AntPathMatcher

/*
 * Copyright 2002-2012 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.util;

import java.util.Comparator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * PathMatcher implementation for Ant-style path patterns. Examples are provided below.
 *
 * <p>Part of this mapping code has been kindly borrowed from <a href="http://ant.apache.org">Apache Ant</a>.
 *
 * <p>The mapping matches URLs using the following rules:<br> <ul> <li>? matches one character</li> <li>* matches zero
 * or more characters</li> <li>** matches zero or more 'directories' in a path</li> </ul>
 *
 * <p>Some examples:<br> <ul> <li><code>com/t?st.jsp</code> - matches <code>com/test.jsp</code> but also
 * <code>com/tast.jsp</code> or <code>com/txst.jsp</code></li> <li><code>com/*.jsp</code> - matches all
 * <code>.jsp</code> files in the <code>com</code> directory</li> <li><code>com/&#42;&#42;/test.jsp</code> - matches all
 * <code>test.jsp</code> files underneath the <code>com</code> path</li> <li><code>org/springframework/&#42;&#42;/*.jsp</code>
 * - matches all <code>.jsp</code> files underneath the <code>org/springframework</code> path</li>
 * <li><code>org/&#42;&#42;/servlet/bla.jsp</code> - matches <code>org/springframework/servlet/bla.jsp</code> but also
 * <code>org/springframework/testing/servlet/bla.jsp</code> and <code>org/servlet/bla.jsp</code></li> </ul>
 *
 * @author Alef Arendsen
 * @author Juergen Hoeller
 * @author Rob Harrop
 * @author Arjen Poutsma
 * @since 16.07.2003
 */
public class AntPathMatcher implements PathMatcher {

	private static final Pattern VARIABLE_PATTERN = Pattern.compile("\\{[^/]+?\\}");

	/** Default path separator: "/" */
	public static final String DEFAULT_PATH_SEPARATOR = "/";

	private String pathSeparator = DEFAULT_PATH_SEPARATOR;

	private final Map<String, AntPathStringMatcher> stringMatcherCache =
			new ConcurrentHashMap<String, AntPathStringMatcher>();


	/** Set the path separator to use for pattern parsing. Default is "/", as in Ant. */
	public void setPathSeparator(String pathSeparator) {
		this.pathSeparator = (pathSeparator != null ? pathSeparator : DEFAULT_PATH_SEPARATOR);
	}


	public boolean isPattern(String path) {
		return (path.indexOf('*') != -1 || path.indexOf('?') != -1);
	}

	public boolean match(String pattern, String path) {
		return doMatch(pattern, path, true, null);
	}

	public boolean matchStart(String pattern, String path) {
		return doMatch(pattern, path, false, null);
	}


	/**
	 * Actually match the given <code>path</code> against the given <code>pattern</code>.
	 * @param pattern the pattern to match against
	 * @param path the path String to test
	 * @param fullMatch whether a full pattern match is required (else a pattern match
	 * as far as the given base path goes is sufficient)
	 * @return <code>true</code> if the supplied <code>path</code> matched, <code>false</code> if it didn't
	 */
	protected boolean doMatch(String pattern, String path, boolean fullMatch,
			Map<String, String> uriTemplateVariables) {

		if (path.startsWith(this.pathSeparator) != pattern.startsWith(this.pathSeparator)) {
			return false;
		}

		String[] pattDirs = StringUtils.tokenizeToStringArray(pattern, this.pathSeparator);
		String[] pathDirs = StringUtils.tokenizeToStringArray(path, this.pathSeparator);

		int pattIdxStart = 0;
		int pattIdxEnd = pattDirs.length - 1;
		int pathIdxStart = 0;
		int pathIdxEnd = pathDirs.length - 1;

		// Match all elements up to the first **
		while (pattIdxStart <= pattIdxEnd && pathIdxStart <= pathIdxEnd) {
			String patDir = pattDirs[pattIdxStart];
			if ("**".equals(patDir)) {
				break;
			}
			if (!matchStrings(patDir, pathDirs[pathIdxStart], uriTemplateVariables)) {
				return false;
			}
			pattIdxStart++;
			pathIdxStart++;
		}

		if (pathIdxStart > pathIdxEnd) {
			// Path is exhausted, only match if rest of pattern is * or **'s
			if (pattIdxStart > pattIdxEnd) {
				return (pattern.endsWith(this.pathSeparator) ? path.endsWith(this.pathSeparator) :
						!path.endsWith(this.pathSeparator));
			}
			if (!fullMatch) {
				return true;
			}
			if (pattIdxStart == pattIdxEnd && pattDirs[pattIdxStart].equals("*") && path.endsWith(this.pathSeparator)) {
				return true;
			}
			for (int i = pattIdxStart; i <= pattIdxEnd; i++) {
				if (!pattDirs[i].equals("**")) {
					return false;
				}
			}
			return true;
		}
		else if (pattIdxStart > pattIdxEnd) {
			// String not exhausted, but pattern is. Failure.
			return false;
		}
		else if (!fullMatch && "**".equals(pattDirs[pattIdxStart])) {
			// Path start definitely matches due to "**" part in pattern.
			return true;
		}

