public class OBJImporter
    {
        public class ObjSurface
        {
            public List<Vector2> uvcoords;
            public List<int> indexList;
            public string name;

            public ObjSurface()
            {
                uvcoords = new List<Vector2>();
                indexList = new List<int>();
            }
        }

        public static ModelObject Load(GraphicsDevice Device)
        {
            StreamReader reader = new StreamReader("belltower.obj");

            List<ObjSurface> objSurfaces = new List<ObjSurface>();
            ObjSurface currentSurface = new ObjSurface();

            bool hasSurface = false;

            List<Vector3> verticies = new List<Vector3>();
            List<Vector2> uvcoords = new List<Vector2>();

            int indCount = 0; // total number of indicies

            while (!reader.EndOfStream)
            {
                string line = reader.ReadLine();

                line = line.Trim();

                if (line.Length < 1)
                    continue;

                switch (line[0])
                {
                    case 'o': // object name

                        break;

                    case 'v': // vertex
                        if (line[1] == 't') // uv coord
                        {
                            string data = line.Substring(3);
                            string[] values = data.Split(' ');

                            Vector2 coord = new Vector2(float.Parse(values[0]), float.Parse(values[1]));

                            currentSurface.uvcoords.Add(coord);
                            uvcoords.Add(coord);
                        }
                        else
                        {
                            string data = line.Substring(2);
                            string[] values = data.Split(' ');

                            Vector3 vert = new Vector3(float.Parse(values[0]), float.Parse(values[1]), float.Parse(values[2]));

                            verticies.Add(vert);
                        }
                        break;

                    case 'f': // face
                        string fData = line.Substring(2);
                        string[] fValues = fData.Split(' ');

                        for (int i = 0; i < fValues.Length; i++)
                        {
                            string[] index = fValues[i].Split('/');

                            currentSurface.indexList.Add(int.Parse(index[0]));
                            indCount++;
                        }
                        break;

                    case 'u': // assume usemtl option
                        string surfaceName = line.Substring(7);

                        if (hasSurface)
                            objSurfaces.Add(currentSurface);

                        currentSurface = new ObjSurface();
                        currentSurface.name = surfaceName;

                        hasSurface = true;

                        //Console.WriteLine(surfaceName);
                        break;
                }
            }

            reader.Close();

            foreach (ObjSurface objSurf in objSurfaces)
                Console.WriteLine("Surface: " + objSurf.name + ", UVs: " + objSurf.uvcoords.Count + ", Indicies: " + objSurf.indexList.Count);




            VertexPositionTexture[] vpt = new VertexPositionTexture[verticies.Count];

            for(int i = 0; i < verticies.Count; i++)
            {
                vpt[i] = new VertexPositionTexture(verticies[i], uvcoords[i]);
            }

            ModelObject modelObject = new ModelObject();
            ModelSurface surface = new ModelSurface();

            VertexBuffer vertexBuffer = new VertexBuffer(Device, VertexPositionTexture.SizeInBytes * verticies.Count, ResourceUsage.None, ResourceManagementMode.Automatic);
            vertexBuffer.SetData<VertexPositionTexture>(vpt);

            surface.VertexBuffer = vertexBuffer;
            
            short[] indicies = new short[indCount];

            int currentInd = 0;
            for (int s = 0; s < objSurfaces.Count; s++)
            {
                for (int i = 0; i < objSurfaces[s].indexList.Count; i++)
                {
                    indicies[currentInd] = (short)(objSurfaces[s].indexList[i] - 1);
                    currentInd++;
                }
            }

            surface.IndexBuffer = new IndexBuffer(Device, typeof(short), indCount, ResourceUsage.None, ResourceManagementMode.Automatic);
            surface.IndexBuffer.SetData<short>(indicies);

            int baseVert = 0;

            foreach (ObjSurface objSurf in objSurfaces)
            {
                ModelSurfacePart part = new ModelSurfacePart();

                part.BaseVertex = 0;
                part.NumVertices = objSurf.indexList.Count;
                part.PrimitiveCount = objSurf.indexList.Count / 3;
                part.StartIndex = baseVert;
                part.StreamOffset = 0;
                part.VertexDeclaration = new VertexDeclaration(Device, VertexPositionTexture.VertexElements);
                part.VertexStride = VertexPositionTexture.SizeInBytes;

                baseVert += objSurf.indexList.Count;

                if (File.Exists(objSurf.name + ".tga"))
                {
                    part.texture = Texture2D.FromFile(Device, objSurf.name + ".tga");
                    part.hasTexture = true;
                }
                else
                    part.hasTexture = false;

                surface.SurfaceParts.Add(part);
            }

            modelObject.Surfaces.Add(surface);

            return modelObject;
        }
    }