/*
 * Copyright 2002-2016 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.web.context.support;

import java.io.IOException;
import java.util.Enumeration;
import java.util.LinkedHashSet;
import java.util.Set;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;
import javax.servlet.ServletContext;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;
import org.springframework.core.io.UrlResource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.util.ResourceUtils;
import org.springframework.util.StringUtils;

ServletContext-aware subclass of PathMatchingResourcePatternResolver, able to find matching resources below the web application root directory via ServletContext.getResourcePaths. Falls back to the superclass' file system checking for other resources. 
Author:
Juergen Hoeller
Since:
1.1.2/**
 * ServletContext-aware subclass of {@link PathMatchingResourcePatternResolver},
 * able to find matching resources below the web application root directory
 * via {@link ServletContext#getResourcePaths}. Falls back to the superclass'
 * file system checking for other resources.
 *
 * @author Juergen Hoeller
 * @since 1.1.2
 */
public class ServletContextResourcePatternResolver extends PathMatchingResourcePatternResolver {

	private static final Log logger = LogFactory.getLog(ServletContextResourcePatternResolver.class);


	
Create a new ServletContextResourcePatternResolver.
Params:
servletContext – the ServletContext to load resources with
See Also:
ServletContextResourceLoader(ServletContext)/**
	 * Create a new ServletContextResourcePatternResolver.
	 * @param servletContext the ServletContext to load resources with
	 * @see ServletContextResourceLoader#ServletContextResourceLoader(javax.servlet.ServletContext)
	 */
	public ServletContextResourcePatternResolver(ServletContext servletContext) {
		super(new ServletContextResourceLoader(servletContext));
	}

	
Create a new ServletContextResourcePatternResolver.
Params:
resourceLoader – the ResourceLoader to load root directories and
actual resources with/**
	 * Create a new ServletContextResourcePatternResolver.
	 * @param resourceLoader the ResourceLoader to load root directories and
	 * actual resources with
	 */
	public ServletContextResourcePatternResolver(ResourceLoader resourceLoader) {
		super(resourceLoader);
	}


	
Overridden version which checks for ServletContextResource and uses ServletContext.getResourcePaths to find matching resources below the web application root directory. In case of other resources, delegates to the superclass version. 
See Also:
doRetrieveMatchingServletContextResources
ServletContextResource
ServletContext.getResourcePaths/**
	 * Overridden version which checks for ServletContextResource
	 * and uses {@code ServletContext.getResourcePaths} to find
	 * matching resources below the web application root directory.
	 * In case of other resources, delegates to the superclass version.
	 * @see #doRetrieveMatchingServletContextResources
	 * @see ServletContextResource
	 * @see javax.servlet.ServletContext#getResourcePaths
	 */
	@Override
	protected Set<Resource> doFindPathMatchingFileResources(Resource rootDirResource, String subPattern)
			throws IOException {

		if (rootDirResource instanceof ServletContextResource) {
			ServletContextResource scResource = (ServletContextResource) rootDirResource;
			ServletContext sc = scResource.getServletContext();
			String fullPattern = scResource.getPath() + subPattern;
			Set<Resource> result = new LinkedHashSet<>(8);
			doRetrieveMatchingServletContextResources(sc, fullPattern, scResource.getPath(), result);
			return result;
		}
		else {
			return super.doFindPathMatchingFileResources(rootDirResource, subPattern);
		}
	}

	
Recursively retrieve ServletContextResources that match the given pattern,
adding them to the given result set.
Params:
servletContext – the ServletContext to work on
fullPattern – the pattern to match against,
with preprended root directory path
dir – the current directory
result – the Set of matching Resources to add to
Throws:
IOException – if directory contents could not be retrieved
See Also:
ServletContextResource
ServletContext.getResourcePaths/**
	 * Recursively retrieve ServletContextResources that match the given pattern,
	 * adding them to the given result set.
	 * @param servletContext the ServletContext to work on
	 * @param fullPattern the pattern to match against,
	 * with preprended root directory path
	 * @param dir the current directory
	 * @param result the Set of matching Resources to add to
	 * @throws IOException if directory contents could not be retrieved
	 * @see ServletContextResource
	 * @see javax.servlet.ServletContext#getResourcePaths
	 */
	protected void doRetrieveMatchingServletContextResources(
			ServletContext servletContext, String fullPattern, String dir, Set<Resource> result)
			throws IOException {

