/*******************************************************************************
*
* McStas, neutron ray-tracing package
*         Copyright (C) 1997-2007, All rights reserved
*         Risoe National Laboratory, Roskilde, Denmark
*         Institut Laue Langevin, Grenoble, France
*
* Component: Monochromator_curved
*
* %I
*
* Written by: Emmanuel Farhi, Kim, Lefmann, Peter Link
* Date: Aug. 24th 2001
* Origin: <a href="http://www.ill.fr">ILL</a>
* Modified by: EF, Aug. 24th 2001: From Mosaic_anisotropic and Mon_2foc
* Modified by: EF, Feb 13th 2002:  Read reflectivity table
* Modified by: EF, Oct 24th 2002:  Read transmission table
*
* Double bent multiple crystal slabs with anisotropic gaussian mosaic.
*
* %Description
* Double bent infinitely thin mosaic crystal, useful as a monochromator or
* analyzer. which uses a small-mosaicity approximation and taking into account
* higher  order scattering. The mosaic is anisotropic gaussian, with different
* FWHMs in the Y and Z directions. The scattering vector is perpendicular to the
* surface. For an unrotated monochromator component, the crystal plane lies in
* the y-z plane (ie. parallel to the beam). The component works in reflection, but
* also transmits the non-diffracted beam. Reflectivity and transmission files may
* be used. The slabs are positioned in the vertical plane (not on a
* cylinder/sphere), and are rotated according to the curvature radius.
* When curvatures are set to 0, the monochromator is flat.
* The curvatures approximation for parallel beam focusing to distance L, with
* monochromator rotation angle A1 are:
*   RV = 2*L*sin(DEG2RAD*A1);
*   RH = 2*L/sin(DEG2RAD*A1);
*
* When you rotate the component by A1 = asin(Q/2/Ki)*RAD2DEG, do not forget to
* rotate the following components by A2=2*A1 (for 1st order) !
*
* Example: Monochromator_curved(zwidth=0.01, yheight=0.01, gap=0.0005, NH=11, NV=11, mosaich=30.0, mosaicv=30.0, r0=0.7, Q=1.8734)
*
* Monochromator lattice parameter
* PG       002 DM=3.355 AA (Highly Oriented Pyrolythic Graphite)
* PG       004 DM=1.677 AA
* Heusler  111 DM=3.362 AA (Cu2MnAl)
* CoFe         DM=1.771 AA (Co0.92Fe0.08)
* Ge       111 DM=3.266 AA
* Ge       311 DM=1.714 AA
* Ge       511 DM=1.089 AA
* Ge       533 DM=0.863 AA
* Si       111 DM=3.135 AA
* Cu       111 DM=2.087 AA
* Cu       002 DM=1.807 AA
* Cu       220 DM=1.278 AA
* Cu       111 DM=2.095 AA
*
* %Parameters
* INPUT PARAMETERS:
*
* zwidth: [m]             horizontal width of an individual slab 
* yheight: [m]            vertical height of an individual slab 
* gap: [m]                typical gap  between adjacent slabs 
* NH: [int]               number of slabs horizontal 
* NV: [int]               number of slabs vertical 
* mosaich: [arc minutes]  Horisontal mosaic FWHM 
* mosaicv: [arc minutes]  Vertical mosaic FWHM 
* r0: [1]                 Maximum reflectivity. O unactivates component 
* Q: [AA-1]               Scattering vector 
* RV: [m]                 radius of vertical focussing. flat for 0 
* RH: [m]                 radius of horizontal focussing. flat for 0 
*
* optional parameters
* DM: [AA]                monochromator d-spacing instead of Q=2*pi/DM 
* mosaic: [arc minutes]   sets mosaich=mosaicv 
* width: [m]              total width of monochromator, along Z 
* height: [m]             total height of monochromator, along Y 
* verbose: [0/1]          verbosity level 
* reflect: [str]          reflectivity file name of text file as 2 columns [k, R] 
* transmit: [str]         transmission file name of text file as 2 columns [k, T] 
* t0: [1]                 transmission efficiency 
* order: [1]              specify the diffraction order, 1 is usually prefered. Use 0 for all 
*
* %Link
* <a href="http://mcstas.risoe.dk/pipermail/neutron-mc/1999q1/000133.html">Additional note</a> from Peter Link.
* %L
* Obsolete Mosaic_anisotropic by Kristian Nielsen
* %L
* Contributed Monochromator_2foc by Peter Link
*
* %End
*******************************************************************************/

