package it.acxent.videoj;

import java.awt.image.BufferedImage;
import java.io.File;
import java.util.LinkedHashSet;
import javax.imageio.ImageIO;
import org.jcodec.api.FrameGrab;
import org.jcodec.common.io.NIOUtils;
import org.jcodec.common.model.Picture;

public class ManageVideoJ {
  public static final LinkedHashSet<String> extractNFrames(String videoFileName, String targetDir, String targetName, int nFrames) throws Exception {
    Timer timer = new Timer();
    timer.start();
    FrameGrab g = FrameGrab.createFrameGrab(NIOUtils.readableChannel(new File(videoFileName)));
    LinkedHashSet<String> frames = new LinkedHashSet<>();
    BufferedImage bufferedImage = null;
    Picture picture = null;
    try {
      File targetDirFile = new File(targetDir);
      if (!targetDirFile.exists())
        targetDirFile.mkdirs(); 
      int movieLen = g.getVideoTrack().getMeta().getTotalFrames();
      int step = movieLen / (nFrames + 1);
      System.out.println("len:" + movieLen + " step: " + step);
      for (int i = 0; i < nFrames; i++) {
        g.seekToFrameSloppy(i * step);
        picture = g.getNativeFrame();
        bufferedImage = AWTUtil.toBufferedImage(picture);
        String currentFile = targetDir + targetDir + "_" + targetName + ".jpg";
        frames.add(currentFile);
        File frameFile = new File(currentFile);
        ImageIO.write(bufferedImage, "jpg", frameFile);
        bufferedImage.flush();
        bufferedImage = null;
        picture = null;
      } 
    } finally {
      if (bufferedImage != null) {
        bufferedImage.flush();
        bufferedImage = null;
      } 
      if (g != null) {
        g.getDecoder().shutdownThreadPool();
        g = null;
      } 
    } 
    timer.stop();
    System.out.println("extractNFrames. DURATA: " + timer.getDurataHourMin());
    return frames;
  }
}