using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Text;
using System.Xml;
using UnityEditor;
using UnityEditor.SceneManagement;
using UnityEngine;
using UnityEngine.SceneManagement;

public class UrhoExporter:IDisposable
{
    [MenuItem("Tools/Export Scene To Urho3D")]
    public static void ExportToUrho()
    {
        using (var exporter = new UrhoExporter(EditorSceneManager.GetActiveScene(), EditorUtility.SaveFilePanel(
            "Save scene as Urho XML",
            "",
            "scene.xml",
            "xml")))
        {
            exporter.Export();
        }

    }

    private Scene _scene;
    private int _id;
    string _outputFileName;
    private TextWriter _stream;
    private XmlTextWriter _writer;
    private string _assetsFolder;

    public UrhoExporter(Scene scene, string outputFileName)
    {
        _scene = scene;
        _outputFileName = Path.GetFullPath(outputFileName);
        _assetsFolder = Path.GetDirectoryName(Path.GetDirectoryName(_outputFileName));
        if (string.IsNullOrEmpty(_assetsFolder))
            _assetsFolder = Path.GetDirectoryName(_outputFileName);

        _stream = File.CreateText(_outputFileName);
        _writer = new XmlTextWriter(_stream);
    }

    public void Export()
    {
        if (string.IsNullOrEmpty(_outputFileName))
            return;

        _writer.WriteStartDocument();
        _writer.WriteWhitespace("\n");

        _writer.WriteStartElement("scene");
        _writer.WriteAttributeString("id", (++_id).ToString());
        _writer.WriteWhitespace("\n");


        var prefix = "\t";
        StartCompoent(prefix, "Octree");
        EndElement(prefix);
        StartCompoent(prefix, "DebugRenderer");
        EndElement(prefix);
        StartCompoent(prefix, "PhysicsWorld");
        EndElement(prefix);

        EnumerateObjects(prefix, _scene.GetRootGameObjects());

        _writer.WriteEndElement();
        _writer.WriteEndDocument();
    }

    public void Dispose()
    {
        if (_stream != null)
        {
            _stream.Dispose();
        }
    }


    private void EnumerateObjects(string prefix, GameObject[] objects)
    {
        foreach (var obj in objects)
        {
            WriteObject(prefix, obj);
        }
    }

    private string GetFileName(string name)
    {
        foreach (var invalidFileNameChar in Path.GetInvalidFileNameChars())
        {
            name = name.Replace(invalidFileNameChar, '_');
        }
        return name;
    }
    private void WriteObject(string prefix,GameObject obj)
    {
        _writer.WriteWhitespace(prefix);
        _writer.WriteStartElement("node");
        _writer.WriteAttributeString("id", (++_id).ToString());
        _writer.WriteWhitespace("\n");

        var subPrefix = prefix + "\t";
        var subSubPrefix = subPrefix + "\t";

        WriteAttribute(subPrefix,  "Is Enabled", obj.activeSelf);
        WriteAttribute(subPrefix,  "Name", obj.name);
        WriteAttribute(subPrefix,  "Tags", obj.tag);
        WriteAttribute(subPrefix,  "Position", obj.transform.localPosition);
        WriteAttribute(subPrefix,  "Rotation", obj.transform.localRotation);
        WriteAttribute(subPrefix,  "Scale", obj.transform.localScale);

        var meshFilter = obj.GetComponent<MeshFilter>();
        var meshRenderer = obj.GetComponent<MeshRenderer>();
        var meshCollider = obj.GetComponent<MeshCollider>();
        var terrain = obj.GetComponent<Terrain>();
        var light = obj.GetComponent<Light>();
        var camera = obj.GetComponent<Camera>();

        if (camera != null)
        {
            StartCompoent(subPrefix, "Camera");

            WriteAttribute(subSubPrefix, "Near Clip", camera.nearClipPlane);
            WriteAttribute(subSubPrefix, "Far Clip", camera.farClipPlane);

            EndElement(subPrefix);
        }

        if (light != null)
        {
            StartCompoent(subPrefix, "Light");
            if (light.type == LightType.Directional)
            {
                WriteAttribute(subSubPrefix, "Light Type", "Directional");
            }
            EndElement(subPrefix);
        }

        if (terrain != null)
        {
            var terrainSize = terrain.terrainData.size;
            var y = terrain.SampleHeight(new Vector3(0, 0, 0));
        }

        if (meshRenderer != null)
        {
            if (meshFilter != null)
            {
                StartCompoent(subPrefix,  "StaticModel");

                var meshRelFileName = GetRelAssetPath(meshFilter.mesh);
                WriteAttribute(subSubPrefix,  "Model", "Model;Models/" + meshRelFileName + ".mdl");

                var meshFileName = Path.Combine(Path.Combine(_assetsFolder, "Models"), meshRelFileName + ".mdl");
                if (!File.Exists(meshFileName))
                {

                    using (var writer = new BinaryWriter(File.Open(meshFileName, FileMode.Create, FileAccess.Write, FileShare.Read)))
                    {
                        WriteMesh(writer, meshFilter.mesh);
                    }
                }

