using System;
using FishNet.Managing;
using FishNet.Managing.Timing;
using FishNet.Object;
using FishNet.Object.Prediction;
using FishNet.Utility.Extension;
using GameKit.Dependencies.Utilities;
using UnityEngine;
using UnityEngine.Scripting;

namespace FishNet.Component.Transforming
{
    /// <summary>
    /// This class is under regular development and it's API may change at any time.
    /// </summary>
    [Obsolete("This class will be removed in version 5.")]
    public sealed class TransformTickSmoother : IResettable
    {
        #region Types.
        private enum InitializeType
        {
            /// <summary>
            /// Not initialized.
            /// </summary>
            Unset,
            /// <summary>
            /// Initialized for network use.
            /// </summary>
            Networked,
            /// <summary>
            /// Initialized for non-network use.
            /// </summary>
            NonNetworked,
        }

        [Preserve]
        private struct TickTransformProperties
        {
            public uint Tick;
            public TransformProperties Properties;

            public TickTransformProperties(uint tick, Transform t)
            {
                Tick = tick;
                Properties = new(t.localPosition, t.localRotation, t.localScale);
            }

            public TickTransformProperties(uint tick, Transform t, Vector3 localScale)
            {
                Tick = tick;
                Properties = new(t.localPosition, t.localRotation, localScale);
            }

            public TickTransformProperties(uint tick, TransformProperties tp)
            {
                Tick = tick;
                Properties = tp;
            }

            public TickTransformProperties(uint tick, TransformProperties tp, Vector3 localScale)
            {
                Tick = tick;
                tp.Scale = localScale;
                Properties = tp;
            }
        }
        #endregion

        #region Private.
        /// <summary>
        /// Object to smooth.
        /// </summary>
        private Transform _graphicalObject;
        /// <summary>
        /// When not MoveRates.UNSET_VALUE the graphical object will teleport into it's next position if the move distance exceeds this value.
        /// </summary>
        private float _teleportThreshold;
        /// <summary>
        /// How quickly to move towards goal values.
        /// </summary>
        private MoveRates _moveRates = new(MoveRates.UNSET_VALUE);
        /// <summary>
        /// True if a pretick occurred since last postTick.
        /// </summary>
        private bool _preTicked;
        /// <summary>
        /// World offset values of the graphical from the NetworkObject during initialization.
        /// </summary>
        private TransformProperties _gfxInitializedOffsetValues;
        /// <summary>
        /// World values of the graphical after it's been aligned to initialized values in PreTick.
        /// </summary>
        private TransformProperties _gfxPreSimulateWorldValues;
        /// <summary>
        /// TickDelta on the TimeManager.
        /// </summary>
        private float _tickDelta;
        /// <summary>
        /// How many ticks to interpolate over when not using adaptive.
        /// </summary>
        private byte _ownerInterpolation;
        /// <summary>
        /// Current interpolation, regardless of if using adaptive or not.
        /// </summary>
        private byte _interpolation;
        /// <summary>
        /// NetworkObject this is for.
        /// </summary>
        private NetworkObject _networkObject;
        /// <summary>
        /// Value to multiply movement by. This is used to reduce or increase the rate the movement buffer is consumed.
        /// </summary>
        private float _movementMultiplier = 1f;
        /// <summary>
        /// TransformProperties to move towards.
        /// </summary>
        private BasicQueue<TickTransformProperties> _transformProperties;
        /// <summary>
        /// Which properties to smooth.
        /// </summary>
        private TransformPropertiesFlag _ownerSmoothedProperties;
        /// <summary>
        /// Which properties to smooth.
        /// </summary>
        private TransformPropertiesFlag _spectatorSmoothedProperties;

        /// <summary>
        /// Updates the smoothedProperties value.
        /// </summary>
        /// <param name="value">New value.</param>
        /// <param name="forSpectator">True if updating values for the spectator, false if updating for owner.</param>
        public void SetSmoothedProperties(TransformPropertiesFlag value, bool forSpectator)
        {
            if (forSpectator)
                _spectatorSmoothedProperties = value;
            else
                _ownerSmoothedProperties = value;
        }

        /// <summary>
        /// Amount of adaptive interpolation to use.
        /// </summary>
        private AdaptiveInterpolationType _adaptiveInterpolation = AdaptiveInterpolationType.VeryLow;

        /// <summary>
        /// Updates the adaptiveInterpolation value.
        /// </summary>
        /// <param name="adaptiveInterpolation">New value.</param>
        public void SetAdaptiveInterpolation(AdaptiveInterpolationType adaptiveInterpolation)
        {
            _adaptiveInterpolation = adaptiveInterpolation;
        }