		// up to last '**'
		while (pattIdxStart <= pattIdxEnd && pathIdxStart <= pathIdxEnd) {
			String patDir = pattDirs[pattIdxEnd];
			if (patDir.equals("**")) {
				break;
			}
			if (!matchStrings(patDir, pathDirs[pathIdxEnd], uriTemplateVariables)) {
				return false;
			}
			pattIdxEnd--;
			pathIdxEnd--;
		}
		if (pathIdxStart > pathIdxEnd) {
			// String is exhausted
			for (int i = pattIdxStart; i <= pattIdxEnd; i++) {
				if (!pattDirs[i].equals("**")) {
					return false;
				}
			}
			return true;
		}

		while (pattIdxStart != pattIdxEnd && pathIdxStart <= pathIdxEnd) {
			int patIdxTmp = -1;
			for (int i = pattIdxStart + 1; i <= pattIdxEnd; i++) {
				if (pattDirs[i].equals("**")) {
					patIdxTmp = i;
					break;
				}
			}
			if (patIdxTmp == pattIdxStart + 1) {
				// '**/**' situation, so skip one
				pattIdxStart++;
				continue;
			}
			// Find the pattern between padIdxStart & padIdxTmp in str between
			// strIdxStart & strIdxEnd
			int patLength = (patIdxTmp - pattIdxStart - 1);
			int strLength = (pathIdxEnd - pathIdxStart + 1);
			int foundIdx = -1;

			strLoop:
			for (int i = 0; i <= strLength - patLength; i++) {
				for (int j = 0; j < patLength; j++) {
					String subPat = pattDirs[pattIdxStart + j + 1];
					String subStr = pathDirs[pathIdxStart + i + j];
					if (!matchStrings(subPat, subStr, uriTemplateVariables)) {
						continue strLoop;
					}
				}
				foundIdx = pathIdxStart + i;
				break;
			}

			if (foundIdx == -1) {
				return false;
			}

			pattIdxStart = patIdxTmp;
			pathIdxStart = foundIdx + patLength;
		}

		for (int i = pattIdxStart; i <= pattIdxEnd; i++) {
			if (!pattDirs[i].equals("**")) {
				return false;
			}
		}

		return true;
	}

	/**
	 * Tests whether or not a string matches against a pattern. The pattern may contain two special characters:<br> '*'
	 * means zero or more characters<br> '?' means one and only one character
	 * @param pattern pattern to match against. Must not be <code>null</code>.
	 * @param str string which must be matched against the pattern. Must not be <code>null</code>.
	 * @return <code>true</code> if the string matches against the pattern, or <code>false</code> otherwise.
	 */
	private boolean matchStrings(String pattern, String str, Map<String, String> uriTemplateVariables) {
		AntPathStringMatcher matcher = this.stringMatcherCache.get(pattern);
		if (matcher == null) {
			matcher = new AntPathStringMatcher(pattern);
			this.stringMatcherCache.put(pattern, matcher);
		}
		return matcher.matchStrings(str, uriTemplateVariables);
	}

	/**
	 * Given a pattern and a full path, determine the pattern-mapped part. <p>For example: <ul>
	 * <li>'<code>/docs/cvs/commit.html</code>' and '<code>/docs/cvs/commit.html</code> -> ''</li>
	 * <li>'<code>/docs/*</code>' and '<code>/docs/cvs/commit</code> -> '<code>cvs/commit</code>'</li>
	 * <li>'<code>/docs/cvs/*.html</code>' and '<code>/docs/cvs/commit.html</code> -> '<code>commit.html</code>'</li>
	 * <li>'<code>/docs/**</code>' and '<code>/docs/cvs/commit</code> -> '<code>cvs/commit</code>'</li>
	 * <li>'<code>/docs/**\/*.html</code>' and '<code>/docs/cvs/commit.html</code> -> '<code>cvs/commit.html</code>'</li>
	 * <li>'<code>/*.html</code>' and '<code>/docs/cvs/commit.html</code> -> '<code>docs/cvs/commit.html</code>'</li>
	 * <li>'<code>*.html</code>' and '<code>/docs/cvs/commit.html</code> -> '<code>/docs/cvs/commit.html</code>'</li>
	 * <li>'<code>*</code>' and '<code>/docs/cvs/commit.html</code> -> '<code>/docs/cvs/commit.html</code>'</li> </ul>
	 * <p>Assumes that {@link #match} returns <code>true</code> for '<code>pattern</code>' and '<code>path</code>', but
	 * does <strong>not</strong> enforce this.
	 */
	public String extractPathWithinPattern(String pattern, String path) {
		String[] patternParts = StringUtils.tokenizeToStringArray(pattern, this.pathSeparator);
		String[] pathParts = StringUtils.tokenizeToStringArray(path, this.pathSeparator);

