/*
 * Copyright 2005-2012 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.transport.http;

import java.util.List;
import javax.servlet.http.HttpServletRequest;

import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
import org.springframework.xml.transform.TransformerObjectSupport;
import org.springframework.xml.xpath.XPathExpression;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Node;

/**
 * Abstract base class for {@link WsdlDefinitionHandlerAdapter} and {@link XsdSchemaHandlerAdapter} that transforms
 * XSD and WSDL location attributes.
 *
 * @author Arjen Poutsma
 * @since 2.1.2
 */
public abstract class LocationTransformerObjectSupport extends TransformerObjectSupport {

	/** Logger available to subclasses. */
	private final Log logger = LogFactory.getLog(getClass());

	/**
	 * Transforms the locations of the given definition document using the given XPath expression.
	 * @param xPathExpression the XPath expression
	 * @param definitionDocument the definition document
	 * @param request the request, used to determine the location to transform to
	 */
	protected void transformLocations(XPathExpression xPathExpression,
									  Document definitionDocument,
									  HttpServletRequest request) {
		Assert.notNull(xPathExpression, "'xPathExpression' must not be null");
		Assert.notNull(definitionDocument, "'definitionDocument' must not be null");
		Assert.notNull(request, "'request' must not be null");

		List<Node> locationNodes = xPathExpression.evaluateAsNodeList(definitionDocument);
		for (Node locationNode : locationNodes) {
			if (locationNode instanceof Attr) {
				Attr location = (Attr) locationNode;
				if (StringUtils.hasLength(location.getValue())) {
					String newLocation = transformLocation(location.getValue(), request);
					if (logger.isDebugEnabled()) {
						logger.debug("Transforming [" + location.getValue() + "] to [" + newLocation + "]");
					}
					location.setValue(newLocation);
				}
			}
		}
	}

	/**
	 * Transform the given location string to reflect the given request. If the given location is a full url, the
	 * scheme, server name, and port are changed. If it is a relative url, the scheme, server name, and port are
	 * prepended. Can be overridden in subclasses to change this behavior.
	 *
	 * <p>For instance, if the location attribute defined in the WSDL is {@code http://localhost:8080/context/services/myService},
	 * and the request URI for the WSDL is {@code http://example.com:80/context/myService.wsdl}, the location
	 * will be changed to {@code http://example.com:80/context/services/myService}.
	 *
	 * <p>If the location attribute defined in the WSDL is {@code /services/myService}, and the request URI for the
	 * WSDL is {@code http://example.com:8080/context/myService.wsdl}, the location will be changed to
	 * {@code http://example.com:8080/context/services/myService}.
	 *
	 * <p>This method is only called when the {@code transformLocations} property is true.
	 */
	protected String transformLocation(String location, HttpServletRequest request) {
		StringBuilder url = new StringBuilder(request.getScheme());
		url.append("://").append(request.getServerName()).append(':').append(request.getServerPort());
		if (location.startsWith("/")) {
			// a relative path, prepend the context path
			url.append(request.getContextPath()).append(location);
			return url.toString();
		}
		else {
			int idx = location.indexOf("://");
			if (idx != -1) {
				// a full url
				idx = location.indexOf('/', idx + 3);
				if (idx != -1) {
					String path = location.substring(idx);
					url.append(path);
					return url.toString();
				}
			}
		}
		// unknown location, return the original
		return location;
	}
}