        /// <summary>
        /// Set interpolation to use for spectated objects if adaptiveInterpolation is off.
        /// </summary>
        private byte _spectatorInterpolation;

        /// <summary>
        /// Sets the spectator interpolation value.
        /// </summary>
        /// <param name="value">New value.</param>
        /// <param name="disableAdaptiveInterpolation">True to also disable adaptive interpolation to use this new value.</param>
        public void SetSpectatorInterpolation(byte value, bool disableAdaptiveInterpolation = true)
        {
            _spectatorInterpolation = value;
            if (disableAdaptiveInterpolation)
                _adaptiveInterpolation = AdaptiveInterpolationType.Off;
        }

        /// <summary>
        /// Previous parent the graphical was attached to.
        /// </summary>
        private Transform _previousParent;
        /// <summary>
        /// True if to detach at runtime.
        /// </summary>
        private bool _detach;
        /// <summary>
        /// True if were an owner of the NetworkObject during PreTick.
        /// This is only used for performance gains.
        /// </summary>
        private bool _useOwnerSmoothing;
        /// <summary>
        /// True if Initialized has been called and settings have not been reset.
        /// </summary>
        private InitializeType _initializeType = InitializeType.Unset;
        /// <summary>
        /// Last tick this was teleported on.
        /// </summary>
        private uint _teleportedTick = TimeManager.UNSET_TICK;
        /// <summary>
        /// Last local tick a reconcile callback was received.
        /// </summary>
        private uint _lastReconcileTick = TimeManager.UNSET_TICK;
        /// <summary>
        /// Transform to track movement on.
        /// </summary>
        private Transform _rootTransform;
        /// <summary>
        /// Frame which smoothing can start.
        /// </summary>
        private int _startFrame;
        #endregion

        #region Const.
        /// <summary>
        /// Default expected interval for reconciles.
        /// </summary>
        private const int RECONCILE_INTERVAL_DEFAULT = int.MaxValue;
        /// <summary>
        /// Maximum allowed entries to be queued over the interpolation amount.
        /// </summary>
        private const int MAXIMUM_QUEUED_OVER_INTERPOLATION = 3;
        #endregion

        [Preserve]
        public TransformTickSmoother() { }

        ~TransformTickSmoother()
        {
            //This is a last resort for if something didnt deinitialize right.
            ResetState();
        }

        /// <summary>
        /// Initializes this smoother for owner and spectator. This should only occur once.
        /// </summary>
        public void InitializeNetworked(NetworkObject nob, Transform graphicalObject, bool detach, float teleportDistance, float tickDelta, byte ownerInterpolation, TransformPropertiesFlag ownerSmoothedProperties, byte spectatorInterpolation, TransformPropertiesFlag specatorSmoothedProperties, AdaptiveInterpolationType adaptiveInterpolation)
        {
            ResetState();

            _networkObject = nob;
            _spectatorInterpolation = spectatorInterpolation;
            _spectatorSmoothedProperties = specatorSmoothedProperties;

            Initialize_Internal(nob.transform, graphicalObject, detach, teleportDistance, tickDelta, ownerInterpolation, ownerSmoothedProperties, forNetworked: true);

            SetAdaptiveInterpolation(adaptiveInterpolation);
            UpdateInterpolation(0);
        }

        private void Initialize_Internal(Transform rootTransform, Transform graphicalObject, bool detach, float teleportDistance, float tickDelta, byte ownerInterpolation, TransformPropertiesFlag ownerSmoothedProperties, bool forNetworked)
        {
            _rootTransform = rootTransform;
            _detach = detach;
            _transformProperties = CollectionCaches<TickTransformProperties>.RetrieveBasicQueue();
            _gfxInitializedOffsetValues = rootTransform.GetTransformOffsets(graphicalObject);
            _tickDelta = tickDelta;
            _graphicalObject = graphicalObject;
            _teleportThreshold = teleportDistance;
            _ownerInterpolation = ownerInterpolation;

            _ownerSmoothedProperties = ownerSmoothedProperties;
            _initializeType = (forNetworked) ? InitializeType.Networked : InitializeType.NonNetworked;
        }

        /// <summary>
        /// Initializes this smoother non-networked use.
        /// </summary>
        public void Initialize(Transform rootTransform, Transform graphicalObject, bool detach, float teleportDistance, float tickDelta, byte ownerInterpolation, TransformPropertiesFlag ownerSmoothedProperties)
        {
            ResetState();