DEFINE COMPONENT Monochromator_curved

SETTING PARAMETERS (string reflect="NULL", string transmit="NULL",
zwidth=0.01, yheight=0.01,gap=0.0005,int NH=11, int NV=11, mosaich=30.0, mosaicv=30.0, r0=0.7, t0=1.0,Q=1.8734,
RV=0, RH=0, DM=0, mosaic=0, width=0, height=0, verbose=0, order=0)

/* Neutron parameters: (x,y,z,vx,vy,vz,t,sx,sy,sz,p) */


SHARE
%{
#pragma acc routine
double GAUSS_monocurved(double x, double mean, double rms){
  return (exp(-((x)-(mean))*((x)-(mean))/(2*(rms)*(rms)))/(sqrt(2*PI)*(rms)));
}

%include "read_table-lib"
%}

USERVARS %{
  int ncol;
  int nrow;
%}

DECLARE
%{
  double mos_rms_y; /* root-mean-square of mosaic, in radians */
  double mos_rms_z;
  double mos_rms_max;
  double mono_Q;
  double SlabWidth;
  double SlabHeight;
  t_Table rTable;
  t_Table tTable;
  int rTableFlag;
  int tTableFlag;
  double *tiltH;
  double *tiltV;
  char ncol_var[128];
  char nrow_var[128];
%}

INITIALIZE
%{
  int i;

  if (mosaic != 0) {
    mos_rms_y = MIN2RAD*mosaic/sqrt(8*log(2));
    mos_rms_z = mos_rms_y; }
  else {
    mos_rms_y = MIN2RAD*mosaich/sqrt(8*log(2));
    mos_rms_z = MIN2RAD*mosaicv/sqrt(8*log(2)); }
  mos_rms_max = mos_rms_y > mos_rms_z ? mos_rms_y : mos_rms_z;

  mono_Q = Q;
  if (DM != 0) mono_Q = 2*PI/DM;

  if (mono_Q <= 0) { fprintf(stderr,"Monochromator_curved: %s: Error scattering vector Q = 0\n", NAME_CURRENT_COMP); exit(-1); }
  if (r0 <  0) { fprintf(stderr,"Monochromator_curved: %s: Error reflectivity r0 is negative\n", NAME_CURRENT_COMP); exit(-1); }
  if (r0 == 0) { fprintf(stderr,"Monochromator_curved: %s: Reflectivity r0 is null. Ignoring component.\n", NAME_CURRENT_COMP); }
  if (NH*NV == 0) { fprintf(stderr,"Monochromator_curved: %s: no slabs ??? (NH or NV=0)\n", NAME_CURRENT_COMP); exit(-1); }


  if (verbose && r0)
  {
    printf("Monochromator_curved: component %s Q=%.3g Angs-1 (DM=%.4g Angs)\n", NAME_CURRENT_COMP, mono_Q, 2*PI/mono_Q);
    if (NH*NV == 1) printf("            flat.\n");
    else
    { if (NH > 1)
      { printf("            horizontal: %i blades", (int)NH);
        if (RH != 0) printf(" focusing with RH=%.3g [m]", RH);
        printf("\n");
      }
      if (NV > 1)
      { printf("            vertical:   %i blades", (int)NV);
        if (RV != 0) printf(" focusing with RV=%.3g [m]", RV);
        printf("\n");
      }
    }
  }

