/*******************************************************************************
 * This file is part of SWIFT.
 * Copyright (c) 2016 Matthieu Schaller (schaller@strw.leidenuniv.nl)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 ******************************************************************************/
#ifndef SWIFT_BASIC_STARS_IO_H
#define SWIFT_BASIC_STARS_IO_H

#include "io_properties.h"
#include "kick.h"
#include "stars_part.h"

/**
 * @brief Specifies which s-particle fields to read from a dataset
 *
 * @param sparts The s-particle array.
 * @param list The list of i/o properties to read.
 * @param num_fields The number of i/o fields to read.
 */
INLINE static void stars_read_particles(struct spart *sparts,
                                        struct io_props *list,
                                        int *num_fields) {

  /* Say how much we want to read */
  *num_fields = 5;

  /* List what we want to read */
  list[0] = io_make_input_field("Coordinates", DOUBLE, 3, COMPULSORY,
                                UNIT_CONV_LENGTH, sparts, x);
  list[1] = io_make_input_field("Velocities", FLOAT, 3, COMPULSORY,
                                UNIT_CONV_SPEED, sparts, v);
  list[2] = io_make_input_field("Masses", FLOAT, 1, COMPULSORY, UNIT_CONV_MASS,
                                sparts, mass);
  list[3] = io_make_input_field("ParticleIDs", LONGLONG, 1, COMPULSORY,
                                UNIT_CONV_NO_UNITS, sparts, id);
  list[4] = io_make_input_field("SmoothingLength", FLOAT, 1, OPTIONAL,
                                UNIT_CONV_LENGTH, sparts, h);
}

INLINE static void convert_spart_pos(const struct engine *e,
                                     const struct spart *sp, double *ret) {

  const struct space *s = e->s;
  if (s->periodic) {
    ret[0] = box_wrap(sp->x[0], 0.0, s->dim[0]);
    ret[1] = box_wrap(sp->x[1], 0.0, s->dim[1]);
    ret[2] = box_wrap(sp->x[2], 0.0, s->dim[2]);
  } else {
    ret[0] = sp->x[0];
    ret[1] = sp->x[1];
    ret[2] = sp->x[2];
  }
  if (e->snapshot_use_delta_from_edge) {
    ret[0] = min(ret[0], s->dim[0] - e->snapshot_delta_from_edge);
    ret[1] = min(ret[1], s->dim[1] - e->snapshot_delta_from_edge);
    ret[2] = min(ret[2], s->dim[2] - e->snapshot_delta_from_edge);
  }
}

INLINE static void convert_spart_vel(const struct engine *e,
                                     const struct spart *sp, float *ret) {
  const int with_cosmology = (e->policy & engine_policy_cosmology);
  const struct cosmology *cosmo = e->cosmology;
  const integertime_t ti_current = e->ti_current;
  const double time_base = e->time_base;
  const float dt_kick_grav_mesh = e->dt_kick_grav_mesh_for_io;

  const integertime_t ti_beg = get_integer_time_begin(ti_current, sp->time_bin);
  const integertime_t ti_end = get_integer_time_end(ti_current, sp->time_bin);

  /* Get time-step since the last kick */
  const float dt_kick_grav =
      kick_get_grav_kick_dt(ti_beg, ti_current, time_base, with_cosmology,
                            cosmo) -
      kick_get_grav_kick_dt(ti_beg, (ti_beg + ti_end) / 2, time_base,
                            with_cosmology, cosmo);

  /* Extrapolate the velocites to the current time */
  const struct gpart *gp = sp->gpart;
  ret[0] = gp->v_full[0] + gp->a_grav[0] * dt_kick_grav;
  ret[1] = gp->v_full[1] + gp->a_grav[1] * dt_kick_grav;
  ret[2] = gp->v_full[2] + gp->a_grav[2] * dt_kick_grav;

  /* Extrapolate the velocites to the current time (mesh forces) */
  ret[0] += gp->a_grav_mesh[0] * dt_kick_grav_mesh;
  ret[1] += gp->a_grav_mesh[1] * dt_kick_grav_mesh;
  ret[2] += gp->a_grav_mesh[2] * dt_kick_grav_mesh;

