using Unity.Collections;
using Unity.Collections.LowLevel.Unsafe;
using UnityEngine;

namespace Unity.Netcode.Components
{
    /// <summary>
    /// A prototype component for syncing animations
    /// </summary>
    [AddComponentMenu("Netcode/" + nameof(NetworkAnimator))]
    [RequireComponent(typeof(Animator))]
    public class NetworkAnimator : NetworkBehaviour
    {
        internal struct AnimationMessage : INetworkSerializable
        {
            // state hash per layer.  if non-zero, then Play() this animation, skipping transitions
            public int StateHash;
            public float NormalizedTime;
            public int Layer;
            public float Weight;
            public byte[] Parameters;

            public void NetworkSerialize<T>(BufferSerializer<T> serializer) where T : IReaderWriter
            {
                serializer.SerializeValue(ref StateHash);
                serializer.SerializeValue(ref NormalizedTime);
                serializer.SerializeValue(ref Layer);
                serializer.SerializeValue(ref Weight);
                serializer.SerializeValue(ref Parameters);
            }
        }

        internal struct AnimationTriggerMessage : INetworkSerializable
        {
            public int Hash;
            public bool Reset;

            public void NetworkSerialize<T>(BufferSerializer<T> serializer) where T : IReaderWriter
            {
                serializer.SerializeValue(ref Hash);
                serializer.SerializeValue(ref Reset);
            }
        }

        [SerializeField] private Animator m_Animator;

        public Animator Animator
        {
            get { return m_Animator; }
            set
            {
                m_Animator = value;
            }
        }

        private bool m_SendMessagesAllowed = false;

        // Animators only support up to 32 params
        public static int K_MaxAnimationParams = 32;

        private int[] m_TransitionHash;
        private int[] m_AnimationHash;
        private float[] m_LayerWeights;

        private unsafe struct AnimatorParamCache
        {
            public int Hash;
            public int Type;
            public fixed byte Value[4]; // this is a max size of 4 bytes
        }

        // 128 bytes per Animator
        private FastBufferWriter m_ParameterWriter = new FastBufferWriter(K_MaxAnimationParams * sizeof(float), Allocator.Persistent);
        private NativeArray<AnimatorParamCache> m_CachedAnimatorParameters;

        // We cache these values because UnsafeUtility.EnumToInt uses direct IL that allows a non-boxing conversion
        private struct AnimationParamEnumWrapper
        {
            public static readonly int AnimatorControllerParameterInt;
            public static readonly int AnimatorControllerParameterFloat;
            public static readonly int AnimatorControllerParameterBool;

            static AnimationParamEnumWrapper()
            {
                AnimatorControllerParameterInt = UnsafeUtility.EnumToInt(AnimatorControllerParameterType.Int);
                AnimatorControllerParameterFloat = UnsafeUtility.EnumToInt(AnimatorControllerParameterType.Float);
                AnimatorControllerParameterBool = UnsafeUtility.EnumToInt(AnimatorControllerParameterType.Bool);
            }
        }

        public override void OnDestroy()
        {
            if (m_CachedAnimatorParameters.IsCreated)
            {
                m_CachedAnimatorParameters.Dispose();
            }

            m_ParameterWriter.Dispose();
        }

        public override void OnNetworkSpawn()
        {
            if (IsServer)
            {
                m_SendMessagesAllowed = true;
                int layers = m_Animator.layerCount;

                m_TransitionHash = new int[layers];
                m_AnimationHash = new int[layers];
                m_LayerWeights = new float[layers];
            }

            var parameters = m_Animator.parameters;
            m_CachedAnimatorParameters = new NativeArray<AnimatorParamCache>(parameters.Length, Allocator.Persistent);

            for (var i = 0; i < parameters.Length; i++)
            {
                var parameter = parameters[i];

                if (m_Animator.IsParameterControlledByCurve(parameter.nameHash))
                {
                    // we are ignoring parameters that are controlled by animation curves - syncing the layer
                    //  states indirectly syncs the values that are driven by the animation curves
                    continue;
                }

                var cacheParam = new AnimatorParamCache
                {
                    Type = UnsafeUtility.EnumToInt(parameter.type),
                    Hash = parameter.nameHash
                };

                unsafe
                {
                    switch (parameter.type)
                    {
                        case AnimatorControllerParameterType.Float:
                            var value = m_Animator.GetFloat(cacheParam.Hash);
                            UnsafeUtility.WriteArrayElement(cacheParam.Value, 0, value);
                            break;
                        case AnimatorControllerParameterType.Int:
                            var valueInt = m_Animator.GetInteger(cacheParam.Hash);
                            UnsafeUtility.WriteArrayElement(cacheParam.Value, 0, valueInt);