  if (reflect != NULL && r0 && strlen(reflect) && strcmp(reflect,"NULL") && strcmp(reflect,"0"))
  {
    if (verbose) fprintf(stdout, "Monochromator_curved: %s: Reflectivity data (k, R) from %s\n", NAME_CURRENT_COMP, reflect);
    Table_Read(&rTable, reflect, 1); /* read 1st block data from file into rTable */
    Table_Rebin(&rTable);         /* rebin as evenly, increasing array */
    if (rTable.rows < 2) Table_Free(&rTable);
    if (verbose) Table_Info(rTable);
    rTableFlag = 1;
  } else {
    rTableFlag = 0;
  }
  if (transmit != NULL && strlen(transmit) && strcmp(transmit,"NULL") && strcmp(transmit,"0"))
  {
    if (verbose) fprintf(stdout, "Monochromator_curved: %s: Transmission data (k, T) from %s\n", NAME_CURRENT_COMP, transmit);
    Table_Read(&tTable, transmit, 1); /* read 1st block data from file into rTable */
    Table_Rebin(&tTable);         /* rebin as evenly, increasing array */
    if (tTable.rows < 2) Table_Free(&tTable);
    if (verbose) Table_Info(tTable);
    tTableFlag = 1;
  } else {
    tTableFlag = 0;
  }

  if (width == 0) SlabWidth = zwidth;
  else SlabWidth = (width+gap)/NH - gap;
  if (height == 0) SlabHeight = yheight;
  else SlabHeight = (height+gap)/NV - gap;

  tiltH=calloc((int)2*(NH+1),sizeof(double));
  tiltV=calloc((int)2*(NV+1),sizeof(double));

  if (!tiltH) printf("Monochromator_curved: %s: Warning: not enough memory to allocate tilts (NH=%i).\n", NAME_CURRENT_COMP, NH);
  else if (RH) { /* pre-compute tilts */
    for (i=0;i<=NH;i++){
      tiltH[i]=asin((i-(NH+1)/2.0)*(SlabWidth+gap)/RH);
    }
  }
  if (!tiltV) printf("Monochromator_curved: %s: Warning: not enough memory to allocate tilts (NV=%i).\n", NAME_CURRENT_COMP, NV);
  else if (RV) {
    for (i=0;i<=NV;i++){
      tiltV[i]=-asin((i-(NV+1)/2.0)*(SlabHeight+gap)/RV);
    }
  }
  sprintf(ncol_var,"ncol_%ld",_comp->_index);
  sprintf(nrow_var,"nrow_%ld",_comp->_index);

%}

TRACE
%{
  double dt;
  double Gauss_X[] = {-0.987992518020485, -0.937273392400706, -0.848206583410427,
    -0.724417731360170, -0.570972172608539, -0.394151347077563,
    -0.201194093997435, 0, 0.201194093997435,
    0.394151347077563, 0.570972172608539, 0.724417731360170,
    0.848206583410427, 0.937273392400706, 0.987992518020485};
  double Gauss_W[] = {0.030753241996117, 0.070366047488108, 0.107159220467172,
    0.139570677926154, 0.166269205816994, 0.186161000115562,
    0.198431485327111, 0.202578241925561, 0.198431485327111,
    0.186161000115562, 0.166269205816994, 0.139570677926154,
    0.107159220467172, 0.070366047488108, 0.030753241996117};

  if(vx != 0.0 && (dt = -x/vx) >= 0.0 && r0)
  {                             /* Moving towards crystal? */
    double zmin,zmax, ymin,ymax;
    double yy,zz;

    zmax = ((NH*(SlabWidth+gap))-gap)/2;
    zmin = -zmax;
    ymax = ((NV*(SlabHeight+gap))-gap)/2;
    ymin = -ymax;

