/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * 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 General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#ifndef __SIM_SIMULATION_SOLVER_HH__
#define __SIM_SIMULATION_SOLVER_HH__

#include "BLI_float3.hh"
#include "BLI_span.hh"

#include "DNA_simulation_types.h"

#include "FN_attributes_ref.hh"

#include "BKE_persistent_data_handle.hh"
#include "BKE_simulation.h"

#include "particle_allocator.hh"
#include "time_interval.hh"

struct Depsgraph;

namespace blender::sim {

class ParticleEmitterContext;
class ParticleForceContext;

class ParticleEmitter {
 public:
  virtual ~ParticleEmitter();
  virtual void emit(ParticleEmitterContext &context) const = 0;
};

class ParticleForce {
 public:
  virtual ~ParticleForce();
  virtual void add_force(ParticleForceContext &context) const = 0;
};

struct SimulationInfluences {
  Map<std::string, Vector<const ParticleForce *>> particle_forces;
  Map<std::string, fn::AttributesInfoBuilder *> particle_attributes_builder;
  Vector<const ParticleEmitter *> particle_emitters;
  VectorSet<ID *> used_data_blocks;
};

class SimulationStateMap {
 private:
  Map<StringRefNull, SimulationState *> states_by_name_;
  Map<StringRefNull, Vector<SimulationState *>> states_by_type_;

 public:
  void add(SimulationState *state)
  {
    states_by_name_.add_new(state->name, state);
    states_by_type_.lookup_or_add_default(state->type).append(state);
  }

  template<typename StateType> StateType *lookup(StringRef name) const
  {
    const char *type = BKE_simulation_get_state_type_name<StateType>();
    return (StateType *)this->lookup_name_type(name, type);
  }

  template<typename StateType> Span<StateType *> lookup() const
  {
    const char *type = BKE_simulation_get_state_type_name<StateType>();
    return this->lookup_type(type).cast<StateType *>();
  }

  SimulationState *lookup_name_type(StringRef name, StringRef type) const
  {
    SimulationState *state = states_by_name_.lookup_default_as(name, nullptr);
    if (state == nullptr) {
      return nullptr;
    }
    if (state->type == type) {
      return state;
    }
    return nullptr;
  }

  Span<SimulationState *> lookup_type(StringRef type) const
  {
    const Vector<SimulationState *> *states = states_by_type_.lookup_ptr_as(type);
    if (states == nullptr) {
      return {};
    }
    else {
      return states->as_span();
    }
  }
};

class SimulationSolveContext {
 private:
  Simulation &simulation_;
  Depsgraph &depsgraph_;
  const SimulationInfluences &influences_;
  TimeInterval solve_interval_;
  const SimulationStateMap &state_map_;
  const bke::PersistentDataHandleMap &id_handle_map_;

 public:
  SimulationSolveContext(Simulation &simulation,
                         Depsgraph &depsgraph,
                         const SimulationInfluences &influences,
                         TimeInterval solve_interval,
                         const SimulationStateMap &state_map,
                         const bke::PersistentDataHandleMap &handle_map)
      : simulation_(simulation),
        depsgraph_(depsgraph),
        influences_(influences),
        solve_interval_(solve_interval),
        state_map_(state_map),
        id_handle_map_(handle_map)
  {
  }

  TimeInterval solve_interval() const
  {
    return solve_interval_;
  }

  const SimulationInfluences &influences() const
  {
    return influences_;
  }

  const bke::PersistentDataHandleMap &handle_map() const
  {
    return id_handle_map_;
  }

  const SimulationStateMap &state_map() const
  {
    return state_map_;
  }
};

class ParticleAllocators {
 private:
  Map<std::string, std::unique_ptr<ParticleAllocator>> &allocators_;

 public:
  ParticleAllocators(Map<std::string, std::unique_ptr<ParticleAllocator>> &allocators)
      : allocators_(allocators)
  {
  }

  ParticleAllocator *try_get_allocator(StringRef particle_simulation_name)
  {
    auto *ptr = allocators_.lookup_ptr_as(particle_simulation_name);
    if (ptr != nullptr) {
      return ptr->get();
    }
    else {
      return nullptr;
    }
  }
};

class ParticleChunkContext {
 private:
  IndexMask index_mask_;
  fn::MutableAttributesRef attributes_;

 public:
  ParticleChunkContext(IndexMask index_mask, fn::MutableAttributesRef attributes)
      : index_mask_(index_mask), attributes_(attributes)
  {
  }

  IndexMask index_mask() const
  {
    return index_mask_;
  }

  fn::MutableAttributesRef attributes()
  {
    return attributes_;
  }

  fn::AttributesRef attributes() const
  {
    return attributes_;
  }
};

class ParticleEmitterContext {
 private:
  SimulationSolveContext &solve_context_;
  ParticleAllocators &particle_allocators_;
  TimeInterval simulation_time_interval_;

 public:
  ParticleEmitterContext(SimulationSolveContext &solve_context,
                         ParticleAllocators &particle_allocators,
                         TimeInterval simulation_time_interval)
      : solve_context_(solve_context),
        particle_allocators_(particle_allocators),
        simulation_time_interval_(simulation_time_interval)
  {
  }

  SimulationSolveContext &solve_context()
  {
    return solve_context_;
  }

  ParticleAllocator *try_get_particle_allocator(StringRef particle_simulation_name)
  {
    return particle_allocators_.try_get_allocator(particle_simulation_name);
  }

  TimeInterval simulation_time_interval() const
  {
    return simulation_time_interval_;
  }
};

class ParticleForceContext {
 private:
  SimulationSolveContext &solve_context_;
  const ParticleChunkContext &particle_chunk_context_;
  MutableSpan<float3> force_dst_;

 public:
  ParticleForceContext(SimulationSolveContext &solve_context,
                       const ParticleChunkContext &particle_chunk_context,
                       MutableSpan<float3> force_dst)
      : solve_context_(solve_context),
        particle_chunk_context_(particle_chunk_context),
        force_dst_(force_dst)
  {
  }

  SimulationSolveContext &solve_context()
  {
    return solve_context_;
  }

  const ParticleChunkContext &particle_chunk() const
  {
    return particle_chunk_context_;
  }

  MutableSpan<float3> force_dst()
  {
    return force_dst_;
  }
};

void initialize_simulation_states(Simulation &simulation,
                                  Depsgraph &depsgraph,
                                  const SimulationInfluences &influences);

void solve_simulation_time_step(Simulation &simulation,
                                Depsgraph &depsgraph,
                                const SimulationInfluences &influences,
                                float time_step);

}  // namespace blender::sim

#endif /* __SIM_SIMULATION_SOLVER_HH__ */