		Set<String> candidates = servletContext.getResourcePaths(dir);
		if (candidates != null) {
			boolean dirDepthNotFixed = fullPattern.contains("**");
			int jarFileSep = fullPattern.indexOf(ResourceUtils.JAR_URL_SEPARATOR);
			String jarFilePath = null;
			String pathInJarFile = null;
			if (jarFileSep > 0 && jarFileSep + ResourceUtils.JAR_URL_SEPARATOR.length() < fullPattern.length()) {
				jarFilePath = fullPattern.substring(0, jarFileSep);
				pathInJarFile = fullPattern.substring(jarFileSep + ResourceUtils.JAR_URL_SEPARATOR.length());
			}
			for (String currPath : candidates) {
				if (!currPath.startsWith(dir)) {
					// Returned resource path does not start with relative directory:
					// assuming absolute path returned -> strip absolute path.
					int dirIndex = currPath.indexOf(dir);
					if (dirIndex != -1) {
						currPath = currPath.substring(dirIndex);
					}
				}
				if (currPath.endsWith("/") && (dirDepthNotFixed || StringUtils.countOccurrencesOf(currPath, "/") <=
						StringUtils.countOccurrencesOf(fullPattern, "/"))) {
					// Search subdirectories recursively: ServletContext.getResourcePaths
					// only returns entries for one directory level.
					doRetrieveMatchingServletContextResources(servletContext, fullPattern, currPath, result);
				}
				if (jarFilePath != null && getPathMatcher().match(jarFilePath, currPath)) {
					// Base pattern matches a jar file - search for matching entries within.
					String absoluteJarPath = servletContext.getRealPath(currPath);
					if (absoluteJarPath != null) {
						doRetrieveMatchingJarEntries(absoluteJarPath, pathInJarFile, result);
					}
				}
				if (getPathMatcher().match(fullPattern, currPath)) {
					result.add(new ServletContextResource(servletContext, currPath));
				}
			}
		}
	}

	
Extract entries from the given jar by pattern.
Params:
jarFilePath – the path to the jar file
entryPattern – the pattern for jar entries to match
result – the Set of matching Resources to add to/**
	 * Extract entries from the given jar by pattern.
	 * @param jarFilePath the path to the jar file
	 * @param entryPattern the pattern for jar entries to match
	 * @param result the Set of matching Resources to add to
	 */
	private void doRetrieveMatchingJarEntries(String jarFilePath, String entryPattern, Set<Resource> result) {
		if (logger.isDebugEnabled()) {
			logger.debug("Searching jar file [" + jarFilePath + "] for entries matching [" + entryPattern + "]");
		}
		try {
			JarFile jarFile = new JarFile(jarFilePath);
			try {
				for (Enumeration<JarEntry> entries = jarFile.entries(); entries.hasMoreElements();) {
					JarEntry entry = entries.nextElement();
					String entryPath = entry.getName();
					if (getPathMatcher().match(entryPattern, entryPath)) {
						result.add(new UrlResource(
								ResourceUtils.URL_PROTOCOL_JAR,
								ResourceUtils.FILE_URL_PREFIX + jarFilePath + ResourceUtils.JAR_URL_SEPARATOR + entryPath));
					}
				}
			}
			finally {
				jarFile.close();
			}
		}
		catch (IOException ex) {
			if (logger.isWarnEnabled()) {
				logger.warn("Cannot search for matching resources in jar file [" + jarFilePath +
						"] because the jar cannot be opened through the file system", ex);
			}
		}
	}

}