using System;
using System.Collections.Generic;
using System.Linq;
#if UNITY_EDITOR
using UnityEditor;
#endif
using UnityEngine.Graphing;

namespace UnityEngine.MaterialGraph
{
    [Title("Input/TextureLOD")]
    public class TextureLODNode : PropertyNode, IGeneratesBodyCode, IMayRequireMeshUV
    {
        protected const string kUVSlotName = "UV";
        protected const string kLODSlotName = "MipMap Level";
        protected const string kOutputSlotRGBAName = "RGBA";
        protected const string kOutputSlotRName = "R";
        protected const string kOutputSlotGName = "G";
        protected const string kOutputSlotBName = "B";
        protected const string kOutputSlotAName = "A";

        public const int UvSlotId = 0;
        public const int LODSlotId = 1;
        public const int OutputSlotRgbaId = 2;
        public const int OutputSlotRId = 3;
        public const int OutputSlotGId = 4;
        public const int OutputSlotBId = 5;
        public const int OutputSlotAId = 6;

        [SerializeField]
        private string m_SerializedTexture;

        [SerializeField]
        private TextureType m_TextureType;

        [Serializable]
        private class TextureHelper
        {
            public Texture2D texture;
        }

        public override bool hasPreview { get { return true; } }

#if UNITY_EDITOR
        public Texture2D defaultTexture
        {
            get
            {
                if (string.IsNullOrEmpty(m_SerializedTexture))
                    return null;

                var tex = new TextureHelper();
                EditorJsonUtility.FromJsonOverwrite(m_SerializedTexture, tex);
                return tex.texture;
            }
            set
            {
                if (defaultTexture == value)
                    return;

                var tex = new TextureHelper();
                tex.texture = value;
                m_SerializedTexture = EditorJsonUtility.ToJson(tex, true);

                if (onModified != null)
                {
                    onModified(this, ModificationScope.Node);
                }
            }
        }
#else
        public Texture2D defaultTexture { get; set; }
#endif

        public TextureType textureType
        {
            get { return m_TextureType; }
            set
            {
                if (m_TextureType == value)
                    return;


                m_TextureType = value;
                if (onModified != null)
                {
                    onModified(this, ModificationScope.Graph);
                }
            }
        }

        public TextureLODNode()
        {
            name = "TextureLOD";
            UpdateNodeAfterDeserialization();
        }

        public sealed override void UpdateNodeAfterDeserialization()
        {
            AddSlot(new MaterialSlot(OutputSlotRgbaId, kOutputSlotRGBAName, kOutputSlotRGBAName, SlotType.Output, SlotValueType.Vector4, Vector4.zero));
            AddSlot(new MaterialSlot(OutputSlotRId, kOutputSlotRName, kOutputSlotRName, SlotType.Output, SlotValueType.Vector1, Vector4.zero));
            AddSlot(new MaterialSlot(OutputSlotGId, kOutputSlotGName, kOutputSlotGName, SlotType.Output, SlotValueType.Vector1, Vector4.zero));
            AddSlot(new MaterialSlot(OutputSlotBId, kOutputSlotBName, kOutputSlotBName, SlotType.Output, SlotValueType.Vector1, Vector4.zero));
            AddSlot(new MaterialSlot(OutputSlotAId, kOutputSlotAName, kOutputSlotAName, SlotType.Output, SlotValueType.Vector1, Vector4.zero));
            AddSlot(new MaterialSlot(UvSlotId, kUVSlotName, kUVSlotName, SlotType.Input, SlotValueType.Vector2, Vector4.zero, false));
            AddSlot(new MaterialSlot(LODSlotId, kLODSlotName, kLODSlotName, SlotType.Input, SlotValueType.Vector1, Vector4.zero, false));
            RemoveSlotsNameNotMatching(validSlots);
        }

        protected int[] validSlots
        {
            get { return new[] { OutputSlotRgbaId, OutputSlotRId, OutputSlotGId, OutputSlotBId, OutputSlotAId, UvSlotId, LODSlotId }; }
        }

