// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_NQE_SOCKET_WATCHER_H_
#define NET_NQE_SOCKET_WATCHER_H_

#include <optional>

#include "base/functional/callback.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/scoped_refptr.h"
#include "base/sequence_checker.h"
#include "base/time/time.h"
#include "net/base/net_export.h"
#include "net/nqe/network_quality_estimator_util.h"
#include "net/socket/socket_performance_watcher.h"
#include "net/socket/socket_performance_watcher_factory.h"

namespace base {
class SingleThreadTaskRunner;
class TickClock;
class TimeDelta;
}  // namespace base

namespace net {

class IPAddress;

namespace {

typedef base::RepeatingCallback<void(
    SocketPerformanceWatcherFactory::Protocol protocol,
    const base::TimeDelta& rtt,
    const std::optional<nqe::internal::IPHash>& host)>
    OnUpdatedRTTAvailableCallback;

typedef base::RepeatingCallback<bool(base::TimeTicks)> ShouldNotifyRTTCallback;

}  // namespace

namespace nqe::internal {

// SocketWatcher implements SocketPerformanceWatcher, and is not thread-safe.
class NET_EXPORT_PRIVATE SocketWatcher : public SocketPerformanceWatcher {
 public:
  // Creates a SocketWatcher which can be used to watch a socket that uses
  // |protocol| as the transport layer protocol. The socket watcher will call
  // |updated_rtt_observation_callback| on |task_runner| every time a new RTT
  // observation is available. |address| is the IPAddress that the socket may
  // connect to. |min_notification_interval| is the minimum interval between
  // consecutive notifications to this socket watcher.
  // |allow_rtt_private_address| is true if |updated_rtt_observation_callback|
  // should be called when RTT observation from a socket connected to private
  // address is received. |tick_clock| is guaranteed to be non-null.
  // |should_notify_rtt_callback| callback should be called back on
  // |task_runner| by the created socket watchers to check if RTT observation
  // should be taken and notified.
  SocketWatcher(SocketPerformanceWatcherFactory::Protocol protocol,
                const IPAddress& address,
                base::TimeDelta min_notification_interval,
                bool allow_rtt_private_address,
                scoped_refptr<base::SingleThreadTaskRunner> task_runner,
                OnUpdatedRTTAvailableCallback updated_rtt_observation_callback,
                ShouldNotifyRTTCallback should_notify_rtt_callback,
                const base::TickClock* tick_clock);

  SocketWatcher(const SocketWatcher&) = delete;
  SocketWatcher& operator=(const SocketWatcher&) = delete;

  ~SocketWatcher() override;

  // SocketPerformanceWatcher implementation:
  bool ShouldNotifyUpdatedRTT() const override;
  void OnUpdatedRTTAvailable(const base::TimeDelta& rtt) override;
  void OnConnectionChanged() override;

 private:
  // Transport layer protocol used by the socket that |this| is watching.
  const SocketPerformanceWatcherFactory::Protocol protocol_;

  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;

  // Called every time a new RTT observation is available.
  OnUpdatedRTTAvailableCallback updated_rtt_observation_callback_;

  // Called to determine if the RTT notification should be notified using
  // |updated_rtt_observation_callback_|.
  ShouldNotifyRTTCallback should_notify_rtt_callback_;

  // Minimum interval betweeen consecutive incoming notifications.
  const base::TimeDelta rtt_notifications_minimum_interval_;

  // True if socket watchers constructed by this factory can use the RTT from
  // the sockets that are connected to the private addresses.
  const bool allow_rtt_private_address_;

  // True if the RTT observations from this socket can be notified using
  // |updated_rtt_observation_callback_|.
  const bool run_rtt_callback_;

  // Time when this was last notified of updated RTT.
  base::TimeTicks last_rtt_notification_;

  raw_ptr<const base::TickClock> tick_clock_;

  SEQUENCE_CHECKER(sequence_checker_);

  // True if the first RTT notification from the QUIC connection has been
  // received.
  bool first_quic_rtt_notification_received_ = false;

  // A unique identifier for the remote host that this socket connects to.
  const std::optional<IPHash> host_;
};

}  // namespace nqe::internal

}  // namespace net

#endif  // NET_NQE_SOCKET_WATCHER_H_