                            break;
                        case AnimatorControllerParameterType.Bool:
                            var valueBool = m_Animator.GetBool(cacheParam.Hash);
                            UnsafeUtility.WriteArrayElement(cacheParam.Value, 0, valueBool);
                            break;
                        case AnimatorControllerParameterType.Trigger:
                        default:
                            break;
                    }
                }

                m_CachedAnimatorParameters[i] = cacheParam;
            }
        }

        public override void OnNetworkDespawn()
        {
            m_SendMessagesAllowed = false;
        }

        private void FixedUpdate()
        {
            if (!m_SendMessagesAllowed || !m_Animator || !m_Animator.enabled)
            {
                return;
            }

            for (int layer = 0; layer < m_Animator.layerCount; layer++)
            {
                int stateHash;
                float normalizedTime;
                if (!CheckAnimStateChanged(out stateHash, out normalizedTime, layer))
                {
                    continue;
                }

                var animMsg = new AnimationMessage
                {
                    StateHash = stateHash,
                    NormalizedTime = normalizedTime,
                    Layer = layer,
                    Weight = m_LayerWeights[layer]
                };

                m_ParameterWriter.Seek(0);
                m_ParameterWriter.Truncate();

                WriteParameters(m_ParameterWriter);
                animMsg.Parameters = m_ParameterWriter.ToArray();

                SendAnimStateClientRpc(animMsg);
            }
        }

        private bool CheckAnimStateChanged(out int stateHash, out float normalizedTime, int layer)
        {
            bool shouldUpdate = false;
            stateHash = 0;
            normalizedTime = 0;

            float layerWeightNow = m_Animator.GetLayerWeight(layer);

            if (!Mathf.Approximately(layerWeightNow, m_LayerWeights[layer]))
            {
                m_LayerWeights[layer] = layerWeightNow;
                shouldUpdate = true;
            }
            if (m_Animator.IsInTransition(layer))
            {
                AnimatorTransitionInfo tt = m_Animator.GetAnimatorTransitionInfo(layer);
                if (tt.fullPathHash != m_TransitionHash[layer])
                {
                    // first time in this transition for this layer
                    m_TransitionHash[layer] = tt.fullPathHash;
                    m_AnimationHash[layer] = 0;
                    shouldUpdate = true;
                }
            }
            else
            {
                AnimatorStateInfo st = m_Animator.GetCurrentAnimatorStateInfo(layer);
                if (st.fullPathHash != m_AnimationHash[layer])
                {
                    // first time in this animation state
                    if (m_AnimationHash[layer] != 0)
                    {
                        // came from another animation directly - from Play()
                        stateHash = st.fullPathHash;
                        normalizedTime = st.normalizedTime;
                    }
                    m_TransitionHash[layer] = 0;
                    m_AnimationHash[layer] = st.fullPathHash;
                    shouldUpdate = true;
                }
            }

            return shouldUpdate;
        }

        /* $AS TODO: Right now we are not checking for changed values this is because
        the read side of this function doesn't have similar logic which would cause
        an overflow read because it doesn't know if the value is there or not. So
        there needs to be logic to track which indexes changed in order for there
        to be proper value change checking. Will revist in 1.1.0.
        */
        private unsafe void WriteParameters(FastBufferWriter writer)
        {
            for (int i = 0; i < m_CachedAnimatorParameters.Length; i++)
            {
                ref var cacheValue = ref UnsafeUtility.ArrayElementAsRef<AnimatorParamCache>(m_CachedAnimatorParameters.GetUnsafePtr(), i);
                var hash = cacheValue.Hash;

                if (cacheValue.Type == AnimationParamEnumWrapper.AnimatorControllerParameterInt)
                {
                    var valueInt = m_Animator.GetInteger(hash);
                    fixed (void* value = cacheValue.Value)
                    {
                        UnsafeUtility.WriteArrayElement(value, 0, valueInt);
                        BytePacker.WriteValuePacked(writer, (uint)valueInt);
                    }
                }
                else if (cacheValue.Type == AnimationParamEnumWrapper.AnimatorControllerParameterBool)
                {
                    var valueBool = m_Animator.GetBool(hash);
                    fixed (void* value = cacheValue.Value)
                    {
                        UnsafeUtility.WriteArrayElement(value, 0, valueBool);
                        writer.WriteValueSafe(valueBool);
                    }
                }
                else if (cacheValue.Type == AnimationParamEnumWrapper.AnimatorControllerParameterFloat)
                {
                    var valueFloat = m_Animator.GetFloat(hash);
                    fixed (void* value = cacheValue.Value)
                    {