            Initialize_Internal(rootTransform, graphicalObject, detach, teleportDistance, tickDelta, ownerInterpolation, ownerSmoothedProperties, false);

            SetAdaptiveInterpolation(AdaptiveInterpolationType.Off);
        }

        /// <summary>
        /// Deinitializes this smoother resetting values.
        /// </summary>
        public void Deinitialize()
        {
            ResetState();
        }

        /// <summary>
        /// Updates interpolation based on localClient latency.
        /// </summary>
        private void UpdateInterpolation(uint clientStateTick)
        {
            /* Use owner interpolation if:
             * - Owner.
             * - Server, since server always interpolates over 1 tick; this only applies as clientHost.
             * - Not networked, use specified 'owner' interpolation.
             */
            if (_initializeType == InitializeType.NonNetworked || _networkObject.IsServerInitialized || _networkObject.Owner.IsLocalClient)
            {
                _interpolation = _ownerInterpolation;
            }
            //Not using owner interpolation.
            else
            {
                if (_adaptiveInterpolation == AdaptiveInterpolationType.Off)
                {
                    _interpolation = _spectatorInterpolation;
                }
                else
                {
                    float interpolation;
                    TimeManager tm = _networkObject.TimeManager;
                    if (clientStateTick == 0)
                    {
                        //Not enough data to calculate; guestimate. This should only happen once.
                        float fRtt = (float)tm.RoundTripTime;
                        interpolation = (fRtt / 10f);
                    }
                    else
                    {
                        interpolation = (tm.LocalTick - clientStateTick);
                    }

                    interpolation *= GetInterpolationMultiplier();
                    interpolation = Mathf.Clamp(interpolation, 2f, (float)byte.MaxValue);
                    _interpolation = (byte)Mathf.CeilToInt(interpolation);

                    float GetInterpolationMultiplier()
                    {
                        switch (_adaptiveInterpolation)
                        {
                            case AdaptiveInterpolationType.ExtremelyLow:
                                return 0.2f;
                            case AdaptiveInterpolationType.VeryLow:
                                return 0.45f;
                            case AdaptiveInterpolationType.Low:
                                return 0.8f;
                            case AdaptiveInterpolationType.Moderate:
                                return 1.05f;
                            case AdaptiveInterpolationType.High:
                                return 1.25f;
                            case AdaptiveInterpolationType.VeryHigh:
                                return 1.5f;
                            //Make no changes for maximum.
                            default:
                                _networkObject.NetworkManager.LogError($"AdaptiveInterpolationType {_adaptiveInterpolation} is unhandled.");
                                return 1f;
                        }
                    }
                }
            }
        }

        internal void OnStartClient()
        {
            if (!_detach)
                return;

            _previousParent = _graphicalObject.parent;
            TransformProperties gfxWorldProperties = _graphicalObject.GetWorldProperties();
            _graphicalObject.SetParent(null);
            _graphicalObject.SetWorldProperties(gfxWorldProperties);
        }

        internal void OnStopClient()
        {
            if (!_detach || _previousParent == null || _graphicalObject == null)
                return;

            _graphicalObject.SetParent(_previousParent);
            _graphicalObject.SetWorldProperties(GetNetworkObjectWorldPropertiesWithOffset());
        }

        /// <summary>
        /// Called every frame.
        /// </summary>
        internal void OnUpdate()
        {
            if (!CanSmooth())
                return;

            MoveToTarget(Time.deltaTime);
        }

        /// <summary>
        /// Called when the TimeManager invokes OnPreTick.
        /// </summary>
        public void OnPreTick()
        {
            if (!CanSmooth())
                return;

            _preTicked = true;
            _useOwnerSmoothing = (_networkObject == null || _networkObject.IsOwner);

            DiscardExcessiveTransformPropertiesQueue();

            //These only need to be set if still attached.
            if (!_detach)
                _gfxPreSimulateWorldValues = _graphicalObject.GetWorldProperties();
        }

        /// <summary>
        /// Called when the PredictionManager invokes OnPreReconcile.
        /// </summary>
        public void OnPreReconcile()
        {
            if (!_networkObject.IsObjectReconciling)
                return;
            if (_networkObject.IsOwner || _adaptiveInterpolation == AdaptiveInterpolationType.Off)
                return;

            uint clientStateTick = _networkObject.PredictionManager.ClientStateTick;
            _lastReconcileTick = clientStateTick;

