using OSGeo.GDAL;
using OSGeo.OGR;
using OSGeo.OSR;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace DataLoader.CS
{
    public class GdalHelper
    {
        private static bool isInited = false;

        private static GdalHelper instance = null;

        private static readonly object obj = new object();

        public static SpatialReference sr4326 = null;

        public static SpatialReference sr104903 = null;

        public static string MOON200 = "GCS_Moon_2000";

        private GdalHelper()
        {
            lock (obj)
            {
                if (!isInited)
                {
                    RegisterGDal();

                    sr4326 = new SpatialReference(null);
                    sr4326.ImportFromEPSG(4326);

                    string wkt = "GEOGCS[\"GCS_Moon_2000\",\r\n" +
                        "    DATUM[\"D_Moon_2000\",\r\n" +
                        "        SPHEROID[\"Moon_2000_IAU_IAG\",1737400,0,\r\n" +
                        "            AUTHORITY[\"ESRI\",\"107903\"]],\r\n" +
                        "        AUTHORITY[\"ESRI\",\"106903\"]],\r\n" +
                        "    PRIMEM[\"Reference_Meridian\",0,\r\n" +
                        "        AUTHORITY[\"ESRI\",\"108900\"]],\r\n" +
                        "    UNIT[\"degree\",0.0174532925199433,\r\n" +
                        "        AUTHORITY[\"EPSG\",\"9122\"]],\r\n" +
                        "    AUTHORITY[\"ESRI\",\"104903\"]]";
                    sr104903 = new SpatialReference(wkt);
                    //sr104903.ImportFromWkt(ref wkt);

                    isInited = true;
                }
            }
        }

        public static GdalHelper Instance
        {
            get
            {
                lock (obj)
                {
                    if (null == instance) instance = new GdalHelper();

                    return instance;
                }
            }
        }

        public void RegisterGDal()
        {
            string gdalData = Path.Combine(StaticData.BasePath, "gdal-data");
            Environment.SetEnvironmentVariable("GDAL_DATA", gdalData);

            string proj7 = Path.Combine(StaticData.BasePath, "proj7\\share");
            Environment.SetEnvironmentVariable("PROJ_LIB", proj7);

            Gdal.SetConfigOption("GDAL_FILENAME_IS_UTF8", "YES"); // NO,YES
            Gdal.SetConfigOption("SHAPE_ENCODING", ""); // 空,gb2312,CP936

            Ogr.RegisterAll();
            Gdal.AllRegister();
        }

        public void ReadTiff()
        {
            string tif = "D:\\Moon\\data\\dom_tif\\moon.tif";

            Dataset ds = Gdal.Open(tif, Access.GA_ReadOnly);
            int x = ds.RasterXSize;
            int y = ds.RasterYSize;

            SpatialReference sr = ds.GetSpatialRef();
            string srName = sr.GetName(); // GCS_Moon_2000
            // string code = sr4326.GetAuthorityCode(null); // 4326
            if (MOON200 != srName) return;

            double[] lt = ImageToGeoSpace(ds, 0, 0); // -179.99998351102391, 89.999983511056882
            double[] rb = ImageToGeoSpace(ds, x, y); // 179.999788852709, -89.9999026708093

            string polygon = string.Format("", "");
        }

        // 从地理空间转换到像素空间
        private int[] Geo2ImageSpace(Dataset ds, double x, double y)
        {
            double[] transform = new double[6];
            ds.GetGeoTransform(transform); // 影像坐标变换参数

            int col = (int)((y * transform[1] - x * transform[4] + transform[0] * transform[4] - transform[3] * transform[1]) / (transform[5] * transform[1] - transform[2] * transform[4])); // 像素所在列
            int row = (int)((x - transform[0] - col * transform[2]) / transform[1]); // 像素所在行

            return new int[] { row, col };
        }

        // 从地理空间转换到像素空间
        private int[] Geo2ImageSpace(double[] transform, double x, double y)
        {
            int col = (int)((y * transform[1] - x * transform[4] + transform[0] * transform[4] - transform[3] * transform[1]) / (transform[5] * transform[1] - transform[2] * transform[4])); // 像素所在列
            int row = (int)((x - transform[0] - col * transform[2]) / transform[1]); // 像素所在行

            return new int[] { row, col };
        }

        // 从像素空间转换到地理空间
        private double[] ImageToGeoSpace(Dataset ds, int row, int col)
        {
            double[] transform = new double[6];
            ds.GetGeoTransform(transform);

            double x = transform[0] + row * transform[1] + col * transform[2];
            double y = transform[3] + row * transform[4] + col * transform[5];

            return new double[] { x, y };
        }
    }
}