using FishNet.Managing;
using FishNet.Connection;
using UnityEngine;
using FishNet.Serializing;
using FishNet.Transporting;
using FishNet.Managing.Logging;
using System.Collections.Generic;
using System.Runtime.CompilerServices;
using FishNet.Utility.Performance;
using System;
#if UNITY_EDITOR
using UnityEditor;
#endif

namespace FishNet.Object
{
    [DisallowMultipleComponent]
    public sealed partial class NetworkObject : MonoBehaviour
    {
        #region Public.
        [field: SerializeField, HideInInspector]
        public bool IsNested { get; private set; }
        /// <summary>
        /// True if this NetworkObject was active during edit. Will be true if placed in scene during edit, and was in active state on run.
        /// </summary>
        [System.NonSerialized]
        internal bool ActiveDuringEdit;
        /// <summary>
        /// Returns if this object was placed in the scene during edit-time.
        /// </summary>
        /// <returns></returns>
        public bool IsSceneObject => (SceneId > 0);
        [Obsolete("Use IsSceneObject instead.")] //Remove on 2023/01/01
        public bool SceneObject => IsSceneObject;
        /// <summary>
        /// ComponentIndex for this NetworkBehaviour.
        /// </summary>
        [field: SerializeField, HideInInspector]
        public byte ComponentIndex { get; private set; }
        /// <summary>
        /// Unique Id for this NetworkObject. This does not represent the object owner.
        /// </summary>
        public int ObjectId { get; private set; }
        /// <summary>
        /// True if this NetworkObject is deinitializing. Will also be true until Initialize is called. May be false until the object is cleaned up if object is destroyed without using Despawn.
        /// </summary>
        internal bool IsDeinitializing { get; private set; } = true;
        /// <summary>
        /// 
        /// </summary>
        [field: SerializeField, HideInInspector]
        private NetworkBehaviour[] _networkBehaviours;
        /// <summary>
        /// NetworkBehaviours within the root and children of this object.
        /// </summary>        
        public NetworkBehaviour[] NetworkBehaviours
        {
            get => _networkBehaviours;
            private set => _networkBehaviours = value;
        }
        /// <summary>
        /// NetworkObject parenting this instance. The parent NetworkObject will be null if there was no parent during serialization.
        /// </summary>
        [field: SerializeField, HideInInspector]
        public NetworkObject ParentNetworkObject { get; private set; }
        /// NetworkObjects nested beneath this one. Recursive NetworkObjects may exist within each entry of this field.
        /// </summary> 
        [field: SerializeField, HideInInspector]
        public List<NetworkObject> ChildNetworkObjects { get; private set; } = new List<NetworkObject>();
        /// <summary>
        /// 
        /// </summary>
        [SerializeField, HideInInspector]
        internal TransformProperties SerializedTransformProperties = new TransformProperties();
        /// <summary>
        /// Current state of the NetworkObject.
        /// </summary>
        [System.NonSerialized]
        internal NetworkObjectState State = NetworkObjectState.Unset;
        #endregion

        #region Serialized.
        /// <summary>
        /// 
        /// </summary>
        [Tooltip("True if the object will always initialize as a networked object. When false the object will not automatically initialize over the network. Using Spawn() on an object will always set that instance as networked.")]
        [SerializeField]
        private bool _isNetworked = true;
        /// <summary>
        /// True if the object will always initialize as a networked object. When false the object will not automatically initialize over the network. Using Spawn() on an object will always set that instance as networked.
        /// </summary>
        public bool IsNetworked
        {
            get => _isNetworked;
            private set => _isNetworked = value;
        }
        /// <summary>
        /// Sets IsNetworked value. This method must be called before Start.
        /// </summary>
        /// <param name="value">New IsNetworked value.</param>
        public void SetIsNetworked(bool value)
        {
            IsNetworked = value;
        }
        /// <summary>
        /// 
        /// </summary>
        [Tooltip("True to make this object global, and added to the DontDestroyOnLoad scene. This value may only be set for instantiated objects, and can be changed if done immediately after instantiating.")]
        [SerializeField]
        private bool _isGlobal;
        /// <summary>
        /// True to make this object global, and added to the DontDestroyOnLoad scene. This value may only be set for instantiated objects, and can be changed if done immediately after instantiating.
        /// </summary>
        public bool IsGlobal
        {
            get => _isGlobal;
            private set => _isGlobal = value;
        }
        /// <summary>
        /// Sets IsGlobal value.
        /// </summary>
        /// <param name="value">New global value.</param>
        public void SetIsGlobal(bool value)
        {
            if (IsNested)
            {
                if (NetworkManager.StaticCanLog(LoggingType.Warning))
                    Debug.LogWarning($"Object {gameObject.name} cannot change IsGlobal because it is nested. Only root objects may be set global.");
            }
            if (!IsDeinitializing)
            {
                if (NetworkManager.StaticCanLog(LoggingType.Warning))
                    Debug.LogWarning($"Object {gameObject.name} cannot change IsGlobal as it's already initialized. IsGlobal may only be changed immediately after instantiating.");
                return;
            }
            if (IsSceneObject)
            {
                if (NetworkManager.StaticCanLog(LoggingType.Warning))
                    Debug.LogWarning($"Object {gameObject.name} cannot have be global because it is a scene object. Only instantiated objects may be global.");
                return;
            }

