/*
 * 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.server.endpoint.adapter.method;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import javax.xml.transform.Source;
import javax.xml.transform.TransformerException;
import javax.xml.transform.stream.StreamResult;

import org.springframework.core.MethodParameter;
import org.springframework.util.Assert;
import org.springframework.ws.server.endpoint.annotation.RequestPayload;
import org.springframework.ws.server.endpoint.annotation.ResponsePayload;
import org.springframework.xml.transform.TransformerObjectSupport;

/**
 * Abstract base class for {@link MethodArgumentResolver} and {@link MethodReturnValueHandler} implementations based on
 * {@link RequestPayload} and {@link ResponsePayload} annotations.
 *
 * @author Arjen Poutsma
 * @since 2.0
 */
public abstract class AbstractPayloadMethodProcessor extends TransformerObjectSupport
		implements MethodArgumentResolver, MethodReturnValueHandler {

	// MethodArgumentResolver

	/**
	 * {@inheritDoc}
	 *
	 * <p>This implementation gets checks if the given parameter is annotated with {@link RequestPayload}, and invokes
	 * {@link #supportsRequestPayloadParameter(org.springframework.core.MethodParameter)} afterwards.
	 */
	@Override
	public final boolean supportsParameter(MethodParameter parameter) {
		Assert.isTrue(parameter.getParameterIndex() >= 0, "Parameter index larger smaller than 0");
		if (parameter.getParameterAnnotation(RequestPayload.class) == null) {
			return false;
		}
		else {
			return supportsRequestPayloadParameter(parameter);
		}
	}

	/**
	 * Indicates whether the given {@linkplain MethodParameter method parameter}, annotated with {@link RequestPayload},
	 * is supported by this resolver.
	 *
	 * @param parameter the method parameter to check
	 * @return {@code true} if this resolver supports the supplied parameter; {@code false} otherwise
	 */
	protected abstract boolean supportsRequestPayloadParameter(MethodParameter parameter);

	// MethodReturnValueHandler
	
	/**
	 * {@inheritDoc}
	 *
	 * <p>This implementation gets checks if the method of the given return type is annotated with {@link ResponsePayload},
	 * and invokes {@link #supportsResponsePayloadReturnType(org.springframework.core.MethodParameter)} afterwards.
	 */
	@Override
	public final boolean supportsReturnType(MethodParameter returnType) {
		Assert.isTrue(returnType.getParameterIndex() == -1, "Parameter index is not -1");
		if (returnType.getMethodAnnotation(ResponsePayload.class) == null) {
			return false;
		}
		else {
			return supportsResponsePayloadReturnType(returnType);
		}
	}

	/**
	 * Indicates whether the given {@linkplain MethodParameter method return type}, annotated with {@link
	 * ResponsePayload}, is supported.
	 *
	 * @param returnType the method parameter to check
	 * @return {@code true} if this resolver supports the supplied return type; {@code false} otherwise
	 */
	protected abstract boolean supportsResponsePayloadReturnType(MethodParameter returnType);

	/**
	 * Converts the given source to a byte array input stream.
	 *
	 * @param source the source to convert
	 * @return the input stream
	 * @throws javax.xml.transform.TransformerException in case of transformation errors
	 */
	protected ByteArrayInputStream convertToByteArrayInputStream(Source source) throws TransformerException {
		ByteArrayOutputStream bos = new ByteArrayOutputStream();
		transform(source, new StreamResult(bos));
		return new ByteArrayInputStream(bos.toByteArray());
	}
}