using System.Linq;
using UnityEngine;
using UnityEngine.Events;
using UnityEngine.EventSystems;

namespace AibisDream.Framework
{
    /// <summary>
    /// EventTrigger扩展
    /// </summary>
    [RequireComponent(typeof(Collider2D))]
    public class EventTriggerEx : EventTrigger
    {
        private IInteraction _interaction;

        private IInteraction Interaction
        {
            get
            {
                // 惰性获取：bridge 可能在 EventTriggerEx 之后才 AddComponent
                if (_interaction == null)
                    _interaction = GetComponent<IInteraction>();
                return _interaction;
            }
        }

        private void Awake()
        {
            _interaction = GetComponent<IInteraction>();
        }

        /// <summary>
        /// 注册事件
        /// </summary>
        /// <param name="triggerType">事件类型</param>
        /// <param name="action">函数</param>
        public void Register(EventTriggerType triggerType, UnityAction<BaseEventData> action)
        {
            if (TryGetTriggerEvent(triggerType, out var triggerEvent))
            {
                triggerEvent.AddListener(action);
            }
            else
            {
                Debug.LogWarning($"{triggerType.ToString()}未添加");
            }
        }

        /// <summary>
        /// 卸载事件
        /// </summary>
        /// <param name="triggerType">事件类型</param>
        /// <param name="action">函数</param>
        public void UnRegister(EventTriggerType triggerType, UnityAction<BaseEventData> action)
        {
            if (TryGetTriggerEvent(triggerType, out var triggerEvent))
            {
                triggerEvent.RemoveListener(action);
            }
            else
            {
                Debug.LogWarning($"{triggerType.ToString()}未添加");
            }
        }

        /// <summary>
        /// 获取触发事件
        /// </summary>
        /// <param name="triggerType">事件类型</param>
        /// <param name="triggerEvent">事件</param>
        /// <returns>是否存在</returns>
        private bool TryGetTriggerEvent(EventTriggerType triggerType, out TriggerEvent triggerEvent)
        {
            var entry = triggers.FirstOrDefault(item => item.eventID == triggerType);
            if (entry == null)
            {
                triggerEvent = null;
                return false;
            }
            else
            {
                triggerEvent = entry.callback;
                return true;
            }
        }

        private bool CanStartInteraction()
        {
            return Interaction != null
                   && Interaction.IsAvailable
                   && EventSystemEx.Instance != null
                   && !EventSystemEx.Instance.isLocked;
        }

        public override void OnPointerEnter(PointerEventData data)
        {
            if (Interaction != null && EventSystemEx.Instance != null)
                EventSystemEx.Instance.OnPointerEnter(Interaction);
            base.OnPointerEnter(data);
        }

        public override void OnPointerExit(PointerEventData data)
        {
            // 退出必须始终清理，否则旋转/细长 Collider 丢 Exit 时会卡住光标
            if (Interaction != null && EventSystemEx.Instance != null)
                EventSystemEx.Instance.OnPointerExit(Interaction);
            base.OnPointerExit(data);
        }

        public override void OnPointerDown(PointerEventData eventData)
        {
            // 对话等场景 isLocked 时仍要让 EventTrigger 上注册的回调执行（如塔罗 PointerDown），
            // 否则会出现能 Hover、但 Down/Up/Click 全不进组件的问题。
            // 仅「开始」交互时受 isLocked / IsAvailable 门控；清理路径见 Up/EndDrag。
            if (CanStartInteraction())
                EventSystemEx.Instance.OnPointerDown(Interaction);
            base.OnPointerDown(eventData);
        }

        public override void OnPointerUp(PointerEventData eventData)
        {
            // 松手必须始终清理 holding，否则充能结束开对话把 isLocked 置真后会永远卡在抓取光标
            if (Interaction != null && EventSystemEx.Instance != null)
                EventSystemEx.Instance.OnPointerUp(Interaction);
            base.OnPointerUp(eventData);
        }

        public override void OnDrag(PointerEventData eventData)
        {
            if (CanStartInteraction())
            {
                EventSystemEx.Instance.OnDrag(Interaction);
                base.OnDrag(eventData);
            }
        }

        public override void OnEndDrag(PointerEventData eventData)
        {
            // 与 PointerUp 相同：清理不受 isLocked 门控
            if (Interaction != null && EventSystemEx.Instance != null)
                EventSystemEx.Instance.OnEndDrag(Interaction);
            base.OnEndDrag(eventData);
        }

        public override void OnBeginDrag(PointerEventData eventData)
        {
            if (CanStartInteraction())
            {
                EventSystemEx.Instance.OnBeginDrag(Interaction);
                base.OnBeginDrag(eventData);
            }
        }

        public override void OnPointerClick(PointerEventData eventData)
        {
            if (CanStartInteraction())
            {
                // EventSystemEx.Instance.OnPointerClick(Interaction);
            }
            base.OnPointerClick(eventData);
        }

        void OnDestroy()
        {
            if (EventSystemEx.Instance != null && Interaction != null)
                EventSystemEx.Instance.UnRegister(Interaction);
        }
    }

    public interface IInteraction
    {
        // 判断是否激活，激活就正常显示鼠标，否则就显示禁用标志
        public bool IsActive { get; }

        // 判断是否可用，可用就正常显示鼠标，否则就保持原有标志不变
        public bool IsAvailable { get; }

        // 返回GameObject
        public GameObject GetGameObject();
    }
}