  /* Conversion from internal units to peculiar velocities */
  ret[0] *= cosmo->a_inv;
  ret[1] *= cosmo->a_inv;
  ret[2] *= cosmo->a_inv;
}

INLINE static void convert_spart_potential(const struct engine *e,
                                           const struct spart *sp, float *ret) {

  if (sp->gpart != NULL)
    ret[0] = gravity_get_comoving_potential(sp->gpart);
  else
    ret[0] = 0.f;
}

/**
 * @brief Specifies which s-particle fields to write to a dataset
 *
 * @param sparts The s-particle array.
 * @param list The list of i/o properties to write.
 * @param num_fields The number of i/o fields to write.
 * @param with_cosmology Are we running a cosmological simulation?
 */
INLINE static void stars_write_particles(const struct spart *sparts,
                                         struct io_props *list, int *num_fields,
                                         int with_cosmology) {

  /* Say how much we want to write */
  *num_fields = 6;

  /* List what we want to write */
  list[0] = io_make_output_field_convert_spart(
      "Coordinates", DOUBLE, 3, UNIT_CONV_LENGTH, 1.f, sparts,
      convert_spart_pos, "Co-moving position of the particles");

  list[1] = io_make_output_field_convert_spart(
      "Velocities", FLOAT, 3, UNIT_CONV_SPEED, 0.f, sparts, convert_spart_vel,
      "Peculiar velocities of the particles. This is a * dx/dt where x is the "
      "co-moving position of the particles.");

  list[2] = io_make_output_field("Masses", FLOAT, 1, UNIT_CONV_MASS, 0.f,
                                 sparts, mass, "Masses of the particles");

  list[3] = io_make_physical_output_field(
      "ParticleIDs", ULONGLONG, 1, UNIT_CONV_NO_UNITS, 0.f, sparts, id,
      /*can convert to comoving=*/0, "Unique ID of the particles");

  list[4] = io_make_output_field(
      "SmoothingLengths", FLOAT, 1, UNIT_CONV_LENGTH, 1.f, sparts, h,
      "Co-moving smoothing lengths (FWHM of the kernel) of the particles");

  list[5] = io_make_output_field_convert_spart(
      "Potentials", FLOAT, 1, UNIT_CONV_POTENTIAL, -1.f, sparts,
      convert_spart_potential, "Gravitational potentials of the particles");

#ifdef DEBUG_INTERACTIONS_STARS

  list += *num_fields;
  *num_fields += 4;

  list[0] = io_make_output_field("Num_ngb_density", INT, 1, UNIT_CONV_NO_UNITS,
                                 sparts, num_ngb_density);
  list[1] = io_make_output_field("Num_ngb_force", INT, 1, UNIT_CONV_NO_UNITS,
                                 sparts, num_ngb_force);
  list[2] = io_make_output_field("Ids_ngb_density", LONGLONG,
                                 MAX_NUM_OF_NEIGHBOURS_STARS,
                                 UNIT_CONV_NO_UNITS, sparts, ids_ngbs_density);
  list[3] = io_make_output_field("Ids_ngb_force", LONGLONG,
                                 MAX_NUM_OF_NEIGHBOURS_STARS,
                                 UNIT_CONV_NO_UNITS, sparts, ids_ngbs_force);
#endif
}

/**
 * @brief Initialize the global properties of the stars scheme.
 *
 * By default, takes the values provided by the hydro.
 *
 * @param sp The #stars_props.
 * @param phys_const The physical constants in the internal unit system.
 * @param us The internal unit system.
 * @param params The parsed parameters.
 * @param p The already read-in properties of the hydro scheme.
 * @param cosmo The cosmological model.
 */
INLINE static void stars_props_init(struct stars_props *sp,
                                    const struct phys_const *phys_const,
                                    const struct unit_system *us,
                                    struct swift_params *params,
                                    const struct hydro_props *p,
                                    const struct cosmology *cosmo) {