                StringBuilder material = new StringBuilder();
                material.Append("Material");
                var meshRendererMaterials = meshRenderer.materials;
                for (int i = 0; i < meshRendererMaterials.Length; ++i)
                {
                    var meshRendererMaterial = meshRendererMaterials[i];
                    var relPath = GetRelAssetPath(meshRendererMaterial);

                    var outputMaterialName = "Materials/" + relPath+".xml";

                    material.Append(";");
                    material.Append(outputMaterialName);

                    var materialFileName = Path.Combine(_assetsFolder, outputMaterialName);
                    if (!File.Exists(materialFileName))
                    {
                        CreateMaterial(materialFileName, meshRendererMaterial);
                    }
                }
                WriteAttribute(subSubPrefix, "Material", material.ToString());

                EndElement(subPrefix);
            }
        }

        if (meshCollider != null)
        {
        }

        var transforms = obj.GetComponentsInChildren<Transform>(true);
        for (int i = 0; i < transforms.Length; ++i)
        {
            if (transforms[i].gameObject != obj)
                WriteObject(subPrefix,  transforms[i].gameObject);
        }

        _writer.WriteWhitespace(prefix);
        _writer.WriteEndElement();
        _writer.WriteWhitespace("\n");
    }



    public const uint Magic2 = 0x32444d55;

    private void WriteMesh(BinaryWriter writer, Mesh _mesh)
    {
        writer.Write(Magic2);
        writer.Write(1);
        for (int vbIndex = 0; vbIndex < 1 /*_mesh.vertexBufferCount*/; ++vbIndex)
        {
            var positions = _mesh.vertices;
            var normals = _mesh.normals;
            var colors = _mesh.colors;
            var tangents = _mesh.tangents;
            var uvs = _mesh.uv;
            var uvs2 = _mesh.uv2;
            var uvs3 = _mesh.uv3;
            var uvs4 = _mesh.uv4;

