import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.TimeZone;

public class FileDownloader {

  public static void main(String[] args) throws Exception {
    downloadWebFile(" https://www.wsitrader.com/Services/CSVDownloadService.svc/GetWindcastIQHourlyForecast?Account=transaltaw&Profile=robert_nagel@transalta.com&Password=clipperw&ForecastDate=2020-02-13&ForecastType=Latest&SiteIds=e44e15bc-4200-11ea-965b-0a68756b68b8",
      "/Users/laichian/Desktop/JavaPractice/", true);
  }

  public static void downloadWebFile(String url, String savePath, boolean appendDateTime) throws Exception {
    URL sURL = new URL(url);
    String time = "";
    String fileExtension = "";

//    System.out.println("URL: " + sURL);
//    System.out.println("save path: " + savePath);

    HttpURLConnection httpConn = (HttpURLConnection) sURL.openConnection();
//    System.out.println("HTTP: " + httpConn);

    String fieldValue = httpConn.getHeaderField("Content-Disposition");
//    System.out.println(fieldValue);
    String fileName = fieldValue.substring(fieldValue.indexOf("filename=\"") + 10, fieldValue.length() - 1);
//    System.out.println(fileName);

    if(fileName.lastIndexOf(".") != -1 && fileName.lastIndexOf(".") != 0) {
      fileExtension = fileName.substring(fileName.lastIndexOf(".") + 1);
    }

    String fileNameWithoutExtension = fileName.replaceFirst("[.][^.]+$", "");

//    System.out.println(fileExtension);
//    System.out.println(fileNameWithoutExtension);
    if (appendDateTime) {
      Date date = new Date();
      DateFormat formatter = new SimpleDateFormat("yyyyMMddHHmmss");
      formatter.setTimeZone(TimeZone.getTimeZone("EST"));
      time = formatter.format(date);
      System.out.println(time);
    }

    BufferedInputStream in = new BufferedInputStream(httpConn.getInputStream());
    FileOutputStream fos = new FileOutputStream(savePath + fileNameWithoutExtension + time + "." +fileExtension);
    BufferedOutputStream out = new BufferedOutputStream(fos, 1024);

    byte[] buffer = new byte[1024];
    int read = 0;
    while((read = in.read(buffer, 0, 1024)) >= 0) {
      out.write(buffer, 0, read);
    }

    out.close();
    in.close();
    System.out.println("Completed");

  }
}