            _networkObserverInitiliazed = false;
            IsGlobal = value;
        }
        [Header("WIP! Not Functional")]
        /// <summary>
        /// 
        /// </summary>
        [Tooltip("True to disable rather than destroy this NetworkObject when being despawned. Scene objects are never destroyed.")]
        [SerializeField]
        private bool _disableOnDespawn;
        /// <summary>
        /// True to disable rather than destroy this NetworkObject when being despawned. Scene objects are never destroyed.
        /// </summary> 
        public bool DisableOnDespawn
        {
            get => _disableOnDespawn;
            private set => _disableOnDespawn = value;
        }
        /// <summary>
        /// Sets AllowDestroy value.
        /// </summary>
        /// <param name="allowDestroy"></param>
        public void SetDisableOnDespawn(bool disableOnDespawn)
        {
            DisableOnDespawn = disableOnDespawn;
        }
        #endregion

        #region Private.
        /// <summary>
        /// True if disabled NetworkBehaviours have been initialized.
        /// </summary>
        private bool _disabledNetworkBehavioursInitialized;
        #endregion


        private void Awake()
        {
            SetChildDespawnedState();
        }

        private void Start()
        {
            TryStartDeactivation();
            ////Also deactivate children.
            //foreach (NetworkObject nob in ChildNetworkObjects)
            //    nob.TryStartDeactivation();
        }

        /// <summary>
        /// Initializes NetworkBehaviours if they are disabled.
        /// </summary>
        private void InitializeNetworkBehavioursIfDisabled()
        {
            if (_disabledNetworkBehavioursInitialized)
                return;
            _disabledNetworkBehavioursInitialized = true;

            for (int i = 0; i < NetworkBehaviours.Length; i++)
                NetworkBehaviours[i].InitializeIfDisabled();
        }

        /// <summary>
        /// Sets Despawned on child NetworkObjects if they are not enabled.
        /// </summary>
        private void SetChildDespawnedState()
        {
            NetworkObject nob;
            for (int i = 0; i < ChildNetworkObjects.Count; i++)
            {
                nob = ChildNetworkObjects[i];
                if (!nob.gameObject.activeSelf)
                    nob.State = NetworkObjectState.Despawned;
            }
        }

        /// <summary>
        /// Deactivates this NetworkObject during it's start cycle if conditions are met.
        /// </summary>
        internal void TryStartDeactivation()
        {
            if (!IsNetworked)
                return;

            //Global.
            if (IsGlobal && !IsSceneObject)
                DontDestroyOnLoad(gameObject);

            if (NetworkManager == null || (!NetworkManager.IsClient && !NetworkManager.IsServer))
            {
                //ActiveDuringEdit is only used for scene objects.
                if (IsSceneObject)
                    ActiveDuringEdit = true;
                gameObject.SetActive(false);
            }
        }

