/**
 * 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.hive.service.auth;

import java.util.Hashtable;
import javax.naming.Context;
import javax.naming.NamingException;
import javax.naming.directory.InitialDirContext;
import javax.security.sasl.AuthenticationException;

import org.apache.hadoop.hive.conf.HiveConf;
import org.apache.hive.service.ServiceUtils;

public class LdapAuthenticationProviderImpl implements PasswdAuthenticationProvider {

  private final String ldapURL;
  private final String baseDN;
  private final String ldapDomain;

  LdapAuthenticationProviderImpl() {
    HiveConf conf = new HiveConf();
    ldapURL = conf.getVar(HiveConf.ConfVars.HIVE_SERVER2_PLAIN_LDAP_URL);
    baseDN = conf.getVar(HiveConf.ConfVars.HIVE_SERVER2_PLAIN_LDAP_BASEDN);
    ldapDomain = conf.getVar(HiveConf.ConfVars.HIVE_SERVER2_PLAIN_LDAP_DOMAIN);
  }

  @Override
  public void Authenticate(String user, String password) throws AuthenticationException {

    Hashtable<String, Object> env = new Hashtable<String, Object>();
    env.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.ldap.LdapCtxFactory");
    env.put(Context.PROVIDER_URL, ldapURL);

    // If the domain is available in the config, then append it unless domain is
    // already part of the username. LDAP providers like Active Directory use a
    // fully qualified user name like foo@bar.com.
    if (!hasDomain(user) && ldapDomain != null) {
      user  = user + "@" + ldapDomain;
    }

    if (password == null || password.isEmpty() || password.getBytes()[0] == 0) {
      throw new AuthenticationException("Error validating LDAP user:" +
          " a null or blank password has been provided");
    }

    // setup the security principal
    String bindDN;
    if (baseDN == null) {
      bindDN = user;
    } else {
      bindDN = "uid=" + user + "," + baseDN;
    }
    env.put(Context.SECURITY_AUTHENTICATION, "simple");
    env.put(Context.SECURITY_PRINCIPAL, bindDN);
    env.put(Context.SECURITY_CREDENTIALS, password);

    try {
      // Create initial context
      Context ctx = new InitialDirContext(env);
      ctx.close();
    } catch (NamingException e) {
      throw new AuthenticationException("Error validating LDAP user", e);
    }
  }

  private boolean hasDomain(String userName) {
    return (ServiceUtils.indexOfDomainMatch(userName) > 0);
  }
}