/* IIOMetadata.java --
   Copyright (C) 2004  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Classpath 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
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
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exception statement from your version. */


package javax.imageio.metadata;

import org.w3c.dom.Node;

/**
 * Represents metadata that describe an image or an image stream.
 * Each ImageIO plugin will represent image data using an opaque
 * object but all such objects should expose their internal
 * information as a tree of IIOMetadataNodes.
 *
 * There are three formats of metadata that a plugin can support:
 *
 * <ul>
 *   <li>a "native" format</li>
 *   <li>a custom format</li>
 *   <li>a standard plugin-neutral format</li>
 * </ul>
 *
 * If a plugin supports more than one format of metadata, the other
 * formats can be retrieved by calling getMetadataFormatNames.
 *
 * The native format is used to transfer metadata from one image to
 * another image of the same type, losslessly.
 *
 * The custom format describes the image metadata and exposes a tree
 * of IIOMetadataNodes but its internal representation is specific to
 * this plugin.
 *
 * The plugin-neutral format uses a generic tree structure as its
 * internal representation.
 *
 * ImageTranscoders may be used to convert metadata understood by one
 * plugin to metadata understood by another, however the conversion
 * may be lossy.
 *
 * @author Michael Koch (konqueror@gmx.de)
 * @author Thomas Fitzsimmons (fitzsim@redhat.com)
 */
public abstract class IIOMetadata
{
  protected IIOMetadataController controller;
  protected IIOMetadataController defaultController;
  protected String[] extraMetadataFormatClassNames;
  protected String[] extraMetadataFormatNames;
  protected String nativeMetadataFormatClassName;
  protected String nativeMetadataFormatName;
  protected boolean standardFormatSupported;

  /**
   * Construct an IIOMetadata object.
   */
  protected IIOMetadata()
  {
    // Do nothing here.
  }

  /**
   * Construct an IIOMetadata object.
   *
   * @param standardMetadataFormatSupported
   * @param nativeMetadataFormatName
   * @param nativeMetadataFormatClassName
   * @param extraMetadataFormatNames
   * @param extraMetadataFormatClassNames
   *
   * @throws IllegalArgumentException if extraMetadataFormatNames has length of
   * zero or extraMetadataFormatNames and extraMetadataFormatClassNames are
   * neither both null, not have the same length
   */
  protected IIOMetadata(boolean standardMetadataFormatSupported,
                        String nativeMetadataFormatName,
                        String nativeMetadataFormatClassName,
                        String[] extraMetadataFormatNames,
                        String[] extraMetadataFormatClassNames)
  {
    if (extraMetadataFormatNames != null
        && extraMetadataFormatNames.length == 0)
      throw new IllegalArgumentException
        ("extraMetadataFormatNames may not be empty");

    if (((extraMetadataFormatNames == null)
         && (extraMetadataFormatClassNames != null))
        || ((extraMetadataFormatNames != null)
            && (extraMetadataFormatClassNames == null))
        || ((extraMetadataFormatNames != null)
            && (extraMetadataFormatClassNames != null)
            && (extraMetadataFormatNames.length !=
                extraMetadataFormatClassNames.length)))
      throw new IllegalArgumentException
        ("extraMetadataFormatNames and extraMetadataFormatClassNames " +
         "have different lengths");

    this.standardFormatSupported = standardMetadataFormatSupported;
    this.nativeMetadataFormatName = nativeMetadataFormatName;
    this.nativeMetadataFormatClassName = nativeMetadataFormatClassName;
    this.extraMetadataFormatNames = extraMetadataFormatNames;
    this.extraMetadataFormatClassNames = extraMetadataFormatClassNames;
  }

  public boolean activateController()
  {
    if (! hasController())
      return false;

    return getDefaultController().activate(this);
  }

  public IIOMetadataController getController()
  {
    return controller;
  }

  public IIOMetadataController getDefaultController()
  {
    return defaultController;
  }

  public String[] getExtraMetadataFormatNames()
  {
    return (String[]) extraMetadataFormatNames.clone();
  }

  public IIOMetadataFormat getMetadataFormat(String formatName)
  {
    if (formatName == null)
      throw new IllegalArgumentException("formatName may not be null");

    String formatClassName = null;

    if (isStandardMetadataFormatSupported()
        && formatName.equals(nativeMetadataFormatName))
      formatClassName = nativeMetadataFormatClassName;
    else
      {
        String[] extraFormatNames = getExtraMetadataFormatNames();

        for (int i = extraFormatNames.length - 1; i >= 0; --i)
          if (extraFormatNames[i].equals(formatName))
            {
              formatClassName = extraFormatNames[i];
              break;
            }
      }

    if (formatClassName == null)
      throw new IllegalArgumentException("unknown format");

    IIOMetadataFormat format;

    try
      {
        format = (IIOMetadataFormat) Class.forName(formatClassName)
                                          .newInstance();
      }
    catch (Exception e)
      {
        IllegalStateException ise = new IllegalStateException();
        ise.initCause(e);
        throw ise;
      }

    return format;
  }

  public String[] getMetadataFormatNames()
  {
    String[] formatNames = getExtraMetadataFormatNames();

    if (isStandardMetadataFormatSupported())
      {
        // Combine native metadata format name and extra metadata format names
        // into one String array.
        String[] tmp = new String[formatNames.length + 1];
        tmp[0] = getNativeMetadataFormatName();

        for (int i = 1; i < tmp.length; ++i)
          tmp[i] = formatNames[i - 1];

        formatNames = tmp;
      }

    return formatNames;
  }

  public String getNativeMetadataFormatName()
  {
    return nativeMetadataFormatName;
  }

  public boolean hasController()
  {
    return getController() != null;
  }

  public abstract boolean isReadOnly();

  public boolean isStandardMetadataFormatSupported()
  {
    return standardFormatSupported;
  }

  public abstract void reset();

  public void setController(IIOMetadataController controller)
  {
    this.controller = controller;
  }

  public abstract Node getAsTree (String formatName);

  protected IIOMetadataNode getStandardChromaNode ()
  {
    return null;
  }

  protected IIOMetadataNode getStandardCompressionNode ()
  {
    return null;
  }

  protected IIOMetadataNode getStandardDataNode ()
  {
    return null;
  }

  protected IIOMetadataNode getStandardDimensionNode ()
  {
    return null;
  }

  protected IIOMetadataNode getStandardDocumentNode ()
  {
    return null;
  }

  protected IIOMetadataNode getStandardTextNode ()
  {
    return null;
  }

  protected IIOMetadataNode getStandardTileNode ()
  {
    return null;
  }

  protected IIOMetadataNode getStandardTransparencyNode ()
  {
    return null;
  }

  private void appendChild (IIOMetadataNode node,
                            IIOMetadataNode child)
  {
    if (child != null)
      node.appendChild(child);
  }

  protected final IIOMetadataNode getStandardTree ()
  {
    IIOMetadataNode node = new IIOMetadataNode();

    appendChild (node, getStandardChromaNode());
    appendChild (node, getStandardCompressionNode());
    appendChild (node, getStandardDataNode());
    appendChild (node, getStandardDimensionNode());
    appendChild (node, getStandardDocumentNode());
    appendChild (node, getStandardTextNode());
    appendChild (node, getStandardTileNode());
    appendChild (node, getStandardTransparencyNode());

    return node;
  }

  public abstract void mergeTree (String formatName,
                                  Node root)
    throws IIOInvalidTreeException;

  public void setFromTree (String formatName, Node root)
    throws IIOInvalidTreeException
  {
    reset();

    mergeTree (formatName, root);
  }
}