using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;
using UnityEditor.ShaderGraph;
using UnityEngine;

namespace UnityEditor.Graphing
{
    class SlotConfigurationException : Exception
    {
        public SlotConfigurationException(string message)
            : base(message)
        {}
    }

    static class NodeUtils
    {
        public static string docURL = "https://github.com/Unity-Technologies/ScriptableRenderPipeline/tree/master/com.unity.shadergraph/Documentation%7E/";

        public static void SlotConfigurationExceptionIfBadConfiguration(AbstractMaterialNode node, IEnumerable<int> expectedInputSlots, IEnumerable<int> expectedOutputSlots)
        {
            var missingSlots = new List<int>();

            var inputSlots = expectedInputSlots as IList<int> ?? expectedInputSlots.ToList();
            missingSlots.AddRange(inputSlots.Except(node.GetInputSlots<ISlot>().Select(x => x.id)));

            var outputSlots = expectedOutputSlots as IList<int> ?? expectedOutputSlots.ToList();
            missingSlots.AddRange(outputSlots.Except(node.GetOutputSlots<ISlot>().Select(x => x.id)));

            if (missingSlots.Count == 0)
                return;

            var toPrint = missingSlots.Select(x => x.ToString());

            throw new SlotConfigurationException(string.Format("Missing slots {0} on node {1}", string.Join(", ", toPrint.ToArray()), node));
        }

        public static IEnumerable<IEdge> GetAllEdges(AbstractMaterialNode node)
        {
            var result = new List<IEdge>();
            var validSlots = ListPool<ISlot>.Get();

            validSlots.AddRange(node.GetInputSlots<ISlot>());
            for (int index = 0; index < validSlots.Count; index++)
            {
                var inputSlot = validSlots[index];
                result.AddRange(node.owner.GetEdges(inputSlot.slotReference));
            }

            validSlots.Clear();
            validSlots.AddRange(node.GetOutputSlots<ISlot>());
            for (int index = 0; index < validSlots.Count; index++)
            {
                var outputSlot = validSlots[index];
                result.AddRange(node.owner.GetEdges(outputSlot.slotReference));
            }

            ListPool<ISlot>.Release(validSlots);
            return result;
        }

        public static string GetDuplicateSafeNameForSlot(AbstractMaterialNode node, int slotId, string name)
        {
            List<MaterialSlot> slots = new List<MaterialSlot>();
            node.GetSlots(slots);

            name = name.Trim();
            return GraphUtil.SanitizeName(slots.Where(p => p.id != slotId).Select(p => p.RawDisplayName()), "{0} ({1})", name);
        }

        // CollectNodesNodeFeedsInto looks at the current node and calculates
        // which child nodes it depends on for it's calculation.
        // Results are returned depth first so by processing each node in
        // order you can generate a valid code block.
        public enum IncludeSelf
        {
            Include,
            Exclude
        }

        public static void DepthFirstCollectNodesFromNode(List<AbstractMaterialNode> nodeList, AbstractMaterialNode node, 
            IncludeSelf includeSelf = IncludeSelf.Include, IEnumerable<int> slotIds = null, List<KeyValuePair<ShaderKeyword, int>> keywordPermutation = null)
        {
            // no where to start
            if (node == null)
                return;

            // already added this node
            if (nodeList.Contains(node))
                return;

            IEnumerable<int> ids;

            // If this node is a keyword node and we have an active keyword permutation
            // The only valid port id is the port that corresponds to that keywords value in the active permutation
            if(node is KeywordNode keywordNode && keywordPermutation != null)
            {
                var valueInPermutation = keywordPermutation.Where(x => x.Key.guid == keywordNode.keywordGuid).FirstOrDefault();
                ids = new int[] { keywordNode.GetSlotIdForPermutation(valueInPermutation) };
            }
            else if (slotIds == null)
            {
                ids = node.GetInputSlots<ISlot>().Select(x => x.id);
            }
            else
            {
                ids = node.GetInputSlots<ISlot>().Where(x => slotIds.Contains(x.id)).Select(x => x.id);
            }

            foreach (var slot in ids)
            {
                foreach (var edge in node.owner.GetEdges(node.GetSlotReference(slot)))
                {
                    var outputNode = node.owner.GetNodeFromGuid(edge.outputSlot.nodeGuid);
                    if (outputNode != null)
                        DepthFirstCollectNodesFromNode(nodeList, outputNode, keywordPermutation: keywordPermutation);
                }
            }

            if (includeSelf == IncludeSelf.Include)
                nodeList.Add(node);
        }

        public static void CollectNodesNodeFeedsInto(List<AbstractMaterialNode> nodeList, AbstractMaterialNode node, IncludeSelf includeSelf = IncludeSelf.Include)
        {
            if (node == null)
                return;

            if (nodeList.Contains(node))
                return;

            foreach (var slot in node.GetOutputSlots<ISlot>())
            {
                foreach (var edge in node.owner.GetEdges(slot.slotReference))
                {
                    var inputNode = node.owner.GetNodeFromGuid(edge.inputSlot.nodeGuid);
                    CollectNodesNodeFeedsInto(nodeList, inputNode);
                }
            }
            if (includeSelf == IncludeSelf.Include)
                nodeList.Add(node);
        }

        public static string GetDocumentationString(AbstractMaterialNode node)
        {
            return $"{docURL}{node.name.Replace(" ", "-")}"+"-Node.md";
        }

        static Stack<MaterialSlot> s_SlotStack = new Stack<MaterialSlot>();

