/*
 * Copyright 2002-2015 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.security.web.util.matcher;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.http.HttpMethod;
import org.springframework.security.web.util.matcher.RequestMatcher;
import org.springframework.util.AntPathMatcher;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;

/**
 * Matcher which compares a pre-defined ant-style pattern against the URL (
 * {@code servletPath + pathInfo}) of an {@code HttpServletRequest}. The query string of
 * the URL is ignored and matching is case-insensitive or case-sensitive depending on the
 * arguments passed into the constructor.
 * <p>
 * Using a pattern value of {@code /**} or {@code **} is treated as a universal match,
 * which will match any request. Patterns which end with {@code /**} (and have no other
 * wildcards) are optimized by using a substring match &mdash; a pattern of
 * {@code /aaa/**} will match {@code /aaa}, {@code /aaa/} and any sub-directories, such as
 * {@code /aaa/bbb/ccc}.
 * </p>
 * <p>
 * For all other cases, Spring's {@link AntPathMatcher} is used to perform the match. See
 * the Spring documentation for this class for comprehensive information on the syntax
 * used.
 * </p>
 *
 * @author Luke Taylor
 * @author Rob Winch
 * @since 3.1
 *
 * @see org.springframework.util.AntPathMatcher
 */
public final class AntPathRequestMatcher implements RequestMatcher {
	private static final Log logger = LogFactory.getLog(AntPathRequestMatcher.class);
	private static final String MATCH_ALL = "/**";

	private final Matcher matcher;
	private final String pattern;
	private final HttpMethod httpMethod;
	private final boolean caseSensitive;

	/**
	 * Creates a matcher with the specific pattern which will match all HTTP methods in a
	 * case insensitive manner.
	 *
	 * @param pattern the ant pattern to use for matching
	 */
	public AntPathRequestMatcher(String pattern) {
		this(pattern, null);
	}

	/**
	 * Creates a matcher with the supplied pattern and HTTP method in a case insensitive
	 * manner.
	 *
	 * @param pattern the ant pattern to use for matching
	 * @param httpMethod the HTTP method. The {@code matches} method will return false if
	 * the incoming request doesn't have the same method.
	 */
	public AntPathRequestMatcher(String pattern, String httpMethod) {
		this(pattern, httpMethod, false);
	}

	/**
	 * Creates a matcher with the supplied pattern which will match the specified Http
	 * method
	 *
	 * @param pattern the ant pattern to use for matching
	 * @param httpMethod the HTTP method. The {@code matches} method will return false if
	 * the incoming request doesn't doesn't have the same method.
	 * @param caseSensitive true if the matcher should consider case, else false
	 */
	public AntPathRequestMatcher(String pattern, String httpMethod, boolean caseSensitive) {
		Assert.hasText(pattern, "Pattern cannot be null or empty");
		this.caseSensitive = caseSensitive;

		if (pattern.equals(MATCH_ALL) || pattern.equals("**")) {
			pattern = MATCH_ALL;
			matcher = null;
		}
		else {
			if (!caseSensitive) {
				pattern = pattern.toLowerCase();
			}

			// If the pattern ends with {@code /**} and has no other wildcards or path
			// variables, then optimize to a sub-path match
			if (pattern.endsWith(MATCH_ALL)
					&& (pattern.indexOf('?') == -1 && pattern.indexOf('{') == -1 && pattern
							.indexOf('}') == -1)
					&& pattern.indexOf("*") == pattern.length() - 2) {
				matcher = new SubpathMatcher(pattern.substring(0, pattern.length() - 3));
			}
			else {
				matcher = new SpringAntMatcher(pattern);
			}
		}

		this.pattern = pattern;
		this.httpMethod = StringUtils.hasText(httpMethod) ? HttpMethod
				.valueOf(httpMethod) : null;
	}

	/**
	 * Returns true if the configured pattern (and HTTP-Method) match those of the
	 * supplied request.
	 *
	 * @param request the request to match against. The ant pattern will be matched
	 * against the {@code servletPath} + {@code pathInfo} of the request.
	 */
	public boolean matches(HttpServletRequest request) {
		if (httpMethod != null && StringUtils.hasText(request.getMethod())
				&& httpMethod != valueOf(request.getMethod())) {
			if (logger.isDebugEnabled()) {
				logger.debug("Request '" + request.getMethod() + " "
						+ getRequestPath(request) + "'" + " doesn't match '" + httpMethod
						+ " " + pattern);
			}

			return false;
		}

		if (pattern.equals(MATCH_ALL)) {
			if (logger.isDebugEnabled()) {
				logger.debug("Request '" + getRequestPath(request)
						+ "' matched by universal pattern '/**'");
			}

			return true;
		}

		String url = getRequestPath(request);

		if (logger.isDebugEnabled()) {
			logger.debug("Checking match of request : '" + url + "'; against '" + pattern
					+ "'");
		}

		return matcher.matches(url);
	}

	private String getRequestPath(HttpServletRequest request) {
		String url = request.getServletPath();

		if (request.getPathInfo() != null) {
			url += request.getPathInfo();
		}

		if (!caseSensitive) {
			url = url.toLowerCase();
		}

		return url;
	}

	public String getPattern() {
		return pattern;
	}

	@Override
	public boolean equals(Object obj) {
		if (!(obj instanceof AntPathRequestMatcher)) {
			return false;
		}

		AntPathRequestMatcher other = (AntPathRequestMatcher) obj;
		return this.pattern.equals(other.pattern) && this.httpMethod == other.httpMethod
				&& this.caseSensitive == other.caseSensitive;
	}

	@Override
	public int hashCode() {
		int code = 31 ^ pattern.hashCode();
		if (httpMethod != null) {
			code ^= httpMethod.hashCode();
		}
		return code;
	}

	@Override
	public String toString() {
		StringBuilder sb = new StringBuilder();
		sb.append("Ant [pattern='").append(pattern).append("'");

		if (httpMethod != null) {
			sb.append(", ").append(httpMethod);
		}

		sb.append("]");

		return sb.toString();
	}

	/**
	 * Provides a save way of obtaining the HttpMethod from a String. If the method is
	 * invalid, returns null.
	 *
	 * @param method the HTTP method to use.
	 *
	 * @return the HttpMethod or null if method is invalid.
	 */
	private static HttpMethod valueOf(String method) {
		try {
			return HttpMethod.valueOf(method);
		}
		catch (IllegalArgumentException e) {
		}

		return null;
	}

	private static interface Matcher {
		boolean matches(String path);
	}

	private static class SpringAntMatcher implements Matcher {
		private static final AntPathMatcher antMatcher = new AntPathMatcher();

		private final String pattern;

		private SpringAntMatcher(String pattern) {
			this.pattern = pattern;
		}

		public boolean matches(String path) {
			return antMatcher.match(pattern, path);
		}
	}

	/**
	 * Optimized matcher for trailing wildcards
	 */
	private static class SubpathMatcher implements Matcher {
		private final String subpath;
		private final int length;

		private SubpathMatcher(String subpath) {
			assert !subpath.contains("*");
			this.subpath = subpath;
			this.length = subpath.length();
		}

		public boolean matches(String path) {
			return path.startsWith(subpath)
					&& (path.length() == length || path.charAt(length) == '/');
		}
	}
}
