#ifndef PARTICLE_H
#define PARTICLE_H

#include <stdlib.h>

#define G_CONSTANT 9.807f

typedef struct {
	float x, y, z;
} Vec3;

typedef struct {
	float r, g, b, a;
} Color;

typedef struct {
	Vec3 position;
	Vec3 velocity;
	Color color;

	float life;
} Particle;

// INFO: This adds adder to out, basicaly out + adder
void vec_add(Vec3 &out, Vec3 adder) {
	out.x += adder.x;
	out.y += adder.y;
	out.z += adder.z;
}

Particle particle_init(Vec3 position, Color color) {
	Particle p;
	p.position = position;
	p.color = color;
	p.velocity = {0.0f, 0.0f, 0.0f};

	p.life = 10;
	return p;
}

int particle_update(Particle *particles, unsigned long long size, float time) {
	int alive_count = 0;
	for (unsigned long long i = 0; i < size; i++) {
		Particle p = particles[i];
		if (p.life == 0) {
			particles[i].position = {0.0f, 0.0f, 0.0f};                        // Start at center
			particles[i].velocity = {(rand() % 100 - 50) / 50.0f, 5.0f, 0.0f}; // Random spray up
			particles[i].life = 2.0f;                                          // Give it 2 seconds of life
			continue;
		}

		p.velocity.y += (G_CONSTANT * time);

		p.position.x += p.velocity.x * time;
		p.position.y += p.velocity.y * time;
		p.position.z += p.velocity.z * time;

		vec_add(p.position, (p.velocity));

        if (p.life > 0) p.life -= time;

		particles[i] = p;
		alive_count++;
	}

	return alive_count;
}

#endif // PARTICLE_H