		StringBuilder builder = new StringBuilder();

		// Add any path parts that have a wildcarded pattern part.
		int puts = 0;
		for (int i = 0; i < patternParts.length; i++) {
			String patternPart = patternParts[i];
			if ((patternPart.indexOf('*') > -1 || patternPart.indexOf('?') > -1) && pathParts.length >= i + 1) {
				if (puts > 0 || (i == 0 && !pattern.startsWith(this.pathSeparator))) {
					builder.append(this.pathSeparator);
				}
				builder.append(pathParts[i]);
				puts++;
			}
		}

		// Append any trailing path parts.
		for (int i = patternParts.length; i < pathParts.length; i++) {
			if (puts > 0 || i > 0) {
				builder.append(this.pathSeparator);
			}
			builder.append(pathParts[i]);
		}

		return builder.toString();
	}

	public Map<String, String> extractUriTemplateVariables(String pattern, String path) {
		Map<String, String> variables = new LinkedHashMap<String, String>();
		boolean result = doMatch(pattern, path, true, variables);
		Assert.state(result, "Pattern \"" + pattern + "\" is not a match for \"" + path + "\"");
		return variables;
	}

	/**
	 * Combines two patterns into a new pattern that is returned.
	 * <p>This implementation simply concatenates the two patterns, unless the first pattern
	 * contains a file extension match (such as {@code *.html}. In that case, the second pattern
	 * should be included in the first, or an {@code IllegalArgumentException} is thrown.
	 * <p>For example: <table>
	 * <tr><th>Pattern 1</th><th>Pattern 2</th><th>Result</th></tr> <tr><td>/hotels</td><td>{@code
	 * null}</td><td>/hotels</td></tr> <tr><td>{@code null}</td><td>/hotels</td><td>/hotels</td></tr>
	 * <tr><td>/hotels</td><td>/bookings</td><td>/hotels/bookings</td></tr> <tr><td>/hotels</td><td>bookings</td><td>/hotels/bookings</td></tr>
	 * <tr><td>/hotels/*</td><td>/bookings</td><td>/hotels/bookings</td></tr> <tr><td>/hotels/&#42;&#42;</td><td>/bookings</td><td>/hotels/&#42;&#42;/bookings</td></tr>
	 * <tr><td>/hotels</td><td>{hotel}</td><td>/hotels/{hotel}</td></tr> <tr><td>/hotels/*</td><td>{hotel}</td><td>/hotels/{hotel}</td></tr>
	 * <tr><td>/hotels/&#42;&#42;</td><td>{hotel}</td><td>/hotels/&#42;&#42;/{hotel}</td></tr>
	 * <tr><td>/*.html</td><td>/hotels.html</td><td>/hotels.html</td></tr> <tr><td>/*.html</td><td>/hotels</td><td>/hotels.html</td></tr>
	 * <tr><td>/*.html</td><td>/*.txt</td><td>IllegalArgumentException</td></tr> </table>
	 * @param pattern1 the first pattern
	 * @param pattern2 the second pattern
	 * @return the combination of the two patterns
	 * @throws IllegalArgumentException when the two patterns cannot be combined
	 */
	public String combine(String pattern1, String pattern2) {
		if (!StringUtils.hasText(pattern1) && !StringUtils.hasText(pattern2)) {
			return "";
		}
		else if (!StringUtils.hasText(pattern1)) {
			return pattern2;
		}
		else if (!StringUtils.hasText(pattern2)) {
			return pattern1;
		}
		else if (!pattern1.contains("{") && match(pattern1, pattern2)) {
			return pattern2;
		}
		else if (pattern1.endsWith("/*")) {
			if (pattern2.startsWith("/")) {
				// /hotels/* + /booking -> /hotels/booking
				return pattern1.substring(0, pattern1.length() - 1) + pattern2.substring(1);
			}
			else {
				// /hotels/* + booking -> /hotels/booking
				return pattern1.substring(0, pattern1.length() - 1) + pattern2;
			}
		}
		else if (pattern1.endsWith("/**")) {
			if (pattern2.startsWith("/")) {
				// /hotels/** + /booking -> /hotels/**/booking
				return pattern1 + pattern2;
			}
			else {
				// /hotels/** + booking -> /hotels/**/booking
				return pattern1 + "/" + pattern2;
			}
		}
		else {
			int dotPos1 = pattern1.indexOf('.');
			if (dotPos1 == -1) {
				// simply concatenate the two patterns
				if (pattern1.endsWith("/") || pattern2.startsWith("/")) {
					return pattern1 + pattern2;
				}
				else {
					return pattern1 + "/" + pattern2;
				}
			}
			String fileName1 = pattern1.substring(0, dotPos1);
			String extension1 = pattern1.substring(dotPos1);
			String fileName2;
			String extension2;
			int dotPos2 = pattern2.indexOf('.');
			if (dotPos2 != -1) {
				fileName2 = pattern2.substring(0, dotPos2);
				extension2 = pattern2.substring(dotPos2);
			}
			else {
				fileName2 = pattern2;
				extension2 = "";
			}
			String fileName = fileName1.endsWith("*") ? fileName2 : fileName1;
			String extension = extension1.startsWith("*") ? extension2 : extension1;

