using System;
using System.Collections.Generic;
using System.Runtime.CompilerServices;
using UnityEngine;
using UnityEngine.Scripting;
using Object = UnityEngine.Object;

namespace AlicizaX.Fsm.Runtime
{
    [Preserve]
    internal sealed class FsmModule : IFsmModule
    {
        private readonly List<IFsmRunner> _active = new List<IFsmRunner>(256);
        private readonly List<IFsmRunner> _toRemove = new List<IFsmRunner>(64);

        public int Priority => 0;

        void IModuleLateUpdate.LateUpdate()
        {
            RemoveFsm();
        }

        private void RemoveFsm()
        {
            if (_toRemove.Count > 0)
            {
                for (int i = 0; i < _toRemove.Count; i++)
                {
                    var f = _toRemove[i];
                    MemoryPool.Release(f);
                    f.Dispose();
                    _active.Remove(f);
                }

                _toRemove.Clear();
            }
        }

        void IModuleUpdate.Update(float elapseSeconds, float realElapseSeconds)
        {
            float dt = Time.deltaTime;
            for (int i = 0; i < _active.Count; i++)
            {
                _active[i].Tick(dt);
            }
        }

        void IModuleAwake.Awake()
        {
        }

        void IModule.Dispose()
        {
            for (int i = _active.Count - 1; _active.Count > 0; i--)
            {
                _toRemove.Add(_active[i]);
            }

            RemoveFsm();
        }

        private Fsm<T> CreatePooled<T>(FsmConfig<T> cfg, T blackboard, UnityEngine.Object owner = null, Func<int, string> stateNameGetter = null)
            where T : class, IMemory
        {
            var fsm = Fsm<T>.Rent(cfg, blackboard, owner, stateNameGetter);
            _active.Add(fsm);
            return fsm;
        }

        public void DestroyFsm<T>(Fsm<T> fsm) where T : class, IMemory
        {
            if (fsm == null) return;
            _toRemove.Add(fsm);
        }

        public Fsm<T> Create<T>(FsmConfig<T> cfg, UnityEngine.Object owner = null, Func<int, string> stateNameGetter = null)
            where T : class, IMemory, new()
        {
            var bb = MemoryPool.Acquire<T>();
            var fsm = CreatePooled(cfg, bb, owner, stateNameGetter);
            return fsm;
        }
    }
}