using System;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;
using UnityEditor.Graphing;

namespace UnityEditor.ShaderGraph
{
    public static class GuidEncoder
    {
        public static string Encode(Guid guid)
        {
            string enc = Convert.ToBase64String(guid.ToByteArray());
            return String.Format("{0:X}", enc.GetHashCode());
        }
    }

    [Serializable]
    public abstract class AbstractMaterialNode : INode, ISerializationCallbackReceiver, IGenerateProperties
    {
        protected static List<MaterialSlot> s_TempSlots = new List<MaterialSlot>();
        protected static List<IEdge> s_TempEdges = new List<IEdge>();

        public enum OutputPrecision
        {
            @fixed,
            @half,
            @float
        }

        [NonSerialized]
        private Guid m_Guid;

        [SerializeField]
        private string m_GuidSerialized;

        [SerializeField]
        private string m_Name;

        [SerializeField]
        private DrawState m_DrawState;

        [NonSerialized]
        private List<ISlot> m_Slots = new List<ISlot>();

        [SerializeField]
        List<SerializationHelper.JSONSerializedElement> m_SerializableSlots = new List<SerializationHelper.JSONSerializedElement>();

        [NonSerialized]
        private bool m_HasError;

        public Identifier tempId { get; set; }

        public IGraph owner { get; set; }

        public OnNodeModified onModified { get; set; }

        public void Dirty(ModificationScope scope)
        {
            if (onModified != null)
                onModified(this, scope);
        }

        public Guid guid
        {
            get { return m_Guid; }
        }

        public string name
        {
            get { return m_Name; }
            set { m_Name = value; }
        }

        public virtual string documentationURL
        {
            get { return null; }
        }

        public virtual bool canDeleteNode
        {
            get { return true; }
        }

        public DrawState drawState
        {
            get { return m_DrawState; }
            set
            {
                m_DrawState = value;
                Dirty(ModificationScope.Node);
            }
        }

        private OutputPrecision m_OutputPrecision = OutputPrecision.@float;

        public OutputPrecision precision
        {
            get { return m_OutputPrecision; }
            set { m_OutputPrecision = value; }
        }

        [SerializeField]
        bool m_PreviewExpanded = true;

        public bool previewExpanded
        {
            get { return m_PreviewExpanded; }
            set
            {
                if (previewExpanded == value)
                    return;
                m_PreviewExpanded = value;
                Dirty(ModificationScope.Node);
            }
        }

        // Nodes that want to have a preview area can override this and return true
        public virtual bool hasPreview
        {
            get { return false; }
        }

        public virtual PreviewMode previewMode
        {
            get { return PreviewMode.Preview2D; }
        }

        public virtual bool allowedInSubGraph
        {
            get { return true; }
        }
        
        public virtual bool allowedInMainGraph
        {
            get { return true; }
        }

        public virtual bool allowedInLayerGraph
        {
            get { return true; }
        }

        public virtual bool hasError
        {
            get { return m_HasError; }
            protected set { m_HasError = value; }
        }

        string m_DefaultVariableName;
        string m_NameForDefaultVariableName;
        Guid m_GuidForDefaultVariableName;

        string defaultVariableName
        {
            get
            {
                if (m_NameForDefaultVariableName != name || m_GuidForDefaultVariableName != guid)
                {
                    m_DefaultVariableName = string.Format("{0}_{1}", NodeUtils.GetHLSLSafeName(name), GuidEncoder.Encode(guid));
                    m_NameForDefaultVariableName = name;
                    m_GuidForDefaultVariableName = guid;
                }
                return m_DefaultVariableName;
            }
        }

        protected AbstractMaterialNode()
        {
            m_DrawState.expanded = true;
            m_Guid = Guid.NewGuid();
            version = 0;
        }

        public Guid RewriteGuid()
        {
            m_Guid = Guid.NewGuid();
            return m_Guid;
        }

        public void GetInputSlots<T>(List<T> foundSlots) where T : ISlot
        {
            foreach (var slot in m_Slots)
            {
                if (slot.isInputSlot && slot is T)
                    foundSlots.Add((T)slot);
            }
        }

