using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;
using UnityEngine.Graphing;

namespace UnityEngine.MaterialGraph
{
    [Serializable]
    [Title("Master/Custom Texture")]
    public class ExportTextureMasterNode : AbstractMasterNode
    {
        public const string ColorSlotName = "Color";
        public const int ColorSlotId = 0;

        public ExportTextureMasterNode()
        {
            name = "ExportTextureMasterNode";
            UpdateNodeAfterDeserialization();
        }

        public sealed override void UpdateNodeAfterDeserialization()
        {
            AddSlot(new MaterialSlot(ColorSlotId, ColorSlotName, ColorSlotName, SlotType.Input, SlotValueType.Vector4, Vector4.zero));

            // clear out slot names that do not match the slots we support
            RemoveSlotsNameNotMatching(new[] { ColorSlotId });
        }

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

        public override string GetSubShader(GenerationMode mode, PropertyGenerator shaderPropertiesVisitor)
        {
            return "";
        }

        public override bool has3DPreview()
        {
            return false;
        }

        public override string GetFullShader(GenerationMode generationMode, string name, out List<PropertyGenerator.TextureInfo> configuredTextures)
        {
            // figure out what kind of preview we want!
            var activeNodeList = ListPool<INode>.Get();
            NodeUtils.DepthFirstCollectNodesFromNode(activeNodeList, this);

            string templateLocation = ShaderGenerator.GetTemplatePath("ExportTexture.template");
            if (!File.Exists(templateLocation))
            {
                configuredTextures = new List<PropertyGenerator.TextureInfo>();
                return string.Empty;
            }

            string template = File.ReadAllText(templateLocation);

            var shaderBodyVisitor = new ShaderGenerator();
            var shaderFunctionVisitor = new ShaderGenerator();
            var shaderPropertiesVisitor = new PropertyGenerator();
            var shaderPropertyUsagesVisitor = new ShaderGenerator();
            var shaderInputVisitor = new ShaderGenerator();

            // always add color because why not.
            shaderInputVisitor.AddShaderChunk("float4 color : COLOR;", true);

            bool needBitangent = activeNodeList.OfType<IMayRequireBitangent>().Any(x => x.RequiresBitangent());
            bool needsWorldPos = activeNodeList.OfType<IMayRequireViewDirection>().Any(x => x.RequiresViewDirection());
            if (needsWorldPos || activeNodeList.OfType<IMayRequireWorldPosition>().Any(x => x.RequiresWorldPosition()))
            {
                shaderBodyVisitor.AddShaderChunk("float3 " + ShaderGeneratorNames.WorldSpacePosition + " = float3(0.0, 0.0, 0.0);", true);
            }

            if (needBitangent || activeNodeList.OfType<IMayRequireNormal>().Any(x => x.RequiresNormal()))
            {
                shaderBodyVisitor.AddShaderChunk("float3 " + ShaderGeneratorNames.WorldSpaceNormal + " = float3(0.0, 0.0, 1.0);", true);
            }

            for (int uvIndex = 0; uvIndex < ShaderGeneratorNames.UVCount; ++uvIndex)
            {
                var channel = (UVChannel)uvIndex;
                if (activeNodeList.OfType<IMayRequireMeshUV>().Any(x => x.RequiresMeshUV(channel)))
                {
                    shaderBodyVisitor.AddShaderChunk("half4 " + channel.GetUVName() + " = float4(IN.localTexcoord.xyz,1.0);", true);
                }
            }

            if (activeNodeList.OfType<IMayRequireViewDirection>().Any(x => x.RequiresViewDirection()))
            {
                shaderBodyVisitor.AddShaderChunk("float3 " + ShaderGeneratorNames.WorldSpaceViewDirection + " = float3(0.0, 0.0, -1.0);", true);
            }

            if (activeNodeList.OfType<IMayRequireScreenPosition>().Any(x => x.RequiresScreenPosition()))
            {
                shaderBodyVisitor.AddShaderChunk("half4 " + ShaderGeneratorNames.ScreenPosition + " = float4(IN.globalTexcoord.xyz, 1.0);", true);
            }
            if (needBitangent || activeNodeList.OfType<IMayRequireTangent>().Any(x => x.RequiresTangent()))
            {
                shaderBodyVisitor.AddShaderChunk("float3 " + ShaderGeneratorNames.WorldSpaceTangent + " = float3(1.0,0.0,0.0);", true);
            }
            if (needBitangent)
            {
                shaderBodyVisitor.AddShaderChunk("float3 " + ShaderGeneratorNames.WorldSpaceBitangent + " = float3(0.0,1.0,0.0);", true);
            }

            if (activeNodeList.OfType<IMayRequireVertexColor>().Any(x => x.RequiresVertexColor()))
            {
                shaderBodyVisitor.AddShaderChunk("float4 " + ShaderGeneratorNames.VertexColor + " = float4(1.0,1.0,1.0,1.0);", true);
            }

            foreach (var activeNode in activeNodeList.OfType<AbstractMaterialNode>())
            {
                if (activeNode is IGeneratesFunction)
                    (activeNode as IGeneratesFunction).GenerateNodeFunction(shaderFunctionVisitor, generationMode);
                if (activeNode is IGeneratesBodyCode)
                    (activeNode as IGeneratesBodyCode).GenerateNodeCode(shaderBodyVisitor, generationMode);

                activeNode.GeneratePropertyBlock(shaderPropertiesVisitor, generationMode);
                activeNode.GeneratePropertyUsages(shaderPropertyUsagesVisitor, generationMode);
            }

            var inputSlot = GetInputSlots<MaterialSlot>().First();
            var edges = owner.GetEdges(inputSlot.slotReference);
            if (edges.Count() > 0)
            {
                var outputRef = edges.First().outputSlot;
                var fromNode = owner.GetNodeFromGuid<AbstractMaterialNode>(outputRef.nodeGuid);
                shaderBodyVisitor.AddShaderChunk("return " + fromNode.GetVariableNameForSlot(outputRef.slotId) + ";", true);
            }
            else
            {
                shaderBodyVisitor.AddShaderChunk("return float4(0.5, 0.5, 0.5, 0.5);", true);
            }

            ListPool<INode>.Release(activeNodeList);

            template = template.Replace("${ShaderName}", name);
            template = template.Replace("${ShaderPropertiesHeader}", shaderPropertiesVisitor.GetShaderString(2));
            template = template.Replace("${ShaderPropertyUsages}", shaderPropertyUsagesVisitor.GetShaderString(3));
            template = template.Replace("${ShaderFunctions}", shaderFunctionVisitor.GetShaderString(3));
            template = template.Replace("${PixelShaderBody}", shaderBodyVisitor.GetShaderString(4));

            //In preview mode we use a different vertex shader, as the custom texture shaders are customized and not preview compatible.
            template = template.Replace("${ShaderIsUsingPreview}", generationMode == GenerationMode.Preview ? "_Preview" : "");

            configuredTextures = shaderPropertiesVisitor.GetConfiguredTexutres();
            return Regex.Replace(template, @"\r\n|\n\r|\n|\r", Environment.NewLine);
        }
    }
}