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/*
 * Copyright 2004-2014 ICEsoft Technologies Canada Corp.
 *
 * 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 org.icefaces.ace.component.fileentry;

import java.io.Serializable;

/**
 * When files are being uploaded, they will be saved into the file-system
 * unless a FileEntryCallback is provided, in which case the application
 * may take responsibility for the process of saving the files. This is
 * useful in cases where the files should be saved into a database, or
 * processed in memory before being written to the file-system, etc.
 * 
 * Each call to begin(-) can be followed by any number of calls to the write(-)
 * methods, and then a call to end(-). Even if the begin(-) call shows that the
 * file had pre-failed (say, due to an invalid file extension), end(-) will
 * still be called, but not any of the write(-) methods. 
 */
public interface FileEntryCallback extends Serializable {
    /**
     * Notify the callback of another file that has been uploaded
     * Check fileInfo.getStatus() to determine if the file has pre-failed
     * uploading, due to too many files uploaded, an invalid file extension,
     * or content type.
     * @param fileInfo Contains all of the information known about the file, before downloading the contents
     */
    public void begin(FileEntryResults.FileInfo fileInfo);

    /**
     * We write in chunks, as we read them in
     */
    public void write(byte[] buffer, int offset, int length);

    /**
     * We write in chunks, as we read them in
     */
    public void write(int data);

    /**
     * If we detect that a file failed, say because it's over quota, then
     * we'll tell the callback, and it might massage the result, to still
     * accept the file, or possibly to fail the file that we thought was ok,
     * by calling FileEntryResults.FileInfo.updateStatus(FileEntryStatus, boolean).
     * @param fileInfo The same object that was passed into begin(FileInfo)
     */
    public void end(FileEntryResults.FileInfo fileInfo);
}