    /* Test-propagate to crystal plane */
    zz=z+vz*dt;
    yy=y+vy*dt;
    if (zz>zmin && zz<zmax && yy>ymin && yy<ymax) { /* Intersect the crystal? */
      double tilth,tiltv;         /* used to calculate tilt angle of slab */
      double ratio, Q_order, k, kux,kuy,kuz;
      double kix,kiy,kiz;
      int    do_transmit = 0;
      int row, col;

      col = ceil ( (zz-zmin)/(SlabWidth +gap));  /* which slab hit ? */
      row = ceil ( (yy-ymin)/(SlabHeight+gap));

      particle_setvar_void(_particle, ncol_var, &col);
      particle_setvar_void(_particle, nrow_var, &row);
      
      if (RH != 0) {
	tilth = tiltH ? tiltH[(int)col] :  asin((col-(NH+1)/2.0)*(SlabWidth+gap)/RH);
      } else {
	tilth=0;
      }
      if (RV != 0) {
	tiltv = tiltV ? tiltV[(int)row] : -asin((row-(NV+1)/2.0)*(SlabHeight+gap)/RV);
      } else {
	tiltv=0;
      }

      /* rotate with tilth (around Y) and tiltv (around Z), center on plate */
      double center_z=zmin+(col-0.5)*(SlabWidth+gap) -gap/2;
      double center_y=ymin+(row-0.5)*(SlabHeight+gap)-gap/2;

      Rotation T;
      rot_set_rotation(T, 0, tilth,    tiltv);
      /* now make the coordinate system change */
      mccoordschange_polarisation(T, &vx, &vy, &vz);
      y= y-center_y;
      z= z-center_z;
      coords_get(rot_apply(T,coords_set(x,y,z)),&x,&y,&z);

      /* this is where polarisation should be handled, plus further down */
      /* mccoordschange_polarisation(t, &sx, &sy, &sz); */

      /* now propagate to slab plane */
      PROP_X0;

      /* Hit a slab or a gap ?*/
      int inside=inside_rectangle(z,y,SlabWidth,SlabHeight);
      if (inside){ /* not in gap ? */
        kix = V2K*vx;             /* Initial wave vector */
        kiy = V2K*vy;
        kiz = V2K*vz;
        /* Get reflection order and corresponding nominal scattering vector q0
          of correct length and direction. Only the order with the closest
          scattering vector is considered */
        ratio = -2*kix/mono_Q;
        Q_order = floor(ratio + .5);
        if(Q_order == 0.0) Q_order = ratio < 0 ? -1 : 1;
        /* Order will be negative when the neutron enters from the back, in
          which case the direction of Q0 is flipped. */
        if(Q_order < 0) Q_order = -Q_order;
        /* Make sure the order is small enough to allow Bragg scattering at the
          given neutron wavelength */
        k = sqrt(kix*kix + kiy*kiy + kiz*kiz);
        kux = kix/k;              /* Unit vector along ki */
        kuy = kiy/k;
        kuz = kiz/k;
        if(Q_order > 2*k/mono_Q) Q_order--;
        if((!order && Q_order > 0) || (Q_order == fabs(order) && order)) {           /* Bragg scattering possible? */
          double q0, q0x, theta, delta, p_reflect, my_r0;

          q0 = Q_order*mono_Q;
          q0x = ratio < 0 ? -q0 : q0;
          theta = asin(q0/(2*k)); /* Actual bragg angle */
          /* Make MC choice: reflect or transmit? */
          delta = asin(fabs(kux)) - theta;

          if (rTableFlag)
          {
            my_r0 = r0*Table_Value(rTable, k, 1); /* 2nd column */ 
          }
          else my_r0 = r0;
          if (my_r0 > 1)
          {
            if (my_r0 > 1.01 && verbose) 
              fprintf(stdout, "Warning: Monochromator_curved : lowered reflectivity from %f to 1 (k=%f)\n", my_r0, k);
            my_r0=0.999;
          }
          if (my_r0 < 0)
          {
            if (verbose) 
              fprintf(stdout, "Warning: Monochromator_curved : raised reflectivity from %f to 0 (k=%f)\n", my_r0, k);
            my_r0=0;
          }

