using System;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;
using UnityEngine.Assertions;

namespace Rokid.UXR.Interaction {
	/// <summary>
	/// Interactable provides a base template for any kind of interactable object.
	/// An Interactable can have Hover and HandleSelected Interactor(s) acting on it.
	/// Concrete Interactables can define whether they have a One-to-One or
	/// One-to-Many relationship with their associated concrete Interactors.
	/// Interactable 为任何类型的可交互对象提供了一个基本模板。
	/// Interactable 可以有 Hover 和 HandleSelected Interactor(s) 作用于它。
	/// 具体的可交互对象可以定义它们是否具有一对一或
	/// 与其关联的具体交互器的一对多关系。
	/// </summary>
	public abstract class Interactable<TInteractor, TInteractable> : MonoBehaviour, IInteractable
	                                    where TInteractor : Interactor<TInteractor, TInteractable>
	                                    where TInteractable : Interactable<TInteractor, TInteractable>
	{
	    [SerializeField, Interface(typeof(IGameObjectFilter)), Optional]
	    private List<MonoBehaviour> _interactorFilters = new List<MonoBehaviour>();
	    private List<IGameObjectFilter> InteractorFilters = null;
	
	    /// <summary>
	    /// The max Interactors and max selecting Interactors that this Interactable can
	    /// have acting on it.
	    /// -1 signifies NO limit (can have any number of Interactors)
	    /// </summary>
	    [SerializeField]
	    private int _maxInteractors = -1;
	
	    [SerializeField]
	    private int _maxSelectingInteractors = -1;
	
	    [SerializeField, Optional]
	    private UnityEngine.Object _data = null;
	    public object Data { get; protected set; } = null;
	
    #region Properties
	    public int MaxInteractors
	    {
	        get
	        {
	            return _maxInteractors;
	        }
	        set
	        {
	            _maxInteractors = value;
	        }
	    }
	
	    public int MaxSelectingInteractors
	    {
	        get
	        {
	            return _maxSelectingInteractors;
	        }
	        set
	        {
	            _maxSelectingInteractors = value;
	        }
	    }
    #endregion
	
	
	    public IEnumerable<IInteractorView> InteractorViews => _interactors.Cast<IInteractorView>();
	    public IEnumerable<IInteractorView> SelectingInteractorViews => _selectingInteractors.Cast<IInteractorView>();
	
	    private HashSet<TInteractor> _interactors = new HashSet<TInteractor>();
	    private HashSet<TInteractor> _selectingInteractors = new HashSet<TInteractor>();
	
	    [SerializeField]
	    private InteractableState _state = InteractableState.Normal;
	    public event Action<InteractableStateChangeArgs> WhenStateChanged = delegate { };
	
	    public event Action<IInteractorView> WhenInteractorViewAdded = delegate { };
	    public event Action<IInteractorView> WhenInteractorViewRemoved = delegate { };
	    public event Action<IInteractorView> WhenSelectingInteractorViewAdded = delegate { };
	    public event Action<IInteractorView> WhenSelectingInteractorViewRemoved = delegate { };
	
	    private MultiAction<TInteractor> _whenInteractorAdded = new MultiAction<TInteractor>();
	    private MultiAction<TInteractor> _whenInteractorRemoved = new MultiAction<TInteractor>();
	    private MultiAction<TInteractor> _whenSelectingInteractorAdded = new MultiAction<TInteractor>();
	    private MultiAction<TInteractor> _whenSelectingInteractorRemoved = new MultiAction<TInteractor>();
	    public MAction<TInteractor> WhenInteractorAdded => _whenInteractorAdded;
	    public MAction<TInteractor> WhenInteractorRemoved => _whenInteractorRemoved;
	    public MAction<TInteractor> WhenSelectingInteractorAdded => _whenSelectingInteractorAdded;
	    public MAction<TInteractor> WhenSelectingInteractorRemoved => _whenSelectingInteractorRemoved;
	
	    public InteractableState State
	    {
	        get
	        {
	            return _state;
	        }
	        private set
	        {
	            if (_state == value) return;
	            InteractableState previousState = _state;
	            _state = value;
	            WhenStateChanged(new InteractableStateChangeArgs(previousState, _state));
	        }
	    }
	
	    private static InteractableRegistry<TInteractor, TInteractable> _registry =
	                                    new InteractableRegistry<TInteractor, TInteractable>();
	
	    public static InteractableRegistry<TInteractor, TInteractable> Registry => _registry;
	
	    protected virtual void InteractorAdded(TInteractor interactor)
	    {
	        WhenInteractorViewAdded(interactor);
	        _whenInteractorAdded.Invoke(interactor);
	    }
	    protected virtual void InteractorRemoved(TInteractor interactor)
	    {
	        WhenInteractorViewRemoved(interactor);
	        _whenInteractorRemoved.Invoke(interactor);
	    }
	
	    protected virtual void SelectingInteractorAdded(TInteractor interactor)
	    {
	        WhenSelectingInteractorViewAdded(interactor);
	        _whenSelectingInteractorAdded.Invoke(interactor);
	    }
	    protected virtual void SelectingInteractorRemoved(TInteractor interactor)
	    {
	        WhenSelectingInteractorViewRemoved(interactor);
	        _whenSelectingInteractorRemoved.Invoke(interactor);
	    }
	
