text: /**
   *    Copyright (C) 2015 MongoDB Inc.
   *
   *    This program is free software: you can redistribute it and/or  modify
   *    it under the terms of the GNU Affero General Public License, version 3,
   *    as published by the Free Software Foundation.
   *
   *    This program is distributed in the hope that it will be useful,
   *    but WITHOUT ANY WARRANTY; without even the implied warranty of
   *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *    GNU Affero General Public License for more details.
   *
   *    You should have received a copy of the GNU Affero General Public License
   *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
   *
   *    As a special exception, the copyright holders give permission to link the
   *    code of portions of this program with the OpenSSL library under certain
   *    conditions as described in each individual source file and distribute
   *    linked combinations including the program with the OpenSSL library. You
   *    must comply with the GNU Affero General Public License in all respects for
   *    all of the code used other than as permitted herein. If you modify file(s)
   *    with this exception, you may extend this exception to your version of the
   *    file(s), but you are not obligated to do so. If you do not wish to do so,
   *    delete this exception statement from your version. If you delete this
   *    exception statement from all source files in the program, then also delete
   *    it in the license file.
   */
  
  #include "mongo/platform/basic.h"
  
  #include <utility>
  
  #include "mongo/rpc/command_reply_builder.h"
  #include "mongo/stdx/memory.h"
  #include "mongo/util/assert_util.h"
  
  namespace mongo {
  namespace rpc {
  
  CommandReplyBuilder::CommandReplyBuilder() : _message{stdx::make_unique<Message>()} {}
  
  CommandReplyBuilder::CommandReplyBuilder(std::unique_ptr<Message> message)
      : _message{std::move(message)} {}
  
  CommandReplyBuilder& CommandReplyBuilder::setMetadata(BSONObj metadata) {
      invariant(_state == State::kMetadata);
      metadata.appendSelfToBufBuilder(_builder);
      _state = State::kCommandReply;
      return *this;
  }
  
  CommandReplyBuilder& CommandReplyBuilder::setRawCommandReply(BSONObj commandReply) {
      invariant(_state == State::kCommandReply);
      commandReply.appendSelfToBufBuilder(_builder);
      _state = State::kOutputDocs;
      return *this;
  }
  
  CommandReplyBuilder& CommandReplyBuilder::addOutputDocs(DocumentRange outputDocs) {
      invariant(_state == State::kOutputDocs);
      auto rangeData = outputDocs.data();
      _builder.appendBuf(rangeData.data(), rangeData.length());
      // leave state as is as we can add as many outputDocs as we want.
      return *this;
  }
  
  CommandReplyBuilder& CommandReplyBuilder::addOutputDoc(BSONObj outputDoc) {
      invariant(_state == State::kOutputDocs);
      outputDoc.appendSelfToBufBuilder(_builder);
      return *this;
  }
  
  ReplyBuilderInterface::State CommandReplyBuilder::getState() const {
      return _state;
  }
  
  Protocol CommandReplyBuilder::getProtocol() const {
      return rpc::Protocol::kOpCommandV1;
  }
  
  void CommandReplyBuilder::reset() {
      // If we are in State::kMetadata, we are already in the 'start' state, so by
      // immediately returning, we save a heap allocation.
      if (_state == State::kMetadata) {
          return;
      }
      _builder.reset();
      _message = stdx::make_unique<Message>();
      _state = State::kMetadata;
  }
  
  std::unique_ptr<Message> CommandReplyBuilder::done() {
      invariant(_state == State::kOutputDocs);
      // TODO: we can elide a large copy here by transferring the internal buffer of
      // the BufBuilder to the Message.
      _message->setData(dbCommandReply, _builder.buf(), _builder.len());
      _state = State::kDone;
      return std::move(_message);
  }
  
  std::size_t CommandReplyBuilder::availableSpaceForOutputDocs() const {
      invariant(State::kDone != _state);
      int intLen = _builder.len();
      invariant(0 <= intLen);
      std::size_t len = static_cast<std::size_t>(intLen);
      std::size_t msgHeaderSz = static_cast<std::size_t>(MsgData::MsgDataHeaderSize);
      invariant(len + msgHeaderSz <= mongo::MaxMessageSizeBytes);
      return mongo::MaxMessageSizeBytes - len - msgHeaderSz;
  }
  
  }  // rpc
  }  // mongo
  