#ifndef CPU_PARTICLES_H
#define CPU_PARTICLES_H

/*************************************************************************/
/*  cpu_particles.h                                                      */
/*************************************************************************/
/*                         This file is part of:                         */
/*                          PANDEMONIUM ENGINE                           */
/*             https://github.com/Relintai/pandemonium_engine            */
/*************************************************************************/
/* Copyright (c) 2022-present Péter Magyar.                              */
/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
/*                                                                       */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the       */
/* "Software"), to deal in the Software without restriction, including   */
/* without limitation the rights to use, copy, modify, merge, publish,   */
/* distribute, sublicense, and/or sell copies of the Software, and to    */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions:                                             */
/*                                                                       */
/* The above copyright notice and this permission notice shall be        */
/* included in all copies or substantial portions of the Software.       */
/*                                                                       */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
/*************************************************************************/

#include "core/containers/rid.h"
#include "core/object/reference.h"
#include "core/os/safe_refcount.h"
#include "scene/3d/visual_instance.h"

class Curve;
class Gradient;

class CPUParticles : public GeometryInstance {
private:
	GDCLASS(CPUParticles, GeometryInstance);

public:
	enum DrawOrder {
		DRAW_ORDER_INDEX,
		DRAW_ORDER_LIFETIME,
		DRAW_ORDER_VIEW_DEPTH,
		DRAW_ORDER_MAX
	};

	enum Parameter {

		PARAM_INITIAL_LINEAR_VELOCITY,
		PARAM_ANGULAR_VELOCITY,
		PARAM_ORBIT_VELOCITY,
		PARAM_LINEAR_ACCEL,
		PARAM_RADIAL_ACCEL,
		PARAM_TANGENTIAL_ACCEL,
		PARAM_DAMPING,
		PARAM_ANGLE,
		PARAM_SCALE,
		PARAM_HUE_VARIATION,
		PARAM_ANIM_SPEED,
		PARAM_ANIM_OFFSET,
		PARAM_MAX
	};

	enum Flags {
		FLAG_ALIGN_Y_TO_VELOCITY,
		FLAG_ROTATE_Y,
		FLAG_DISABLE_Z,
		FLAG_MAX
	};

	enum EmissionShape {
		EMISSION_SHAPE_POINT,
		EMISSION_SHAPE_SPHERE,
		EMISSION_SHAPE_BOX,
		EMISSION_SHAPE_POINTS,
		EMISSION_SHAPE_DIRECTED_POINTS,
		EMISSION_SHAPE_RING,
		EMISSION_SHAPE_MAX
	};

private:
	bool emitting;

	// Previous minimal data for the particle,
	// for interpolation.
	struct ParticleBase {
		void blank() {
			for (int n = 0; n < 4; n++) {
				custom[n] = 0.0;
			}
		}
		Transform transform;
		Color color;
		float custom[4];
	};

	struct Particle : public ParticleBase {
		void copy_to(ParticleBase &r_o) {
			r_o.transform = transform;
			r_o.color = color;
			memcpy(r_o.custom, custom, sizeof(custom));
		}
		Vector3 velocity;
		bool active;
		float angle_rand;
		float scale_rand;
		float hue_rot_rand;
		float anim_offset_rand;
		Color start_color_rand;
		float time;
		float lifetime;
		Color base_color;

		uint32_t seed;
	};

	float time;
	float inactive_time;
	float frame_remainder;
	int cycle;
	bool redraw;

	RID multimesh;

	PoolVector<Particle> particles;
	LocalVector<ParticleBase> particles_prev;
	PoolVector<float> particle_data;
	PoolVector<float> particle_data_prev;
	PoolVector<int> particle_order;

	struct SortLifetime {
		const Particle *particles;

		bool operator()(int p_a, int p_b) const {
			return particles[p_a].time > particles[p_b].time;
		}
	};

	struct SortAxis {
		const Particle *particles;
		Vector3 axis;
		bool operator()(int p_a, int p_b) const {
			return axis.dot(particles[p_a].transform.origin) < axis.dot(particles[p_b].transform.origin);
		}
	};

	//

	bool one_shot;

	float lifetime;
	float pre_process_time;
	float explosiveness_ratio;
	float randomness_ratio;
	float lifetime_randomness;
	float speed_scale;
	bool local_coords;
	int fixed_fps;
	bool fractional_delta;

	SafeFlag can_update;

	DrawOrder draw_order;

	Ref<Mesh> mesh;

	////////

	Vector3 direction;
	float spread;
	float flatness;

	float parameters[PARAM_MAX];
	float randomness[PARAM_MAX];

	Ref<Curve> curve_parameters[PARAM_MAX];
	Color color;
	Ref<Gradient> color_ramp;
	Ref<Gradient> color_initial_ramp;

	bool flags[FLAG_MAX];

	EmissionShape emission_shape;
	float emission_sphere_radius;
	Vector3 emission_box_extents;
	PoolVector<Vector3> emission_points;
	PoolVector<Vector3> emission_normals;
	PoolVector<Color> emission_colors;
	int emission_point_count;
	float emission_ring_height;
	float emission_ring_inner_radius;
	float emission_ring_radius;
	Vector3 emission_ring_axis;

	Vector3 gravity;

	void _update_internal(bool p_on_physics_tick);
	void _particles_process(float p_delta);
	void _particle_process(Particle &r_p, const Transform &p_emission_xform, float p_local_delta, float &r_tv);
	void _update_particle_data_buffer();

	Mutex update_mutex;
	bool _interpolated = false;