        private void OnDisable()
        {
            /* If deinitializing and an owner exist
             * then remove object from owner. */
            if (IsDeinitializing && Owner.IsValid)
                Owner.RemoveObject(this);
            /* If not nested then check to despawn this OnDisable.
             * A nob may become disabled without being despawned if it's
             * beneath another deinitializing nob. This can be true even while
             * not nested because users may move a nob under another at runtime.
             * 
             * This object must also be activeSelf, meaning that it became disabled
             * because a parent was. If not activeSelf then it's possible the
             * user simply deactivated the object themselves. */
            else if (IsServer && !IsNested && gameObject.activeSelf)
            {
                bool canDespawn = false;
                Transform nextParent = transform.parent;
                while (nextParent != null)
                {
                    if (nextParent.TryGetComponent(out NetworkObject pNob))
                    {
                        //If nob is deinitialized then this one cannot exist.
                        if (pNob.IsDeinitializing)
                        {
                            canDespawn = true;
                            break;
                        }
                    }
                    nextParent = nextParent.parent;
                }

                if (canDespawn)
                    Despawn();
            }
        }

        private void OnDestroy()
        {
            //Does this need to be here? I'm thinking no, remove it and examine later. //todo
            if (Owner.IsValid)
                Owner.RemoveObject(this);
            //Already being deinitialized by FishNet.
            if (IsDeinitializing)
                return;

            //Was destroyed without going through the proper methods.
            if (NetworkManager.IsServer)
                NetworkManager.ServerManager.Objects.NetworkObjectUnexpectedlyDestroyed(this);
            if (NetworkManager.IsClient)
                NetworkManager.ClientManager.Objects.NetworkObjectUnexpectedlyDestroyed(this);

            /* When destroyed unexpectedly it's
             * impossible to know if this occurred on
             * the server or client side, so send callbacks
             * for both. */
            if (IsServer)
                InvokeStopCallbacks(true);
            if (IsClient)
                InvokeStopCallbacks(false);

            /* If owner exist then remove object from owner.
             * This has to be called here as well OnDisable because
             * the OnDisable will only remove the object if
             * deinitializing. This is because the object shouldn't
             * be removed from owner if the object is simply being
             * disabled, but not deinitialized. But in the scenario
             * the object is unexpectedly destroyed, which is how we
             * arrive here, the object needs to be removed from owner. */
            if (Owner.IsValid)
                Owner.RemoveObject(this);

            Observers.Clear();
            IsDeinitializing = true;

            SetActiveStatus(false, true);
            SetActiveStatus(false, false);
            //Do not need to set state if being destroyed.
            //Don't need to reset sync types if object is being destroyed.
        }

        /// <summary>
        /// Sets IsClient or IsServer to isActive.
        /// </summary>
        private void SetActiveStatus(bool isActive, bool server)
        {
            if (server)
                IsServer = isActive;
            else
                IsClient = isActive;
        }
        /// <summary>
        /// Initializes this script. This is only called once even when as host.
        /// </summary>
        /// <param name="networkManager"></param>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        internal void PreinitializeInternal(NetworkManager networkManager, int objectId, NetworkConnection owner, bool asServer)
        {
            State = NetworkObjectState.Spawned;
            InitializeNetworkBehavioursIfDisabled();
            IsDeinitializing = false;
            //QOL references.
            NetworkManager = networkManager;
            ServerManager = networkManager.ServerManager;
            ClientManager = networkManager.ClientManager;
            ObserverManager = networkManager.ObserverManager;
            TransportManager = networkManager.TransportManager;
            TimeManager = networkManager.TimeManager;
            SceneManager = networkManager.SceneManager;
            RollbackManager = networkManager.RollbackManager;

            SetOwner(owner);
            ObjectId = objectId;

            /* This must be called at the beginning
             * so that all conditions are handled by the observer
             * manager prior to the preinitialize call on networkobserver. 
             * The method called is dependent on NetworkManager being set. */
            AddDefaultNetworkObserverConditions();

            for (int i = 0; i < NetworkBehaviours.Length; i++)
                NetworkBehaviours[i].InitializeOnceInternal();

            /* NetworkObserver uses some information from
             * NetworkBehaviour so it must be preinitialized
             * after NetworkBehaviours are. */
            if (asServer)
                InitializeOnceObservers();

            //Add to connection objects if owner exist.
            if (owner != null)
                owner.AddObject(this);
        }