            writer.Write(positions.Length);
            var elements = new List<MeshStreamWriter>();
            if (positions.Length > 0)
            {
                elements.Add(new MeshVector3Stream(positions, VertexElementSemantic.SEM_POSITION));
            }
            if (normals.Length > 0)
            {
                elements.Add(new MeshVector3Stream(normals, VertexElementSemantic.SEM_NORMAL));
            }
            //if (colors.Length > 0)
            //{
            //    elements.Add(new MeshColorStream(colors, VertexElementSemantic.SEM_COLOR));
            //}
            //if (tangents.Length > 0)
            //{
            //    elements.Add(new MeshVector4Stream(tangents, VertexElementSemantic.SEM_TANGENT));
            //}
            if (uvs.Length > 0)
            {
                elements.Add(new MeshVector2Stream(uvs, VertexElementSemantic.SEM_TEXCOORD, 0));
            }
            if (uvs2.Length > 0)
            {
                elements.Add(new MeshVector2Stream(uvs2, VertexElementSemantic.SEM_TEXCOORD, 1));
            }
            if (uvs3.Length > 0)
            {
                elements.Add(new MeshVector2Stream(uvs2, VertexElementSemantic.SEM_TEXCOORD, 2));
            }
            if (uvs4.Length > 0)
            {
                elements.Add(new MeshVector2Stream(uvs2, VertexElementSemantic.SEM_TEXCOORD, 3));
            }
            writer.Write(elements.Count);
            for (int i = 0; i < elements.Count; ++i)
            {
                writer.Write(elements[i].Element);
            }
            int morphableVertexRangeStartIndex = 0;
            int morphableVertexCount = 0;
            writer.Write(morphableVertexRangeStartIndex);
            writer.Write(morphableVertexCount);
            for (int index = 0; index < positions.Length; ++index)
            {
                for (int i = 0; i < elements.Count; ++i)
                {
                    elements[i].Write(writer, index);
                }
            }
            var indicesPerSubMesh = new List<int[]>();
            int totalIndices = 0;
            for (int subMeshIndex = 0; subMeshIndex < _mesh.subMeshCount; ++subMeshIndex)
            {
                var indices = _mesh.GetIndices(subMeshIndex);
                indicesPerSubMesh.Add(indices);
                totalIndices += indices.Length;
            }
            writer.Write(1);
            writer.Write(totalIndices);
            if (positions.Length < 65536)
            {
                writer.Write(2);
                for (int subMeshIndex = 0; subMeshIndex < _mesh.subMeshCount; ++subMeshIndex)
                {
                    for (int i = 0; i < indicesPerSubMesh[subMeshIndex].Length; ++i)
                    {
                        writer.Write((ushort)indicesPerSubMesh[subMeshIndex][i]);
                    }
                }
            }
            else
            {
                writer.Write(4);
                for (int subMeshIndex = 0; subMeshIndex < _mesh.subMeshCount; ++subMeshIndex)
                {
                    for (int i = 0; i < indicesPerSubMesh[subMeshIndex].Length; ++i)
                    {
                        writer.Write(indicesPerSubMesh[subMeshIndex][i]);
                    }
                }
            }
            writer.Write(indicesPerSubMesh.Count);
            totalIndices = 0;
            for (int subMeshIndex = 0; subMeshIndex < indicesPerSubMesh.Count; ++subMeshIndex)
            {
                var numberOfBoneMappingEntries = 0;
                writer.Write(numberOfBoneMappingEntries);
                var numberOfLODLevels = 1;
                writer.Write(numberOfLODLevels);
                writer.Write(0.0f);
                writer.Write((int)PrimitiveType.TRIANGLE_LIST);
                writer.Write(0);
                writer.Write(0);
                writer.Write(totalIndices);
                writer.Write(indicesPerSubMesh[subMeshIndex].Length);
                totalIndices += indicesPerSubMesh[subMeshIndex].Length;
                writer.Write(0);
                var numOfBones = 0;
                writer.Write(numOfBones);
            }
            float minX, minY, minZ;
            float maxX, maxY, maxZ;
            maxX = maxY = maxZ = float.MinValue;
            minX = minY = minZ = float.MaxValue;
            for (int i = 0; i < positions.Length; ++i)
            {
                if (minX > positions[i].x)
                    minX = positions[i].x;
                if (minY > positions[i].y)
                    minY = positions[i].y;
                if (minZ > positions[i].z)
                    minZ = positions[i].z;
                if (maxX < positions[i].x)
                    maxX = positions[i].x;
                if (maxY < positions[i].y)
                    maxY = positions[i].y;
                if (maxZ < positions[i].z)
                    maxZ = positions[i].z;
            }
            writer.Write(minX);
            writer.Write(minY);
            writer.Write(minZ);
            writer.Write(maxX);
            writer.Write(maxY);
            writer.Write(maxZ);
        }
    }
    public enum PrimitiveType
    {
        TRIANGLE_LIST = 0,
        LINE_LIST,
        POINT_LIST,
        TRIANGLE_STRIP,
        LINE_STRIP,
        TRIANGLE_FAN
    }
    public enum VertexElementType
    {
        TYPE_INT = 0,
        TYPE_FLOAT,
        TYPE_VECTOR2,
        TYPE_VECTOR3,
        TYPE_VECTOR4,
        TYPE_UBYTE4,
        TYPE_UBYTE4_NORM,
        MAX_VERTEX_ELEMENT_TYPES
    }
    public enum VertexElementSemantic
    {
        SEM_POSITION = 0,
        SEM_NORMAL,
        SEM_BINORMAL,
        SEM_TANGENT,
        SEM_TEXCOORD,
        SEM_COLOR,
        SEM_BLENDWEIGHTS,
        SEM_BLENDINDICES,
        SEM_OBJECTINDEX,
        MAX_VERTEX_ELEMENT_SEMANTICS
    }
    internal abstract  class MeshStreamWriter
    {
        public int Element;
        public abstract void Write(BinaryWriter writer, int index);
    }
    internal class MeshVector3Stream: MeshStreamWriter
    {
        private Vector3[] positions;

        public MeshVector3Stream(Vector3[] positions, VertexElementSemantic sem, int index = 0)
        {
            this.positions = positions;
            Element = (int)VertexElementType.TYPE_VECTOR3 | ((int)sem << 8) | (index <<16);
        }

        public override void Write(BinaryWriter writer, int index)
        {
            writer.Write(positions[index].x);
            writer.Write(positions[index].y);
            writer.Write(positions[index].z);
        }
    }

    internal class MeshVector2Stream : MeshStreamWriter
    {
        private Vector2[] positions;
        public MeshVector2Stream(Vector2[] positions, VertexElementSemantic sem, int index = 0)
        {
            this.positions = positions;
            Element = (int)VertexElementType.TYPE_VECTOR2 | ((int)sem << 8) | (index << 16);
        }