	    public ICollection<TInteractor> Interactors => _interactors;
	
	    public ICollection<TInteractor> SelectingInteractors => _selectingInteractors;
	
	    public void AddInteractor(TInteractor interactor)
	    {
	        _interactors.Add(interactor);
	        InteractorAdded(interactor);
	        UpdateInteractableState();
	    }
	
	    public void RemoveInteractor(TInteractor interactor)
	    {
	        if (!_interactors.Remove(interactor))
	        {
	            return;
	        }
	        interactor.InteractableChangesUpdate();
	        InteractorRemoved(interactor);
	        UpdateInteractableState();
	    }
	
	    public void AddSelectingInteractor(TInteractor interactor)
	    {
	        _selectingInteractors.Add(interactor);
	        SelectingInteractorAdded(interactor);
	        UpdateInteractableState();
	    }
	
	    public void RemoveSelectingInteractor(TInteractor interactor)
	    {
	        if (!_selectingInteractors.Remove(interactor))
	        {
	            return;
	        }
	        interactor.InteractableChangesUpdate();
	        SelectingInteractorRemoved(interactor);
	        UpdateInteractableState();
	    }
	
	    private void UpdateInteractableState()
	    {
	
	        if (_selectingInteractors.Count > 0)
	        {
	            State = InteractableState.Select;
	        }
	        else if (_interactors.Count > 0)
	        {
	            State = InteractableState.Hover;
	        }
	        else
	        {
	            State = InteractableState.Normal;
	        }
	    }
	
	    public bool CanBeSelectedBy(TInteractor interactor)
	    {
	
	        if (MaxSelectingInteractors >= 0 &&
	            _selectingInteractors.Count == MaxSelectingInteractors)
	        {
	            return false;
	        }
	
	        if (MaxInteractors >= 0 &&
	            _interactors.Count == MaxInteractors &&
	            !_interactors.Contains(interactor))
	        {
	            return false;
	        }
	
	        if (InteractorFilters == null)
	        {
	            return true;
	        }
	
	        foreach (IGameObjectFilter interactorFilter in InteractorFilters)
	        {
	            if (!interactorFilter.Filter(interactor.gameObject))
	            {
	                return false;
	            }
	        }
	
	        return true;
	    }
	
	    public bool HasInteractor(TInteractor interactor)
	    {
	        return _interactors.Contains(interactor);
	    }
	
	    public bool HasSelectingInteractor(TInteractor interactor)
	    {
	        return _selectingInteractors.Contains(interactor);
	    }
	
	    public void Enable()
	    {
	        // RKLog.Info($"====Interaction==== {this.gameObject.name}, register interactable");
	        _registry.Register((TInteractable)this);
	        State = InteractableState.Normal;
	    }
	
	    public void Disable()
	    {
	        List<TInteractor> selectingInteractorsCopy = new List<TInteractor>(_selectingInteractors);
	        foreach (TInteractor selectingInteractor in selectingInteractorsCopy)
	        {
	            RemoveSelectingInteractor(selectingInteractor);
	        }
	
	        List<TInteractor> interactorsCopy = new List<TInteractor>(_interactors);
	        foreach (TInteractor interactor in interactorsCopy)
	        {
	            RemoveInteractor(interactor);
	        }
	
	        RKLog.Info($"====Interaction==== {this.gameObject.name}, unregister interactable");
	        _registry.Unregister((TInteractable)this);
	    }
	
	    public void RemoveInteractorByIdentifier(int id)
	    {
	        TInteractor foundInteractor = null;
	        foreach (TInteractor selectingInteractor in _selectingInteractors)
	        {
	            if (selectingInteractor.Identifier == id)
	            {
	                foundInteractor = selectingInteractor;
	                break;
	            }
	        }
	
	        if (foundInteractor != null)
	        {
	            RemoveSelectingInteractor(foundInteractor);
	        }
	
	        foundInteractor = null;
	
	        foreach (TInteractor interactor in _interactors)
	        {
	            if (interactor.Identifier == id)
	            {
	                foundInteractor = interactor;
	                break;
	            }
	        }
	
	        if (foundInteractor == null)
	        {
	            return;
	        }
	
	        RemoveInteractor(foundInteractor);
	    }
	
	    protected virtual void Awake()
	    {
	        InteractorFilters = _interactorFilters.ConvertAll(mono => mono as IGameObjectFilter);
	    }
	
	    protected virtual void Start()
	    {
	        foreach (IGameObjectFilter filter in InteractorFilters)
	        {
	            Assert.IsNotNull(filter);
	        }
	
	        if (Data == null)
	        {
	            _data = this;
	            Data = _data;
	        }
	    }
	
	    protected virtual void OnEnable()
	    {
	        Enable();
	    }
	
	    protected virtual void OnDisable()
	    {
	        Disable();
	    }
	
	    protected virtual void SetRegistry(InteractableRegistry<TInteractor, TInteractable> registry)
	    {
	        if (registry == _registry) return;
	
	        var interactables = _registry.List();
	        foreach (TInteractable interactable in interactables)
	        {
	            registry.Register(interactable);
	            _registry.Unregister(interactable);
	        }
	        _registry = registry;
	    }
	
	}
	
}