, zmax,
                 xmax, ymax, zmax,
                 xmin, ymax, zmax,
                 xmin, ymin, zmax);
    line(xmin, ymin, zmin, xmin, ymin, zmax);
    line(xmax, ymin, zmin, xmax, ymin, zmax);
    line(xmin, ymax, zmin, xmin, ymax, zmax);
    line(xmax, ymax, zmin, xmax, ymax, zmax);
  }
  else if (shape == 2) {	/* sphere */
    circle("xy", 0,  0.0, 0, R);
    circle("xz", 0,  0.0, 0, R);
    circle("yz", 0,  0.0, 0, R);
  }
%}
END