/*******************************************************************************
 * 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_NONE_H
#define SWIFT_COOLING_NONE_H

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

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

/* Local includes. */
#include "cooling_struct.h"
#include "cosmology.h"
#include "entropy_floor.h"
#include "hydro.h"
#include "hydro_properties.h"
#include "part.h"

/**
 * @brief Common operations performed on the cooling function at a
 * given time-step or redshift.
 *
 * @param cosmo The current cosmological model.
 * @param cooling The #cooling_function_data used in the run.
 * @param s The #space containing all the particles.
 */
INLINE static void cooling_update(const struct cosmology* cosmo,
                                  struct cooling_function_data* cooling,
                                  struct space* s) {
  // Add content if required.
}

/**
 * @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 cosmo The current cosmological model.
 * @param hydro_props The properties of the hydro scheme.
 * @param cooling The #cooling_function_data used in the run.
 * @param p Pointer to the particle data.
 * @param xp Pointer to the extended particle data.
 * @param dt The time-step of this particle.
 * @param dt_therm The time-step operator used for thermal quantities.
 */
__attribute__((always_inline)) INLINE static void cooling_cool_part(
    const struct phys_const* restrict phys_const,
    const struct unit_system* restrict us,
    const struct cosmology* restrict cosmo,
    const struct hydro_props* hydro_props,
    const struct entropy_floor_properties* floor_props,
    const struct cooling_function_data* restrict cooling,
    struct part* restrict p, struct xpart* restrict xp, const float dt,
    const float dt_therm) {}

/**
 * @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 cosmo The current cosmological model.
 * @param hydro_props The properties of the hydro scheme.
 * @param us The internal system of units.
 * @param p Pointer to the particle data.
 * @param xp Pointer to the extended data of the particle.
 */
__attribute__((always_inline)) INLINE static float cooling_timestep(
    const struct cooling_function_data* restrict cooling,
    const struct phys_const* restrict phys_const,
    const struct cosmology* restrict cosmo,
    const struct unit_system* restrict us,
    const struct hydro_props* hydro_props, const struct part* restrict p,
    const struct xpart* restrict xp) {

  return FLT_MAX;
}

/**
 * @brief Sets the cooling properties of the (x-)particles to a valid start
 * state.
 *
 * Nothing to do here.
 *
 * @param phys_const The physical constant in internal units.
 * @param us The unit system.
 * @param cosmo The current cosmological model.
 * @param data The properties of the cooling function.
 * @param p Pointer to the particle data.
 * @param xp Pointer to the extended particle data.
 */
__attribute__((always_inline)) INLINE static void cooling_first_init_part(
    const struct phys_const* restrict phys_const,
    const struct unit_system* restrict us,
    const struct cosmology* restrict cosmo,
    const struct cooling_function_data* data, const struct part* restrict p,
    struct xpart* restrict xp) {}

/**
 * @brief Compute the temperature of a #part based on the cooling function.
 *
 * @param phys_const #phys_const data structure.
 * @param hydro_props The properties of the hydro scheme.
 * @param us The internal system of units.
 * @param cosmo #cosmology data structure.
 * @param cooling #cooling_function_data struct.
 * @param p #part data.
 * @param xp Pointer to the #xpart data.
 */
INLINE static float cooling_get_temperature(
    const struct phys_const* restrict phys_const,
    const struct hydro_props* restrict hydro_props,
    const struct unit_system* restrict us,
    const struct cosmology* restrict cosmo,
    const struct cooling_function_data* restrict cooling,
    const struct part* restrict p, const struct xpart* restrict xp) {

  /* Physical constants */
  const double m_H = phys_const->const_proton_mass;
  const double k_B = phys_const->const_boltzmann_k;

  /* Gas properties */
  const double T_transition = hydro_props->hydrogen_ionization_temperature;
  const double mu_neutral = hydro_props->mu_neutral;
  const double mu_ionised = hydro_props->mu_ionised;

  /* Particle temperature */
  const double u = hydro_get_physical_internal_energy(p, xp, cosmo);

  /* Temperature over mean molecular weight */
  const double T_over_mu = hydro_gamma_minus_one * u * m_H / k_B;

  /* Are we above or below the HII -> HI transition? */
  if (T_over_mu > (T_transition + 1.) / mu_ionised)
    return T_over_mu * mu_ionised;
  else if (T_over_mu < (T_transition - 1.) / mu_neutral)
    return T_over_mu * mu_neutral;
  else
    return T_transition;
}

/**
 * @brief Returns the total radiated energy by this particle.
 *
 * No cooling, so return 0.
 *
 * @param xp The extended particle data
 */
__attribute__((always_inline)) INLINE static float cooling_get_radiated_energy(
    const struct xpart* restrict xp) {

  return 0.f;
}

/**
 * @brief Initialises the cooling properties.
 *
 * Nothing to do here.
 *
 * @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 hydro_props The properties of the hydro scheme.
 * @param cooling The cooling properties to initialize
 */
static INLINE void cooling_init_backend(struct swift_params* parameter_file,
                                        const struct unit_system* us,
                                        const struct phys_const* phys_const,
                                        const struct hydro_props* hydro_props,
                                        struct cooling_function_data* cooling) {
}

/**
 * @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 'No cooling'.");
}

/**
 * @brief Clean-up the memory allocated for the cooling routines
 *
 * @param cooling the cooling data structure.
 */
static INLINE void cooling_clean(struct cooling_function_data* cooling) {}

/**
 * @brief Write a cooling struct to the given FILE as a stream of bytes.
 *
 * Empty structure so nothing to do here.
 *
 * @param cooling the struct
 * @param stream the file stream
 */
static INLINE void cooling_struct_dump(
    const struct cooling_function_data* cooling, FILE* stream) {}

/**
 * @brief Restore a hydro_props struct from the given FILE as a stream of
 * bytes.
 *
 * Empty structure so nothing to do here.
 *
 * @param cooling the struct
 * @param stream the file stream
 * @param cosmo #cosmology structure
 */
static INLINE void cooling_struct_restore(struct cooling_function_data* cooling,
                                          FILE* stream,
                                          const struct cosmology* cosmo) {}

#endif /* SWIFT_COOLING_NONE_H */