                        UnsafeUtility.WriteArrayElement(value, 0, valueFloat);
                        writer.WriteValueSafe(valueFloat);
                    }
                }
            }
        }

        private unsafe void ReadParameters(FastBufferReader reader)
        {
            for (int i = 0; i < m_CachedAnimatorParameters.Length; i++)
            {
                ref var cacheValue = ref UnsafeUtility.ArrayElementAsRef<AnimatorParamCache>(m_CachedAnimatorParameters.GetUnsafePtr(), i);
                var hash = cacheValue.Hash;

                if (cacheValue.Type == AnimationParamEnumWrapper.AnimatorControllerParameterInt)
                {
                    ByteUnpacker.ReadValuePacked(reader, out int newValue);
                    m_Animator.SetInteger(hash, newValue);
                    fixed (void* value = cacheValue.Value)
                    {
                        UnsafeUtility.WriteArrayElement(value, 0, newValue);
                    }
                }
                else if (cacheValue.Type == AnimationParamEnumWrapper.AnimatorControllerParameterBool)
                {
                    reader.ReadValueSafe(out bool newBoolValue);
                    m_Animator.SetBool(hash, newBoolValue);
                    fixed (void* value = cacheValue.Value)
                    {
                        UnsafeUtility.WriteArrayElement(value, 0, newBoolValue);
                    }
                }
                else if (cacheValue.Type == AnimationParamEnumWrapper.AnimatorControllerParameterFloat)
                {
                    reader.ReadValueSafe(out float newFloatValue);
                    m_Animator.SetFloat(hash, newFloatValue);
                    fixed (void* value = cacheValue.Value)
                    {
                        UnsafeUtility.WriteArrayElement(value, 0, newFloatValue);
                    }
                }
            }
        }

        /// <summary>
        /// Internally-called RPC client receiving function to update some animation parameters on a client when
        ///   the server wants to update them
        /// </summary>
        /// <param name="animSnapshot">the payload containing the parameters to apply</param>
        /// <param name="clientRpcParams">unused</param>
        [ClientRpc]
        private unsafe void SendAnimStateClientRpc(AnimationMessage animSnapshot, ClientRpcParams clientRpcParams = default)
        {
            if (animSnapshot.StateHash != 0)
            {
                m_Animator.Play(animSnapshot.StateHash, animSnapshot.Layer, animSnapshot.NormalizedTime);
            }
            m_Animator.SetLayerWeight(animSnapshot.Layer, animSnapshot.Weight);

            if (animSnapshot.Parameters != null && animSnapshot.Parameters.Length != 0)
            {
                // We use a fixed value here to avoid the copy of data from the byte buffer since we own the data
                fixed (byte* parameters = animSnapshot.Parameters)
                {
                    var reader = new FastBufferReader(parameters, Allocator.None, animSnapshot.Parameters.Length);
                    ReadParameters(reader);
                }
            }
        }

        /// <summary>
        /// Internally-called RPC client receiving function to update a trigger when the server wants to forward
        ///   a trigger for a client to play / reset
        /// </summary>
        /// <param name="animSnapshot">the payload containing the trigger data to apply</param>
        /// <param name="clientRpcParams">unused</param>
        [ClientRpc]
        private void SendAnimTriggerClientRpc(AnimationTriggerMessage animSnapshot, ClientRpcParams clientRpcParams = default)
        {
            if (animSnapshot.Reset)
            {
                m_Animator.ResetTrigger(animSnapshot.Hash);
            }
            else
            {
                m_Animator.SetTrigger(animSnapshot.Hash);
            }
        }

        /// <summary>
        /// Sets the trigger for the associated animation
        ///  Note, triggers are special vs other kinds of parameters.  For all the other parameters we watch for changes
        ///  in FixedUpdate and users can just set them normally off of Animator. But because triggers are transitory
        ///  and likely to come and go between FixedUpdate calls, we require users to set them here to guarantee us to
        ///  catch it...then we forward it to the Animator component
        /// </summary>
        /// <param name="triggerName">The string name of the trigger to activate</param>
        public void SetTrigger(string triggerName)
        {
            SetTrigger(Animator.StringToHash(triggerName));
        }

        /// <summary>
        /// Sets the trigger for the associated animation.  See note for SetTrigger(string)
        /// </summary>
        /// <param name="hash">The hash for the trigger to activate</param>
        /// <param name="reset">If true, resets the trigger</param>
        public void SetTrigger(int hash, bool reset = false)
        {
            var animMsg = new AnimationTriggerMessage();
            animMsg.Hash = hash;
            animMsg.Reset = reset;

            if (IsServer)
            {
                //  trigger the animation locally on the server...
                if (reset)
                {
                    m_Animator.ResetTrigger(hash);
                }
                else
                {
                    m_Animator.SetTrigger(hash);
                }

                // ...then tell all the clients to do the same
                SendAnimTriggerClientRpc(animMsg);
            }
            else
            {
                Debug.LogWarning("Trying to call NetworkAnimator.SetTrigger on a client...ignoring");
            }
        }

        /// <summary>
        /// Resets the trigger for the associated animation.  See note for SetTrigger(string)
        /// </summary>
        /// <param name="triggerName">The string name of the trigger to reset</param>
        public void ResetTrigger(string triggerName)
        {
            ResetTrigger(Animator.StringToHash(triggerName));
        }

        /// <summary>
        /// Resets the trigger for the associated animation.  See note for SetTrigger(string)
        /// </summary>
        /// <param name="hash">The hash for the trigger to reset</param>
        public void ResetTrigger(int hash)
        {
            SetTrigger(hash, true);
        }
    }
}