/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.shiro.web.tags;

import javax.servlet.jsp.JspException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


/**
 * JSP tag that renders the tag body if the current user known to the system, either from a successful login attempt
 * (not necessarily during the current session) or from 'RememberMe' services.
 *
 * <p><b>Note:</b> This is <em>less</em> restrictive than the <code>AuthenticatedTag</code> since it only assumes
 * the user is who they say they are, either via a current session login <em>or</em> via Remember Me services, which
 * makes no guarantee the user is who they say they are.  The <code>AuthenticatedTag</code> however
 * guarantees that the current user has logged in <em>during their current session</em>, proving they really are
 * who they say they are.
 *
 * <p>The logically opposite tag of this one is the {@link org.apache.shiro.web.tags.GuestTag}.
 *
 * @since 0.9
 */
public class UserTag extends SecureTag {

    private static final Logger LOGGER = LoggerFactory.getLogger(UserTag.class);

    public int onDoStartTag() throws JspException {
        if (getSubject() != null && getSubject().getPrincipal() != null) {
            if (LOGGER.isTraceEnabled()) {
                LOGGER.trace("Subject has known identity (aka 'principal').  "
                        + "Tag body will be evaluated.");
            }
            return EVAL_BODY_INCLUDE;
        } else {
            if (LOGGER.isTraceEnabled()) {
                LOGGER.trace("Subject does not exist or have a known identity (aka 'principal').  "
                        + "Tag body will not be evaluated.");
            }
            return SKIP_BODY;
        }
    }

}
