using System;
using System.Collections.Generic;
using RPGCore.Core.Objects;
using RPGCore.ObjectModules.EventObjectModule.Events;
using RPGCoreCommon.Settings;
using UnityEngine;

namespace RPGCore.Core
{
    /// <summary>
    /// This MonoBehaviour allow any <see cref="BaseObject"/> to call <see cref="OnEnter"/> and <see cref="OnExit"/>.<br/>
    /// Setting <see cref="Collider"/>'s <see cref="Collider.isTrigger"/> to true is required!<br/>
    /// </summary>
    public class Trigger : MonoBehaviour
    {
        private event Action<BaseObject> OnEnterEvent;
        private event Action<BaseObject> OnExitEvent;
        
        private readonly Dictionary<BaseObject, int> _collisionCounter = new();

        public static Trigger AddToGameObject(GameObject go, Action<BaseObject> onEnter, Action<BaseObject> onExit)
        {
            go.layer = SettingsManager.Get<CoreSettings>().triggerLayer;
            
            var interactTrigger = go.AddComponent<Trigger>();
            interactTrigger.OnEnterEvent += onEnter;
            interactTrigger.OnExitEvent += onExit;

            return interactTrigger;
        }

        internal void OnEnter(BaseObject obj)
        {
            var alreadyTouching = _collisionCounter.ContainsKey(obj);
            if (!alreadyTouching) _collisionCounter.Add(obj, 0);
            _collisionCounter[obj]++;

            if (!alreadyTouching)
            {
                obj.events.Register<TriggerClearEvent>(OnClear);
                OnEnterEvent?.Invoke(obj);
            }
        }

        internal void OnExit(BaseObject obj)
        {
            if (!_collisionCounter.ContainsKey(obj))
            {
                Debug.LogError("Object tried to leave trigger, but never entered it!", obj);
                return;
            }
            
            _collisionCounter[obj]--;
            if (_collisionCounter[obj] == 0) Clear(obj);
        }

        private void OnClear(TriggerClearEvent ev)
        {
            Clear(ev.obj);
        }

        private void Clear(BaseObject obj)
        {
            obj.events.Unregister<TriggerClearEvent>(OnClear);
            _collisionCounter.Remove(obj);
            OnExitEvent?.Invoke(obj);
        }
    }
}