// Copyright 2015 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 CHROMEOS_COMPONENTS_PROXIMITY_AUTH_REMOTE_DEVICE_LIFE_CYCLE_IMPL_H_
#define CHROMEOS_COMPONENTS_PROXIMITY_AUTH_REMOTE_DEVICE_LIFE_CYCLE_IMPL_H_

#include <memory>

#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "base/observer_list.h"
#include "base/timer/timer.h"
#include "chromeos/components/proximity_auth/messenger_observer.h"
#include "chromeos/components/proximity_auth/remote_device_life_cycle.h"
#include "chromeos/services/secure_channel/public/cpp/client/connection_attempt.h"
#include "chromeos/services/secure_channel/public/cpp/client/secure_channel_client.h"
#include "chromeos/services/secure_channel/public/mojom/secure_channel.mojom.h"
#include "components/cryptauth/authenticator.h"
#include "components/cryptauth/connection.h"
#include "components/cryptauth/connection_finder.h"
#include "components/cryptauth/remote_device_ref.h"

namespace chromeos {
namespace secure_channel {
class ClientChannel;
class SecureChannelClient;
}  // namespace secure_channel
}  // namespace chromeos

namespace cryptauth {
class SecureContext;
}

namespace proximity_auth {

class Messenger;

// Implementation of RemoteDeviceLifeCycle.
class RemoteDeviceLifeCycleImpl
    : public RemoteDeviceLifeCycle,
      public chromeos::secure_channel::ConnectionAttempt::Delegate,
      public MessengerObserver {
 public:
  // Creates the life cycle for controlling the given |remote_device|.
  // |proximity_auth_client| is not owned.
  RemoteDeviceLifeCycleImpl(
      cryptauth::RemoteDeviceRef remote_device,
      base::Optional<cryptauth::RemoteDeviceRef> local_device,
      chromeos::secure_channel::SecureChannelClient* secure_channel_client);
  ~RemoteDeviceLifeCycleImpl() override;

  // RemoteDeviceLifeCycle:
  void Start() override;
  cryptauth::RemoteDeviceRef GetRemoteDevice() const override;
  cryptauth::Connection* GetConnection() const override;
  chromeos::secure_channel::ClientChannel* GetChannel() const override;

  RemoteDeviceLifeCycle::State GetState() const override;
  Messenger* GetMessenger() override;
  void AddObserver(Observer* observer) override;
  void RemoveObserver(Observer* observer) override;

 protected:
  // Creates and returns a cryptauth::ConnectionFinder instance for
  // |remote_device_|.
  // Exposed for testing.
  virtual std::unique_ptr<cryptauth::ConnectionFinder> CreateConnectionFinder();

  // Creates and returns an Authenticator instance for |connection_|.
  // Exposed for testing.
  virtual std::unique_ptr<cryptauth::Authenticator> CreateAuthenticator();

 private:
  // Transitions to |new_state|, and notifies observers.
  void TransitionToState(RemoteDeviceLifeCycle::State new_state);

  // Transtitions to FINDING_CONNECTION state. Creates and starts
  // |connection_finder_|.
  void FindConnection();

  // Called when |connection_finder_| finds a connection.
  void OnConnectionFound(std::unique_ptr<cryptauth::Connection> connection);

  // Callback when |authenticator_| completes authentication.
  void OnAuthenticationResult(
      cryptauth::Authenticator::Result result,
      std::unique_ptr<cryptauth::SecureContext> secure_context);

  // Creates the messenger which parses status updates.
  void CreateMessenger();

  // chromeos::secure_channel::ConnectionAttempt::Delegate:
  void OnConnectionAttemptFailure(
      chromeos::secure_channel::mojom::ConnectionAttemptFailureReason reason)
      override;
  void OnConnection(std::unique_ptr<chromeos::secure_channel::ClientChannel>
                        channel) override;

  // MessengerObserver:
  void OnDisconnected() override;

  // The remote device being controlled.
  const cryptauth::RemoteDeviceRef remote_device_;

  // Represents this device (i.e. this Chromebook) for a particular profile.
  base::Optional<cryptauth::RemoteDeviceRef> local_device_;

  // The entrypoint to the SecureChannel API.
  chromeos::secure_channel::SecureChannelClient* secure_channel_client_;

  // The current state in the life cycle.
  RemoteDeviceLifeCycle::State state_;

  // Observers added to the life cycle.
  base::ObserverList<Observer>::Unchecked observers_{
      base::ObserverListPolicy::EXISTING_ONLY};

  // The connection that is established by |connection_finder_|.
  std::unique_ptr<cryptauth::Connection> connection_;

  // Context for encrypting and decrypting messages. Created after
  // authentication succeeds. Ownership is eventually passed to |messenger_|.
  std::unique_ptr<cryptauth::SecureContext> secure_context_;

  // The messenger for sending and receiving messages in the
  // SECURE_CHANNEL_ESTABLISHED state.
  std::unique_ptr<Messenger> messenger_;

  // Authenticates the remote device after it is connected. Used in the
  // AUTHENTICATING state.
  std::unique_ptr<cryptauth::Authenticator> authenticator_;

  // Used in the FINDING_CONNECTION state to establish a connection to the
  // remote device.
  std::unique_ptr<cryptauth::ConnectionFinder> connection_finder_;

  std::unique_ptr<chromeos::secure_channel::ConnectionAttempt>
      connection_attempt_;

  // Ownership is eventually passed to |messenger_|.
  std::unique_ptr<chromeos::secure_channel::ClientChannel> channel_;

  // After authentication fails, this timer waits for a period of time before
  // retrying the connection.
  base::OneShotTimer authentication_recovery_timer_;

  base::WeakPtrFactory<RemoteDeviceLifeCycleImpl> weak_ptr_factory_;

  DISALLOW_COPY_AND_ASSIGN(RemoteDeviceLifeCycleImpl);
};

}  // namespace proximity_auth

#endif  // CHROMEOS_COMPONENTS_PROXIMITY_AUTH_REMOTE_DEVICE_LIFE_CYCLE_IMPL_H_
