// Copyright 2014 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.

#include "google_apis/gcm/engine/heartbeat_manager.h"

#include "google_apis/gcm/protocol/mcs.pb.h"
#include "net/base/network_change_notifier.h"

namespace gcm {

namespace {
// The default heartbeat when on a mobile or unknown network .
const int64 kCellHeartbeatDefaultMs = 1000 * 60 * 28;  // 28 minutes.
// The default heartbeat when on WiFi (also used for ethernet).
const int64 kWifiHeartbeatDefaultMs = 1000 * 60 * 15;  // 15 minutes.
// The default heartbeat ack interval.
const int64 kHeartbeatAckDefaultMs = 1000 * 60 * 1;  // 1 minute.
}  // namespace

HeartbeatManager::HeartbeatManager()
    : waiting_for_ack_(false),
      heartbeat_interval_ms_(0),
      server_interval_ms_(0),
      heartbeat_timer_(true  /* retain user task */,
                       false  /* not repeating */),
      weak_ptr_factory_(this) {}

HeartbeatManager::~HeartbeatManager() {}

void HeartbeatManager::Start(
    const base::Closure& send_heartbeat_callback,
    const base::Closure& trigger_reconnect_callback) {
  DCHECK(!send_heartbeat_callback.is_null());
  DCHECK(!trigger_reconnect_callback.is_null());
  send_heartbeat_callback_ = send_heartbeat_callback;
  trigger_reconnect_callback_ = trigger_reconnect_callback;

  // Kicks off the timer.
  waiting_for_ack_ = false;
  RestartTimer();
}

void HeartbeatManager::Stop() {
  heartbeat_timer_.Stop();
  waiting_for_ack_ = false;
}

void HeartbeatManager::OnHeartbeatAcked() {
  if (!heartbeat_timer_.IsRunning())
    return;

  DCHECK(!send_heartbeat_callback_.is_null());
  DCHECK(!trigger_reconnect_callback_.is_null());
  waiting_for_ack_ = false;
  RestartTimer();
}

void HeartbeatManager::UpdateHeartbeatConfig(
    const mcs_proto::HeartbeatConfig& config) {
  if (!config.IsInitialized() ||
      !config.has_interval_ms() ||
      config.interval_ms() <= 0) {
    return;
  }
  DVLOG(1) << "Updating heartbeat interval to " << config.interval_ms();
  server_interval_ms_ = config.interval_ms();
}

base::TimeTicks HeartbeatManager::GetNextHeartbeatTime() const {
  if (heartbeat_timer_.IsRunning())
    return heartbeat_timer_.desired_run_time();
  else
    return base::TimeTicks();
}

void HeartbeatManager::OnHeartbeatTriggered() {
  if (waiting_for_ack_) {
    LOG(WARNING) << "Lost connection to MCS, reconnecting.";
    Stop();
    trigger_reconnect_callback_.Run();
    return;
  }

  waiting_for_ack_ = true;
  RestartTimer();
  send_heartbeat_callback_.Run();
}

void HeartbeatManager::RestartTimer() {
  if (!waiting_for_ack_) {
    // Recalculate the timer interval based network type.
    if (server_interval_ms_ != 0) {
      // If a server interval is set, it overrides any local one.
      heartbeat_interval_ms_ = server_interval_ms_;
    } else if (net::NetworkChangeNotifier::GetConnectionType() ==
                   net::NetworkChangeNotifier::CONNECTION_WIFI ||
               net::NetworkChangeNotifier::GetConnectionType() ==
                   net::NetworkChangeNotifier::CONNECTION_ETHERNET) {
      heartbeat_interval_ms_ = kWifiHeartbeatDefaultMs;
    } else {
      // For unknown connections, use the longer cellular heartbeat interval.
      heartbeat_interval_ms_ = kCellHeartbeatDefaultMs;
    }
    DVLOG(1) << "Sending next heartbeat in "
             << heartbeat_interval_ms_ << " ms.";
  } else {
    heartbeat_interval_ms_ = kHeartbeatAckDefaultMs;
    DVLOG(1) << "Resetting timer for ack with "
             << heartbeat_interval_ms_ << " ms interval.";
  }
  heartbeat_timer_.Start(FROM_HERE,
                         base::TimeDelta::FromMilliseconds(
                             heartbeat_interval_ms_),
                         base::Bind(&HeartbeatManager::OnHeartbeatTriggered,
                                    weak_ptr_factory_.GetWeakPtr()));
}

}  // namespace gcm