package org.jcodec.movtool;

import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.util.ArrayList;
import java.util.List;
import org.jcodec.common.io.IOUtils;
import org.jcodec.common.io.NIOUtils;
import org.jcodec.common.io.SeekableByteChannel;
import org.jcodec.containers.mp4.BoxFactory;
import org.jcodec.containers.mp4.BoxUtil;
import org.jcodec.containers.mp4.MP4Util;
import org.jcodec.containers.mp4.boxes.Box;
import org.jcodec.containers.mp4.boxes.Header;
import org.jcodec.containers.mp4.boxes.NodeBox;

public class Undo {
  public static void main1(String[] args) throws IOException {
    if (args.length < 1) {
      System.err.println("Syntax: qt-undo [-l] <movie>");
      System.err.println("\t-l\t\tList all the previous versions of this movie.");
      System.exit(-1);
    } 
    Undo undo = new Undo();
    if ("-l".equals(args[0])) {
      List<MP4Util.Atom> list = undo.list(args[1]);
      System.out.println("" + list.size() - 1 + " versions.");
    } else {
      undo.undo(args[0]);
    } 
  }
  
  private void undo(String fineName) throws IOException {
    List<MP4Util.Atom> versions = list(fineName);
    if (versions.size() < 2) {
      System.err.println("Nowhere to rollback.");
      return;
    } 
    RandomAccessFile raf = null;
    try {
      raf = new RandomAccessFile(new File(fineName), "rw");
      raf.seek(versions.get(versions.size() - 2).getOffset() + 4L);
      raf.write(new byte[] { (byte)109, (byte)111, (byte)111, (byte)118 });
      raf.seek(versions.get(versions.size() - 1).getOffset() + 4L);
      raf.write(new byte[] { (byte)102, (byte)114, (byte)101, (byte)101 });
    } finally {
      IOUtils.closeQuietly(raf);
    } 
  }
  
  private List<MP4Util.Atom> list(String fileName) throws IOException {
    ArrayList<MP4Util.Atom> result = new ArrayList<>();
    SeekableByteChannel is = null;
    try {
      is = NIOUtils.readableChannel(new File(fileName));
      int version = 0;
      for (MP4Util.Atom atom : MP4Util.getRootAtoms(is)) {
        if ("free".equals(atom.getHeader().getFourcc()) && isMoov(is, atom))
          result.add(atom); 
        if ("moov".equals(atom.getHeader().getFourcc())) {
          result.add(atom);
          break;
        } 
      } 
    } finally {
      IOUtils.closeQuietly(is);
    } 
    return result;
  }
  
  private boolean isMoov(SeekableByteChannel is, MP4Util.Atom atom) throws IOException {
    is.setPosition(atom.getOffset() + atom.getHeader().headerSize());
    try {
      Box mov = BoxUtil.parseBox(NIOUtils.fetchFromChannel(is, (int)atom.getHeader().getSize()), Header.createHeader("moov", 
            atom.getHeader().getSize()), BoxFactory.getDefault());
      return (mov instanceof org.jcodec.containers.mp4.boxes.MovieBox && BoxUtil.containsBox((NodeBox)mov, "mvhd"));
    } catch (Throwable t) {
      return false;
    } 
  }
}