          p_reflect = fabs(my_r0)*exp(-kiz*kiz/(kiy*kiy + kiz*kiz)*(delta*delta)/
                            (2*mos_rms_y*mos_rms_y))*
                        exp(-kiy*kiy/(kiy*kiy + kiz*kiz)*(delta*delta)/
                            (2*mos_rms_z*mos_rms_z));

          double rr=rand01();
          if(rr <= p_reflect) { /* Reflect */
            double bx,by,bz,ax,ay,az,phi;
            double cos_2theta,k_sin_2theta,cos_phi,sin_phi,q_x,q_y,q_z;
            double total,c1x,c1y,c1z,w,mos_sample;
            int i=0;

            cos_2theta   = cos(2*theta);
            k_sin_2theta = k*sin(2*theta);
            /* Get unit normal to plane containing ki and most probable kf */
            vec_prod(bx, by, bz, kix, kiy, kiz, q0x, 0, 0);
            NORM(bx,by,bz);
            bx = bx * k_sin_2theta;
            by = by * k_sin_2theta;
            bz = bz * k_sin_2theta;
            /* Get unit vector normal to ki and b */
            vec_prod(ax, ay, az, bx, by, bz, kux, kuy, kuz);
            /* Compute the total scattering probability at this ki */
            total = 0;
            /* Choose width of Gaussian distribution to sample the angle
            * phi on the Debye-Scherrer cone for the scattered neutron.
            * The radius of the Debye-Scherrer cone is smaller by a
            * factor 1/cos(theta) than the radius of the (partial) sphere
            * describing the possible orientations of Q due to mosaicity, so we
            * start with a width 1/cos(theta) greater than the largest of
            * the two mosaics. */
            mos_sample = mos_rms_max/cos(theta);
            c1x = kix*(cos_2theta-1);
            c1y = kiy*(cos_2theta-1);
            c1z = kiz*(cos_2theta-1);
            /* Loop, repeatedly reducing the sample width until it is small
            * enough to avoid sampling scattering directions with
            * ridiculously low scattering probability.
            * Use a cut-off at 5 times the gauss width for considering
            * scattering probability as well as for integration limits
            * when integrating the sampled distribution below. */
            for(i=0; i<100; i++) {
              w = 5*mos_sample;
              cos_phi = cos(w);
              sin_phi = sin(w);
              q_x =  c1x + cos_phi*ax + sin_phi*bx;
              q_y = (c1y + cos_phi*ay + sin_phi*by)/mos_rms_z;
              q_z = (c1z + cos_phi*az + sin_phi*bz)/mos_rms_y;
              /* Stop when we get near a factor of 25=5^2. */
              if(q_z*q_z + q_y*q_y < (25/(2.0/3.0))*(q_x*q_x))
                break;
              mos_sample *= (2.0/3.0);
            }
            /* Now integrate the chosen sampling distribution, using a
            * cut-off at five times sigma. */
            for(i = 0; i < (sizeof(Gauss_X)/sizeof(double)); i++)
            {
              phi = w*Gauss_X[i];
              cos_phi = cos(phi);
              sin_phi = sin(phi);
              q_x = c1x + cos_phi*ax + sin_phi*bx;
              q_y = c1y + cos_phi*ay + sin_phi*by;
              q_z = c1z + cos_phi*az + sin_phi*bz;
              p_reflect = GAUSS_monocurved((q_z/q_x),0,mos_rms_y)*
                          GAUSS_monocurved((q_y/q_x),0,mos_rms_z);
              total += Gauss_W[i]*p_reflect;
            }
            total *= w;
            /* Choose point on Debye-Scherrer cone. Sample from a Gaussian of
             * width 1/cos(theta) greater than the mosaic and correct for any
             * error by adjusting the neutron weight later. */
            phi = mos_sample*randnorm();
            /* Compute final wave vector kf and scattering vector q = ki - kf */
            cos_phi = cos(phi);
            sin_phi = sin(phi);
            q_x = c1x + cos_phi*ax + sin_phi*bx;
            q_y = c1y + cos_phi*ay + sin_phi*by;
            q_z = c1z + cos_phi*az + sin_phi*bz;
            p_reflect = GAUSS_monocurved((q_z/q_x),0,mos_rms_y)*
                        GAUSS_monocurved((q_y/q_x),0,mos_rms_z);

