/*
 * Copyright (C) 2009 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.backup;

import android.os.ParcelFileDescriptor;

/**
 * A convenient interface to be used with the
 * {@link android.backup.BackupHelperAgent} to implement backup and restore of
 * arbitrary data types.
 * <p>
 * STOPSHOP: document!
 */
public interface BackupHelper {
    /**
     * Based on <code>oldState</code>, determine which of the files from the
     * application's data directory need to be backed up, write them to
     * <code>data</code>, and fill in <code>newState</code> with the state as it
     * exists now.
     */
    public void performBackup(ParcelFileDescriptor oldState, BackupDataOutput data,
            ParcelFileDescriptor newState);

    /**
     * Called by BackupHelperAgent to restore one entity from the restore dataset.
     * <p class=note>
     * Do not close the <code>data</code> stream.  Do not read more than
     * <code>data.size()</code> bytes from <code>data</code>.
     */
    public void restoreEntity(BackupDataInputStream data);

    /**
     * Called by BackupHelperAgent to write the new backup state file corresponding to
     * the current state of the app's data at the time the backup operation was
     * performed.
     */
    public void writeNewStateDescription(ParcelFileDescriptor fd);
}