	// Hard coded to true for now, if we decide after testing to always enable this
	// when using interpolation we can remove the variable, else we can expose to the UI.
	bool _streaky = true;

	void _update_render_thread();

	void _set_redraw(bool p_redraw);
	void _set_particles_processing(bool p_enable);
	void _refresh_interpolation_state();

	void _fill_particle_data(const ParticleBase &p_source, float *r_dest, bool p_active) const {
		const Transform &t = p_source.transform;

		if (p_active) {
			r_dest[0] = t.basis.rows[0][0];
			r_dest[1] = t.basis.rows[0][1];
			r_dest[2] = t.basis.rows[0][2];
			r_dest[3] = t.origin.x;
			r_dest[4] = t.basis.rows[1][0];
			r_dest[5] = t.basis.rows[1][1];
			r_dest[6] = t.basis.rows[1][2];
			r_dest[7] = t.origin.y;
			r_dest[8] = t.basis.rows[2][0];
			r_dest[9] = t.basis.rows[2][1];
			r_dest[10] = t.basis.rows[2][2];
			r_dest[11] = t.origin.z;
		} else {
			memset(r_dest, 0, sizeof(float) * 12);
		}

		Color c = p_source.color;
		uint8_t *data8 = (uint8_t *)&r_dest[12];
		data8[0] = CLAMP(c.r * 255.0, 0, 255);
		data8[1] = CLAMP(c.g * 255.0, 0, 255);
		data8[2] = CLAMP(c.b * 255.0, 0, 255);
		data8[3] = CLAMP(c.a * 255.0, 0, 255);

		r_dest[13] = p_source.custom[0];
		r_dest[14] = p_source.custom[1];
		r_dest[15] = p_source.custom[2];
		r_dest[16] = p_source.custom[3];
	}

protected:
	static void _bind_methods();
	void _notification(int p_what);
	virtual void _validate_property(PropertyInfo &property) const;

public:
	AABB get_aabb() const;
	PoolVector<Face3> get_faces(uint32_t p_usage_flags) const;

	void set_emitting(bool p_emitting);
	void set_amount(int p_amount);
	void set_lifetime(float p_lifetime);
	void set_one_shot(bool p_one_shot);
	void set_pre_process_time(float p_time);
	void set_explosiveness_ratio(float p_ratio);
	void set_randomness_ratio(float p_ratio);
	void set_lifetime_randomness(float p_random);
	void set_use_local_coordinates(bool p_enable);
	void set_speed_scale(float p_scale);

	bool is_emitting() const;
	int get_amount() const;
	float get_lifetime() const;
	bool get_one_shot() const;
	float get_pre_process_time() const;
	float get_explosiveness_ratio() const;
	float get_randomness_ratio() const;
	float get_lifetime_randomness() const;
	bool get_use_local_coordinates() const;
	float get_speed_scale() const;

	void set_fixed_fps(int p_count);
	int get_fixed_fps() const;

	void set_fractional_delta(bool p_enable);
	bool get_fractional_delta() const;

	void set_draw_order(DrawOrder p_order);
	DrawOrder get_draw_order() const;

	void set_mesh(const Ref<Mesh> &p_mesh);
	Ref<Mesh> get_mesh() const;

	///////////////////

	void set_direction(Vector3 p_direction);
	Vector3 get_direction() const;

	void set_spread(float p_spread);
	float get_spread() const;

	void set_flatness(float p_flatness);
	float get_flatness() const;

	void set_param(Parameter p_param, float p_value);
	float get_param(Parameter p_param) const;

	void set_param_randomness(Parameter p_param, float p_value);
	float get_param_randomness(Parameter p_param) const;

	void set_param_curve(Parameter p_param, const Ref<Curve> &p_curve);
	Ref<Curve> get_param_curve(Parameter p_param) const;

	void set_color(const Color &p_color);
	Color get_color() const;

	void set_color_ramp(const Ref<Gradient> &p_ramp);
	Ref<Gradient> get_color_ramp() const;

	void set_color_initial_ramp(const Ref<Gradient> &p_ramp);
	Ref<Gradient> get_color_initial_ramp() const;

	void set_particle_flag(Flags p_flag, bool p_enable);
	bool get_particle_flag(Flags p_flag) const;

	void set_emission_shape(EmissionShape p_shape);
	void set_emission_sphere_radius(float p_radius);
	void set_emission_box_extents(Vector3 p_extents);
	void set_emission_points(const PoolVector<Vector3> &p_points);
	void set_emission_normals(const PoolVector<Vector3> &p_normals);
	void set_emission_colors(const PoolVector<Color> &p_colors);
	void set_emission_ring_height(float p_height);
	void set_emission_ring_inner_radius(float p_inner_radius);
	void set_emission_ring_radius(float p_radius);
	void set_emission_ring_axis(Vector3 p_axis);

	EmissionShape get_emission_shape() const;
	float get_emission_sphere_radius() const;
	Vector3 get_emission_box_extents() const;
	PoolVector<Vector3> get_emission_points() const;
	PoolVector<Vector3> get_emission_normals() const;
	PoolVector<Color> get_emission_colors() const;
	float get_emission_ring_height() const;
	float get_emission_ring_inner_radius() const;
	float get_emission_ring_radius() const;
	Vector3 get_emission_ring_axis() const;

	void set_gravity(const Vector3 &p_gravity);
	Vector3 get_gravity() const;

	virtual String get_configuration_warning() const;

	void restart();

	CPUParticles();
	~CPUParticles();
};

VARIANT_ENUM_CAST(CPUParticles::DrawOrder)
VARIANT_ENUM_CAST(CPUParticles::Parameter)
VARIANT_ENUM_CAST(CPUParticles::Flags)
VARIANT_ENUM_CAST(CPUParticles::EmissionShape)

#endif // CPU_PARTICLES_H