        public override void Write(BinaryWriter writer, int index)
        {
            writer.Write(positions[index].x);
            writer.Write(positions[index].y);
        }
    }
    private void CreateMaterial(string materialFileName, Material material)
    {
        Directory.CreateDirectory(Path.GetDirectoryName(materialFileName));
        using (var writer = XmlTextWriter.Create(materialFileName))
        {
            writer.WriteStartDocument();
            writer.WriteStartElement("material");
            writer.WriteStartElement("technique");
            writer.WriteAttributeString("name", "Techniques/Diff.xml");
            writer.WriteAttributeString("quality", "0");
            writer.WriteEndElement();

            var shader = material.shader;
            for (int i = 0; i < ShaderUtil.GetPropertyCount(shader); i++)
            {
                if (ShaderUtil.GetPropertyType(shader, i) == ShaderUtil.ShaderPropertyType.TexEnv)
                {
                    var propertyName = ShaderUtil.GetPropertyName(shader, i);
                    Texture texture = material.GetTexture(propertyName);
                    if (texture != null)
                    {
                        switch (propertyName)
                        {
                            case "_MainTex":
                                WriteTexture(texture, writer, "diffuse");
                                break;
                            case "_SpecGlossMap":
                                WriteTexture(texture, writer, "specular");
                                break;
                            case "_ParallaxMap":
                                break;
                            case "_BumpMap":
                                WriteTexture(texture, writer, "normal");
                                break;
                            case "_DetailAlbedoMap":
                                break;
                            case "_DetailNormalMap":
                                break;
                            default:
                                Debug.LogWarning(propertyName);
                                break;
                        }
                    }
                }
            }
            writer.WriteEndElement();
            writer.WriteEndDocument();
        }
    }

    private void WriteTexture(Texture materialMainTexture, XmlWriter writer, string name)
    {
        if (materialMainTexture == null)
            return;

        var relPath = GetRelAssetPath(materialMainTexture);
        var dataPath = Application.dataPath;
        var outputPath = "Textures/" + relPath;

        writer.WriteStartElement("texture");
        writer.WriteAttributeString("unit", name);
        writer.WriteAttributeString("name", outputPath);
        writer.WriteEndElement();

        string destFileName = Path.Combine(this._assetsFolder, outputPath);
        if (!File.Exists(destFileName))
        {
            Directory.CreateDirectory(Path.GetDirectoryName(destFileName));
            File.Copy(Path.Combine(dataPath,relPath), destFileName);
        }
    }

    private string GetRelAssetPath(UnityEngine.Object assetObject)
    {
        var path = AssetDatabase.GetAssetPath(assetObject);
        if (string.IsNullOrEmpty(path))
            return GetFileName(assetObject.name);
        var relPath = path.Substring(path.IndexOf('/') + 1);
        return relPath;
    }
    private void WriteAttribute(string prefix, string name, float pos)
    {
        WriteAttribute(prefix, name, string.Format(CultureInfo.InvariantCulture, "{0}", pos));
    }
    private void WriteAttribute(string prefix,string name, Vector3 pos)
    {
        WriteAttribute(prefix, name, string.Format(CultureInfo.InvariantCulture, "{0} {1} {2}", pos.x, pos.y, pos.z));
    }
    private void WriteAttribute(string prefix, string name, Quaternion pos)
    {
        WriteAttribute(prefix, name, string.Format(CultureInfo.InvariantCulture, "{0} {1} {2} {3}", pos.w, pos.x, pos.y, pos.z));
    }
    private void WriteAttribute(string prefix, string name, bool flag)
    {
        WriteAttribute(prefix, name, flag ? "true" : "false");
    }

    private void EndElement(string prefix)
    {
        _writer.WriteWhitespace(prefix);
        _writer.WriteEndElement();
        _writer.WriteWhitespace("\n");
    }

    private void StartCompoent(string prefix, string type)
    {
        _writer.WriteWhitespace(prefix);
        _writer.WriteStartElement("component");
        _writer.WriteAttributeString("type", type);
        _writer.WriteAttributeString("id", (++_id).ToString());
        _writer.WriteWhitespace("\n");

    }

    private void WriteAttribute(string prefix, string name, string vaue)
    {
        _writer.WriteWhitespace(prefix);
        _writer.WriteStartElement("attribute");
        _writer.WriteAttributeString("name", name);
        _writer.WriteAttributeString("value", vaue);
        _writer.WriteEndElement();
        _writer.WriteWhitespace("\n");
    }
}