using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using AibisDream.Framework;
using AibisDream.Kit;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;

namespace AibisDream
{
    public class CursorManager : Singleton<CursorManager>
    {
        private const float DelayTime = 0.1f;

        [SerializeField]
        private GameObject border;
        
        [Header("指针图片")] public Sprite defaultCursor;
        public Sprite nextTalk, talking, option, interactive, holding, disable;

        private Image _cursor;
        private GraphicRaycaster _raycaster;
        
        private Sprite _curCursor;
        private CursorState _stateCache;

        #region 状态相关

        private Coroutine _switchCoroutine;
        private CursorState _curState = CursorState.Default;
        private bool _isTalking;
        private bool _isInGame;

        #endregion

        // 卸载时注销事件
        private readonly List<IUnRegister> _unRegisters = new();

        private void Start()
        {
            border.SetActive(true);
            InitRefs();
            InitCursor();
        }

        private void InitCursor()
        {
            Cursor.visible = false;
            SwitchCursor(defaultCursor);
        }

        private void OnEnable()
        {
            RegisterEvent();
        }

        private void OnDisable()
        {
            // 注销所有事件
            foreach (var eventUnRegister in _unRegisters)
            {
                eventUnRegister.UnRegister();
            }

            _unRegisters.Clear();
        }

        private void InitRefs()
        {
            _cursor = transform.Find("Cursor").GetComponent<Image>();
            _raycaster = UIManager.Instance.Canvas.GetComponent<GraphicRaycaster>();
        }

        private void RegisterEvent()
        {
            // 此处监听所有可能对鼠标状态产生影响的事件
            RegisterGameEvent();
            RegisterDialogEvent();
            RegisterTriggerEvent();
        }

        private void RegisterGameEvent()
        {
            _unRegisters.Add(EnumEventSystem.Global.Register(GameLoopEnum.GameStart, OnGameStart));
            _unRegisters.Add(EnumEventSystem.Global.Register(GameLoopEnum.GameQuit, OnGameQuit));
            _unRegisters.Add(EnumEventSystem.Global.Register(GameLoopEnum.PauseGame, OnPauseGame));
            _unRegisters.Add(EnumEventSystem.Global.Register(GameLoopEnum.UnPauseGame, OnUnPauseGame));
        }

        private void OnGameStart()
        {
            _isInGame = true;
        }

        private void OnUnPauseGame()
        {
            _curState = _stateCache;
            _stateCache = CursorState.Default;

            _isInGame = true;
        }

        private void OnPauseGame()
        {
            _stateCache = _curState;
            _curState = CursorState.Default;

            _isInGame = false;
        }

        private void OnGameQuit()
        {
            _curCursor = defaultCursor;
            
            _curState = CursorState.Default;
            _stateCache = CursorState.Default;
            
            _isInGame = false;
        }

        private void RegisterDialogEvent()
        {
            // 对话相关
            _unRegisters.Add(EnumEventSystem.Global.Register<DialogEventEnum, DialogText>(DialogEventEnum.LineStart,
                OnLineStart));
            _unRegisters.Add(EnumEventSystem.Global.Register(DialogEventEnum.LineShown, () => SwitchCursor(nextTalk)));
            _unRegisters.Add(EnumEventSystem.Global.Register(DialogEventEnum.LineEnd, OnLineEnd));
            _unRegisters.Add(EnumEventSystem.Global.Register(DialogEventEnum.OptionShow, OnOptionShow));
            _unRegisters.Add(
                EnumEventSystem.Global.Register<DialogEventEnum, DialogText>(DialogEventEnum.OptionSelected,
                    OnOptionSelect));
        }

        private void RegisterTriggerEvent()
        {
            // 交互相关
            _unRegisters.Add(EnumEventSystem.Global.Register(InteractionEventEnum.Start, OnInteractiveStart));
            _unRegisters.Add(EnumEventSystem.Global.Register(InteractionEventEnum.End, OnInteractiveEnd));

