/*
 * Copyright 2005-2014 the original author or authors.
 *
 * 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.springframework.ws.mime;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import javax.activation.DataHandler;
import javax.activation.DataSource;
import javax.activation.FileDataSource;

import org.springframework.core.io.InputStreamSource;
import org.springframework.core.io.Resource;
import org.springframework.util.Assert;

/**
 * Abstract implementation of the {@link MimeMessage} interface. Contains convenient default implementations.
 *
 * @author Arjen Poutsma
 * @since 1.0.0
 */
public abstract class AbstractMimeMessage implements MimeMessage {

	@Override
	public final Attachment addAttachment(String contentId, File file) throws AttachmentException {
		Assert.hasLength(contentId, "contentId must not be empty");
		Assert.notNull(file, "File must not be null");
		DataHandler dataHandler = new DataHandler(new FileDataSource(file));
		return addAttachment(contentId, dataHandler);
	}

	@Override
	public final Attachment addAttachment(String contentId, InputStreamSource inputStreamSource, String contentType) {
		Assert.hasLength(contentId, "contentId must not be empty");
		Assert.notNull(inputStreamSource, "InputStreamSource must not be null");
		if (inputStreamSource instanceof Resource && ((Resource) inputStreamSource).isOpen()) {
			throw new IllegalArgumentException("Passed-in Resource contains an open stream: invalid argument. " +
					"MIME requires an InputStreamSource that creates a fresh stream for every call.");
		}
		DataHandler dataHandler = new DataHandler(new InputStreamSourceDataSource(inputStreamSource, contentType));
		return addAttachment(contentId, dataHandler);
	}

	/**
	 * Activation framework {@code DataSource} that wraps a Spring {@code InputStreamSource}.
	 *
	 * @author Arjen Poutsma
	 * @since 1.0.0
	 */
	private static class InputStreamSourceDataSource implements DataSource {

		private final InputStreamSource inputStreamSource;

		private final String contentType;

		public InputStreamSourceDataSource(InputStreamSource inputStreamSource, String contentType) {
			this.inputStreamSource = inputStreamSource;
			this.contentType = contentType;
		}

		@Override
		public InputStream getInputStream() throws IOException {
			return inputStreamSource.getInputStream();
		}

		@Override
		public OutputStream getOutputStream() {
			throw new UnsupportedOperationException("Read-only javax.activation.DataSource");
		}

		@Override
		public String getContentType() {
			return contentType;
		}

		@Override
		public String getName() {
			if (inputStreamSource instanceof Resource) {
				Resource resource = (Resource) inputStreamSource;
				return resource.getFilename();
			}
			else {
				throw new UnsupportedOperationException("DataSource name not available");
			}
		}

	}

}