using System;
using BumpCombat.Constants;
using UnityEngine;

namespace BumpCombat.Progression
{
    public sealed class ExperienceProgress
    {
        private float fractionalExperience;

        public event Action<int, int, int> ExperienceChanged;
        public event Action<int> LevelGained;

        public int Level { get; private set; } = 1;
        public int CurrentExperience { get; private set; }
        public int RequiredExperience => RequiredExperienceForLevel(Level);

        public void Reset()
        {
            Level = 1;
            CurrentExperience = 0;
            fractionalExperience = 0f;
        }

        public void AddEvaluated(float evaluatedAmount)
        {
            fractionalExperience += Mathf.Max(0f, evaluatedAmount);
            int wholeExperience = Mathf.FloorToInt(
                fractionalExperience + 0.0001f);
            fractionalExperience = Mathf.Max(
                0f,
                fractionalExperience - wholeExperience);
            CurrentExperience += wholeExperience;

            while (CurrentExperience >= RequiredExperience)
            {
                CurrentExperience -= RequiredExperience;
                Level++;
                LevelGained?.Invoke(Level);
            }

            ExperienceChanged?.Invoke(
                CurrentExperience,
                RequiredExperience,
                Level);
        }

        internal static int RequiredExperienceForLevel(int level)
        {
            LevelUpConstants tuning = GameplayConstants.Current.LevelUp;
            return tuning.BaseExperienceToNextLevel
                + (Mathf.Max(1, level) - 1)
                * tuning.AdditionalExperiencePerLevel;
        }
    }
}