/*******************************************************************************
 * Copyright (c) 2024, 2026, Olivier Ayache.  All rights reserved.
 *
 * This file is part of AVPKit.
 *
 * AVPKit is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * AVPKit is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with AVPKit.  If not, see <http://www.gnu.org/licenses/>.
 *******************************************************************************/

package com.avpkit.mediatool.demos;

import java.io.File;

import com.avpkit.mediatool.IMediaReader;
import com.avpkit.mediatool.IMediaViewer;
import com.avpkit.mediatool.IMediaWriter;
import com.avpkit.mediatool.MediaToolAdapter;
import com.avpkit.mediatool.ToolFactory;
import com.avpkit.mediatool.event.AudioSamplesEvent;
import com.avpkit.mediatool.event.IAddStreamEvent;
import com.avpkit.mediatool.event.IAudioSamplesEvent;
import com.avpkit.mediatool.event.ICloseCoderEvent;
import com.avpkit.mediatool.event.ICloseEvent;
import com.avpkit.mediatool.event.IOpenCoderEvent;
import com.avpkit.mediatool.event.IOpenEvent;
import com.avpkit.mediatool.event.IVideoPictureEvent;
import com.avpkit.mediatool.event.VideoPictureEvent;
import com.avpkit.core.IAudioSamples;
import com.avpkit.core.IVideoPicture;

import static java.lang.System.out;
import static java.lang.System.exit;

/** 
 * A very simple media transcoder which uses {@link IMediaReader}, {@link
 * IMediaWriter} and {@link IMediaViewer}.
 */

public class ConcatenateAudioAndVideo
{
  /**
   * Concatenate two files.
   * 
   * @param args 3 strings; an input file 1, input file 2, and an output file.
   */
  
  public static void main(String[] args)
  {
    if (args.length < 3)
    {
      out.println("Concatent two files.  The destination " +
        "format will be guessed from the file extention.");
      out.println("");
      out.println("   ConcatentateTwoFiles <source-file1> <source-file2> <destination-file>");
      out.println("");
      out.println(
        "The destination type will be guess from the supplied file extsion.");
      exit(0);
    }

    File source1 = new File(args[0]);
    File source2 = new File(args[1]);
    
    if (!source1.exists())
    {
      out.println("Source file does not exist: " + source1);
      exit(0);
    }

    if (!source2.exists())
    {
      out.println("Source file does not exist: " + source2);
      exit(0);
    }

    concatenate(args[0], args[1], args[2]);
  }

  /**
   * Concatenate two source files into one destination file.
   * 
   * @param sourceUrl1 the file which will appear first in the output
   * @param sourceUrl2 the file which will appear second in the output
   * @param destinationUrl the file which will be produced
   */

  public static void concatenate(String sourceUrl1, String sourceUrl2,
    String destinationUrl)
  {
    out.printf("transcode %s + %s -> %s\n", sourceUrl1, sourceUrl2,
      destinationUrl);

    //////////////////////////////////////////////////////////////////////
    //                                                                  //
    // NOTE: be sure that the audio and video parameters match those of //
    // your input media                                                 //
    //                                                                  //
    //////////////////////////////////////////////////////////////////////

    // video parameters

    final int videoStreamIndex = 0;
    final int videoStreamId = 0;
    final int width = 480;
    final int height = 360;

    // audio parameters

    final int audioStreamIndex = 1;
    final int audioStreamId = 0;
    final int channelCount = 2;
    final int sampleRate = 44100; // Hz

    // create the first media reader

    IMediaReader reader1 = ToolFactory.makeReader(sourceUrl1);

    // create the second media reader

    IMediaReader reader2 = ToolFactory.makeReader(sourceUrl2);

    // create the media concatenator

    MediaConcatenator concatenator = new MediaConcatenator(audioStreamIndex,
      videoStreamIndex);

    // concatenator listens to both readers

    reader1.addListener(concatenator);
    reader2.addListener(concatenator);

    // create the media writer which listens to the concatenator

    IMediaWriter writer = ToolFactory.makeWriter(destinationUrl);
    concatenator.addListener(writer);

    // add the video stream

    writer.addVideoStream(videoStreamIndex, videoStreamId, width, height);

    // add the audio stream

    writer.addAudioStream(audioStreamIndex, audioStreamId, channelCount,
      sampleRate);

