// Copyright (c) 2011 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.

#ifndef CHROME_BROWSER_EXTENSIONS_SYNCABLE_EXTENSION_SETTINGS_STORAGE_H_
#define CHROME_BROWSER_EXTENSIONS_SYNCABLE_EXTENSION_SETTINGS_STORAGE_H_
#pragma once

#include "base/compiler_specific.h"
#include "base/memory/weak_ptr.h"
#include "base/values.h"
#include "chrome/browser/extensions/extension_settings_storage.h"
#include "chrome/browser/extensions/extension_setting_sync_data.h"
#include "chrome/browser/sync/api/syncable_service.h"
#include "chrome/browser/sync/api/sync_change.h"

// Decorates an ExtensionSettingsStorage with sync behaviour.
class SyncableExtensionSettingsStorage : public ExtensionSettingsStorage {
 public:
  explicit SyncableExtensionSettingsStorage(
      std::string extension_id,
      // Ownership taken.
      ExtensionSettingsStorage* delegate);

  virtual ~SyncableExtensionSettingsStorage();

  // ExtensionSettingsStorage implementation.
  virtual Result Get(const std::string& key) OVERRIDE;
  virtual Result Get(const std::vector<std::string>& keys) OVERRIDE;
  virtual Result Get() OVERRIDE;
  virtual Result Set(const std::string& key, const Value& value) OVERRIDE;
  virtual Result Set(const DictionaryValue& settings) OVERRIDE;
  virtual Result Remove(const std::string& key) OVERRIDE;
  virtual Result Remove(const std::vector<std::string>& keys) OVERRIDE;
  virtual Result Clear() OVERRIDE;

  // Sync-related methods, analogous to those on SyncableService (handled by
  // ExtensionSettings).
  SyncError StartSyncing(
      const DictionaryValue& sync_state,
      // Must NOT be NULL. Ownership NOT taken.
      SyncChangeProcessor* sync_processor);
  void StopSyncing();
  std::vector<SyncError> ProcessSyncChanges(
      const ExtensionSettingSyncDataList& sync_changes);

 private:
  // Either adds to sync or send updates to sync for some settings.
  // Whether they're adds or updates depends on the state of |synced_keys_|.
  void SendAddsOrUpdatesToSync(
      const std::set<std::string>& changed_keys,
      const DictionaryValue& settings);

  // Sends deletes to sync for some settings.
  void SendDeletesToSync(const std::set<std::string>& keys);

  // Sends all local settings to sync (synced settings assumed to be empty).
  SyncError SendLocalSettingsToSync(
      const DictionaryValue& settings);

  // Overwrites local state with sync state.
  SyncError OverwriteLocalSettingsWithSync(
      const DictionaryValue& sync_state, const DictionaryValue& settings);

  // Id of the extension these settings are for.
  std::string const extension_id_;

  // Storage area to sync.
  const scoped_ptr<ExtensionSettingsStorage> delegate_;

  // Sync processor.  Non-NULL while sync is enabled (between calls to
  // StartSyncing and StopSyncing).
  SyncChangeProcessor* sync_processor_;

  // Keys of the settings that are currently being synced.
  std::set<std::string> synced_keys_;

  DISALLOW_COPY_AND_ASSIGN(SyncableExtensionSettingsStorage);
};

#endif  // CHROME_BROWSER_EXTENSIONS_SYNCABLE_EXTENSION_SETTINGS_STORAGE_H_