  /* Kernel properties */
  sp->eta_neighbours = parser_get_opt_param_float(
      params, "Stars:resolution_eta", p->eta_neighbours);

  /* Tolerance for the smoothing length Newton-Raphson scheme */
  sp->h_tolerance =
      parser_get_opt_param_float(params, "Stars:h_tolerance", p->h_tolerance);

  /* Get derived properties */
  sp->target_neighbours = pow_dimension(sp->eta_neighbours) * kernel_norm;
  const float delta_eta = sp->eta_neighbours * (1.f + sp->h_tolerance);
  sp->delta_neighbours =
      (pow_dimension(delta_eta) - pow_dimension(sp->eta_neighbours)) *
      kernel_norm;

  /* Number of iterations to converge h */
  sp->max_smoothing_iterations = parser_get_opt_param_int(
      params, "Stars:max_ghost_iterations", p->max_smoothing_iterations);

  /* Time integration properties */
  const float max_volume_change =
      parser_get_opt_param_float(params, "Stars:max_volume_change", -1);
  if (max_volume_change == -1)
    sp->log_max_h_change = p->log_max_h_change;
  else
    sp->log_max_h_change = logf(powf(max_volume_change, hydro_dimension_inv));
}

/**
 * @brief Print the global properties of the stars scheme.
 *
 * @param sp The #stars_props.
 */
INLINE static void stars_props_print(const struct stars_props *sp) {

  /* Now stars */
  message("Stars kernel: %s with eta=%f (%.2f neighbours).", kernel_name,
          sp->eta_neighbours, sp->target_neighbours);

  message("Stars relative tolerance in h: %.5f (+/- %.4f neighbours).",
          sp->h_tolerance, sp->delta_neighbours);

  message(
      "Stars integration: Max change of volume: %.2f "
      "(max|dlog(h)/dt|=%f).",
      pow_dimension(expf(sp->log_max_h_change)), sp->log_max_h_change);

  message("Maximal iterations in ghost task set to %d",
          sp->max_smoothing_iterations);
}

#if defined(HAVE_HDF5)
INLINE static void stars_props_print_snapshot(hid_t h_grpstars,
                                              hid_t h_grp_columns,
                                              const struct stars_props *sp) {

  io_write_attribute_s(h_grpstars, "Kernel function", kernel_name);
  io_write_attribute_f(h_grpstars, "Kernel target N_ngb",
                       sp->target_neighbours);
  io_write_attribute_f(h_grpstars, "Kernel delta N_ngb", sp->delta_neighbours);
  io_write_attribute_f(h_grpstars, "Kernel eta", sp->eta_neighbours);
  io_write_attribute_f(h_grpstars, "Smoothing length tolerance",
                       sp->h_tolerance);
  io_write_attribute_f(h_grpstars, "Volume log(max(delta h))",
                       sp->log_max_h_change);
  io_write_attribute_f(h_grpstars, "Volume max change time-step",
                       pow_dimension(expf(sp->log_max_h_change)));
  io_write_attribute_i(h_grpstars, "Max ghost iterations",
                       sp->max_smoothing_iterations);
}
#endif

/**
 * @brief Free the memory allocated for the stellar properties.
 *
 * Nothing to do here.
 *
 * @param sp The #stars_props structure.
 */
INLINE static void stars_props_clean(struct stars_props *sp) {}

/**
 * @brief Write a #stars_props struct to the given FILE as a stream of bytes.
 *
 * @param p the struct
 * @param stream the file stream
 */
INLINE static void stars_props_struct_dump(const struct stars_props *p,
                                           FILE *stream) {
  restart_write_blocks((void *)p, sizeof(struct stars_props), 1, stream,
                       "starsprops", "stars props");
}

/**
 * @brief Restore a stars_props struct from the given FILE as a stream of
 * bytes.
 *
 * @param p the struct
 * @param stream the file stream
 */
INLINE static void stars_props_struct_restore(const struct stars_props *p,
                                              FILE *stream) {
  restart_read_blocks((void *)p, sizeof(struct stars_props), 1, stream, NULL,
                      "stars props");
}
#endif /* SWIFT_BASIC_STAR_IO_H */