/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you 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.apache.openaz.xacml.admin.util;

import java.io.IOException;

import com.vaadin.server.FileDownloader;
import com.vaadin.server.StreamResource;
import com.vaadin.server.StreamResource.StreamSource;
import com.vaadin.server.VaadinRequest;
import com.vaadin.server.VaadinResponse;
import com.vaadin.ui.UI;

public class OnDemandFileDownloader extends FileDownloader {
	private static final long serialVersionUID = 1L;
	private final OnDemandStreamResource resource;

	public interface OnDemandStreamResource extends StreamSource {
		String getFilename ();
	}

  public OnDemandFileDownloader(OnDemandStreamResource resource) {
		super(new StreamResource(resource, ""));
		this.resource = resource;
		if (this.resource == null) {
			throw new NullPointerException("Can't send null resource");
		}
	}

	@Override
	public boolean handleConnectorRequest(VaadinRequest request,
			VaadinResponse response, String path) throws IOException {
		this.getResource().setFilename(this.resource.getFilename());
		return super.handleConnectorRequest(request, response, path);
	}

	private StreamResource getResource() {
		StreamResource resource = null;
		UI.getCurrent().getSession().lock();
		try {
			resource = (StreamResource) this.getResource("dl");
		} finally {
			UI.getCurrent().getSession().unlock();
		}
		return resource;
	}
}