			return fileName + extension;
		}
	}

	/**
	 * Given a full path, returns a {@link Comparator} suitable for sorting patterns in order of explicitness.
	 * <p>The returned <code>Comparator</code> will {@linkplain java.util.Collections#sort(java.util.List,
	 * java.util.Comparator) sort} a list so that more specific patterns (without uri templates or wild cards) come before
	 * generic patterns. So given a list with the following patterns: <ol> <li><code>/hotels/new</code></li>
	 * <li><code>/hotels/{hotel}</code></li> <li><code>/hotels/*</code></li> </ol> the returned comparator will sort this
	 * list so that the order will be as indicated.
	 * <p>The full path given as parameter is used to test for exact matches. So when the given path is {@code /hotels/2},
	 * the pattern {@code /hotels/2} will be sorted before {@code /hotels/1}.
	 * @param path the full path to use for comparison
	 * @return a comparator capable of sorting patterns in order of explicitness
	 */
	public Comparator<String> getPatternComparator(String path) {
		return new AntPatternComparator(path);
	}


	private static class AntPatternComparator implements Comparator<String> {

		private final String path;

		private AntPatternComparator(String path) {
			this.path = path;
		}

		public int compare(String pattern1, String pattern2) {
			if (pattern1 == null && pattern2 == null) {
				return 0;
			}
			else if (pattern1 == null) {
				return 1;
			}
			else if (pattern2 == null) {
				return -1;
			}
			boolean pattern1EqualsPath = pattern1.equals(path);
			boolean pattern2EqualsPath = pattern2.equals(path);
			if (pattern1EqualsPath && pattern2EqualsPath) {
				return 0;
			}
			else if (pattern1EqualsPath) {
				return -1;
			}
			else if (pattern2EqualsPath) {
				return 1;
			}
			int wildCardCount1 = getWildCardCount(pattern1);
			int wildCardCount2 = getWildCardCount(pattern2);

			int bracketCount1 = StringUtils.countOccurrencesOf(pattern1, "{");
			int bracketCount2 = StringUtils.countOccurrencesOf(pattern2, "{");

			int totalCount1 = wildCardCount1 + bracketCount1;
			int totalCount2 = wildCardCount2 + bracketCount2;

			if (totalCount1 != totalCount2) {
				return totalCount1 - totalCount2;
			}

			int pattern1Length = getPatternLength(pattern1);
			int pattern2Length = getPatternLength(pattern2);

			if (pattern1Length != pattern2Length) {
				return pattern2Length - pattern1Length;
			}

			if (wildCardCount1 < wildCardCount2) {
				return -1;
			}
			else if (wildCardCount2 < wildCardCount1) {
				return 1;
			}

			if (bracketCount1 < bracketCount2) {
				return -1;
			}
			else if (bracketCount2 < bracketCount1) {
				return 1;
			}

			return 0;
		}

		private int getWildCardCount(String pattern) {
			if (pattern.endsWith(".*")) {
				pattern = pattern.substring(0, pattern.length() - 2);
			}
			return StringUtils.countOccurrencesOf(pattern, "*");
		}

		/**
		 * Returns the length of the given pattern, where template variables are considered to be 1 long.
		 */
		private int getPatternLength(String pattern) {
			Matcher m = VARIABLE_PATTERN.matcher(pattern);
			return m.replaceAll("#").length();
		}
	}

}