[CrOS Tether] Sort Tether network lists.

chromeos/components/tether/host_scan_device_prioritizer_impl.cc

Index: chromeos/components/tether/host_scan_device_prioritizer_impl.cc
diff --git a/chromeos/components/tether/host_scan_device_prioritizer_impl.cc b/chromeos/components/tether/host_scan_device_prioritizer_impl.cc
new file mode 100644
index 0000000000000000000000000000000000000000..f293ec1817e8863c45c494c23c2ebae3018517d7
--- /dev/null
+++ b/chromeos/components/tether/host_scan_device_prioritizer_impl.cc
@@ -0,0 +1,105 @@
+// Copyright 2017 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 "chromeos/components/tether/host_scan_device_prioritizer_impl.h"
+
+#include "base/memory/ptr_util.h"
+#include "base/values.h"
+#include "chromeos/components/tether/device_id_tether_network_guid_map.h"
+#include "chromeos/components/tether/pref_names.h"
+#include "chromeos/components/tether/tether_host_response_recorder.h"
+#include "chromeos/network/network_state.h"
+#include "chromeos/network/network_state_handler.h"
+#include "components/prefs/pref_registry_simple.h"
+#include "components/prefs/pref_service.h"
+
+namespace chromeos {
+
+namespace tether {
+
+namespace {
+
+cryptauth::RemoteDevice Move(const cryptauth::RemoteDevice& remote_device) {
+  return remote_device;
+}
+
+std::unique_ptr<ManagedState> Move(
+    std::unique_ptr<ManagedState>& tether_network_state) {
+  return std::move(tether_network_state);
+}
+
+}  // namespace
+
+HostScanDevicePrioritizerImpl::HostScanDevicePrioritizerImpl(
+    TetherHostResponseRecorder* tether_host_response_recorder,
+    DeviceIdTetherNetworkGuidMap* device_id_tether_network_guid_map)
+    : tether_host_response_recorder_(tether_host_response_recorder),
+      device_id_tether_network_guid_map_(device_id_tether_network_guid_map) {}
+
+HostScanDevicePrioritizerImpl::~HostScanDevicePrioritizerImpl() {}
+
+void HostScanDevicePrioritizerImpl::SortByHostScanOrder(
+    std::vector<cryptauth::RemoteDevice>* remote_devices) const {
+  SortNetworks(remote_devices);
+}
+
+void HostScanDevicePrioritizerImpl::SortTetherNetworkList(
+    NetworkStateHandler::ManagedStateList* tether_networks) const {
+  SortNetworks(tether_networks);
+}
+
+template <typename T>
+void HostScanDevicePrioritizerImpl::SortNetworks(
+    std::vector<T>* list_to_sort) const {
+  // First, fetch the hosts which have previously responded.
+  std::vector<std::string> prioritized_ids =
+      tether_host_response_recorder_->GetPreviouslyAvailableHostIds();
+
+  std::vector<std::string> previously_connectable_host_ids =
+      tether_host_response_recorder_->GetPreviouslyConnectedHostIds();
+  if (!previously_connectable_host_ids.empty()) {
+    // If there is a most-recently connectable host, insert it at the front of
+    // the list.
+    prioritized_ids.insert(prioritized_ids.begin(),
+                           previously_connectable_host_ids[0]);
+  }
+
+  // Iterate from the last stored ID to the first stored ID. This ensures that
+  // the items at the front of the list end up in the front of the prioritized
+  // |list_to_sort| vector.
+  for (auto prioritized_it = prioritized_ids.rbegin();
+       prioritized_it != prioritized_ids.rend(); ++prioritized_it) {
+    // Iterate through |list_to_sort| to see if a device ID exists which is
+    // equal to |stored_id|. If one exists, remove it from its previous
+    // position in the list and add it at the front instead.
+    for (auto list_to_sort_it = list_to_sort->begin();
+         list_to_sort_it != list_to_sort->end(); ++list_to_sort_it) {
+      if (GetDeviceId(*list_to_sort_it) != *prioritized_it) {
+        continue;
+      }
+
+      T entry_to_move = Move(*list_to_sort_it);
+      list_to_sort->erase(list_to_sort_it);
+      list_to_sort->emplace(list_to_sort->begin(), Move(entry_to_move));
+      break;
+    }
+  }
+}
+
+std::string HostScanDevicePrioritizerImpl::GetDeviceId(
+    const cryptauth::RemoteDevice& remote_device) const {
+  return remote_device.GetDeviceId();
+}
+
+std::string HostScanDevicePrioritizerImpl::GetDeviceId(
+    const std::unique_ptr<ManagedState>& tether_network_state) const {
+  NetworkState* network_state =
+      static_cast<NetworkState*>(tether_network_state.get());
+  return device_id_tether_network_guid_map_->GetDeviceIdForTetherNetworkGuid(
+      network_state->guid());
+}
+
+}  // namespace tether
+
+}  // namespace chromeos