            vx = K2V*(kix+q_x);
            vy = K2V*(kiy+q_y);
            vz = K2V*(kiz+q_z);
            p_reflect /= total*GAUSS_monocurved(phi,0,mos_sample);
            if (p_reflect <= 0) ABSORB;
            if (p_reflect > 1)  p_reflect = 1;
            p = p * p_reflect;

          } /* End MC choice to reflect or transmit neutron (if tmp<p_reflect) */
          else{
            do_transmit = 1;
          }
            /* else transmit neutron */
        } /* End bragg scattering possible (if order) */
        else {
          do_transmit=1;
        }
        if (do_transmit)
        {
          double my_t0;
          if (tTableFlag != 0)
          {
            my_t0 = t0*Table_Value(tTable, k, 1); /* 2nd column */ 
          }
          else my_t0 = t0;
          /* do not SCATTER, else GROUP does not work */
          if (my_t0 > 1)
          {
            if (my_t0 > 1.01 && verbose) 
              fprintf(stdout, "Warning: Monochromator_curved : lowered transmission from %f to 1 (k=%f)\n", my_t0, k);
            my_t0=0.999;
          }
          if (my_t0 > 0) p = p * my_t0;
          else ABSORB;
        }
      } /* end if not in gap */
      /* rotate back in component frame */
      Rotation TT;
      rot_transpose(T, TT);
      /* now make the coordinate system change */
      mccoordschange_polarisation(TT, &vx, &vy, &vz);
      coords_get(rot_apply(TT,coords_set(x,y,z)),&x,&y,&z);
      y= y+center_y;
      z= z+center_z;
      /* Visualise scattering point in proper, component frame 
	 - but only if the neutron is reflected, that is none of:
	 * transmitted
	 * falling outside the slab material */	
      if(!do_transmit) SCATTER;

      /* mccoordschange_polarisation(tt, &sx, &sy, &sz); */
    } /* End intersect the crystal (if z) */
    else {
      /* restore neutron state when no interaction */
      RESTORE_NEUTRON(INDEX_CURRENT_COMP, x, y, z, vx, vy, vz, t, sx, sy, sz, p);
    }
  } /* End neutron moving towards crystal (if vx)*/
%}

FINALLY
%{
  if(rTableFlag){
    Table_Free(&rTable);
  }
  if(tTableFlag){
    Table_Free(&tTable);
  }
  if (tiltH) free(tiltH);
  if (tiltV) free(tiltV);
%}

MCDISPLAY
%{
  int ih;

  for(ih = 0; ih < NH; ih++)
  {
    int iv;
    for(iv = 0; iv < NV; iv++)
    {
      double zmin,zmax,ymin,ymax;
      double xt, yt;

      zmin = (SlabWidth+gap)*(ih-NH/2.0)+gap/2;
      zmax = zmin+SlabWidth;
      ymin = (SlabHeight+gap)*(iv-NV/2.0)+gap/2;
      ymax = ymin+SlabHeight;

      if (RH) xt = -(zmax*zmax - zmin*zmin)/RH/2;
      else    xt = 0;

      if (RV) yt = -(ymax*ymax - ymin*ymin)/RV/2;
      else    yt = 0;
      multiline(5, xt+yt, (double)ymin, (double)zmin,
                   xt-yt, (double)ymax, (double)zmin,
                  -xt-yt, (double)ymax, (double)zmax,
                  -xt+yt, (double)ymin, (double)zmax,
                   xt+yt, (double)ymin, (double)zmin);
     }
   }
%}

END
