chrome/browser/ui/webui/ntp/suggestions_page_handler.h

// Copyright (c) 2012 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_UI_WEBUI_NTP_SUGGESTIONS_PAGE_HANDLER_H_
#define CHROME_BROWSER_UI_WEBUI_NTP_SUGGESTIONS_PAGE_HANDLER_H_

#include <string>

#include "base/scoped_observer.h"
#include "chrome/browser/ui/webui/ntp/suggestions_combiner.h"
#include "components/history/core/browser/history_types.h"
#include "components/history/core/browser/top_sites_observer.h"
#include "content/public/browser/web_ui_message_handler.h"

class GURL;

namespace base {
class ListValue;
class Value;
}

namespace user_prefs {
class PrefRegistrySyncable;
}

// The handler for Javascript messages related to the "suggestions" view.
//
// This class manages one preference:
// - The URL blacklist: URLs we do not want to show in the thumbnails list.  It
//   is a dictionary for quick access (it associates a dummy boolean to the URL
//   string).
class SuggestionsHandler : public content::WebUIMessageHandler,
                           public SuggestionsCombiner::Delegate,
                           public history::TopSitesObserver {
 public:
  SuggestionsHandler();
  ~SuggestionsHandler() override;

  // WebUIMessageHandler override and implementation.
  void RegisterMessages() override;

  // Callback for the "getSuggestions" message.
  void HandleGetSuggestions(const base::ListValue* args);

  // Callback for the "blacklistURLFromSuggestions" message.
  void HandleBlacklistURL(const base::ListValue* args);

  // Callback for the "removeURLsFromSuggestionsBlacklist" message.
  void HandleRemoveURLsFromBlacklist(const base::ListValue* args);

  // Callback for the "clearSuggestionsURLsBlacklist" message.
  void HandleClearBlacklist(const base::ListValue* args);

  // Callback for the "suggestedSitesAction" message.
  void HandleSuggestedSitesAction(const base::ListValue* args);

  // Callback for the "suggestedSitesSelected" message.
  void HandleSuggestedSitesSelected(const base::ListValue* args);

  // history::TopSitesObserver implementation.
  void TopSitesLoaded(history::TopSites* top_sites) override;
  void TopSitesChanged(history::TopSites* top_sites) override;

  // SuggestionsCombiner::Delegate implementation.
  void OnSuggestionsReady() override;

  static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);

 private:
  // Puts the passed URL in the blacklist (so it does not show as a thumbnail).
  void BlacklistURL(const GURL& url);

  // Returns the key used in url_blacklist_ for the passed |url|.
  std::string GetDictionaryKeyForURL(const std::string& url);

  // Sends pages_value_ to the javascript side to and resets page_value_.
  void SendPagesValue();

  // Scoped observer to help with TopSitesObserver registration.
  ScopedObserver<history::TopSites, history::TopSitesObserver> scoped_observer_;

  // We pre-fetch the first set of result pages.  This variable is false until
  // we get the first getSuggestions() call.
  bool got_first_suggestions_request_;

  // Used to combine suggestions from various sources.
  scoped_ptr<SuggestionsCombiner> suggestions_combiner_;

  // Whether the user has viewed the 'suggested' pane.
  bool suggestions_viewed_;

  // Whether the user has performed a "tracked" action to leave the page or not.
  bool user_action_logged_;

  DISALLOW_COPY_AND_ASSIGN(SuggestionsHandler);
};

#endif  // CHROME_BROWSER_UI_WEBUI_NTP_SUGGESTIONS_PAGE_HANDLER_H_