package org.springblade.modules.dem;

import lombok.SneakyThrows;
import org.geotools.coverage.grid.GridCoordinates2D;
import org.geotools.coverage.grid.GridCoverage2D;
import org.geotools.gce.geotiff.GeoTiffReader;
import org.geotools.geometry.DirectPosition2D;
import org.geotools.referencing.CRS;
import org.geotools.referencing.crs.DefaultGeographicCRS;
import org.locationtech.jts.geom.Coordinate;
import org.opengis.geometry.DirectPosition;
import org.opengis.referencing.crs.CoordinateReferenceSystem;
import org.opengis.referencing.operation.MathTransform2D;

import java.io.File;

public class DemUtils {

	/**
	 * 根据点获取海拔高
	 * @param file
	 * @param point
	 * @return
	 */
	@SneakyThrows
	public static int calculateMaxByPoint(File file, Coordinate point) {
		//获取高程文件
		GeoTiffReader reader = new GeoTiffReader(file);
		GridCoverage2D coverage = reader.read(null);

		CoordinateReferenceSystem crs = coverage.getCoordinateReferenceSystem2D();
		DirectPosition position = new DirectPosition2D(crs, point.x, point.y);

		int[] pixelValue = (int[]) coverage.evaluate(position);

		return pixelValue[0];
	}

	/**
	 * 计算两点之间最高海拔
	 * @param file
	 * @param start
	 * @param end
	 * @return
	 */
	@SneakyThrows
	public static Coordinate calculateMaxElevation(File file, Coordinate start, Coordinate end) {
		//获取高程文件
		GeoTiffReader reader = new GeoTiffReader(file);
		GridCoverage2D coverage = reader.read(null);

		CoordinateReferenceSystem crs = coverage.getCoordinateReferenceSystem2D();
		MathTransform2D toGrid = (MathTransform2D) CRS.findMathTransform(DefaultGeographicCRS.WGS84, crs, true);
		MathTransform2D fromGrid = (MathTransform2D) CRS.findMathTransform(crs, DefaultGeographicCRS.WGS84, true);

		DirectPosition2D startPos = new DirectPosition2D(start.x, start.y);
		DirectPosition2D endPos = new DirectPosition2D(end.x, end.y);

		GridCoordinates2D startGrid = new GridCoordinates2D();
		GridCoordinates2D endGrid = new GridCoordinates2D();
		toGrid.transform(startPos, startGrid);
		toGrid.transform(endPos, endGrid);

		int maxPixelValue = Integer.MIN_VALUE;

		Coordinate retCoordinate = new Coordinate();

		// 线性插值，计算中间的点
		for (int i = 0; i <= 10000; i++) {

			double t = i / 10000.0;

			double lon = start.x + t * (end.x - start.x);
			double lat = start.y + t * (end.y - start.y);

			DirectPosition position = new DirectPosition2D(crs, lon, lat);
			int[] pixelValue = (int[]) coverage.evaluate(position);

			if (pixelValue[0] > maxPixelValue) {
				maxPixelValue = pixelValue[0];
				retCoordinate.setX(lon);
				retCoordinate.setY(lat);
				retCoordinate.setZ(maxPixelValue);
			}
		}

		return retCoordinate;

	}

	public static void main(String[] args) {
		Coordinate start = new Coordinate(115.856725497, 28.624514734);
////		Coordinate end = new Coordinate(115.84832847430599, 28.629107705136526);
//		Coordinate end = new Coordinate(115.85650343813958, 28.62419061027172);
//
		String demPath = "C:\\Users\\vip_x\\Desktop\\无人机\\高程\\江西省12.5米DEM_CGCS2000\\江西省12.5米DEM_CGCS2000.tif";
		File file = new File(demPath);
//
//		Coordinate height = calculateMaxElevation(file,start,end);
//		System.out.println("height:" + height);
//
////		double maxElevation = calculateMaxElevation(file, start, end);
////		System.out.println("Maximum elevation between points: " + maxElevation);
//
		int height2 = calculateMaxByPoint(file,start);
		System.out.println("height2 = " + height2);
	}

}