/*

  * Entagged Audio Tag library

  * Copyright (c) 2004-2005 Christian Laireiter <liree@web.de>

  * 

  * This library 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 2.1 of the License, or (at your option) any later version.

  *  

  * This library 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 this library; if not, write to the Free Software

  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

  */

 package org.jaudiotagger.audio.asf.data;

 import org.jaudiotagger.audio.asf.util.Utils;

 import java.math.BigInteger;

 import java.nio.charset.Charset;

 import java.util.HashSet;

 import java.util.List;

 /**

  * Each ASF file starts with a so called header. <br>

  * This header contains other chunks. Each chunk starts with a 16 byte GUID

  * followed by the length (in bytes) of the chunk (including GUID). The length

  * number takes 8 bytes and is unsigned. Finally the chunk's data appears. <br>

  * 

  * @author Christian Laireiter

  */

 public final class AsfHeader extends ChunkContainer

 {

     /**

      * The charset "UTF-16LE" is mandatory for ASF handling.

      */

     public final static Charset ASF_CHARSET = Charset.forName("UTF-16LE"); //$NON-NLS-1$

     /**

      * Stores the {@link GUID} instances, which are allowed multiple times

      * within an ASF header.

      */

     private final static HashSet<GUID> MULTI_CHUNKS;

     /**

      * Byte sequence representing the zero term character.

      */

     public final static byte[] ZERO_TERM = {0, 0};

     static

     {

         MULTI_CHUNKS = new HashSet<GUID>();

         MULTI_CHUNKS.add(GUID.GUID_STREAM);

     }

     /**

      * An ASF header contains multiple chunks. <br>

      * The count of those is stored here.

      */

     private final long chunkCount;

     /**

      * Creates an instance.

      * 

      * @param pos

      *            see {@link Chunk#position}

      * @param chunkLen

      *            see {@link Chunk#chunkLength}

      * @param chunkCnt

      */

     public AsfHeader(long pos, BigInteger chunkLen, long chunkCnt)

     {

         super(GUID.GUID_HEADER, pos, chunkLen);

         this.chunkCount = chunkCnt;

     }

     /**

     * This method looks for an content description object in this header instance, if not found

     * there, it tries to get one from a contained ASF header extension object.

     * 

     * @return content description if found, <code>null</code> otherwise.

     */

     public ContentDescription findContentDescription()

     {

         ContentDescription result = getContentDescription();

         if (result == null && getExtendedHeader() != null)

         {

             result = getExtendedHeader().getContentDescription();

         }

         return result;

     }

     /**

      * This method looks for an extended content description object in this header instance, if not found

      * there, it tries to get one from a contained ASF header extension object.

      * 

      * @return extended content description if found, <code>null</code> otherwise.

      */

     public ExtendedContentDescription findExtendedContentDescription()

     {

         ExtendedContentDescription result = getExtendedContentDescription();

         if (result == null && getExtendedHeader() != null)

         {

             result = getExtendedHeader().getExtendedContentDescription();

         }

         return result;

     }

     /**

      * This method returns the first audio stream chunk found in the asf file or

      * stream.

      * 

      * @return Returns the audioStreamChunk.

      */

     public AudioStreamChunk getAudioStreamChunk()

     {

         AudioStreamChunk result = null;

         final List<Chunk> streamChunks = assertChunkList(GUID.GUID_STREAM);

         for (int i = 0; i < streamChunks.size() && result == null; i++)

         {

             if (streamChunks.get(i) instanceof AudioStreamChunk)

             {

                 result = (AudioStreamChunk) streamChunks.get(i);

             }

         }

         return result;

     }

     /**

      * Returns the amount of chunks, when this instance was created.<br>

      * If chunks have been added, this won't be reflected with this call.<br>

      * For that use {@link #getChunks()}.

      * 

      * @return Chunkcount at instance creation.

      */

     public long getChunkCount()

     {

         return this.chunkCount;

     }

     /**

      * @return Returns the contentDescription.

      */

     public ContentDescription getContentDescription()

     {

         return (ContentDescription) getFirst(GUID.GUID_CONTENTDESCRIPTION, ContentDescription.class);

     }

     /**

      * @return Returns the encodingChunk.

      */

     public EncodingChunk getEncodingChunk()

     {

         return (EncodingChunk) getFirst(GUID.GUID_ENCODING, EncodingChunk.class);

     }

     /**

      * @return Returns the encodingChunk.

      */

     public EncryptionChunk getEncryptionChunk()

     {

         return (EncryptionChunk) getFirst(GUID.GUID_CONTENT_ENCRYPTION, EncryptionChunk.class);

     }

     /**

      * @return Returns the tagHeader.

      */

     public ExtendedContentDescription getExtendedContentDescription()

     {

         return (ExtendedContentDescription) getFirst(GUID.GUID_EXTENDED_CONTENT_DESCRIPTION, ExtendedContentDescription.class);

     }

     /**

      * @return Returns the extended header.

      */

     public AsfExtendedHeader getExtendedHeader()

     {

         return (AsfExtendedHeader) getFirst(GUID.GUID_HEADER_EXTENSION, AsfExtendedHeader.class);

     }

     /**

      * @return Returns the fileHeader.

      */

     public FileHeader getFileHeader()

     {

         return (FileHeader) getFirst(GUID.GUID_FILE, FileHeader.class);

     }

     /**

      * @return Returns the streamBitratePropertiesChunk.

      */

     public StreamBitratePropertiesChunk getStreamBitratePropertiesChunk()

     {

         return (StreamBitratePropertiesChunk) getFirst(GUID.GUID_STREAM_BITRATE_PROPERTIES, StreamBitratePropertiesChunk.class);

     }

     /**

      * 

      * {@inheritDoc}

      */

     public String prettyPrint(final String prefix)

     {

         StringBuffer result = new StringBuffer(super

                         .prettyPrint(prefix, prefix + "  | : Contains: \"" + getChunkCount() + "\" chunks" + Utils.LINE_SEPARATOR));

         return result.toString();

     }

 }