            UpdateInterpolation(clientStateTick);
        }

        /// <summary>
        /// Called when the TimeManager invokes OnPostReplay.
        /// </summary>
        /// <param name="clientTick">Replay tick for the local client.</param>
        public void OnPostReplicateReplay(uint clientTick)
        {
            if (_networkObject.IsOwner || _adaptiveInterpolation == AdaptiveInterpolationType.Off)
                return;
            if (_transformProperties.Count == 0)
                return;
            if (clientTick <= _teleportedTick)
                return;
            uint firstTick = _transformProperties.Peek().Tick;
            //Already in motion to first entry, or first entry passed tick.
            if (clientTick <= firstTick)
                return;

            ModifyTransformProperties(clientTick, firstTick);
        }

        /// <summary>
        /// Called when TimeManager invokes OnPostTick.
        /// </summary>
        /// <param name="clientTick">Local tick of the client.</param>
        public void OnPostTick(uint clientTick)
        {
            if (!CanSmooth())
                return;
            if (clientTick <= _teleportedTick)
                return;

            //If preticked then previous transform values are known.
            if (_preTicked)
            {
                DiscardExcessiveTransformPropertiesQueue();

                //Only needs to be put to pretick position if not detached.
                if (!_detach)
                    _graphicalObject.SetWorldProperties(_gfxPreSimulateWorldValues);

                AddTransformProperties(clientTick);
            }
            //If did not pretick then the only thing we can do is snap to instantiated values.
            else
            {
                //Only set to position if not to detach.
                if (!_detach)
                    _graphicalObject.SetWorldProperties(GetNetworkObjectWorldPropertiesWithOffset());
            }
        }

        /// <summary>
        /// Teleports the graphical to it's starting position and clears the internal movement queue.
        /// </summary>
        public void Teleport()
        {
            if (_networkObject == null)
                return;
            _teleportedTick = _networkObject.TimeManager.LocalTick;
            ClearTransformPropertiesQueue();
            TransformProperties startProperties = _networkObject.transform.GetWorldProperties();
            startProperties.Add(_gfxInitializedOffsetValues);
            _graphicalObject.SetWorldProperties(startProperties);
        }

        /// <summary>
        /// Clears the pending movement queue.
        /// </summary>
        private void ClearTransformPropertiesQueue()
        {
            _transformProperties.Clear();
            //Also unset move rates since there is no more queue.
            _moveRates = new(MoveRates.UNSET_VALUE);
        }

        /// <summary>
        /// Discards datas over interpolation limit from movement queue.
        /// </summary>
        private void DiscardExcessiveTransformPropertiesQueue()
        {
            int propertiesCount = _transformProperties.Count;
            int dequeueCount = (propertiesCount - (_interpolation + MAXIMUM_QUEUED_OVER_INTERPOLATION));
            //If there are entries to dequeue.
            if (dequeueCount > 0)
            {
                TickTransformProperties tpp = default;
                for (int i = 0; i < dequeueCount; i++)
                    tpp = _transformProperties.Dequeue();

                SetMoveRates(tpp.Properties);
            }
        }

        /// <summary>
        /// Adds a new transform properties and sets move rates if needed.
        /// </summary>
        private void AddTransformProperties(uint tick)
        {
            TickTransformProperties tpp = new(tick, GetNetworkObjectWorldPropertiesWithOffset());
            _transformProperties.Enqueue(tpp);

            //If first entry then set move rates.
            if (_transformProperties.Count == 1)
            {
                TransformProperties gfxWorldProperties = _graphicalObject.GetWorldProperties();
                SetMoveRates(gfxWorldProperties);
                _startFrame = Time.frameCount + 1;
            }
        }

        /// <summary>
        /// Modifies a transform property for a tick. This does not error check for empty collections.
        /// </summary>
        /// <param name="firstTick">First tick in the queue. If 0 this will be looked up.</param>
        private void ModifyTransformProperties(uint clientTick, uint firstTick)
        {
            uint tick = clientTick;
            /*Ticks will always be added incremental by 1 so it's safe to jump ahead the difference
             * of tick and firstTick. */
            int index = (int)(tick - firstTick);
            //Replace with new data.
            if (index < _transformProperties.Count)
            {
                if (tick != _transformProperties[index].Tick)
                {
                    //Should not be possible.
                }
                else
                {
                    _transformProperties[index] = new(tick, GetNetworkObjectWorldPropertiesWithOffset(), _graphicalObject.localScale);
                }
            }
            else
            {
                //This should never happen.
            }
        }

        /// <summary>
        /// Returns TransformProperties of the NetworkObject with the graphicals world offset.
        /// </summary>
        /// <returns></returns>
        private TransformProperties GetNetworkObjectWorldPropertiesWithOffset() => _networkObject.transform.GetWorldProperties(_gfxInitializedOffsetValues);

