// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MOJO_EDK_SYSTEM_PROXY_MESSAGE_PIPE_ENDPOINT_H_
#define MOJO_EDK_SYSTEM_PROXY_MESSAGE_PIPE_ENDPOINT_H_

#include "base/memory/ref_counted.h"
#include "mojo/edk/system/message_in_transit.h"
#include "mojo/edk/system/message_pipe_endpoint.h"
#include "mojo/public/cpp/system/macros.h"

namespace mojo {
namespace system {

class ChannelEndpoint;
class LocalMessagePipeEndpoint;
class MessagePipe;

// A |ProxyMessagePipeEndpoint| is an endpoint which delegates everything to a
// |ChannelEndpoint|, which may be co-owned by a |Channel|. Like any
// |MessagePipeEndpoint|, a |ProxyMessagePipeEndpoint| is owned by a
// |MessagePipe|.
//
// For example, a |MessagePipe| with one endpoint local and the other endpoint
// remote consists of a |LocalMessagePipeEndpoint| and a
// |ProxyMessagePipeEndpoint|, with only the local endpoint being accessible via
// a |MessagePipeDispatcher|.
class ProxyMessagePipeEndpoint final : public MessagePipeEndpoint {
 public:
  explicit ProxyMessagePipeEndpoint(ChannelEndpoint* channel_endpoint);
  ~ProxyMessagePipeEndpoint() override;

  // Returns |channel_endpoint_| and resets |channel_endpoint_| to null. This
  // may be called at most once, after which |Close()| need not be called.
  //
  // Note: The returned |ChannelEndpoint| must have its client changed while
  // still under |MessagePipe|'s lock (which this must have also been called
  // under).
  scoped_refptr<ChannelEndpoint> ReleaseChannelEndpoint();

  // |MessagePipeEndpoint| implementation:
  Type GetType() const override;
  bool OnPeerClose() override;
  void EnqueueMessage(std::unique_ptr<MessageInTransit> message) override;
  void Close() override;

 private:
  void DetachIfNecessary();

  scoped_refptr<ChannelEndpoint> channel_endpoint_;

  MOJO_DISALLOW_COPY_AND_ASSIGN(ProxyMessagePipeEndpoint);
};

}  // namespace system
}  // namespace mojo

#endif  // MOJO_EDK_SYSTEM_PROXY_MESSAGE_PIPE_ENDPOINT_H_