        /// <summary>
        /// Adds a NetworkBehaviour and serializes it's components.
        /// </summary>
        internal T AddAndSerialize<T>() where T : NetworkBehaviour //runtimeNB make public.
        {
            int startingLength = NetworkBehaviours.Length;
            T result = gameObject.AddComponent<T>();
            //Add to network behaviours.
            Array.Resize(ref _networkBehaviours, startingLength + 1);
            _networkBehaviours[startingLength] = result;
            //Serialize values and return.
            result.SerializeComponents(this, (byte)startingLength);
            return result;
        }

        /// <summary>
        /// Updates NetworkBehaviours and initializes them with serialized values.
        /// </summary>
        /// <param name="fromPrefabCollection">True if this call originated from a prefab collection, such as during it's initialization.</param>
        internal void UpdateNetworkBehaviours(NetworkObject parentNob, ref byte componentIndex) //runtimeNB make public.
        {
            /* This method can be called by the developer initializing prefabs, the prefab collection doing it automatically,
             * or when the networkobject is modified or added to an object.
             * 
             * Prefab collections generally contain all prefabs, meaning they will not only call this on the topmost
             * networkobject but also each child, as the child would be it's own prefab in the collection. This assumes
             * that is, the child is a nested prefab.
             * 
             * Because of this potential a check must be done where if the componentIndex is 0 we must look
             * for a networkobject above this one. If there is a networkObject above this one then we know the prefab
             * is being initialized individually, not part of a recursive check. In this case exit early
             * as the parent would have already resolved the needed information. */

            //If first componentIndex make sure there's no more than maximum allowed nested nobs.
            if (componentIndex == 0)
            {
                //Not possible for index to be 0 and nested.
                if (IsNested)
                    return;
                byte maxNobs = 255;
                if (GetComponentsInChildren<NetworkObject>(true).Length > maxNobs)
                {
                    Debug.LogError($"The number of child NetworkObjects on {gameObject.name} exceeds the maximum of {maxNobs}.");
                    return;
                }
            }

            Debug.Log("Setting componentIndex on " + gameObject.name + " to " + componentIndex + ". SceneId is " + this.SceneId);
            ComponentIndex = componentIndex;
            ParentNetworkObject = parentNob;

            //Transforms which can be searched for networkbehaviours.
            ListCache<Transform> transformCache = ListCaches.GetTransformCache();
            transformCache.Reset();
            ChildNetworkObjects.Clear();

            transformCache.AddValue(transform);
            for (int z = 0; z < transformCache.Written; z++)
            {
                Transform currentT = transformCache.Collection[z];
                for (int i = 0; i < currentT.childCount; i++)
                {
                    Transform t = currentT.GetChild(i);
                    /* If contains a nob then do not add to transformsCache.
                     * Do add to ChildNetworkObjects so it can be initialized when
                     * parent is. */
                    if (t.TryGetComponent(out NetworkObject childNob))
                    {
                        /* Make sure both objects have the same value for
                         * IsSceneObject. It's possible the user instantiated
                         * an object and placed it beneath a scene object
                         * before the scene initialized. They may also
                         * add a scene object under an instantiated, even though
                         * this almost certainly will break things. */
                        if (IsSceneObject == childNob.IsSceneObject)
                            ChildNetworkObjects.Add(childNob);
                    }
                    else
                    {
                        transformCache.AddValue(t);
                    }
                }
            }

            int written;
            //Iterate all cached transforms and get networkbehaviours.
            ListCache<NetworkBehaviour> nbCache = ListCaches.GetNetworkBehaviourCache();
            nbCache.Reset();
            written = transformCache.Written;
            List<Transform> ts = transformCache.Collection;
            //
            for (int i = 0; i < written; i++)
                nbCache.AddValues(ts[i].GetNetworkBehaviours());

            //Copy to array.
            written = nbCache.Written;
            List<NetworkBehaviour> nbs = nbCache.Collection;
            NetworkBehaviours = new NetworkBehaviour[written];
            //
            for (int i = 0; i < written; i++)
            {
                NetworkBehaviours[i] = nbs[i];
                NetworkBehaviours[i].SerializeComponents(this, (byte)i);
            }

            ListCaches.StoreCache(transformCache);
            ListCaches.StoreCache(nbCache);

