using System.Collections.Generic;
using SepCore.Entity;
using UnityEngine;

namespace SepCore.EnemyManager
{
    public class EnemyRegistry
    {
        private readonly List<EntityBase> _enemies;
        private readonly Dictionary<int, EntityBase> _enemyById;

        public int Count { get; private set; }
        public List<EntityBase> Enemies => _enemies;

        public EnemyRegistry()
        {
            _enemies = new List<EntityBase>();
            _enemyById = new Dictionary<int, EntityBase>();
        }

        public void Register(EnemyBase enemy)
        {
            if (enemy == null) return;

            Count++;
            RemoveFromCache(enemy.Id);
            _enemies.Add(enemy);
            _enemyById[enemy.Id] = enemy;
        }

        public void Remove(int entityId)
        {
            if (Count > 0)
            {
                Count--;
            }

            RemoveFromCache(entityId);
        }

        public bool TryGet(int entityId, out EntityBase enemy)
        {
            enemy = null;
            if (!_enemyById.TryGetValue(entityId, out EntityBase cachedEnemy))
            {
                return false;
            }

            if (cachedEnemy == null || !cachedEnemy.Available)
            {
                _enemyById.Remove(entityId);
                return false;
            }

            enemy = cachedEnemy;
            return true;
        }

        public void Clear()
        {
            _enemies.Clear();
            _enemyById.Clear();
            Count = 0;
        }

        private void RemoveFromCache(int entityId)
        {
            _enemyById.Remove(entityId);

            for (int i = _enemies.Count - 1; i >= 0; i--)
            {
                EntityBase cachedEnemy = _enemies[i];
                if (cachedEnemy == null || cachedEnemy.Id == entityId)
                {
                    if (cachedEnemy != null)
                    {
                        _enemyById.Remove(cachedEnemy.Id);
                    }

                    _enemies.RemoveAt(i);
                }
            }
        }
    }
}