        /// <summary>
        /// Returns if prediction can be used on this rigidbody.
        /// </summary>
        /// <returns></returns>
        private bool CanSmooth()
        {
            if (_graphicalObject == null)
                return false;
            if (_networkObject != null && _networkObject.EnablePrediction && !_networkObject.EnableStateForwarding && !_networkObject.IsController)
                return false;
            if (_networkObject.IsServerOnlyStarted)
                return false;

            return true;
        }

        /// <summary>
        /// Sets new rates based on next entries in transformProperties queue, against a supplied TransformProperties.
        /// </summary>
        private void SetMoveRates(in TransformProperties prevValues)
        {
            if (_transformProperties.Count == 0)
            {
                _moveRates = new(MoveRates.UNSET_VALUE);
                return;
            }

            TransformProperties nextValues = _transformProperties.Peek().Properties;
            float duration = _tickDelta;
            float teleportT = _teleportThreshold;

            _moveRates = MoveRates.GetMoveRates(prevValues, nextValues, duration, teleportT);
            _moveRates.TimeRemaining = duration;

            SetMovementMultiplier();
        }

        private void SetMovementMultiplier()
        {
            /* If there's more in queue than interpolation then begin to move faster based on overage.
             * Move 5% faster for every overage. */
            int overInterpolation = (_transformProperties.Count - _interpolation);
            //If needs to be adjusted.
            if (overInterpolation != 0)
            {
                _movementMultiplier += (0.015f * overInterpolation);
            }
            //If does not need to be adjusted.
            else
            {
                //If interpolation is 1 then slow down just barely to accomodate for frame delta variance.
                if (_interpolation == 1)
                    _movementMultiplier = 1f;
            }

            _movementMultiplier = Mathf.Clamp(_movementMultiplier, 0.95f, 1.05f);
        }

        /// <summary>
        /// Moves transform to target values.
        /// </summary>
        private void MoveToTarget(float delta)
        {
            if (Time.frameCount < _startFrame)
                return;
            int tpCount = _transformProperties.Count;
            //No data.
            if (tpCount == 0)
                return;
            /* If buffer is considerably under goal then halt
             * movement. This will allow the buffer to grow. */
            if ((tpCount - _interpolation) < -4)
                return;

            TickTransformProperties ttp = _transformProperties.Peek();
            TransformPropertiesFlag smoothedProperties = (_useOwnerSmoothing) ? _ownerSmoothedProperties : _spectatorSmoothedProperties;
            _moveRates.Move(_graphicalObject, ttp.Properties, smoothedProperties, (delta * _movementMultiplier), useWorldSpace: true);

            float tRemaining = _moveRates.TimeRemaining;
            //if TimeLeft is <= 0f then transform is at goal. Grab a new goal if possible.
            if (tRemaining <= 0f)
            {
                //Dequeue current entry and if there's another call a move on it.
                _transformProperties.Dequeue();

                //If there are entries left then setup for the next.
                if (_transformProperties.Count > 0)
                {
                    SetMoveRates(ttp.Properties);
                    //If delta is negative then call move again with abs.
                    if (tRemaining < 0f)
                        MoveToTarget(Mathf.Abs(tRemaining));
                }
                //No remaining, set to snap.
                else
                {
                    ClearTransformPropertiesQueue();
                }
            }
        }

        public void ResetState()
        {
            if (_initializeType == InitializeType.Unset)
                return;

            if (_graphicalObject != null)
            {
                if (_rootTransform != null)
                {
                    //Check isQuitting for UnityEditor fix //https://github.com/FirstGearGames/FishNet/issues/818
                    if (_detach && !ApplicationState.IsQuitting())
                        _graphicalObject.SetParent(_rootTransform);
                    _graphicalObject.SetWorldProperties(GetNetworkObjectWorldPropertiesWithOffset());
                    _graphicalObject = null;
                }
                else if (_detach)
                {
                    UnityEngine.Object.Destroy(_graphicalObject.gameObject);
                }
            }

            _networkObject = null;
            _teleportedTick = TimeManager.UNSET_TICK;
            _lastReconcileTick = TimeManager.UNSET_TICK;
            _movementMultiplier = 1f;
            CollectionCaches<TickTransformProperties>.StoreAndDefault(ref _transformProperties);
            _teleportThreshold = default;
            _moveRates = default;
            _preTicked = default;
            _gfxInitializedOffsetValues = default;
            _gfxPreSimulateWorldValues = default;
            _tickDelta = default;
            _interpolation = default;
        }

        public void InitializeState() { }
    }
}