        public void GetOutputSlots<T>(List<T> foundSlots) where T : ISlot
        {
            foreach (var slot in m_Slots)
            {
                if (slot.isOutputSlot && slot is T)
                    foundSlots.Add((T)slot);
            }
        }

        public void GetSlots<T>(List<T> foundSlots) where T : ISlot
        {
            foreach (var slot in m_Slots)
            {
                if (slot is T)
                    foundSlots.Add((T)slot);
            }
        }

        public virtual void CollectShaderProperties(PropertyCollector properties, GenerationMode generationMode)
        {
            foreach (var inputSlot in this.GetInputSlots<MaterialSlot>())
            {
                var edges = owner.GetEdges(inputSlot.slotReference);
                if (edges.Any())
                    continue;

                inputSlot.AddDefaultProperty(properties, generationMode);
            }
        }

        public string GetSlotValue(int inputSlotId, GenerationMode generationMode)
        {
            var inputSlot = FindSlot<MaterialSlot>(inputSlotId);
            if (inputSlot == null)
                return string.Empty;

            var edges = owner.GetEdges(inputSlot.slotReference).ToArray();

            if (edges.Any())
            {
                var fromSocketRef = edges[0].outputSlot;
                var fromNode = owner.GetNodeFromGuid<AbstractMaterialNode>(fromSocketRef.nodeGuid);
                if (fromNode == null)
                    return string.Empty;

                var slot = fromNode.FindOutputSlot<MaterialSlot>(fromSocketRef.slotId);
                if (slot == null)
                    return string.Empty;

                return ShaderGenerator.AdaptNodeOutput(fromNode, slot.id, inputSlot.concreteValueType);
            }

            return inputSlot.GetDefaultValue(generationMode);
        }

        private static bool ImplicitConversionExists(ConcreteSlotValueType from, ConcreteSlotValueType to)
        {
            if (from == to)
                return true;

            var fromCount = SlotValueHelper.GetChannelCount(from);
            var toCount = SlotValueHelper.GetChannelCount(to);


            // can convert from v1 vectors :)
            if (from == ConcreteSlotValueType.Vector1 && toCount > 0)
                return true;

            if (toCount == 0)
                return false;

            if (toCount <= fromCount)
                return true;

            return false;
        }

        private ConcreteSlotValueType ConvertDynamicInputTypeToConcrete(IEnumerable<ConcreteSlotValueType> inputTypes)
        {
            var concreteSlotValueTypes = inputTypes as IList<ConcreteSlotValueType> ?? inputTypes.ToList();

            var inputTypesDistinct = concreteSlotValueTypes.Distinct().ToList();
            switch (inputTypesDistinct.Count)
            {
                case 0:
                    return ConcreteSlotValueType.Vector1;
                case 1:
                    return inputTypesDistinct.FirstOrDefault();
                default:
                    // find the 'minumum' channel width excluding 1 as it can promote
                    inputTypesDistinct.RemoveAll(x => x == ConcreteSlotValueType.Vector1);
                    var ordered = inputTypesDistinct.OrderByDescending(x => x);
                    if (ordered.Any())
                        return ordered.FirstOrDefault();
                    break;
            }
            return ConcreteSlotValueType.Vector1;
        }

        public virtual void ValidateNode()
        {
            var isInError = false;

            // all children nodes needs to be updated first
            // so do that here
            var slots = ListPool<MaterialSlot>.Get();
            GetInputSlots(slots);
            foreach (var inputSlot in slots)
            {
                inputSlot.hasError = false;

                var edges = owner.GetEdges(inputSlot.slotReference);
                foreach (var edge in edges)
                {
                    var fromSocketRef = edge.outputSlot;
                    var outputNode = owner.GetNodeFromGuid(fromSocketRef.nodeGuid);
                    if (outputNode == null)
                        continue;

                    outputNode.ValidateNode();
                    if (outputNode.hasError)
                        isInError = true;
                }
            }
            ListPool<MaterialSlot>.Release(slots);

            var dynamicInputSlotsToCompare = DictionaryPool<DynamicVectorMaterialSlot, ConcreteSlotValueType>.Get();
            var skippedDynamicSlots = ListPool<DynamicVectorMaterialSlot>.Get();

