chrome/browser/ash/crosapi/search_provider_ash.h

// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CHROME_BROWSER_ASH_CROSAPI_SEARCH_PROVIDER_ASH_H_
#define CHROME_BROWSER_ASH_CROSAPI_SEARCH_PROVIDER_ASH_H_

#include <memory>
#include <string>

#include "base/memory/weak_ptr.h"
#include "chrome/browser/ash/crosapi/search_controller_ash.h"
#include "chromeos/crosapi/mojom/launcher_search.mojom.h"
#include "mojo/public/cpp/bindings/pending_remote.h"
#include "mojo/public/cpp/bindings/receiver_set.h"

namespace crosapi {

// IMPORTANT: This search API should only be used by the launcher, because
// in-flight queries will be cancelled whenever a new query is issued.
// Use `SearchControllerFactoryAsh` instead to create a new dedicated instance.
//
// This class is the crosapi entry-point for launcher omnibox search. It lives
// in ash-chrome on the UI thread. Omnibox results are obtained as follows:
//
//   1) On creation, each lacros instance requests a `SearchControllerRegistry`
//      (all of which are implemented by the same instance of this class), and
//      sends across a handle to its search controller.
//
//      TODO(1329709): Currently, a search controller is accepted exactly if a
//      new lacros instance is created after the previous instance is dead.
//      Correct this.
//
//   2) Once the search controller handle has been received, clients (i.e. code
//      in ash-chrome) can use the `Search` method to fetch omnibox results,
//      which delegates to the search controller over Mojo.
//
//      Internally, `SearchControllerAsh` implements one
//      `SearchResultsPublisher` per search request (even though the search
//      controller can only execute one search at a time) in order to notify old
//      clients if their search is preempted. It's likely that this can be
//      simplified in the future.
class SearchProviderAsh : public mojom::SearchControllerRegistry {
 public:
  SearchProviderAsh();
  SearchProviderAsh(const SearchProviderAsh&) = delete;
  SearchProviderAsh& operator=(const SearchProviderAsh&) = delete;
  ~SearchProviderAsh() override;

  void BindReceiver(
      mojo::PendingReceiver<mojom::SearchControllerRegistry> receiver);

  using SearchResultsReceivedCallback =
      SearchControllerAsh::SearchResultsReceivedCallback;

  // If non-null, this is guaranteed to be connected.
  SearchControllerAsh* GetController();

  // mojom::SearchControllerRegistry overrides:
  void RegisterSearchController(
      mojo::PendingRemote<mojom::SearchController> search_controller) override;

 private:
  void OnSearchControllerDisconnected(
      base::WeakPtr<SearchControllerAsh> controller);

  // Constructed in `RegisterSearchController`, when lacros-chrome registers
  // its singleton search controller.
  // Destructed in `OnSearchControllerDisconnected`, when the remote is
  // disconnected.
  // If non-null, this is guaranteed to be connected (outside of
  // `OnSearchControllerDisconnected`).
  std::unique_ptr<SearchControllerAsh> search_controller_;

  mojo::ReceiverSet<mojom::SearchControllerRegistry> registry_receivers_;

  base::WeakPtrFactory<SearchProviderAsh> weak_factory_{this};
};

}  // namespace crosapi

#endif  // CHROME_BROWSER_ASH_CROSAPI_SEARCH_PROVIDER_ASH_H_