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

namespace AibisDream.Framework
{
    public class EventSystemEx : Singleton<EventSystemEx>
    {
        #region 状态

        public bool isLocked;
        private bool _dialogueLocked;
        private int _scopedLockDepth;

        #endregion

        private List<GameObject> pointerOverObjList;
        private List<GameObject> draggingObjList;
        private List<GameObject> holdingObjList;

        #region 事件触发中转

        public void OnPointerEnter(IInteraction interaction)
        {
            if (!pointerOverObjList.Contains(interaction.GetGameObject()))
            {
                pointerOverObjList.Add(interaction.GetGameObject());
            }
        }

        public void OnPointerExit(IInteraction interaction)
        {
            pointerOverObjList.Remove(interaction.GetGameObject());
        }

        public void OnPointerDown(IInteraction interaction)
        {
            if (!holdingObjList.Contains(interaction.GetGameObject()))
            {
                holdingObjList.Add(interaction.GetGameObject());
            }
        }

        public void OnPointerUp(IInteraction interaction)
        {
            holdingObjList.Remove(interaction.GetGameObject());
        }

        public void OnDrag(IInteraction interaction)
        {
            if (!draggingObjList.Contains(interaction.GetGameObject()))
            {
                draggingObjList.Add(interaction.GetGameObject());
            }
        }

        public void OnEndDrag(IInteraction interaction)
        {
            draggingObjList.Remove(interaction.GetGameObject());
        }

        public void OnBeginDrag(IInteraction interaction)
        {
            if (!draggingObjList.Contains(interaction.GetGameObject()))
            {
                draggingObjList.Add(interaction.GetGameObject());
            }
        }

        public TriggerEnum GetPointerState()
        {
            if (holdingObjList.Count > 0 || draggingObjList.Count > 0)
            {
                return TriggerEnum.Dragging;
            }
            else if (pointerOverObjList.Count > 0)
            {
                return TriggerEnum.PointerOver;
            }
            else
            {
                return TriggerEnum.None;
            }
        }

        public void UnRegister(IInteraction interaction)
        {
            pointerOverObjList.Remove(interaction.GetGameObject());
            draggingObjList.Remove(interaction.GetGameObject());
            holdingObjList.Remove(interaction.GetGameObject());
        }

        #endregion

        /// <summary>
        /// 兜底：鼠标左键已抬起时强制清空 holding/dragging。
        /// 防止 EventTrigger 在 isLocked 时跳过 Up/EndDrag 清理后光标一直停在抓取。
        /// </summary>
        private void LateUpdate()
        {
            if (Input.GetMouseButton(0)) return;

            if (holdingObjList.Count > 0)
                holdingObjList.Clear();
            if (draggingObjList.Count > 0)
                draggingObjList.Clear();
        }

        private void HandleDialogueComplete()
        {
            _dialogueLocked = false;
            RefreshLockState();
        }

        private void HandleDialogueStart()
        {
            _dialogueLocked = true;
            RefreshLockState();
        }

        public IDisposable AcquireInteractionLock(string reason)
        {
            _scopedLockDepth++;
            RefreshLockState();
            Debug.Log(
                $"[EventSystemEx] Acquire interaction lock: {reason ?? "(unspecified)"}, " +
                $"depth={_scopedLockDepth}");
            return new InteractionLockScope(this, reason);
        }

        private void ReleaseInteractionLock(string reason)
        {
            _scopedLockDepth = Math.Max(0, _scopedLockDepth - 1);
            RefreshLockState();
            Debug.Log(
                $"[EventSystemEx] Release interaction lock: {reason ?? "(unspecified)"}, " +
                $"depth={_scopedLockDepth}");
        }

        private void RefreshLockState()
        {
            isLocked = _dialogueLocked || _scopedLockDepth > 0;
        }

        #region 单例必须的代码

        public override void OnSingletonInit()
        {
            pointerOverObjList = new List<GameObject>();
            draggingObjList = new List<GameObject>();
            holdingObjList = new List<GameObject>();
            _dialogueLocked = false;
            _scopedLockDepth = 0;
            RefreshLockState();

            EnumEventSystem.Global.Register(GameLifecycleEvent.SessionStarted, ClearAll);
            EnumEventSystem.Global.Register(GameLifecycleEvent.SessionEnded, ClearAll);

            EnumEventSystem.Global.Register(InteractionEventEnum.DialogEnd, HandleDialogueComplete);
            EnumEventSystem.Global.Register(InteractionEventEnum.DialogStart, HandleDialogueStart);
        }

        private void ClearAll()
        {
            pointerOverObjList.Clear();
            draggingObjList.Clear();
            holdingObjList.Clear();
        }

        public override void OnSingletonDestroy()
        {
            EnumEventSystem.Global.UnRegister(GameLifecycleEvent.SessionStarted, ClearAll);
            EnumEventSystem.Global.UnRegister(GameLifecycleEvent.SessionEnded, ClearAll);

            EnumEventSystem.Global.UnRegister(InteractionEventEnum.DialogEnd, HandleDialogueComplete);
            EnumEventSystem.Global.UnRegister(InteractionEventEnum.DialogStart, HandleDialogueStart);

            _dialogueLocked = false;
            _scopedLockDepth = 0;
            RefreshLockState();
        }

        private sealed class InteractionLockScope : IDisposable
        {
            private EventSystemEx _owner;
            private readonly string _reason;

            public InteractionLockScope(EventSystemEx owner, string reason)
            {
                _owner = owner;
                _reason = reason;
            }

            public void Dispose()
            {
                if (_owner == null)
                {
                    return;
                }

                _owner.ReleaseInteractionLock(_reason);
                _owner = null;
            }
        }

        #endregion
    }

    public enum TriggerEnum
    {
        None,
        Dragging,
        PointerOver
    }
}