/*
 * Copyright 2010-2016 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.security.web.util.matcher;

import javax.servlet.http.HttpServletRequest;

import org.springframework.expression.EvaluationContext;
import org.springframework.expression.Expression;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.StandardEvaluationContext;
import org.springframework.security.web.authentication.DelegatingAuthenticationEntryPoint;
import org.springframework.security.web.util.matcher.RequestMatcher;

/**
 * A RequestMatcher implementation which uses a SpEL expression
 *
 * <p>
 * With the default EvaluationContext ({@link ELRequestMatcherContext}) you can use
 * <code>hasIpAdress()</code> and <code>hasHeader()</code>
 * </p>
 *
 * <p>
 * See {@link DelegatingAuthenticationEntryPoint} for an example configuration.
 * </p>
 *
 *
 * @author Mike Wiesner
 * @since 3.0.2
 */
public class ELRequestMatcher implements RequestMatcher {

	private final Expression expression;

	public ELRequestMatcher(String el) {
		SpelExpressionParser parser = new SpelExpressionParser();
		expression = parser.parseExpression(el);
	}

	public boolean matches(HttpServletRequest request) {
		EvaluationContext context = createELContext(request);
		return expression.getValue(context, Boolean.class).booleanValue();
	}

	/**
	 * Subclasses can override this methode if they want to use a different EL root
	 * context
	 *
	 * @return EL root context which is used to evaluate the expression
	 */
	public EvaluationContext createELContext(HttpServletRequest request) {
		return new StandardEvaluationContext(new ELRequestMatcherContext(request));
	}

}
