using BumpCombat.Core;
using System;
using BumpCombat.Constants;
using BumpCombat.Player;
using UnityEngine;

namespace BumpCombat.Progression
{
    [RequireComponent(typeof(PlayerStats))]
    public sealed class ExperienceSystem : MonoBehaviour
    {
        private PlayerStats playerStats;
        private float fractionalExperience;

        public event Action<int, int, int> OnExperienceChanged;
        public event Action<int> OnLevelGained;
        public event Action OnExperienceOrbPickedUp;

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

        private void Awake()
        {
            playerStats = GetComponent<PlayerStats>();
        }

        private void Start()
        {
            OnExperienceChanged?.Invoke(CurrentExperience, RequiredExperience, Level);
        }

        public void AddExperience(int amount)
        {
            AddExperienceInternal(amount);
        }

        public void AddMissionExperience(int amount)
        {
            AddExperienceInternal(amount);
        }

        public void CollectExperienceOrb(int amount)
        {
            AddExperienceInternal(amount);
            OnExperienceOrbPickedUp?.Invoke();
        }

        private void AddExperienceInternal(int amount)
        {
            fractionalExperience += Mathf.Max(0f, playerStats.Evaluate(
                CharacterStat.ExperienceGain,
                Mathf.Max(0, amount)));
            int wholeExperience = Mathf.FloorToInt(
                fractionalExperience + 0.0001f);
            fractionalExperience = Mathf.Max(
                0f,
                fractionalExperience - wholeExperience);
            CurrentExperience += wholeExperience;
            while (CurrentExperience >= RequiredExperience)
            {
                CurrentExperience -= RequiredExperience;
                Level++;
                OnLevelGained?.Invoke(Level);
            }

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

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