using System;
using Sandbox;

namespace Goo.Animation;

public record struct SpringColor
{
    public Color Current;
    public Color Target;
    public Color Velocity;
    public float Frequency;
    public float Damping;

    public SpringColor(Color initial, float frequency, float damping)
    {
        Current = initial;
        Target = initial;
        Velocity = default;
        Frequency = frequency;
        Damping = damping;
    }

    public void Update(float dt)
    {
        float vr = Velocity.r, vg = Velocity.g, vb = Velocity.b, va = Velocity.a;
        Current = new Color(
            MathX.SpringDamp(Current.r, Target.r, ref vr, dt, Frequency, Damping),
            MathX.SpringDamp(Current.g, Target.g, ref vg, dt, Frequency, Damping),
            MathX.SpringDamp(Current.b, Target.b, ref vb, dt, Frequency, Damping),
            MathX.SpringDamp(Current.a, Target.a, ref va, dt, Frequency, Damping));
        Velocity = new Color(vr, vg, vb, va);
    }

    public bool IsSettled =>
        MathF.Abs(Target.r - Current.r) < 0.0001f &&
        MathF.Abs(Target.g - Current.g) < 0.0001f &&
        MathF.Abs(Target.b - Current.b) < 0.0001f &&
        MathF.Abs(Target.a - Current.a) < 0.0001f &&
        MathF.Abs(Velocity.r) < 0.0001f &&
        MathF.Abs(Velocity.g) < 0.0001f &&
        MathF.Abs(Velocity.b) < 0.0001f &&
        MathF.Abs(Velocity.a) < 0.0001f;

    /// <summary>Advances by dt and returns true while still moving; chain calls with | (not ||) so every damper advances each frame.</summary>
    public bool Tick(float dt) { Update(dt); return !IsSettled; }
}