/*******************************************************************************
 * This file is part of SWIFT.
 * Copyright (c) 2016 Matthieu Schaller (matthieu.schaller@durham.ac.uk)
 *
 * 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_COOLING_GRACKLE_H
#define SWIFT_COOLING_GRACKLE_H

/**
 * @file src/cooling/none/cooling.h
 * @brief Empty infrastructure for the cases without cooling function
 */

/* Some standard headers. */
#include <float.h>
#include <math.h>

/* Local includes. */
#include "error.h"
#include "hydro.h"
#include "parser.h"
#include "part.h"
#include "physical_constants.h"
#include "units.h"

/* include the grackle wrapper */
#include "grackle_wrapper.h"

/**
 * @brief Compute the cooling rate
 *
 * We do nothing.
 *
 * @param phys_const The physical constants in internal units.
 * @param us The internal system of units.
 * @param cooling The #cooling_function_data used in the run.
 * @param p Pointer to the particle data.
 * @param dt The time-step of this particle.
 *
 * @return du / dt
 */
__attribute__((always_inline)) INLINE static double cooling_rate(
    const struct phys_const* restrict phys_const,
    const struct unit_system* restrict us,
    const struct cooling_function_data* restrict cooling,
    struct part* restrict p, float dt) {

  if (cooling->GrackleRedshift == -1) error("TODO time dependant redshift");

  /* Get current internal energy (dt=0) */
  double u_old = hydro_get_internal_energy(p);
  double u_new = u_old;
  /* Get current density */
  const float rho = hydro_get_density(p);
  /* Actual scaling fractor */
  const float a_now = 1. / (1. + cooling->GrackleRedshift);

  /* 0.02041 (= 1 Zsun in Grackle v2.0, but = 1.5761 Zsun in
     Grackle v2.1) */
  double Z = 0.02041;

  if (wrap_do_cooling(rho, &u_new, dt, Z, a_now) == 0) {
    error("Error in do_cooling.\n");
    return 0;
  }

  return (u_new - u_old) / dt;
}

/**
 * @brief Apply the cooling function to a particle.
 *
 * We do nothing.
 *
 * @param phys_const The physical constants in internal units.
 * @param us The internal system of units.
 * @param cooling The #cooling_function_data used in the run.
 * @param p Pointer to the particle data.
 * @param dt The time-step of this particle.
 */
__attribute__((always_inline)) INLINE static void cooling_cool_part(
    const struct phys_const* restrict phys_const,
    const struct unit_system* restrict us,
    const struct cooling_function_data* restrict cooling,
    struct part* restrict p, struct xpart* restrict xp, float dt) {

  if (dt == 0.) return;

  /* Current du_dt */
  const float hydro_du_dt = hydro_get_internal_energy_dt(p);

  float du_dt;
  float delta_u;

  du_dt = cooling_rate(phys_const, us, cooling, p, dt);

  delta_u = du_dt * dt;

  /* record energy lost */
  xp->cooling_data.radiated_energy += -delta_u * hydro_get_mass(p);

  /* Update the internal energy */
  hydro_set_internal_energy_dt(p, hydro_du_dt + du_dt);
}

/**
 * @brief Computes the cooling time-step.
 *
 * We return FLT_MAX so as to impose no limit on the time-step.
 *
 * @param cooling The #cooling_function_data used in the run.
 * @param phys_const The physical constants in internal units.
 * @param us The internal system of units.
 * @param p Pointer to the particle data.
 */
__attribute__((always_inline)) INLINE static float cooling_timestep(
    const struct cooling_function_data* restrict cooling,
    const struct phys_const* restrict phys_const,
    const struct unit_system* restrict us, const struct part* restrict p) {

  return FLT_MAX;
}

/**
 * @brief Sets the cooling properties of the (x-)particles to a valid start
 * state.
 *
 * @param p Pointer to the particle data.
 * @param xp Pointer to the extended particle data.
 */
__attribute__((always_inline)) INLINE static void cooling_init_part(
    const struct part* restrict p, struct xpart* restrict xp) {

  xp->cooling_data.radiated_energy = 0.f;
}

/**
 * @brief Returns the total radiated energy by this particle.
 *
 * @param xp The extended particle data
 */
__attribute__((always_inline)) INLINE static float cooling_get_radiated_energy(
    const struct xpart* restrict xp) {

  return xp->cooling_data.radiated_energy;
}

/**
 * @brief Initialises the cooling properties.
 *
 * @param parameter_file The parsed parameter file.
 * @param us The current internal system of units.
 * @param phys_const The physical constants in internal units.
 * @param cooling The cooling properties to initialize
 */
static INLINE void cooling_init_backend(
    const struct swift_params* parameter_file, const struct unit_system* us,
    const struct phys_const* phys_const,
    struct cooling_function_data* cooling) {

  double units_density, units_length, units_time;
  int grackle_chemistry;
  int UVbackground;

  parser_get_param_string(parameter_file, "GrackleCooling:GrackleCloudyTable",
                          cooling->GrackleCloudyTable);
  cooling->UVbackground =
      parser_get_param_int(parameter_file, "GrackleCooling:UVbackground");
  cooling->GrackleRedshift =
      parser_get_param_double(parameter_file, "GrackleCooling:GrackleRedshift");
  cooling->GrackleHSShieldingDensityThreshold = parser_get_param_double(
      parameter_file, "GrackleCooling:GrackleHSShieldingDensityThreshold");

  UVbackground = cooling->UVbackground;
  grackle_chemistry = 0; /* forced to be zero : read table */

  units_density = us->UnitMass_in_cgs / pow(us->UnitLength_in_cgs, 3);
  units_length = us->UnitLength_in_cgs;
  units_time = us->UnitTime_in_cgs;

#ifdef SWIFT_DEBUG_CHECKS
  float threshold = cooling->GrackleHSShieldingDensityThreshold;

  threshold /= phys_const->const_proton_mass;
  threshold /= pow(us->UnitLength_in_cgs, 3);

  message("***************************************");
  message("initializing grackle cooling function");
  message("");
  message("CloudyTable                        = %s",
          cooling->GrackleCloudyTable);
  message("UVbackground                       = %d", UVbackground);
  message("GrackleRedshift                    = %g", cooling->GrackleRedshift);
  message("GrackleHSShieldingDensityThreshold = %g atom/cm3", threshold);
#endif

  if (wrap_init_cooling(cooling->GrackleCloudyTable, UVbackground,
                        units_density, units_length, units_time,
                        grackle_chemistry) != 1) {
    error("Error in initialize_chemistry_data.");
  }

#ifdef SWIFT_DEBUG_CHECKS
  grackle_print_data();
  message("");
  message("***************************************");
#endif
}

/**
 * @brief Prints the properties of the cooling model to stdout.
 *
 * @param cooling The properties of the cooling function.
 */
static INLINE void cooling_print_backend(
    const struct cooling_function_data* cooling) {

  message("Cooling function is 'Grackle'.");
  message("CloudyTable                        = %s",
          cooling->GrackleCloudyTable);
  message("UVbackground                       = %d", cooling->UVbackground);
  message("GrackleRedshift                    = %g", cooling->GrackleRedshift);
  message("GrackleHSShieldingDensityThreshold = %g atom/cm3",
          cooling->GrackleHSShieldingDensityThreshold);
}

#endif /* SWIFT_COOLING_GRACKLE_H */