// 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.
//
// A simple wrapper around invalidation::InvalidationClient that
// handles all the startup/shutdown details and hookups.

#ifndef COMPONENTS_INVALIDATION_IMPL_SYNC_INVALIDATION_LISTENER_H_
#define COMPONENTS_INVALIDATION_IMPL_SYNC_INVALIDATION_LISTENER_H_

#include <memory>
#include <string>

#include "base/callback_forward.h"
#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "base/sequence_checker.h"
#include "components/invalidation/impl/invalidation_state_tracker.h"
#include "components/invalidation/impl/state_writer.h"
#include "components/invalidation/impl/sync_system_resources.h"
#include "components/invalidation/impl/unacked_invalidation_set.h"
#include "components/invalidation/public/ack_handler.h"
#include "components/invalidation/public/invalidation_export.h"
#include "components/invalidation/public/invalidator_state.h"
#include "google/cacheinvalidation/include/invalidation-listener.h"

namespace syncer {

class ObjectIdInvalidationMap;
class RegistrationManager;

// SyncInvalidationListener is not thread-safe and lives on the sync
// thread.
class INVALIDATION_EXPORT SyncInvalidationListener
    : public invalidation::InvalidationListener,
      public StateWriter,
      public SyncNetworkChannel::Observer,
      public AckHandler {
 public:
  typedef base::Callback<invalidation::InvalidationClient*(
      invalidation::SystemResources*,
      int,
      const invalidation::string&,
      const invalidation::string&,
      invalidation::InvalidationListener*)> CreateInvalidationClientCallback;

  class INVALIDATION_EXPORT Delegate {
   public:
    virtual ~Delegate();

    virtual void OnInvalidate(
        const ObjectIdInvalidationMap& invalidations) = 0;

    virtual void OnInvalidatorStateChange(InvalidatorState state) = 0;
  };

  explicit SyncInvalidationListener(
      std::unique_ptr<SyncNetworkChannel> network_channel);

  // Calls Stop().
  ~SyncInvalidationListener() override;

  // Does not take ownership of |delegate| or |state_writer|.
  // |invalidation_state_tracker| must be initialized.
  void Start(
      const CreateInvalidationClientCallback&
          create_invalidation_client_callback,
      const std::string& client_id,
      const std::string& client_info,
      const std::string& invalidation_bootstrap_data,
      const UnackedInvalidationsMap& initial_object_states,
      const base::WeakPtr<InvalidationStateTracker>& invalidation_state_tracker,
      const scoped_refptr<base::SequencedTaskRunner>&
          invalidation_state_tracker_task_runner,
      Delegate* delegate);

  void UpdateCredentials(const std::string& email, const std::string& token);

  // Update the set of object IDs that we're interested in getting
  // notifications for.  May be called at any time.
  void UpdateRegisteredIds(const ObjectIdSet& ids);

  // invalidation::InvalidationListener implementation.
  void Ready(invalidation::InvalidationClient* client) override;
  void Invalidate(invalidation::InvalidationClient* client,
                  const invalidation::Invalidation& invalidation,
                  const invalidation::AckHandle& ack_handle) override;
  void InvalidateUnknownVersion(
      invalidation::InvalidationClient* client,
      const invalidation::ObjectId& object_id,
      const invalidation::AckHandle& ack_handle) override;
  void InvalidateAll(invalidation::InvalidationClient* client,
                     const invalidation::AckHandle& ack_handle) override;
  void InformRegistrationStatus(
      invalidation::InvalidationClient* client,
      const invalidation::ObjectId& object_id,
      invalidation::InvalidationListener::RegistrationState reg_state) override;
  void InformRegistrationFailure(invalidation::InvalidationClient* client,
                                 const invalidation::ObjectId& object_id,
                                 bool is_transient,
                                 const std::string& error_message) override;
  void ReissueRegistrations(invalidation::InvalidationClient* client,
                            const std::string& prefix,
                            int prefix_length) override;
  void InformError(invalidation::InvalidationClient* client,
                   const invalidation::ErrorInfo& error_info) override;

  // AckHandler implementation.
  void Acknowledge(const invalidation::ObjectId& id,
                   const syncer::AckHandle& handle) override;
  void Drop(const invalidation::ObjectId& id,
            const syncer::AckHandle& handle) override;

  // StateWriter implementation.
  void WriteState(const std::string& state) override;

  // SyncNetworkChannel::Observer implementation.
  void OnNetworkChannelStateChanged(
      InvalidatorState invalidator_state) override;

  void DoRegistrationUpdate();

  void RequestDetailedStatus(
      base::Callback<void(const base::DictionaryValue&)> callback) const;

  void StopForTest();

 private:
  void Stop();

  InvalidatorState GetState() const;

  void EmitStateChange();

  // Sends invalidations to their appropriate destination.
  //
  // If there are no observers registered for them, they will be saved for
  // later.
  //
  // If there are observers registered, they will be saved (to make sure we
  // don't drop them until they've been acted on) and emitted to the observers.
  void DispatchInvalidations(const ObjectIdInvalidationMap& invalidations);

  // Saves invalidations.
  //
  // This call isn't synchronous so we can't guarantee these invalidations will
  // be safely on disk by the end of the call, but it should ensure that the
  // data makes it to disk eventually.
  void SaveInvalidations(const ObjectIdInvalidationMap& to_save);

  // Emits previously saved invalidations to their registered observers.
  void EmitSavedInvalidations(const ObjectIdInvalidationMap& to_emit);

  // Generate a Dictionary with all the debugging information.
  std::unique_ptr<base::DictionaryValue> CollectDebugData() const;

  base::WeakPtr<AckHandler> AsWeakPtr();

  std::unique_ptr<SyncNetworkChannel> sync_network_channel_;
  SyncSystemResources sync_system_resources_;
  UnackedInvalidationsMap unacked_invalidations_map_;
  base::WeakPtr<InvalidationStateTracker> invalidation_state_tracker_;
  scoped_refptr<base::SequencedTaskRunner>
      invalidation_state_tracker_task_runner_;
  Delegate* delegate_;
  std::unique_ptr<invalidation::InvalidationClient> invalidation_client_;
  std::unique_ptr<RegistrationManager> registration_manager_;
  // Stored to pass to |registration_manager_| on start.
  ObjectIdSet registered_ids_;

  // The states of the ticl and the push client.
  InvalidatorState ticl_state_;
  InvalidatorState push_client_state_;

  SEQUENCE_CHECKER(sequence_checker_);

  base::WeakPtrFactory<SyncInvalidationListener> weak_ptr_factory_{this};

  DISALLOW_COPY_AND_ASSIGN(SyncInvalidationListener);
};

}  // namespace syncer

#endif  // COMPONENTS_INVALIDATION_IMPL_SYNC_INVALIDATION_LISTENER_H_