// Copyright 2018 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 COMPONENTS_ARC_TIMER_ARC_TIMER_H_
#define COMPONENTS_ARC_TIMER_ARC_TIMER_H_

#include <stdint.h>

#include <memory>
#include <set>

#include "base/callback.h"
#include "base/files/file.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_refptr.h"
#include "base/memory/weak_ptr.h"
#include "base/task_scheduler/post_task.h"
#include "base/time/time.h"
#include "components/arc/common/timer.mojom.h"
#include "components/arc/timer/create_timer_request.h"
#include "components/timers/alarm_timer_chromeos.h"
#include "mojo/public/cpp/bindings/binding.h"

namespace arc {

// Implements the timer interface exported to the instance. All accesses to an
// instance of this class must happen on a single sequence that supports
// blocking operations and the |base::FileDescriptorWatcher| API.
//
// In the current implementation, |ArcTimer| objects are bound to a mojo proxy
// on a separate sequence in |arc_timer_bridge.cc|. Mojo guarantees to call
// all callbacks on the sequence that the mojo::Binding was created on.
// Consequently, even the timer expiration i.e. |OnExpiration| happens on the
// sequence and is allowed to do I/O.
class ArcTimer : public mojom::Timer {
  // Called when there is connection error on the mojo |binding_|. Called on the
  // the sequence this object was created on.
  using ConnectionErrorCallback = base::OnceCallback<void(ArcTimer* timer)>;

 public:
  ArcTimer(base::ScopedFD expiration_fd,
           mojo::InterfaceRequest<mojom::Timer> request,
           ConnectionErrorCallback connection_error_callback);
  ~ArcTimer() override;

  // mojom::Timer overrides. Runs on the sequence this object was created
  // on since this class is bound to a mojo proxy on a separate sequence.
  void Start(base::TimeTicks absolute_expiration_time,
             StartCallback callback) override;

 private:
  // Handles connection errors with the instance. Runs on the sequence this
  // object was created on.
  void HandleConnectionError();

  // Callback fired when the timer in |ArcTimer| expires. Runs on the sequence
  // this object was created on.
  void OnExpiration();

  mojo::Binding<mojom::Timer> binding_;

  // The timer that will be scheduled. Only accessed from the sequence on which
  // this object is created.
  timers::SimpleAlarmTimer timer_;

  // The file descriptor which will be written to when |timer| expires. Only
  // accessed from the sequence on which this object is created.
  base::ScopedFD expiration_fd_;

  ConnectionErrorCallback connection_error_callback_;

  DISALLOW_COPY_AND_ASSIGN(ArcTimer);
};

}  // namespace arc

#endif  // COMPONENTS_ARC_TIMER_ARC_TIMER_H_