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 SimuTools.Tools
{
    public class GdalHelper
    {
        private static bool isInited;

        private static GdalHelper instance;

        private static readonly object obj = new object();

        public static SpatialReference sr4326 { set; get; }

        public static SpatialReference sr4490 { set; get; }

        public static readonly String CGCS2000 = "CGCS2000";

        /// <summary>
        /// 构造函数
        /// </summary>
        private GdalHelper()
        {
            lock (obj)
            {
                if (!isInited)
                {
                    RegisterGDal();

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

                    sr4490 = new SpatialReference(null);
                    sr4490.ImportFromEPSG(4490);

                    isInited = true;
                }
            }
        }

        /// <summary>
        /// 实例
        /// </summary>
        public static GdalHelper Instance
        {
            get
            {
                lock (obj)
                {
                    if (null == instance)
                    {
                        instance = new GdalHelper();
                    }

                    return instance;
                }
            }
        }

        /// <summary>
        /// 注册GDAL
        /// </summary>
        public void RegisterGDal()
        {
            string gdalData = Path.Combine(Handle.BaseDir, "gdal-data");
            Environment.SetEnvironmentVariable("GDAL_DATA", gdalData);

            string proj7 = Path.Combine(Handle.BaseDir, "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();
        }

        /**
         * 获取Dataset的最小点
         */
        private static Geometry GetMinPoint(Dataset ds)
        {
            double[] transform = new double[6];
            ds.GetGeoTransform(transform);

            double xMin = transform[0];
            double yMin = transform[3] - ds.RasterYSize * transform[1];

            Geometry point = new Geometry(wkbGeometryType.wkbPoint);
            point.AddPoint(xMin, yMin, 0);

            return Transform(ds, point);
        }

        /**
         * 获取Dataset的最大点
         */
        private static Geometry GetMaxPoint(Dataset ds)
        {
            /*
             * transform[0] 左上角x坐标
             * transform[1] 东西方向分辨率
             * transform[2] 旋转角度, 0表示图像 "北方朝上"
             *
             * transform[3] 左上角y坐标
             * transform[4] 旋转角度, 0表示图像 "北方朝上"
             * transform[5] 南北方向分辨率
             */
            double[] transform = new double[6];
            ds.GetGeoTransform(transform);

            double xMax = transform[0] + (ds.RasterYSize * transform[1]);
            double yMax = transform[3];

            Geometry point = new Geometry(wkbGeometryType.wkbPoint);
            point.AddPoint(xMax, yMax, 0);

            return Transform(ds, point);
        }

        /**
         * 坐标转换
         */
        public static Geometry Transform(Dataset ds, Geometry point)
        {
            point.AssignSpatialReference(ds.GetSpatialRef());
            if (ds.GetSpatialRef().IsGeographic() > 0)
            {
                return point;
            }

            String srsName = ds.GetSpatialRef().GetName();
            if (srsName.Contains(CGCS2000))
            {
                point.TransformTo(sr4490);
            }
            else
            {
                point.TransformTo(sr4326);
            }
            point.SwapXY();

            return point;
        }

        /**
         * 创建金字塔
         */
        public static void CreatePyramid(String file)
        {
            Dataset ds = null;
            try
            {
                if (!File.Exists(file)) return;

                ds = Gdal.Open(file, Access.GA_ReadOnly);
                if (null == ds) return;

                Band band = ds.GetRasterBand(1);
                if (0 == band.GetOverviewCount())
                {
                    ds.BuildOverviews("nearest", new int[] { 2, 4, 6, 8, 16 });
                }
            }
            catch (Exception ex)
            {
                LogOut.Error(ex.Message);
            }
            finally
            {
                if (null != ds) ds.Dispose();
            }
        }
    }
}