            // iterate the input slots
            s_TempSlots.Clear();
            GetInputSlots(s_TempSlots);
            foreach (var inputSlot in s_TempSlots)
            {
                // if there is a connection
                var edges = owner.GetEdges(inputSlot.slotReference).ToList();
                if (!edges.Any())
                {
                    if (inputSlot is DynamicVectorMaterialSlot)
                        skippedDynamicSlots.Add(inputSlot as DynamicVectorMaterialSlot);
                    continue;
                }

                // get the output details
                var outputSlotRef = edges[0].outputSlot;
                var outputNode = owner.GetNodeFromGuid(outputSlotRef.nodeGuid);
                if (outputNode == null)
                    continue;

                var outputSlot = outputNode.FindOutputSlot<MaterialSlot>(outputSlotRef.slotId);
                if (outputSlot == null)
                    continue;

                if (outputSlot.hasError)
                {
                    inputSlot.hasError = true;
                    continue;
                }

                var outputConcreteType = outputSlot.concreteValueType;
                // dynamic input... depends on output from other node.
                // we need to compare ALL dynamic inputs to make sure they
                // are compatable.
                if (inputSlot is DynamicVectorMaterialSlot)
                {
                    dynamicInputSlotsToCompare.Add((DynamicVectorMaterialSlot)inputSlot, outputConcreteType);
                    continue;
                }

                // if we have a standard connection... just check the types work!
                if (!ImplicitConversionExists(outputConcreteType, inputSlot.concreteValueType))
                    inputSlot.hasError = true;
            }

            // we can now figure out the dynamic slotType
            // from here set all the
            var dynamicType = ConvertDynamicInputTypeToConcrete(dynamicInputSlotsToCompare.Values);
            foreach (var dynamicKvP in dynamicInputSlotsToCompare)
                dynamicKvP.Key.SetConcreteType(dynamicType);
            foreach (var skippedSlot in skippedDynamicSlots)
                skippedSlot.SetConcreteType(dynamicType);

            s_TempSlots.Clear();
            GetInputSlots(s_TempSlots);
            var inputError = s_TempSlots.Any(x => x.hasError);

            // configure the output slots now
            // their slotType will either be the default output slotType
            // or the above dynanic slotType for dynamic nodes
            // or error if there is an input error
            s_TempSlots.Clear();
            GetOutputSlots(s_TempSlots);
            foreach (var outputSlot in s_TempSlots)
            {
                outputSlot.hasError = false;

                if (inputError)
                {
                    outputSlot.hasError = true;
                    continue;
                }

                if (outputSlot is DynamicVectorMaterialSlot)
                {
                    (outputSlot as DynamicVectorMaterialSlot).SetConcreteType(dynamicType);
                    continue;
                }
            }

            isInError |= inputError;
            s_TempSlots.Clear();
            GetOutputSlots(s_TempSlots);
            isInError |= s_TempSlots.Any(x => x.hasError);
            isInError |= CalculateNodeHasError();
            hasError = isInError;

            if (!hasError)
            {
                ++version;
            }

            ListPool<DynamicVectorMaterialSlot>.Release(skippedDynamicSlots);
            DictionaryPool<DynamicVectorMaterialSlot, ConcreteSlotValueType>.Release(dynamicInputSlotsToCompare);
        }

        public int version { get; private set; }

        //True if error
        protected virtual bool CalculateNodeHasError()
        {
            return false;
        }

        public virtual void CollectPreviewMaterialProperties(List<PreviewProperty> properties)
        {
            s_TempSlots.Clear();
            GetInputSlots(s_TempSlots);
            foreach (var s in s_TempSlots)
            {
                s_TempEdges.Clear();
                owner.GetEdges(s.slotReference, s_TempEdges);
                if (s_TempEdges.Any())
                    continue;

                var item = s.GetPreviewProperty(GetVariableNameForSlot(s.id));
                if (item.name == null)
                    continue;

                properties.Add(item);
            }
        }

        public virtual string GetVariableNameForSlot(int slotId)
        {
            var slot = FindSlot<MaterialSlot>(slotId);
            if (slot == null)
                throw new ArgumentException(string.Format("Attempting to use MaterialSlot({0}) on node of type {1} where this slot can not be found", slotId, this), "slotId");
            return string.Format("_{0}_{1}", GetVariableNameForNode(), NodeUtils.GetHLSLSafeName(slot.shaderOutputName));
        }

