using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using System.Globalization;
using System.Text;
namespace Nxr.Internal
{ 
    public class ObjMaterial : MonoBehaviour
    {
        /// <summary>
        /// 全局变量
        /// </summary>
        private Texture2D globalTexture;

        /// <summary>
        /// 材质名称列表
        /// </summary>
        private ArrayList materialNames;

        /// <summary>
        /// 漫反射颜色列表
        /// </summary>
        private List<Vector3> diffuseColors;

        /// <summary>
        /// 漫反射贴图列表
        /// </summary>
        private ArrayList diffuseTextures;

        /// <summary>
        /// 当前实例
        /// </summary>
        private static ObjMaterial instance;
        public static ObjMaterial Instance
        {
            get
            {
                if (instance == null)
                    instance = GameObject.FindObjectOfType<ObjMaterial>();
                if (instance == null)
                    instance = new GameObject("ObjMatrial").AddComponent<ObjMaterial>();
                return instance;
            }
        }

        void Awake()
        {
            this.diffuseColors = new List<Vector3>();
            this.diffuseTextures = new ArrayList();
            this.materialNames = new ArrayList();
        }

        /// <summary>
        /// 从一个文本化后的mtl文件加载一组材质
        /// </summary>
        /// <param name="mtlText">文本化的mtl文件</param>
        /// <param name="texturePath">贴图文件夹路径</param>
        public Material[] LoadFormMtl(string mtlText, string texturePath, byte[] textureContent)
        {
            Debug.Log("LoadFormMtl="+ texturePath + ".");
            if (mtlText == "")
                return null;
            materialNames.Clear();
            //将文本化后的内容按行分割
            string[] allLines = mtlText.Split('\n');
            foreach (string line in allLines)
            {
                //按照空格分割每一行的内容
                string[] chars = line.Split(' ');
                switch (chars[0])
                {
                    case "newmtl":
                        //处理材质名
                        materialNames.Add(chars[1]);
                        break;
                    case "Ka":
                        //暂时仅考虑漫反射
                        break;
                    case "Kd":
                        //处理漫反射
                        diffuseColors.Add(new Vector3(
                            ConvertToFloat(chars[1]),
                            ConvertToFloat(chars[2]),
                            ConvertToFloat(chars[3])
                            ));
                        break;
                    case "Ks":
                        //暂时仅考虑漫反射
                        break;
                    case "Ke":
                        //Todo
                        break;
                    case "Ni":
                        //Todo
                        break;
                    case "e":
                        //Todo
                        break;
                    case "illum":
                        //Todo
                        break;
                    case "map_Ka":
                        //暂时仅考虑漫反射
                        break;
                    case "map_Kd":
                        //处理漫反射贴图
                        //因为mtl文件中的贴图使用的是绝对路径
                        //所以这里需要截取它的文件名来和材质相对应起来
                        string textureName = chars[1].Substring(chars[1].LastIndexOf("\\") + 1, chars[1].Length - chars[1].LastIndexOf("\\") - 1);
                        //默认贴图格式为.png
                        textureName = textureName.Replace(".dds", ".png").Replace("\r", ""); ;
                        diffuseTextures.Add(textureName);
                        break;
                    case "map_Ks":
                        //暂时仅考虑漫反射
                        break;
                    default: continue;
                }
            }

            //准备一个数组来存储材质
            Material[] materials = new Material[materialNames.Count];

            for (int i = 0; i < materialNames.Count; i++)
            {
                //创建一个内置的Diffuse材质
                Material mat = new Material(Shader.Find("Unlit/Texture"));
                //设置材质名称
                mat.name = materialNames[i].ToString();
                //加载贴图
                if (textureContent == null)
                {
                    StartCoroutine(LoadTexture(mat, texturePath + "/" + diffuseTextures[i]));
                }
                else
                {
                    globalTexture = new Texture2D(1, 1);
#if UNITY_2017_1
                    ImageConversion.LoadImage(globalTexture, textureContent);
#else
                    globalTexture.LoadImage(textureContent);
#endif
                }
                //设置贴图
                mat.mainTexture = globalTexture;
                if (diffuseColors.Count > 0) mat.color = new Color(
                    diffuseColors[0].x, diffuseColors[0].y, diffuseColors[0].z
                    );

                materials[i] = mat;
            }

            return materials;
        }


        /// <summary>
        /// 将一个字符串转换为浮点类型
        /// </summary>
        /// <param name="s">待转换的字符串</param>
        /// <returns></returns>
        private float ConvertToFloat(string s)
        {
            return System.Convert.ToSingle(s, CultureInfo.InvariantCulture);
        }

        /// <summary>
        /// 加载指定路径的贴图	
        /// </summary>
        /// <returns>The texture.</returns>
        /// <param name="fileName">贴图路径</param>
        IEnumerator LoadTexture(Material mat, string fileName)
        {
            Debug.Log("LoadTexture=" + fileName + ".");
            //使用WWW下载贴图
            WWW www = new WWW(fileName);
            yield return www;

            if (www != null && string.IsNullOrEmpty(www.error))
            {
                if (www.isDone)
                {
                    globalTexture = www.texture;
                    mat.mainTexture = globalTexture;
                }
            }
            else
            {
                globalTexture = null;
            }
        }
    }
}