using StereoKit;
using System;

namespace snake;

static class VFX
{
    public static Particle[] particles = new Particle[32];
    static int index = 0;

    public static void Init()
    {
        for (int i = 0; i < particles.Length; i++)
        {
            particles[i] = new();
        }
    }

    public static void Play(XYZi pos)
    {
        for (int i = 0; i < 8; i++)
        {
            index = (index + 1) % particles.Length;
            Particle particle = particles[index];
            particle.pos = pos.ToVec3;
            particle.vel = Quat.FromAngles(Random.Shared.NextSingle() * 360, 0, 0) * Quat.FromAngles(0, Random.Shared.NextSingle() * 360, 0) * Vec3.Forward * 6.0f;
            particle.ori = Quat.Identity;
            particle.scl = (1.0f / 8) * Maths.smooth_stop(Random.Shared.NextSingle());
        }
    }

    public static void Frame()
    {
        for (int i = 0; i < particles.Length; i++)
        {
            Particle particle = particles[i];
            if (particle.vel.MagnitudeSq > float.Epsilon)
            {
                particle.pos += particle.vel * Time.Stepf;
                float scl_rad = particle.scl * 0.5f * 0.333f;
                Vec3 next_pos = V.XYZ(
                    Maths.s_clamp(particle.pos.x, Mono.SD_X - 0.5f - scl_rad),
                    Maths.s_clamp(particle.pos.y, Mono.SD_Y - 0.5f - scl_rad),
                    Maths.s_clamp(particle.pos.z, Mono.SD_Z - 0.5f - scl_rad)
                );
                if (next_pos.x != particle.pos.x || next_pos.y != particle.pos.y || next_pos.z != particle.pos.z)
                {
                    particle.pos = next_pos;
                    particle.vel = Vec3.Zero;
                }
            }
        }
    }
}

public class Particle
{
    public Vec3 pos, vel;
    public Quat ori;
    public float scl;

    public Particle()
    {
        this.pos = Vec3.Zero;
        this.vel = Vec3.Zero;
        this.ori = Quat.Identity;
        this.scl = 0.0f;
    }
}