/*

* Copyright (c) 2008-2009 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:

*

*/

package com.nokia.mj.impl.storage;

import com.nokia.mj.impl.storage.StorageSessionImpl;

import com.nokia.mj.impl.utils.Logger;

import com.nokia.mj.impl.rt.support.Jvm;

/**

 * StorageConnection is communication channel to storage.

 */

final class StorageConnection

{

    /**

     * Native session handle

     */

    private int iSessionHandle = 0;

    static

    {

        Jvm.loadSystemLibrary("javastorage");

    }

    /**

     * Constructs native JavaDataAccess instance.

     */

    StorageConnection()

    {

        if (0 != iSessionHandle)

        {

            Logger.WLOG(Logger.EJavaStorage, "Session already created");

            return;

        }

        int ret = _startSession();

        if (ret < 0)

        {

            throw new StorageException("Native storage session failed:"

                                       + String.valueOf(ret));

        }

        iSessionHandle = ret;

    }

    /*** ----------------------------- PUBLIC ------------------------------ */

    /*** ---------------------------- PROTECTED ---------------------------- */

    /*** ----------------------------- PACKAGE ----------------------------- */

    /**

     * Open connection to Java Storage database.

     *

     * @param aHeaders Connection headers.

     * @param aStorageName Storage to open connection.

     * @return sessionID if open was successful.

     * @throws StorageException if open fails.

     */

    String open(String aHeaders, String aStorageName)

    throws StorageException

    {

        // Received message is checked and exception thrown by native side.

        return _open(iSessionHandle, aHeaders, aStorageName);

    }

    /**

     * Close JavaStorage connection.

     *

     * @param aHeaders connection headers to identify closed connection.

     * @throws StorageException if communication fails or server return error.

     */

    void close(String aHeaders) throws StorageException

    {

        // If error exception is thrown by native side.

        _close(iSessionHandle, aHeaders);

    }

    /**

     * Execute SQL statement to JavaStorage.

     *

     * @param aHeaders Connection headers to identify used connection.

     * @param aSqlStatement SQL statement to be executed.

     * @return response to SQL query. This can be for instance queried

     *         application attributes in String format.

     * @throws StorageException if communication fails or server return error.

     */

    String execute(String aHeaders, String aSqlStatement)

    throws StorageException

    {

        // Received message is checked and exception thrown by native side.

        return _execute(iSessionHandle, aHeaders, aSqlStatement);

    }

    /**

     * Closes native JavaStorage session. If it is still open to

     * free native resources

     */

    void closeSession()

    {

        // Close native JavaStorage session if it is still open

        if (0 != iSessionHandle)

        {

            _closeSession(iSessionHandle);

            iSessionHandle = 0;

        }

    }

    /*** ----------------------------- PRIVATE ---------------------------- */

    /*** ----------------------------- NATIVE ----------------------------- */

    /**

     * Starts native application registration session.

     *

     * @return native session handle or Symbian error code (negative number)

     */

    private static native int _startSession();

    /**

     * Closes native application registration session.

     *

     * @param aSessionHandle the session to be closed

     */

    private static native void _closeSession(int aSessionHandle);

    /**

     * Open JavaStorage connection.

     *

     * @param aHeaders connection headers.

     * @param aStorageName database name.

     * @return connection sessionID.

     */

    private native String _open(int aSessionHandle,

                                String aHeaders,

                                String aStorageName);

    /**

     * Close JavaStorage connection.

     *

     * @param aHeaders connection headers to identify closed connection.

     * @return error code if closing failed.

     */

    private native void _close(int aSessionHandle, String aHeaders);

    /**

     * Execute SQL statement to JavaStorage.

     *

     * @param aHeaders Connection headers to identify used connection.

     * @param aSqlStatement SQL statement to be executed.

     * @return response to SQL query. This can be for instance queried

     *         application attributes in String format.

     */

    private native String _execute(int aSessionHandle,

                                   String aHeaders,

                                   String aSqlStatement);

}