import javax.imageio.metadata.*;

import javax.imageio.stream.*;

sclass GIFRewriter {

  settable File inputFile;

  settable bool debug;

  byte[] data;

  int numImages;

  ImageReader reader;

  S metaFormatName;

  Image get() ctex {

    if (!inputFile.exists()) null;

    // Load anything but GIF the normal way

    if (!isGIF(inputFile))

      ret ImageIO.read(inputFile);

    reader = ImageIO.getImageReadersByFormatName("gif").next();

    // Give it the stream to decode from

    reader.setInput(ImageIO.createImageInputStream(inputFile));

    numImages = reader.getNumImages(true);

    // Get 'metaFormatName'. Need first frame for that.

    IIOMetadata imageMetaData = reader.getImageMetadata(0);

    metaFormatName = imageMetaData.getNativeMetadataFormatName();

    // Prepare streams for image encoding

    new ByteArrayOutputStream baoStream;

    {

      temp ImageOutputStream ios = ImageIO.createImageOutputStream(baoStream);

      // Get GIF writer that's compatible with reader

      ImageWriter writer = ImageIO.getImageWriter(reader);

      // Give it the stream to encode to

      writer.setOutput(ios);

      writer.prepareWriteSequence(null);

      for i to numImages: {

        // Get input image

        BufferedImage frameIn = reader.read(i);

        frameIn = transformImage(frameIn);

        // Get input metadata

        IIOMetadataNode root = (IIOMetadataNode)reader.getImageMetadata(i).getAsTree(metaFormatName);

        // Find GraphicControlExtension node

        int nNodes = root.getLength();

        for j to nNodes: {

          org.w3c.dom.Node node = root.item(j);

          if (node.getNodeName().equalsIgnoreCase("GraphicControlExtension")) {

            cast node to IIOMetadataNode;

            if (parseInt(node.getAttribute("delayTime")) == 0)

              node.setAttribute("delayTime", "10");

          }

          // Create output metadata

          IIOMetadata metadata = writer.getDefaultImageMetadata(new ImageTypeSpecifier(frameIn), null);

          // Copy metadata to output metadata

          metadata.setFromTree(metadata.getNativeMetadataFormatName(), root);

          // Create output image

          IIOImage frameOut = new IIOImage(frameIn, null, metadata);

          // Encode output image

          writer.writeToSequence(frameOut, writer.getDefaultWriteParam());

        }

        writer.endWriteSequence();

      }

      // Create image using encoded data

      data = baoStream.toByteArray();

      if (debug) print("Data size: " + l(data));

      ret Toolkit.getDefaultToolkit().createImage(data);

    }

  }

  bool animationSpeedIsBugged() ctex {

    for i to numImages: {

      IIOMetadataNode root = cast reader.getImageMetadata(i).getAsTree(metaFormatName);

      int nNodes = root.getLength();

      for j to nNodes: {

        org.w3c.dom.Node node = root.item(j);

        if (node.getNodeName().equalsIgnoreCase("GraphicControlExtension")) {

          cast node to IIOMetadataNode;

          if (parseInt(node.getAttribute("delayTime")) == 0) true;

        }

      }

    }

    false;

  }

  swappable BufferedImage transformImage(BufferedImage image) { ret image; }

}