        public static ShaderStage GetEffectiveShaderStage(MaterialSlot initialSlot, bool goingBackwards)
        {
            var graph = initialSlot.owner.owner;
            s_SlotStack.Clear();
            s_SlotStack.Push(initialSlot);
            while (s_SlotStack.Any())
            {
                var slot = s_SlotStack.Pop();
                ShaderStage stage;
                if (slot.stageCapability.TryGetShaderStage(out stage))
                    return stage;

                if (goingBackwards && slot.isInputSlot)
                {
                    foreach (var edge in graph.GetEdges(slot.slotReference))
                    {
                        var node = graph.GetNodeFromGuid(edge.outputSlot.nodeGuid);
                        s_SlotStack.Push(node.FindOutputSlot<MaterialSlot>(edge.outputSlot.slotId));
                    }
                }
                else if (!goingBackwards && slot.isOutputSlot)
                {
                    foreach (var edge in graph.GetEdges(slot.slotReference))
                    {
                        var node = graph.GetNodeFromGuid(edge.inputSlot.nodeGuid);
                        s_SlotStack.Push(node.FindInputSlot<MaterialSlot>(edge.inputSlot.slotId));
                    }
                }
                else
                {
                    var ownerSlots = Enumerable.Empty<MaterialSlot>();
                    if (goingBackwards && slot.isOutputSlot)
                        ownerSlots = slot.owner.GetInputSlots<MaterialSlot>();
                    else if (!goingBackwards && slot.isInputSlot)
                        ownerSlots = slot.owner.GetOutputSlots<MaterialSlot>();
                    foreach (var ownerSlot in ownerSlots)
                        s_SlotStack.Push(ownerSlot);
                }
            }
            // We default to fragment shader stage if all connected nodes were compatible with both.
            return ShaderStage.Fragment;
        }

        public static ShaderStageCapability GetEffectiveShaderStageCapability(MaterialSlot initialSlot, bool goingBackwards)
        {
            var graph = initialSlot.owner.owner;
            s_SlotStack.Clear();
            s_SlotStack.Push(initialSlot);
            while (s_SlotStack.Any())
            {
                var slot = s_SlotStack.Pop();
                ShaderStage stage;
                if (slot.stageCapability.TryGetShaderStage(out stage))
                    return slot.stageCapability;

                if (goingBackwards && slot.isInputSlot)
                {
                    foreach (var edge in graph.GetEdges(slot.slotReference))
                    {
                        var node = graph.GetNodeFromGuid(edge.outputSlot.nodeGuid);
                        s_SlotStack.Push(node.FindOutputSlot<MaterialSlot>(edge.outputSlot.slotId));
                    }
                }
                else if (!goingBackwards && slot.isOutputSlot)
                {
                    foreach (var edge in graph.GetEdges(slot.slotReference))
                    {
                        var node = graph.GetNodeFromGuid(edge.inputSlot.nodeGuid);
                        s_SlotStack.Push(node.FindInputSlot<MaterialSlot>(edge.inputSlot.slotId));
                    }
                }
                else
                {
                    var ownerSlots = Enumerable.Empty<MaterialSlot>();
                    if (goingBackwards && slot.isOutputSlot)
                        ownerSlots = slot.owner.GetInputSlots<MaterialSlot>();
                    else if (!goingBackwards && slot.isInputSlot)
                        ownerSlots = slot.owner.GetOutputSlots<MaterialSlot>();
                    foreach (var ownerSlot in ownerSlots)
                        s_SlotStack.Push(ownerSlot);
                }
            }

            return ShaderStageCapability.All;
        }

        public static string GetSlotDimension(ConcreteSlotValueType slotValue)
        {
            switch (slotValue)
            {
                case ConcreteSlotValueType.Vector1:
                    return String.Empty;
                case ConcreteSlotValueType.Vector2:
                    return "2";
                case ConcreteSlotValueType.Vector3:
                    return "3";
                case ConcreteSlotValueType.Vector4:
                    return "4";
                case ConcreteSlotValueType.Matrix2:
                    return "2x2";
                case ConcreteSlotValueType.Matrix3:
                    return "3x3";
                case ConcreteSlotValueType.Matrix4:
                    return "4x4";
                default:
                    return "Error";
            }
        }

        public static string GetHLSLSafeName(string input)
        {
            char[] arr = input.ToCharArray();
            arr = Array.FindAll<char>(arr, (c => (Char.IsLetterOrDigit(c))));
            var safeName = new string(arr);
            if (safeName.Length > 1 && char.IsDigit(safeName[0]))
            {
                safeName = $"var{safeName}";
            }
            return safeName;
        }

        private static string GetDisplaySafeName(string input)
        {
            //strip valid display characters from slot name
            //current valid characters are whitespace and ( ) _ separators
            StringBuilder cleanName = new StringBuilder();
            foreach (var c in input)
            {
                if (c != ' ' && c != '(' && c != ')' && c != '_')
                    cleanName.Append(c);
            }

            return cleanName.ToString();
        }

        public static bool ValidateSlotName(string inName, out string errorMessage)
        {
            //check for invalid characters between display safe and hlsl safe name
            if (GetDisplaySafeName(inName) != GetHLSLSafeName(inName))
            {
                errorMessage = "Slot name(s) found invalid character(s). Valid characters: A-Z, a-z, 0-9, _ ( ) ";
                return true;
            }

            //if clean, return null and false
            errorMessage = null;
            return false;
        }

        public static string FloatToShaderValue(float value)
        {
            if (Single.IsPositiveInfinity(value))
                return "1.#INF";
            else if (Single.IsNegativeInfinity(value))
                return "-1.#INF";
            else if (Single.IsNaN(value))
                return "NAN";
            else
            {
                return value.ToString(CultureInfo.InvariantCulture);
            }
        }
    }
}