/**
 * 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 backtype.storm.security.auth;

import java.security.Principal;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import javax.security.auth.Subject;
import javax.servlet.http.HttpServletRequest;

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

import backtype.storm.security.auth.ReqContext;

public class DefaultHttpCredentialsPlugin implements IHttpCredentialsPlugin {
    private static final Logger LOG = LoggerFactory.getLogger(DefaultHttpCredentialsPlugin.class);

    /**
     * No-op
     * 
     * @param storm_conf Storm configuration
     */
    @Override
    public void prepare(Map storm_conf) {
        // Do nothing.
    }

    /**
     * Gets the user name from the request principal.
     * 
     * @param req the servlet request
     * @return the authenticated user, or null if none is authenticated
     */
    @Override
    public String getUserName(HttpServletRequest req) {
        Principal princ = null;
        if (req != null && (princ = req.getUserPrincipal()) != null) {
            String userName = princ.getName();
            if (userName != null && !userName.isEmpty()) {
                LOG.debug("HTTP request had user (" + userName + ")");
                return userName;
            }
        }
        return null;
    }

    /**
     * Populates a given context with a new Subject derived from the credentials in a servlet request.
     * 
     * @param context the context to be populated
     * @param req the servlet request
     * @return the context
     */
    @Override
    public ReqContext populateContext(ReqContext context, HttpServletRequest req) {
        String userName = getUserName(req);

        String doAsUser = req.getHeader("doAsUser");
        if (doAsUser == null) {
            doAsUser = req.getParameter("doAsUser");
        }

        if (doAsUser != null) {
            context.setRealPrincipal(new SingleUserPrincipal(userName));
            userName = doAsUser;
        }

        Set<Principal> principals = new HashSet<Principal>();
        if (userName != null) {
            Principal p = new SingleUserPrincipal(userName);
            principals.add(p);
        }
        Subject s = new Subject(true, principals, new HashSet(), new HashSet());
        context.setSubject(s);

        return context;
    }
}