/******************************************************************************
 * Copyright (C) Ultraleap, Inc. 2011-2021.                                   *
 *                                                                            *
 * Use subject to the terms of the Apache License 2.0 available at            *
 * http://www.apache.org/licenses/LICENSE-2.0, or another agreement           *
 * between Ultraleap and you, your company or other organization.             *
 ******************************************************************************/

using UnityEngine;

namespace Leap.Unity
{

    /// <summary>
    /// A simple interface that allows an object to act as a 'proxy'
    /// interface to another object.  The proxy can store a serialized
    /// representation of a value on another object.  The value of
    /// the proxy can either be updated from the object (pull), or
    /// be pushed out to the object (push).
    /// 
    /// This interface is normally used in animation systems where
    /// something that needs to be animated does not have an easily
    /// animatable representation.  The proxy stands in as the animatable
    /// representation, while still allowing normal reads and writes.
    /// </summary>
    public interface IValueProxy
    {

        /// <summary>
        /// Called when this proxy should push its serialized representation
        /// out to the target object.
        /// </summary>
        void OnPushValue();

        /// <summary>
        /// Called when this proxy should pull from the target object into
        /// its serialized representation.
        /// </summary>
        void OnPullValue();
    }

    /// <summary>
    /// A helpful implementation of IValueProxy.  The class is a monobehaviour and so
    /// can be attached to game objects.  Auto-pushing can also be turned on and off.
    /// When Auto-pushing is enabled, the behaviour will push the value on every
    /// LateUpdate.
    /// </summary>
    public abstract class AutoValueProxy : MonoBehaviour, IValueProxy
    {

        [SerializeField, HideInInspector]
        private bool _autoPushingEnabled = false;
        public bool autoPushingEnabled
        {
            get
            {
                return _autoPushingEnabled;
            }
            set
            {
                _autoPushingEnabled = value;
            }
        }

        public abstract void OnPullValue();
        public abstract void OnPushValue();

        private void LateUpdate()
        {
            if (_autoPushingEnabled)
            {
                OnPushValue();
            }
        }
    }
}