/*

* Copyright (c) 2002 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description:  This class implements functionalities defined in the

*                MetaDataControl interface (included in

*                javax.microedition.media.control package).

*

*/

package com.nokia.microedition.media.control;

import java.util.Vector;

import java.util.Enumeration;

// CLASS DEFINITION

/**

 * The <code>MetaDataControl</code> class implements functionalities defined

 * in the <code>MetaDataControl</code> interface (included in

 * <code>javax.microedition.media.control</code> package).

 */

public class MetaDataControl

        extends ControlImpl

        implements javax.microedition.media.control.MetaDataControl

{

    /**

     * The metadata keys received from the native side. It is assumed that

     * the keys will not change during the lifetime of a media clip or

     * stream. Key data is used so frequently that we want to buffer it

     * here at Java side.

     */

    private String[] iKeys = null;

    private static final String[] DEFAULT_DATA = { MetaDataControl.AUTHOR_KEY,

            MetaDataControl.COPYRIGHT_KEY,

            MetaDataControl.DATE_KEY,

            MetaDataControl.TITLE_KEY

                                                 };

    private static final String DEFAULT_DATA_VALUE = "unknown";

    // Static initialization

    /**

     * Creates an instance of <code>MetaDataControl</code>.

     */

    public MetaDataControl()

    {

    }

    /**

     * Returns acceptable metadata keys.

     *

     * The keys can be used for getting specific metadata value associated to each key.

     *

     * @See <code>javax.microedition.media.control.MetaDataControl</code>

     * interface documentation for details.

     *

     * @return Acceptable key values.

     *

     */

    public String[] getKeys()

    {

        checkState();

        int keyCount = _getKeysCount(iEventSource, iControlHandle);

        if (keyCount < 0)    // can't read key count

        {

            iKeys = DEFAULT_DATA;

            return iKeys;

        }

        Vector keys = new Vector(keyCount + 1);

        for (int i = 0; i < keyCount; i++)

        {

            String currentKey = _getKey(iEventSource, iControlHandle, i);

            if (currentKey == null)  // can't read key value

            {

                iKeys = DEFAULT_DATA;

                return iKeys;

            }

            keys.addElement(currentKey);

        }

        // Check if the default keys are already in the key vector

        // and if not, then add them

        for (int i = 0; i < DEFAULT_DATA.length; i++)

        {

            checkAddKey(keys, DEFAULT_DATA[ i ]);

        }

        iKeys = new String[ keys.size()];

        keys.copyInto(iKeys);

        return iKeys;

    }

    /**

     * Check if there is already a key in vector and if not, then

     * add one.

     * @param aKeys vector containing keys to be checked and which to add

     * new key

     * @param aKey key string to be added if not already present in aKeys

     */

    private void checkAddKey(Vector aKeys, String aKey)

    {

        for (Enumeration e = aKeys.elements(); e.hasMoreElements();)

        {

            String currentElement = (String)e.nextElement();

            if (currentElement.equals(aKey))

            {

                return;

            }

        }

        // Otherwise add the key

        aKeys.addElement(new String(aKey));

    }

    /**

     * Fetches a value of the given metadata key.

     *

     * See <code>javax.microedition.media.control.MetaDataControl</code>

     * interface documentation for details.

     *

     * @param aKey Key of the metadata value to be returned.

     *

     * @return Value of the metadata.

     *

     * @exception IllegalArgumentException Thrown if the given key is

     * <code>null</code> or invalid.

     */

    public String getKeyValue(String aKey)

    {

        checkState();

        if (null == aKey)

        {

            throw new IllegalArgumentException("Key cannot be null");

        }

        getKeys();   // Buffer the keys if not present

        int arrLen = iKeys.length;

        int i = 0;

        // Check if the given key is valid and return the value.

        while (i < arrLen)

        {

            if (iKeys[ i ].equals(aKey))

            {

                String value =  _getKeyValue(iEventSource, iControlHandle, aKey);

                // if key is ok but value is null then this key does not really

                // exist and it must be checked whether it is one from DEFAULT_DATA

                if (value == null)

                {

                    for (int j = 0; j < DEFAULT_DATA.length; j++)

                    {

                        if (aKey.equals(DEFAULT_DATA[ j ]))

                        {

                            return(DEFAULT_DATA_VALUE);

                        }

                    }

                }

                return value;

            }

            ++i;

        }

        // No match - invalid key.

        throw new IllegalArgumentException("Invalid non-null key");

    }

    private native int _getKeysCount(int aEventSource,

                                     int aControlHandle);

    private native String _getKey(int aEventSource,

                                  int aControlHandle,

                                  int aIndex);

    private native String _getKeyValue(int aEventSource,

                                       int aControlHandle,

                                       String aKey);

}   //end of file