        public virtual string GetVariableNameForNode()
        {
            return defaultVariableName;
        }

        public void AddSlot(ISlot slot)
        {
            if (!(slot is MaterialSlot))
                throw new ArgumentException(string.Format("Trying to add slot {0} to Material node {1}, but it is not a {2}", slot, this, typeof(MaterialSlot)));

            var addingSlot = (MaterialSlot)slot;
            var foundSlot = FindSlot<MaterialSlot>(slot.id);

            // this will remove the old slot and add a new one
            // if an old one was found. This allows updating values
            m_Slots.RemoveAll(x => x.id == slot.id);
            m_Slots.Add(slot);
            slot.owner = this;

            Dirty(ModificationScope.Topological);

            if (foundSlot == null)
                return;

            addingSlot.CopyValuesFrom(foundSlot);
        }

        public void RemoveSlot(int slotId)
        {
            // Remove edges that use this slot
            // no owner can happen after creation
            // but before added to graph
            if (owner != null)
            {
                var edges = owner.GetEdges(GetSlotReference(slotId));

                foreach (var edge in edges.ToArray())
                    owner.RemoveEdge(edge);
            }

            //remove slots
            m_Slots.RemoveAll(x => x.id == slotId);

            Dirty(ModificationScope.Topological);
        }

        public void RemoveSlotsNameNotMatching(IEnumerable<int> slotIds, bool supressWarnings = false)
        {
            var invalidSlots = m_Slots.Select(x => x.id).Except(slotIds);

            foreach (var invalidSlot in invalidSlots.ToArray())
            {
                if (!supressWarnings)
                    Debug.LogWarningFormat("Removing Invalid MaterialSlot: {0}", invalidSlot);
                RemoveSlot(invalidSlot);
            }
        }

        public SlotReference GetSlotReference(int slotId)
        {
            var slot = FindSlot<ISlot>(slotId);
            if (slot == null)
                throw new ArgumentException("Slot could not be found", "slotId");
            return new SlotReference(guid, slotId);
        }

        public T FindSlot<T>(int slotId) where T : ISlot
        {
            foreach (var slot in m_Slots)
            {
                if (slot.id == slotId && slot is T)
                    return (T)slot;
            }
            return default(T);
        }

        public T FindInputSlot<T>(int slotId) where T : ISlot
        {
            foreach (var slot in m_Slots)
            {
                if (slot.isInputSlot && slot.id == slotId && slot is T)
                    return (T)slot;
            }
            return default(T);
        }

        public T FindOutputSlot<T>(int slotId) where T : ISlot
        {
            foreach (var slot in m_Slots)
            {
                if (slot.isOutputSlot && slot.id == slotId && slot is T)
                    return (T)slot;
            }
            return default(T);
        }

        public virtual IEnumerable<ISlot> GetInputsWithNoConnection()
        {
            return this.GetInputSlots<ISlot>().Where(x => !owner.GetEdges(GetSlotReference(x.id)).Any());
        }

        public virtual void OnBeforeSerialize()
        {
            m_GuidSerialized = m_Guid.ToString();
            m_SerializableSlots = SerializationHelper.Serialize<ISlot>(m_Slots);
        }

        public virtual void OnAfterDeserialize()
        {
            if (!string.IsNullOrEmpty(m_GuidSerialized))
                m_Guid = new Guid(m_GuidSerialized);
            else
                m_Guid = Guid.NewGuid();

            m_Slots = SerializationHelper.Deserialize<ISlot>(m_SerializableSlots, GraphUtil.GetLegacyTypeRemapping());
            m_SerializableSlots = null;
            foreach (var s in m_Slots)
                s.owner = this;
            UpdateNodeAfterDeserialization();
        }

        public virtual void UpdateNodeAfterDeserialization()
        {}

        public bool IsSlotConnected(int slotId)
        {
            var slot = FindSlot<MaterialSlot>(slotId);
            return slot != null && owner.GetEdges(slot.slotReference).Any();
        }
    }
}