/*
    * Copyright The Apache Software Foundation
    *
    * 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.hadoop.hbase.ipc;
  
  import org.apache.hadoop.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.security.User;
  
  import com.google.protobuf.BlockingService;
  
  import java.net.InetAddress;
  
  /**
   * Represents client information (authenticated username, remote address, protocol)
   * for the currently executing request within a RPC server handler thread.  If
   * called outside the context of a RPC request, all values will be
   * <code>null</code>.
   */
  @InterfaceAudience.Private
  public class RequestContext {
    private static ThreadLocal<RequestContext> instance =
        new ThreadLocal<RequestContext>() {
          protected RequestContext initialValue() {
            return new RequestContext(null, null, null);
          }
        };
  
    public static RequestContext get() {
      return instance.get();
    }
  
  
    /**
     * Returns the user credentials associated with the current RPC request or
     * <code>null</code> if no credentials were provided.
     * @return A User
     */
    public static User getRequestUser() {
      RequestContext ctx = instance.get();
      if (ctx != null) {
        return ctx.getUser();
      }
      return null;
    }
  
    /**
     * Returns the username for any user associated with the current RPC
     * request or <code>null</code> if no user is set.
     */
    public static String getRequestUserName() {
      User user = getRequestUser();
      if (user != null) {
        return user.getShortName();
      }
      return null;
    }
  
    /**
     * Indicates whether or not the current thread is within scope of executing
     * an RPC request.
     */
    public static boolean isInRequestContext() {
      RequestContext ctx = instance.get();
      if (ctx != null) {
        return ctx.isInRequest();
      }
      return false;
    }
  
    /**
     * Initializes the client credentials for the current request.
     * @param user
     * @param remoteAddress
     * @param service
     */
    public static void set(User user,
        InetAddress remoteAddress, BlockingService service) {
      RequestContext ctx = instance.get();
      ctx.user = user;
      ctx.remoteAddress = remoteAddress;
      ctx.service = service;
      ctx.inRequest = true;
   }
 
   /**
    * Clears out the client credentials for a given request.
    */
   public static void clear() {
     RequestContext ctx = instance.get();
     ctx.user = null;
     ctx.remoteAddress = null;
     ctx.service = null;
     ctx.inRequest = false;
   }
 
   private User user;
   private InetAddress remoteAddress;
   private BlockingService service;
   // indicates we're within a RPC request invocation
   private boolean inRequest;
 
   private RequestContext(User user, InetAddress remoteAddr, BlockingService service) {
     this.user = user;
     this.remoteAddress = remoteAddr;
     this.service = service;
   }
 
   public User getUser() {
     return user;
   }
 
   public InetAddress getRemoteAddress() {
     return remoteAddress;
   }
 
   public BlockingService getService() {
     return this.service;
   }
 
   public boolean isInRequest() {
     return inRequest;
   }
 }