        // Node generations
        public virtual void GenerateNodeCode(ShaderGenerator visitor, GenerationMode generationMode)
        {
            var uvSlot = FindInputSlot<MaterialSlot>(UvSlotId);
            var lodSlot = FindInputSlot<MaterialSlot>(LODSlotId);
            
            if (uvSlot == null)
                return;

            if (lodSlot == null)
                return;

            var uvName = string.Format("{0}", UVChannel.uv0.GetUVName());
            var lodName = "";

            var edges = owner.GetEdges(uvSlot.slotReference).ToList();
            var edgesLOD = owner.GetEdges(lodSlot.slotReference).ToList();

            if (edges.Count > 0)
            {
                var edge = edges[0];
                var fromNode = owner.GetNodeFromGuid<AbstractMaterialNode>(edge.outputSlot.nodeGuid);
                uvName = ShaderGenerator.AdaptNodeOutput(fromNode, edge.outputSlot.slotId, ConcreteSlotValueType.Vector2, true);
            }

            if (edgesLOD.Count > 0)
            {
                var edge = edgesLOD[0];
                var fromNode = owner.GetNodeFromGuid<AbstractMaterialNode>(edge.outputSlot.nodeGuid);
                lodName = ShaderGenerator.AdaptNodeOutput(fromNode, edge.outputSlot.slotId, ConcreteSlotValueType.Vector1, true);
            }

            //if no input is specified, default to mipmap 0
            else
                lodName = "0";

            string body = "tex2Dlod (" + propertyName + ", " + precision + "4(" + uvName + ".x," + uvName + ".y, 0," + lodName + "));";
            if (m_TextureType == TextureType.Bump)
                body = precision + "4(UnpackNormal(" + body + "), 0)";
            visitor.AddShaderChunk(precision + "4 " + GetVariableNameForNode() + " = " + body + ";", true);
        }

        public override string GetVariableNameForSlot(int slotId)
        {
            string slotOutput;
            switch (slotId)
            {
                case OutputSlotRId:
                    slotOutput = ".r";
                    break;
                case OutputSlotGId:
                    slotOutput = ".g";
                    break;
                case OutputSlotBId:
                    slotOutput = ".b";
                    break;
                case OutputSlotAId:
                    slotOutput = ".a";
                    break;
                default:
                    slotOutput = "";
                    break;
            }
            return GetVariableNameForNode() + slotOutput;
        }

        public override void CollectPreviewMaterialProperties(List<PreviewProperty> properties)
        {
            properties.Add(GetPreviewProperty());
        }

        // Properties
        public override void GeneratePropertyBlock(PropertyGenerator visitor, GenerationMode generationMode)
        {
            visitor.AddShaderProperty(
                new TexturePropertyChunk(
                    propertyName,
                    description,
                    defaultTexture, m_TextureType,
                    PropertyChunk.HideState.Visible,
                    exposedState == ExposedState.Exposed ?
                        TexturePropertyChunk.ModifiableState.Modifiable
                        : TexturePropertyChunk.ModifiableState.NonModifiable));
        }

        public override void GeneratePropertyUsages(ShaderGenerator visitor, GenerationMode generationMode)
        {
            visitor.AddShaderChunk("sampler2D " + propertyName + ";", true);
        }

        /*
            public override bool DrawSlotDefaultInput(Rect rect, Slot inputSlot)
            {
                var uvSlot = FindInputSlot(kUVSlotName);
                if (uvSlot != inputSlot)
                    return base.DrawSlotDefaultInput(rect, inputSlot);


                var rectXmax = rect.xMax;
                rect.x = rectXmax - 70;
                rect.width = 70;

                EditorGUI.DrawRect(rect, new Color(0.0f, 0.0f, 0.0f, 0.7f));
                GUI.Label(rect, "From Mesh");

                return false;
            }
            */

        public override PreviewProperty GetPreviewProperty()
        {
            return new PreviewProperty
            {
                m_Name = propertyName,
                m_PropType = PropertyType.Texture2D,
                m_Texture = defaultTexture
            };
        }

        public override PropertyType propertyType { get { return PropertyType.Texture2D; } }

        public bool RequiresMeshUV(UVChannel channel)
        {
            if (channel != UVChannel.uv0)
            {
                return false;
            }

            var uvSlot = FindInputSlot<MaterialSlot>(UvSlotId);
            if (uvSlot == null)
                return true;

            var edges = owner.GetEdges(uvSlot.slotReference).ToList();
            return edges.Count == 0;
        }
    }
}