import ucar.ma2.Array;
import ucar.ma2.Index;
import ucar.ma2.InvalidRangeException;
import ucar.nc2.NetcdfFile;
import ucar.nc2.NetcdfFiles;
import ucar.nc2.Variable;

import java.io.IOException;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

/**
 * Unit test for simple App.
 */
public class TestReadGrib2ByNC {
    public static void main(String[] args){
        // String ncFile = "surface.nc";
        String file = "C:\\Users\\shi_y\\Desktop\\java_learn\\data_download\\GFSData\\UTC-20230910\\BJT-20230911-0200.grib2";
        try (NetcdfFile ncFile = NetcdfFiles.open(file)) {
            // 打印文件相关信息
            // System.out.println(ncfile.toString());

            // 获取时间变量
            Variable timeVar = ncFile.findVariable("time");
            String units = timeVar.findAttribute("units").getStringValue();
            System.out.println(units);
            // 读取时间变量 surface.nc的单位是"hours since 1900-01-01 00:00:00.0"
            System.out.println(timeVar.getFileTypeId());
            double[] timeArray = (double[]) timeVar.read().copyTo1DJavaArray();

            DateTimeFormatter unitsFormat = DateTimeFormatter.ofPattern("'Hour since 'yyyy-MM-dd'T'HH:mm:ss'Z'");
            LocalDateTime unitsDateTime = LocalDateTime.parse(units, unitsFormat).plusHours((long) timeArray[0]);
            System.out.println(unitsDateTime);
            // 指定变量名读取变量
            Variable t2m = ncFile.findVariable("Temperature_isobaric");

            // 打印变量的相关信息
            System.out.println(t2m.toString());

            if (t2m != null) {
                System.out.println(t2m.findDimensionIndex("lon"));
            }
            // 读取所有的数据
            assert t2m != null;
            Array v = t2m.read("0, 0, 10:20, 20:30").reduce(0).reduce(0);
            Index index = v.getIndex(); // 用于跟踪当前索引的位置
            index = index.set(1);
            System.out.println(v.getShort(index));


        } catch (IOException ioe) {
            // Handle less-cool exceptions here
            throw new RuntimeException(ioe);
        } catch (InvalidRangeException e) {
            throw new RuntimeException(e);
        }
    }

}