            //Tell children nobs to update their NetworkBehaviours.
            foreach (NetworkObject item in ChildNetworkObjects)
            {
                componentIndex++;
                item.UpdateNetworkBehaviours(this, ref componentIndex);
            }
        }

        /// <summary>
        /// Called after all data is synchronized with this NetworkObject.
        /// </summary>
        internal void Initialize(bool asServer)
        {
            InitializeCallbacks(asServer);
        }

        /// <summary>
        /// Called to prepare this object to be destroyed or disabled.
        /// </summary>
        internal void Deinitialize(bool asServer)
        {
            InvokeStopCallbacks(asServer);
            if (asServer)
            {
                IsDeinitializing = true;
            }
            else
            {
                //Client only.
                if (!NetworkManager.IsServer)
                    IsDeinitializing = true;

                RemoveClientRpcLinkIndexes();
            }

            ResetSyncTypes(asServer);
            if (asServer)
                Observers.Clear();

            SetActiveStatus(false, asServer);
            //State = NetworkObjectState.Despawned;
        }

        ///// <summary>
        ///// Disables this object and resets network values.
        ///// </summary>
        //internal void DisableNetworkObject()
        //{
        //    SetOwner(null, false);
        //    ObjectId = -1;
        //    Observers.Clear();
        //    NetworkManager = null;
        //}

        /// <summary>
        /// Removes ownership from all clients.
        /// </summary>
        public void RemoveOwnership()
        {
            GiveOwnership(null, true);
        }
        /// <summary>
        /// Gives ownership to newOwner.
        /// </summary>
        /// <param name="newOwner"></param>
        public void GiveOwnership(NetworkConnection newOwner)
        {
            GiveOwnership(newOwner, true);
        }
        /// <summary>
        /// Gives ownership to newOwner.
        /// </summary>
        /// <param name="newOwner"></param>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        internal void GiveOwnership(NetworkConnection newOwner, bool asServer)
        {
            /* Additional asServer checks. */
            if (asServer)
            {
                if (!NetworkManager.IsServer)
                {
                    if (NetworkManager.CanLog(LoggingType.Warning))
                        Debug.LogWarning($"Ownership cannot be given for object {gameObject.name}. Only server may give ownership.");
                    return;
                }

                //If the same owner don't bother sending a message, just ignore request.
                if (newOwner == Owner && asServer)
                    return;

                if (newOwner != null && newOwner.IsActive && !newOwner.LoadedStartScenes)
                {
                    if (NetworkManager.CanLog(LoggingType.Warning))
                        Debug.LogWarning($"Ownership has been transfered to ConnectionId {newOwner.ClientId} but this is not recommended until after they have loaded start scenes. You can be notified when a connection loads start scenes by using connection.OnLoadedStartScenes on the connection, or SceneManager.OnClientLoadStartScenes.");
                }
            }

            bool activeNewOwner = (newOwner != null && newOwner.IsActive);

            //Set prevOwner, disallowing null.
            NetworkConnection prevOwner = Owner;
            if (prevOwner == null)
                prevOwner = NetworkManager.EmptyConnection;

            SetOwner(newOwner);
            /* Only modify objects if asServer or not
             * host. When host, server would
             * have already modified objects
             * collection so there is no need
             * for client to as well. */
            if (asServer || !NetworkManager.IsHost)
            {
                if (activeNewOwner)
                    newOwner.AddObject(this);
                if (prevOwner.IsValid)
                    prevOwner.RemoveObject(this);
            }
            //After changing owners invoke callbacks.
            InvokeOwnership(prevOwner, asServer);

            //If asServer send updates to clients as needed.
            if (asServer)
            {
                if (activeNewOwner)
                    ServerManager.Objects.RebuildObservers(this, newOwner);

                using (PooledWriter writer = WriterPool.GetWriter())
                {
                    writer.WritePacketId(PacketId.OwnershipChange);
                    writer.WriteNetworkObject(this);
                    writer.WriteNetworkConnection(Owner);
                    //If sharing then send to all observers.
                    if (NetworkManager.ServerManager.ShareIds)
                    {
                        NetworkManager.TransportManager.SendToClients((byte)Channel.Reliable, writer.GetArraySegment(), this);
                    }
                    //Only sending to old / new.
                    else
                    {
                        if (prevOwner.IsActive)
                            NetworkManager.TransportManager.SendToClient((byte)Channel.Reliable, writer.GetArraySegment(), prevOwner);
                        if (activeNewOwner)
                            NetworkManager.TransportManager.SendToClient((byte)Channel.Reliable, writer.GetArraySegment(), newOwner);
                    }
                }

                if (prevOwner.IsActive)
                    ServerManager.Objects.RebuildObservers(prevOwner);
            }
        }

