// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef COMPONENTS_SYNC_BOOKMARKS_BOOKMARK_REMOTE_UPDATES_HANDLER_H_
#define COMPONENTS_SYNC_BOOKMARKS_BOOKMARK_REMOTE_UPDATES_HANDLER_H_

#include <vector>

#include "base/memory/raw_ptr.h"
#include "components/sync/engine/commit_and_get_updates_types.h"
#include "components/sync_bookmarks/synced_bookmark_tracker.h"

namespace bookmarks {
class BookmarkNode;
}  // namespace bookmarks

namespace favicon {
class FaviconService;
}  // namespace favicon

namespace sync_bookmarks {

class BookmarkModelView;

// Responsible for processing one batch of remote updates received from the sync
// server.
class BookmarkRemoteUpdatesHandler {
 public:
  // |bookmark_model|, |favicon_service| and |bookmark_tracker| must not be null
  // and must outlive this object.
  BookmarkRemoteUpdatesHandler(BookmarkModelView* bookmark_model,
                               favicon::FaviconService* favicon_service,
                               SyncedBookmarkTracker* bookmark_tracker);

  BookmarkRemoteUpdatesHandler(const BookmarkRemoteUpdatesHandler&) = delete;
  BookmarkRemoteUpdatesHandler& operator=(const BookmarkRemoteUpdatesHandler&) =
      delete;

  // Processes the updates received from the sync server in |updates| and
  // updates the |bookmark_model_| and |bookmark_tracker_| accordingly. If
  // |got_new_encryption_requirements| is true, it recommits all tracked
  // entities except those in |updates| which should use the latest encryption
  // key and hence don't need recommitting.
  void Process(const syncer::UpdateResponseDataList& updates,
               bool got_new_encryption_requirements);

  // Returns the tracked entity that should be affected by a remote change, or
  // null if there is none (e.g. indicating a remote creation).
  static SyncedBookmarkTrackerEntity* DetermineLocalTrackedEntityToUpdate(
      SyncedBookmarkTracker* bookmark_tracker,
      const syncer::EntityData& update_entity);

  // Public for testing.
  static std::vector<const syncer::UpdateResponseData*>
  ReorderValidUpdatesForTest(const syncer::UpdateResponseDataList* updates);

  static size_t ComputeChildNodeIndexForTest(
      const bookmarks::BookmarkNode* parent,
      const sync_pb::UniquePosition& unique_position,
      const SyncedBookmarkTracker* bookmark_tracker);

 private:
  // Reorders incoming updates such that parent creation is before child
  // creation and child deletion is before parent deletion, and deletions should
  // come last. The returned pointers point to the elements in the original
  // |updates|. In this process, invalid updates are filtered out.
  static std::vector<const syncer::UpdateResponseData*> ReorderValidUpdates(
      const syncer::UpdateResponseDataList* updates);

  // Given a remote update entity, it returns the parent bookmark node of the
  // corresponding node. It returns null if the parent node cannot be found.
  const bookmarks::BookmarkNode* GetParentNode(
      const syncer::EntityData& update_entity) const;

  // Processes a remote creation of a bookmark node.
  // 1. For permanent folders, they are only registered in |bookmark_tracker_|.
  // 2. If the nodes parent cannot be found, the remote creation update is
  //    ignored.
  // 3. Otherwise, a new node is created in the local bookmark model and
  //    registered in |bookmark_tracker_|.
  //
  // Returns the newly tracked entity or null if the creation failed.
  SyncedBookmarkTrackerEntity* ProcessCreate(
      const syncer::UpdateResponseData& update);

  // Processes a remote update of a bookmark node. |update| must not be a
  // deletion, and the server_id must be already tracked, otherwise, it is a
  // creation that gets handled in ProcessCreate(). |tracked_entity| is
  // the tracked entity for that server_id. It is passed as a dependency instead
  // of performing a lookup inside ProcessUpdate() to avoid wasting CPU
  // cycles for doing another lookup (this code runs on the UI thread).
  void ProcessUpdate(const syncer::UpdateResponseData& update,
                     SyncedBookmarkTrackerEntity* tracked_entity);

  // Processes a remote delete of a bookmark node. |update_entity| must not be a
  // deletion. |tracked_entity| is the tracked entity for that server_id. It is
  // passed as a dependency instead of performing a lookup inside
  // ProcessDelete() to avoid wasting CPU cycles for doing another lookup
  // (this code runs on the UI thread).
  void ProcessDelete(const syncer::EntityData& update_entity,
                     SyncedBookmarkTrackerEntity* tracked_entity);

  // Processes a conflict where the bookmark has been changed both locally and
  // remotely. It applies the general policy the server wins except in the case
  // of remote deletions in which local wins. |tracked_entity| is the tracked
  // entity for that server_id. It is passed as a dependency instead of
  // performing a lookup inside ProcessDelete() to avoid wasting CPU cycles for
  // doing another lookup (this code runs on the UI thread). Returns the tracked
  // entity (if any) as a result of resolving the conflict, which is often the
  // same as the input |tracked_entity|, but may also be different, including
  // null (if the conflict led to untracking).
  [[nodiscard]] SyncedBookmarkTrackerEntity* ProcessConflict(
      const syncer::UpdateResponseData& update,
      SyncedBookmarkTrackerEntity* tracked_entity);

  // Recursively removes the entities corresponding to |node| and its children
  // from |bookmark_tracker_|.
  void RemoveEntityAndChildrenFromTracker(const bookmarks::BookmarkNode* node);

  // Initiate reupload for the update with |entity_data|. |tracked_entity| must
  // not be nullptr.
  void ReuploadEntityIfNeeded(const syncer::EntityData& entity_data,
                              SyncedBookmarkTrackerEntity* tracked_entity);

  const raw_ptr<BookmarkModelView> bookmark_model_;
  const raw_ptr<favicon::FaviconService> favicon_service_;
  const raw_ptr<SyncedBookmarkTracker> bookmark_tracker_;
};

}  // namespace sync_bookmarks

#endif  // COMPONENTS_SYNC_BOOKMARKS_BOOKMARK_REMOTE_UPDATES_HANDLER_H_