path: root/chromeos/dbus/nfc_tag_client.cc

// Copyright 2013 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/dbus/nfc_tag_client.h"

#include <set>

#include "base/bind.h"
#include "base/memory/weak_ptr.h"
#include "base/observer_list.h"
#include "base/stl_util.h"
#include "base/strings/stringprintf.h"
#include "chromeos/dbus/fake_nfc_tag_client.h"
#include "chromeos/dbus/nfc_adapter_client.h"
#include "dbus/bus.h"
#include "dbus/message.h"
#include "third_party/cros_system_api/dbus/service_constants.h"

using chromeos::nfc_client_helpers::DBusObjectMap;

namespace chromeos {

namespace {

typedef std::vector<dbus::ObjectPath> ObjectPathVector;

}  // namespace

NfcTagClient::Properties::Properties(
    dbus::ObjectProxy* object_proxy,
    const PropertyChangedCallback& callback)
    : NfcPropertySet(object_proxy,
                     nfc_tag::kNfcTagInterface,
                     callback) {
  RegisterProperty(nfc_tag::kTypeProperty, &type);
  RegisterProperty(nfc_tag::kProtocolProperty, &protocol);
  RegisterProperty(nfc_tag::kRecordsProperty, &records);
  RegisterProperty(nfc_tag::kReadOnlyProperty, &read_only);
}

NfcTagClient::Properties::~Properties() {
}

// The NfcTagClient implementation used in production.
class NfcTagClientImpl : public NfcTagClient,
                         public NfcAdapterClient::Observer,
                         public nfc_client_helpers::DBusObjectMap::Delegate {
 public:
  explicit NfcTagClientImpl(NfcAdapterClient* adapter_client)
      : bus_(NULL),
        adapter_client_(adapter_client),
        weak_ptr_factory_(this) {
    DCHECK(adapter_client);
  }

  virtual ~NfcTagClientImpl() {
    adapter_client_->RemoveObserver(this);
  }

  // NfcTagClient override.
  virtual void AddObserver(NfcTagClient::Observer* observer) OVERRIDE {
    DCHECK(observer);
    observers_.AddObserver(observer);
  }

  // NfcTagClient override.
  virtual void RemoveObserver(NfcTagClient::Observer* observer) OVERRIDE {
    DCHECK(observer);
    observers_.RemoveObserver(observer);
  }

  // NfcTagClient override.
  virtual Properties* GetProperties(const dbus::ObjectPath& object_path)
      OVERRIDE {
    return static_cast<Properties*>(
        object_map_->GetObjectProperties(object_path));
  }

  // NfcTagClient override.
  virtual void Write(
      const dbus::ObjectPath& object_path,
      const RecordAttributes& attributes,
      const base::Closure& callback,
      const nfc_client_helpers::ErrorCallback& error_callback) OVERRIDE {
    dbus::ObjectProxy* object_proxy = object_map_->GetObjectProxy(object_path);
    if (!object_proxy) {
      std::string error_message =
          base::StringPrintf("NFC tag with object path \"%s\" does not exist.",
                             object_path.value().c_str());
      LOG(ERROR) << error_message;
      error_callback.Run(nfc_client_helpers::kUnknownObjectError,
                         error_message);
      return;
    }

    // |attributes| should not be empty.
    if (attributes.empty()) {
      std::string error_message =
          "Cannot write data to tag with empty arguments.";
      LOG(ERROR) << error_message;
      error_callback.Run(nfc_error::kInvalidArguments, error_message);
      return;
    }

    // Create the arguments.
    dbus::MethodCall method_call(nfc_tag::kNfcTagInterface, nfc_tag::kWrite);
    dbus::MessageWriter writer(&method_call);
    dbus::MessageWriter array_writer(NULL);
    dbus::MessageWriter dict_entry_writer(NULL);
    writer.OpenArray("{sv}", &array_writer);
    for (RecordAttributes::const_iterator iter = attributes.begin();
         iter != attributes.end(); ++iter) {
      array_writer.OpenDictEntry(&dict_entry_writer);
      dict_entry_writer.AppendString(iter->first);
      dict_entry_writer.AppendVariantOfString(iter->second);
      array_writer.CloseContainer(&dict_entry_writer);
    }
    writer.CloseContainer(&array_writer);

    object_proxy->CallMethodWithErrorCallback(
        &method_call,
        dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
        base::Bind(&nfc_client_helpers::OnSuccess, callback),
        base::Bind(&nfc_client_helpers::OnError, error_callback));
  }

 protected:
  // DBusClient override.
  virtual void Init(dbus::Bus* bus) OVERRIDE {
    VLOG(1) << "Creating NfcTagClientImpl";
    DCHECK(bus);
    bus_ = bus;
    object_map_.reset(new nfc_client_helpers::DBusObjectMap(
        nfc_tag::kNfcTagServiceName, this, bus));
    DCHECK(adapter_client_);
    adapter_client_->AddObserver(this);
  }

 private:
  // NfcAdapterClient::Observer override.
  virtual void AdapterPropertyChanged(
      const dbus::ObjectPath& object_path,
      const std::string& property_name) OVERRIDE {
    // Update the tag proxies.
    DCHECK(adapter_client_);
    NfcAdapterClient::Properties *adapter_properties =
        adapter_client_->GetProperties(object_path);