            _unRegisters.Add(
                EnumEventSystem.Global.Register<TriggerEnum, IInteraction>(TriggerEnum.PointerEnter, OnPointerEnter));
            _unRegisters.Add(
                EnumEventSystem.Global.Register<TriggerEnum, IInteraction>(TriggerEnum.PointerExit, OnPointerExit));
            _unRegisters.Add(
                EnumEventSystem.Global.Register<TriggerEnum, IInteraction>(TriggerEnum.PointerDown, OnPointerDown));
            _unRegisters.Add(
                EnumEventSystem.Global.Register<TriggerEnum, IInteraction>(TriggerEnum.PointerUp, OnPointerUp));
        }

        private void Update()
        {
            UpdateCursor();
            HandleDialog();
        }

        private void UpdateCursor()
        {
            // 再判断是不是浮在可交互物上
            _cursor.sprite = !_isInGame || IsOverSelected() ? defaultCursor : _curCursor;
        }

        private void HandleDialog()
        {
            if (!_isInGame) return;
            if (!Input.GetMouseButtonDown(0) && !Input.GetKeyDown(KeyCode.Space)) return;
            
            // 控制对话
            if (_isTalking)
            {
                DialogController.Instance.JumpLine();
            }
        }

        private bool IsOverSelected()
        {
            if (!EventSystem.current.IsPointerOverGameObject())
            {
                return false;
            }
            
            var eventData = new PointerEventData(EventSystem.current)
            {
                position = Input.mousePosition
            };
            
            var results = new List<RaycastResult>();
            _raycaster.Raycast(eventData, results);
            
            return results.Count > 0 && results.Any(result => result.gameObject.CompareTag("Selectable"));
        }

        private void LateUpdate()
        {
            // // 将虚拟指针与鼠标位置同步
            // RectTransformUtility.ScreenPointToLocalPointInRectangle(_cursorCanvas, Input.mousePosition,
            //     CameraKit.Instance.uiCamera, out var worldPos);

            _cursor.rectTransform.position = Input.mousePosition;

            // 在输入状态，要单独处理
        }

        #region 对话相关

        private void OnLineStart(DialogText line)
        {
            _isTalking = true;
            SwitchCursor(talking);
        }

        private void OnLineEnd()
        {
            StopDelayCursor();
            _switchCoroutine = StartCoroutine(DelayAction(() =>
            {
                _isTalking = false;
                _curCursor = defaultCursor;
            }));
        }

        private void OnOptionShow()
        {
            _isTalking = true;
            SwitchCursor(option);
        }

        private void OnOptionSelect(DialogText line)
        {
            StopDelayCursor();
            _switchCoroutine = StartCoroutine(DelayAction(() =>
            {
                _isTalking = false;
                _curCursor = defaultCursor;
            }));
        }

        #endregion

        #region 交互相关

        private void OnInteractiveStart()
        {
            _curState = CursorState.Interactive;
            if (EventSystemEx.Instance.pointerOverObj)
            {
                SwitchCursor(interactive);
            }
        }

        private void OnInteractiveEnd()
        {
            _curState = CursorState.Default;
            // 退出时把Cursor置为Default
            SwitchCursor(defaultCursor);
        }

        private void OnPointerEnter(IInteraction target)
        {
            if (_curState == CursorState.Interactive && !_isTalking)
            {
                // 如果不可交互，就显示不可交互的指针
                SwitchCursor(target.IsActive ? interactive : disable);
            }
        }

        private void OnPointerExit(IInteraction target)
        {
            if (_curState == CursorState.Interactive && !_isTalking)
            {
                SwitchCursor(defaultCursor);
            }
        }

        private void OnPointerDown(IInteraction target)
        {
            if (_curState == CursorState.Interactive && !_isTalking)
            {
                SwitchCursor(target.IsActive ? holding : defaultCursor);
            }
        }

        private void OnPointerUp(IInteraction target)
        {
            if (_curState == CursorState.Interactive && !_isTalking)
            {
                // 如果松手时还在物体之上
                SwitchCursor(EventSystemEx.Instance.holdingObj == target.GetGameObject() ? interactive : defaultCursor);
            }
        }

        #endregion

        #region 指针切换

        /// <summary>
        /// 直接切指针
        /// </summary>
        /// <param name="sprite">指针图片</param>
        private void SwitchCursor(Sprite sprite)
        {
            StopDelayCursor();
            _curCursor = sprite;
        }

        private void StopDelayCursor()
        {
            if (_switchCoroutine != null)
            {
                StopCoroutine(_switchCoroutine);
                _switchCoroutine = null;
            }
        }

        #endregion

        private static IEnumerator DelayAction(Action action)
        {
            yield return new WaitForSeconds(DelayTime);
            action.Invoke();
        }
    }

    public enum CursorState
    {
        Default,
        Interactive
    }
}