// Copyright (c) 2012 The Chromium OS 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 LOGIN_MANAGER_LIVENESS_CHECKER_IMPL_H_
#define LOGIN_MANAGER_LIVENESS_CHECKER_IMPL_H_

#include <base/cancelable_callback.h>
#include <base/macros.h>
#include <base/memory/ref_counted.h>
#include <base/memory/weak_ptr.h>
#include <base/time/time.h>

#include "login_manager/liveness_checker.h"

namespace dbus {
class ObjectProxy;
class Response;
}  // namespace dbus

namespace login_manager {
class ProcessManagerServiceInterface;

// An implementation of LivenessChecker that pings a service (owned by Chrome)
// over D-Bus, and expects the response to a ping to come in reliably before the
// next ping is sent.  If not, it may ask |manager| to abort the browser
// process.
//
// Actual aborting behavior is controlled by the enable_aborting flag.
class LivenessCheckerImpl : public LivenessChecker {
 public:
  LivenessCheckerImpl(ProcessManagerServiceInterface* manager,
                      dbus::ObjectProxy* dbus_proxy,
                      bool enable_aborting,
                      base::TimeDelta interval);
  LivenessCheckerImpl(const LivenessCheckerImpl&) = delete;
  LivenessCheckerImpl& operator=(const LivenessCheckerImpl&) = delete;

  ~LivenessCheckerImpl() override;

  // Implementation of LivenessChecker.
  void Start() override;
  void Stop() override;
  bool IsRunning() override;

  // If a liveness check is outstanding, kills the browser and clears liveness
  // tracking state.  This instance will be stopped at that point in time.
  // If no ping is outstanding, sends a liveness check to the browser over DBus,
  // then reschedules itself after interval.
  void CheckAndSendLivenessPing(base::TimeDelta interval);

  void set_manager(ProcessManagerServiceInterface* manager) {
    manager_ = manager;
  }

 private:
  // Handle async response to liveness ping by setting last_ping_acked_,
  // iff there is a successful response.
  void HandleAck(dbus::Response* response);

  ProcessManagerServiceInterface* manager_;  // Owned by the caller.
  dbus::ObjectProxy* dbus_proxy_;            // Owned by the caller.

  const bool enable_aborting_;
  const base::TimeDelta interval_;
  bool last_ping_acked_ = true;
  base::CancelableClosure liveness_check_;
  base::WeakPtrFactory<LivenessCheckerImpl> weak_ptr_factory_{this};
};
}  // namespace login_manager

#endif  // LOGIN_MANAGER_LIVENESS_CHECKER_IMPL_H_