    // read packets from the first source file until done

    while (reader1.readPacket() == null)
      ;

    // read packets from the second source file until done

    while (reader2.readPacket() == null)
      ;

    // close the writer

    writer.close();
  }
  
  static class MediaConcatenator extends MediaToolAdapter
  {
    // the current offset
    
    private long mOffset = 0;
    
    // the next video timestamp
    
    private long mNextVideo = 0;
    
    // the next audio timestamp
    
    private long mNextAudio = 0;

    // the index of the audio stream
    
    private final int mAudoStreamIndex;
    
    // the index of the video stream
    
    private final int mVideoStreamIndex;
    
    /**
     * Create a concatenator.
     * 
     * @param audioStreamIndex index of audio stream
     * @param videoStreamIndex index of video stream
     */
    
    public MediaConcatenator(int audioStreamIndex, int videoStreamIndex)
    {
      mAudoStreamIndex = audioStreamIndex;
      mVideoStreamIndex = videoStreamIndex;
    }
    
    public void onAudioSamples(IAudioSamplesEvent event)
    {
      IAudioSamples samples = event.getAudioSamples();
      
      // set the new time stamp to the original plus the offset established
      // for this media file

      long newTimeStamp = samples.getTimeStamp() + mOffset;

      // keep track of predicted time of the next audio samples, if the end
      // of the media file is encountered, then the offset will be adjusted
      // to this time.

      mNextAudio = samples.getNextPts();

      // set the new timestamp on audio samples

      samples.setTimeStamp(newTimeStamp);

      // create a new audio samples event with the one true audio stream
      // index

      super.onAudioSamples(new AudioSamplesEvent(this, samples,
        mAudoStreamIndex));
    }

    public void onVideoPicture(IVideoPictureEvent event)
    {
      IVideoPicture picture = event.getMediaData();
      long originalTimeStamp = picture.getTimeStamp();

      // set the new time stamp to the original plus the offset established
      // for this media file

      long newTimeStamp = originalTimeStamp + mOffset;

      // keep track of predicted time of the next video picture, if the end
      // of the media file is encountered, then the offset will be adjusted
      // to this this time.
      //
      // You'll note in the audio samples listener above we used
      // a method called getNextPts().  Video pictures don't have
      // a similar method because frame-rates can be variable, so
      // we don't now.  The minimum thing we do know though (since
      // all media containers require media to have monotonically
      // increasing time stamps), is that the next video timestamp
      // should be at least one tick ahead.  So, we fake it.
      
      mNextVideo = originalTimeStamp + 1;

      // set the new timestamp on video samples

      picture.setTimeStamp(newTimeStamp);

      // create a new video picture event with the one true video stream
      // index

      super.onVideoPicture(new VideoPictureEvent(this, picture,
        mVideoStreamIndex));
    }
    
    public void onClose(ICloseEvent event)
    {
      // update the offset by the larger of the next expected audio or video
      // frame time

      mOffset = Math.max(mNextVideo, mNextAudio);

      if (mNextAudio < mNextVideo)
      {
        // In this case we know that there is more video in the
        // last file that we read than audio. Technically you
        // should pad the audio in the output file with enough
        // samples to fill that gap, as many media players (e.g.
        // Quicktime, Microsoft Media Player, MPlayer) actually
        // ignore audio time stamps and just play audio sequentially.
        // If you don't pad, in those players it may look like
        // audio and video is getting out of sync.

        // However kiddies, this is demo code, so that code
        // is left as an exercise for the readers. As a hint,
        // see the IAudioSamples.defaultPtsToSamples(...) methods.
      }
    }

    public void onAddStream(IAddStreamEvent event)
    {
      // overridden to ensure that add stream events are not passed down
      // the tool chain to the writer, which could cause problems
    }

    public void onOpen(IOpenEvent event)
    {
      // overridden to ensure that open events are not passed down the tool
      // chain to the writer, which could cause problems
    }

    public void onOpenCoder(IOpenCoderEvent event)
    {
      // overridden to ensure that open coder events are not passed down the
      // tool chain to the writer, which could cause problems
    }

    public void onCloseCoder(ICloseCoderEvent event)
    {
      // overridden to ensure that close coder events are not passed down the
      // tool chain to the writer, which could cause problems
    }
  }
}