using System;
using RR.Game2D.Core.Managers;
using UnityEngine;

namespace RR.Game2D.Behaviour
{
    /// <summary>
    /// Система очков:
    /// хранит количество собранных монет и убитых врагов,
    /// считает итоговый счет при завершении игры.
    /// Формула: Score = E * (P + 45C + 90K + 10K^2) - 0.5T
    /// </summary>
    [DefaultExecutionOrder(-900)]
    public class ScoreSystem : MonoBehaviour
    {
        public static ScoreSystem Instance { get; private set; }

        [Header("Коэффициенты исхода")]
        [SerializeField] private float winMultiplier = 1f;
        [SerializeField] private float loseMultiplier = 0.6f;

        public int CollectedCoins { get; private set; }
        public int TotalCollectedCoins => CollectedCoins;
        public int KilledEnemies { get; private set; }
        public int EnvironmentalPoints { get; private set; }
        public int CurrentScore { get; private set; }
        public int FinalScore { get; private set; }
        public bool IsFinalized { get; private set; }

        public event Action<int, int> StatsChanged;
        public event Action<int> EnvironmentalPointsChanged;
        public event Action<int> CurrentScoreChanged;
        public event Action<int, float, bool> ScoreCalculated;

        private bool _subscribed;

        [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.BeforeSceneLoad)]
        private static void Bootstrap()
        {
            if (Instance != null) return;

            GameObject go = new(nameof(ScoreSystem));
            go.AddComponent<ScoreSystem>();
            DontDestroyOnLoad(go);
        }

        private void Awake()
        {
            if (Instance != null && Instance != this)
            {
                Destroy(gameObject);
                return;
            }

            Instance = this;
            DontDestroyOnLoad(gameObject);
            ResetStats();
        }

        private void Start()
        {
            TrySubscribe();
        }

        private void OnEnable()
        {
            TrySubscribe();
        }

        private void OnDisable()
        {
            Unsubscribe();
        }

        public void RegisterCoinCollected(int amount = 1)
        {
            if (amount <= 0 || IsFinalized) return;

            // This is the cumulative coin count for score calculation.
            // It is intentionally separate from GameManager.Coins, which is used by gameplay/UI and life-award thresholds.
            CollectedCoins += amount;
            StatsChanged?.Invoke(CollectedCoins, KilledEnemies);
            RefreshCurrentScore();
        }

        public void RegisterEnemyKilled(int amount = 1)
        {
            if (amount <= 0 || IsFinalized) return;
            KilledEnemies += amount;
            StatsChanged?.Invoke(CollectedCoins, KilledEnemies);
            RefreshCurrentScore();
        }

        public void RegisterEnvironmentalPoints(int amount = 1)
        {
            if (amount <= 0 || IsFinalized) return;

            EnvironmentalPoints += amount;
            EnvironmentalPointsChanged?.Invoke(EnvironmentalPoints);
            RefreshCurrentScore();
        }

        public int CalculatePreviewScore(float gameTime, bool isWin)
        {
            float e = isWin ? winMultiplier : loseMultiplier;
            float baseScore = EnvironmentalPoints + 45f * CollectedCoins + 90f * KilledEnemies + 10f * KilledEnemies * KilledEnemies;
            float rawScore = e * baseScore - 0.5f * gameTime;

            return Mathf.Max(0, Mathf.RoundToInt(rawScore));
        }

        public int GetDisplayScore(float gameTime, bool isWin = true)
        {
            if (IsFinalized)
            {
                return FinalScore;
            }

            return CalculatePreviewScore(gameTime, isWin);
        }

        public void ResetStats()
        {
            CollectedCoins = 0;
            KilledEnemies = 0;
            EnvironmentalPoints = 0;
            CurrentScore = 0;
            FinalScore = 0;
            IsFinalized = false;
            StatsChanged?.Invoke(CollectedCoins, KilledEnemies);
            EnvironmentalPointsChanged?.Invoke(EnvironmentalPoints);
            CurrentScoreChanged?.Invoke(CurrentScore);
        }

        private void TrySubscribe()
        {
            if (_subscribed || GameManager.Instance == null) return;

            GameManager.Instance.GameWonEvent += OnGameWon;
            GameManager.Instance.GameOverEvent += OnGameOver;
            _subscribed = true;
        }

        private void Unsubscribe()
        {
            if (!_subscribed || GameManager.Instance == null) return;

            GameManager.Instance.GameWonEvent -= OnGameWon;
            GameManager.Instance.GameOverEvent -= OnGameOver;
            _subscribed = false;
        }

        private void OnGameWon(float gameTime)
        {
            Calculate(gameTime, true);
        }

        private void OnGameOver(float gameTime)
        {
            Calculate(gameTime, false);
        }

        private void Calculate(float gameTime, bool isWin)
        {
            if (IsFinalized) return;

            FinalScore = CalculatePreviewScore(gameTime, isWin);
            CurrentScore = FinalScore;
            IsFinalized = true;

            CurrentScoreChanged?.Invoke(CurrentScore);
            ScoreCalculated?.Invoke(FinalScore, gameTime, isWin);
        }

        private void RefreshCurrentScore()
        {
            if (IsFinalized)
            {
                return;
            }

            float gameTime = GameManager.Instance != null ? GameManager.Instance.GetCurrentGameTime() : 0f;
            CurrentScore = CalculatePreviewScore(gameTime, true);
            CurrentScoreChanged?.Invoke(CurrentScore);
        }
    }
}