using System;
using System.Collections;
using System.Collections.Generic;
using AibisDream.Framework;
using UnityEngine;

namespace AibisDream.Kit
{
    public class ActionKitMonoBehaviourEvents : Singleton<ActionKitMonoBehaviourEvents>
    {
        public EasyEvent OnUpdate { get; private set; }
        private readonly EasyEvent _onFixedUpdate = new();
        private readonly EasyEvent _onLateUpdate = new();
        private readonly EasyEvent _onGUIEvent = new();
        private readonly EasyEvent<bool> _onApplicationFocusEvent = new();
        private readonly EasyEvent<bool> _onApplicationPauseEvent = new();
        private readonly EasyEvent _onApplicationQuitEvent = new();

        public override void OnSingletonInit()
        {
            hideFlags = HideFlags.HideInHierarchy;
            OnUpdate = new EasyEvent();
        }

        public override void OnSingletonDestroy()
        {
            OnUpdate.UnRegisterAll();
        }

        private void Update()
        {
            OnUpdate?.Trigger();

            QueueUpdate();
        }

        private void OnGUI()
        {
            _onGUIEvent?.Trigger();
        }

        private void FixedUpdate()
        {
            _onFixedUpdate?.Trigger();
        }

        private void LateUpdate()
        {
            _onLateUpdate?.Trigger();
        }

        private void OnApplicationFocus(bool hasFocus)
        {
            _onApplicationFocusEvent?.Trigger(hasFocus);
        }

        private void OnApplicationPause(bool pauseStatus)
        {
            _onApplicationPauseEvent?.Trigger(pauseStatus);
        }
        
        private void OnApplicationQuit()
        {
            _onApplicationQuitEvent?.Trigger();
        }

        public void ExecuteCoroutine(IEnumerator coroutine, Action onFinish)
        {
            StartCoroutine(DoExecuteCoroutine(coroutine, onFinish));
        }

        IEnumerator DoExecuteCoroutine(IEnumerator coroutine, Action onFinish)
        {
            yield return coroutine;
            onFinish?.Invoke();
        }

        #region ActionQueue移植

        private readonly List<IActionQueueCallback> _actionQueueCallbacks = new();

        /// <summary>
        /// 确保存在可用的 <see cref="ActionKitMonoBehaviourEvents"/> 实例。
        /// 由于 <see cref="Singleton{T}"/> 不会自动创建对象，当场景里没有该组件时，某些 Action 的 Deinit 回收入队会触发 NRE。
        /// </summary>
        private static ActionKitMonoBehaviourEvents EnsureInstance()
        {
            if (Instance != null) return Instance;
            if (!Application.isPlaying) return null;

            var go = new GameObject(nameof(ActionKitMonoBehaviourEvents));
            DontDestroyOnLoad(go);
            return go.AddComponent<ActionKitMonoBehaviourEvents>();
        }

        /// <summary>
        /// 获取或创建全局事件载体（用于 StartGlobal、回收队列等）。
        /// </summary>
        public static ActionKitMonoBehaviourEvents GetOrCreate()
        {
            return EnsureInstance();
        }

        public static void AddCallback(IActionQueueCallback actionQueueCallback)
        {
            var inst = EnsureInstance();

            // 在退出/非运行态等情况下无法创建实例时，直接执行回调避免 NRE（回收/清理类回调通常是幂等的）。
            if (inst == null)
            {
                actionQueueCallback?.Call();
                return;
            }

            inst._actionQueueCallbacks.Add(actionQueueCallback);
        }

        // Update is called once per frame
        private void QueueUpdate()
        {
            if (_actionQueueCallbacks.Count > 0)
            {
                foreach (var actionQueueCallback in _actionQueueCallbacks)
                {
                    actionQueueCallback.Call();
                }
                
                _actionQueueCallbacks.Clear();
            }
        }

        #endregion
    }
}