    // Ignore changes to properties other than "Tags".
    if (property_name != adapter_properties->tags.name())
      return;

    VLOG(1) << "NFC tags changed.";

    // Add all the new tags.
    const ObjectPathVector& received_tags =
        adapter_properties->tags.value();
    for (ObjectPathVector::const_iterator iter = received_tags.begin();
         iter != received_tags.end(); ++iter) {
      const dbus::ObjectPath &tag_path = *iter;
      if (object_map_->AddObject(tag_path)) {
        VLOG(1) << "Found NFC tag: " << tag_path.value();
        FOR_EACH_OBSERVER(NfcTagClient::Observer, observers_,
                          TagFound(tag_path, object_path));
      }
    }

    // Remove all tags that were lost.
    const DBusObjectMap::ObjectMap& known_tags =
        object_map_->object_map();
    std::set<dbus::ObjectPath> tags_set(received_tags.begin(),
                                        received_tags.end());
    DBusObjectMap::ObjectMap::const_iterator iter = known_tags.begin();
    while (iter != known_tags.end()) {
      // Make a copy here, as the iterator will be invalidated by
      // DBusObjectMap::RemoveObject below, but |device_path| is needed to
      // notify observers right after. We want to make sure that we notify
      // the observers AFTER we remove the object, so that method calls
      // to the removed object paths in observer implementations fail
      // gracefully.
      dbus::ObjectPath tag_path = iter->first;
      ++iter;
      if (!ContainsKey(tags_set, tag_path)) {
        VLOG(1) << "Lost NFC tag: " << tag_path.value();
        object_map_->RemoveObject(tag_path);
        FOR_EACH_OBSERVER(NfcTagClient::Observer, observers_,
                          TagLost(tag_path, object_path));
      }
    }
  }

  // nfc_client_helpers::DBusObjectMap::Delegate override.
  virtual NfcPropertySet* CreateProperties(
      dbus::ObjectProxy* object_proxy) OVERRIDE {
    return new Properties(
        object_proxy,
        base::Bind(&NfcTagClientImpl::OnPropertyChanged,
                   weak_ptr_factory_.GetWeakPtr(),
                   object_proxy->object_path()));
  }

  // Called by NfcPropertySet when a property value is changed, either by
  // result of a signal or response to a GetAll() or Get() call.
  void OnPropertyChanged(const dbus::ObjectPath& object_path,
                         const std::string& property_name) {
    VLOG(1) << "Tag property changed; Path: " << object_path.value()
            << " Property: " << property_name;
    FOR_EACH_OBSERVER(NfcTagClient::Observer, observers_,
                      TagPropertyChanged(object_path, property_name));
  }

  // We maintain a pointer to the bus to be able to request proxies for
  // new NFC tags that appear.
  dbus::Bus* bus_;

  // Mapping from object paths to object proxies and properties structures that
  // were already created by us.
  scoped_ptr<nfc_client_helpers::DBusObjectMap> object_map_;

  // The manager client that we listen to events notifications from.
  NfcAdapterClient* adapter_client_;

  // List of observers interested in event notifications.
  ObserverList<NfcTagClient::Observer> observers_;

  // Weak pointer factory for generating 'this' pointers that might live longer
  // than we do.
  // Note: This should remain the last member so it'll be destroyed and
  // invalidate its weak pointers before any other members are destroyed.
  base::WeakPtrFactory<NfcTagClientImpl> weak_ptr_factory_;

  DISALLOW_COPY_AND_ASSIGN(NfcTagClientImpl);
};

NfcTagClient::NfcTagClient() {
}

NfcTagClient::~NfcTagClient() {
}

NfcTagClient* NfcTagClient::Create(DBusClientImplementationType type,
                                   NfcAdapterClient* adapter_client) {
  if (type == REAL_DBUS_CLIENT_IMPLEMENTATION)
    return new NfcTagClientImpl(adapter_client);
  DCHECK_EQ(STUB_DBUS_CLIENT_IMPLEMENTATION, type);
  return new FakeNfcTagClient();
}

}  // namespace chromeos