        /// <summary>
        /// Sets the owner of this object.
        /// </summary>
        /// <param name="owner"></param>
        /// <param name="allowNull"></param>
        private void SetOwner(NetworkConnection owner)
        {
            Owner = owner;
        }

        /// <summary>
        /// Returns if this NetworkObject is a scene object, and has changed.
        /// </summary>
        /// <returns></returns>
        internal ChangedTransformProperties GetTransformChanges(TransformProperties stp)
        {
            ChangedTransformProperties ctp = ChangedTransformProperties.Unset;
            if (transform.localPosition != stp.Position)
                ctp |= ChangedTransformProperties.LocalPosition;
            if (transform.localRotation != stp.Rotation)
                ctp |= ChangedTransformProperties.LocalRotation;
            if (transform.localScale != stp.LocalScale)
                ctp |= ChangedTransformProperties.LocalScale;

            return ctp;
        }

        /// <summary>
        /// Returns if this NetworkObject is a scene object, and has changed.
        /// </summary>
        /// <returns></returns>
        internal ChangedTransformProperties GetTransformChanges(GameObject prefab)
        {
            Transform t = prefab.transform;
            ChangedTransformProperties ctp = ChangedTransformProperties.Unset;
            if (transform.position != t.position)
                ctp |= ChangedTransformProperties.LocalPosition;
            if (transform.rotation != t.rotation)
                ctp |= ChangedTransformProperties.LocalRotation;
            if (transform.localScale != t.localScale)
                ctp |= ChangedTransformProperties.LocalScale;

            return ctp;
        }

        #region Editor.
#if UNITY_EDITOR

        /// <summary>
        /// Sets IsNested and returns the result.
        /// </summary>
        /// <returns></returns>
        private bool SetIsNestedThroughTraversal()
        {
            Transform parent = transform.parent;
            //Iterate long as parent isn't null, and isnt self.
            while (parent != null && parent != transform)
            {
                if (parent.TryGetComponent<NetworkObject>(out _))
                {
                    //      Debug.Log("Found in parent");
                    IsNested = true;
                    return IsNested;
                }

                parent = parent.parent;
            }

            //No NetworkObject found in parents, meaning this is not nested.
            IsNested = false;
            return IsNested;

        }

        private void OnValidate()
        {
            SetIsNestedThroughTraversal();
            SceneUpdateNetworkBehaviours();
            ReferenceIds_OnValidate();

            if (IsGlobal && IsSceneObject)
                Debug.LogWarning($"Object {gameObject.name} will have it's IsGlobal state ignored because it is a scene object. Instantiated copies will still be global. This warning is informative only.");
        }

        private void Reset()
        {
            SetIsNestedThroughTraversal();
            SerializeTransformProperties();
            SceneUpdateNetworkBehaviours();
            ReferenceIds_Reset();
        }

        private void SceneUpdateNetworkBehaviours()
        {
            //In a scene.
            if (!string.IsNullOrEmpty(gameObject.scene.name))
            {
                if (IsNested)
                    return;

                byte componentIndex = 0;
                UpdateNetworkBehaviours(null, ref componentIndex);
            }

        }

        private void OnDrawGizmosSelected()
        {
            SerializeTransformProperties();
        }

        /// <summary>
        /// Serializes TransformProperties to current transform properties.
        /// </summary>
        private void SerializeTransformProperties()
        {
            /* Use this method to set scene data since it doesn't need to exist outside 
            * the editor and because its updated regularly while selected. */
            //If a scene object.
            if (!EditorApplication.isPlaying && !string.IsNullOrEmpty(gameObject.scene.name))
            {
                SerializedTransformProperties = new TransformProperties(
                    transform.localPosition, transform.localRotation, transform.localScale);
            }
        }
#endif
        #endregion
    }

}