using System;
using System.Collections.Generic;
using UniRx;
using UniRx.Triggers;
using UnityEngine;
using Object = UnityEngine.Object;

namespace RND
{
    public class ObjectPool : MonoBehaviour
    {
        public GameObject Template { get; private set; }

        private readonly List<GameObject> _buffer = new List<GameObject>();
        private readonly List<GameObject> _inactive = new List<GameObject>();
        private readonly CompositeDisposable _destroySub = new CompositeDisposable();

        public ObjectPool Init(GameObject template)
        {
            Template = template;
            return this;
        }

        public GameObject Reuse()
        {
            GameObject result;
            if (_inactive.Count > 0)
            {
                int lastIndex = _inactive.Count - 1;
                result = _inactive[lastIndex];
                _inactive.RemoveAt(lastIndex);
            }
            else
            {
                result = InstantiateObject();
            }

            result.SetActive(true);
            result.SendMessage("OnReused", SendMessageOptions.DontRequireReceiver);
            return result;
        }

        private GameObject InstantiateObject()
        {
            GameObject result = Instantiate(Template, transform);
            result.AddComponentOnce<TemplateReference>().Template = Template;
            result.OnDestroyAsObservable().Subscribe(_ =>
            {
                _buffer.Remove(result);
                _inactive.Remove(result);
            }).AddTo(_destroySub); // TODO - убрать зависимость от UniRx
            _buffer.Add(result);
            return result;
        }

        public void Release(GameObject instance)
        {
            if(instance == null)
                return;

            if (!_buffer.Contains(instance))
                throw new Exception($"{instance.name} doesn't belong to this pool");

            instance.SetActive(false);
            instance.SendMessage("OnReleased", SendMessageOptions.DontRequireReceiver);
            _inactive.Add(instance);
        }

        private void OnDestroy()
        {
            _destroySub.Dispose();
            _buffer.ForEach(Destroy);
            _buffer.Clear();
            _inactive.Clear();
        }

        public void Destroy()
        {
            Object.Destroy(gameObject);
        }
    }
}