Unity C# Fibbonachi LevelUp Xp progress

FibbonachiXp.cs

using System;
using UnityEngine;

namespace GG.Utils
{
    [Serializable]
    public class FibbonachiXp
    {
        //just useful value (approx)
        public const float FIBBONACHI_MULTIPLIER = 1.618f;

        public event Action<int> OnLevelUp;
        public event Action<int> OnXpChanged;

        [field: SerializeField]
        public int Level { get; private set; }

        public int NextLevelUpTarget => CurrentStepSize + AllPassedStepsSum;

        [field: SerializeField]
        public int PreviousStepSize { get; private set; }

        [field: SerializeField]
        public int CurrentStepSize { get; private set; }

        [field: SerializeField]
        public int AllPassedStepsSum { get; private set; }

        public int LeftForLevelUp => CurrentStepSize - PassedForLevelUp;
        public int PassedForLevelUp => TotalXp - AllPassedStepsSum;

        [field: SerializeField]
        public int TotalXp { get; private set; }

        public FibbonachiXp(int firstStepSize)
        {
            Level = 1;
            TotalXp = 0;
            AllPassedStepsSum = 0;
            CurrentStepSize = firstStepSize;
            PreviousStepSize = firstStepSize / 2;
            OnXpChanged?.Invoke(TotalXp);
        }

        /// <summary>
        /// Increment Xp
        /// </summary>
        /// <param name="xp">amount to increment on</param>
        /// <returns>amount of levelups</returns>
        public int AddXp(int xp)
        {
            TotalXp += xp;
            int levelups = 0;
            OnXpChanged?.Invoke(TotalXp);
            while (TotalXp >= NextLevelUpTarget)
            {
                LevelUp();
                levelups++;
            }
            return levelups;
        }

        private void LevelUp()
        {
            AllPassedStepsSum += CurrentStepSize;
            int newXp = CurrentStepSize + PreviousStepSize;
            PreviousStepSize = CurrentStepSize;
            CurrentStepSize = newXp;
            Level++;
            OnLevelUp?.Invoke(Level);
        }
    }
}