chrome/browser/web_resource/web_resource_service.h

// Copyright (c) 2010 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_WEB_RESOURCE_WEB_RESOURCE_SERVICE_H_
#define CHROME_BROWSER_WEB_RESOURCE_WEB_RESOURCE_SERVICE_H_
#pragma once

#include <string>

#include "base/file_path.h"
#include "chrome/browser/prefs/pref_service.h"
#include "chrome/browser/utility_process_host.h"
#include "chrome/common/web_resource/web_resource_unpacker.h"

class Profile;

namespace WebResourceServiceUtil {

// Certain promotions should only be shown to certain classes of users. This
// function will change to reflect each kind of promotion.
bool CanShowPromo(Profile* profile);

}  // namespace WebResourceService

// A WebResourceService fetches data from a web resource server to be used to
// dynamically change the appearance of the New Tab Page. For example, it has
// been used to fetch "tips" to be displayed on the NTP, or to display
// promotional messages to certain groups of Chrome users.
//
// TODO(mirandac): Arrange for a server to be set up specifically for promo
// messages, which have until now been piggybacked onto the old tips server
// structure. (see http://crbug.com/70634 for details.)
class WebResourceService
    : public UtilityProcessHost::Client {
 public:
  explicit WebResourceService(Profile* profile);

  // Sleep until cache needs to be updated, but always for at least 5 seconds
  // so we don't interfere with startup.  Then begin updating resources.
  void StartAfterDelay();

  // We have successfully pulled data from a resource server; now launch
  // the process that will parse the JSON, and then update the cache.
  void UpdateResourceCache(const std::string& json_data);

  // Unpack the web resource as a set of tips. Expects json in the form of:
  // {
  //   "lang": "en",
  //   "topic": {
  //     "topid_id": "24013",
  //     "topics": [
  //     ],
  //     "answers": [
  //       {
  //         "answer_id": "18625",
  //         "inproduct": "Text here will be shown as a tip",
  //       },
  //       ...
  //     ]
  //   }
  // }
  //
  // Public for unit testing.
  void UnpackTips(const DictionaryValue& parsed_json);

  // Unpack the web resource as a custom promo signal. Expects a start and end
  // signal, with the promo to be shown in the tooltip of the start signal
  // field. Delivery will be in json in the form of:
  // {
  //   "topic": {
  //     "answers": [
  //       {
  //         "answer_id": "1067976",
  //         "name": "promo_start",
  //         "question": "1:24",
  //         "tooltip":
  //       "Click \u003ca href=http://www.google.com\u003ehere\u003c/a\u003e!",
  //         "inproduct": "10/8/09 12:00",
  //         "inproduct_target": null
  //       },
  //       {
  //         "answer_id": "1067976",
  //         "name": "promo_end",
  //         "question": "",
  //         "tooltip": "",
  //         "inproduct": "10/8/11 12:00",
  //         "inproduct_target": null
  //       },
  //       ...
  //     ]
  //   }
  // }
  //
  // Because the promo signal data is piggybacked onto the tip server, the
  // values don't exactly correspond with the field names:
  //
  // For "promo_start" or "promo_end", the date to start or stop showing the
  // promotional line is given by the "inproduct" line.
  // For "promo_start", the promotional line itself is given in the "tooltip"
  // field. The "question" field gives the type of builds that should be shown
  // this promo (see the BuildType enum in web_resource_service.cc) and the
  // number of hours that each promo group should see it, separated by ":".
  // For example, "7:24" would indicate that all builds should see the promo,
  // and each group should see it for 24 hours.
  //
  // Public for unit testing.
  void UnpackPromoSignal(const DictionaryValue& parsed_json);

  // Unpack the web resource as a custom logo signal. Expects a start and end
  // signal. Delivery will be in json in the form of:
  // {
  //   "topic": {
  //     "answers": [
  //       {
  //         "answer_id": "107366",
  //         "name": "custom_logo_start",
  //         "question": "",
  //         "tooltip": "",
  //         "inproduct": "10/8/09 12:00",
  //         "inproduct_target": null
  //       },
  //       {
  //         "answer_id": "107366",
  //         "name": "custom_logo_end",
  //         "question": "",
  //         "tooltip": "",
  //         "inproduct": "10/8/09 12:00",
  //         "inproduct_target": null
  //       },
  //       ...
  //     ]
  //   }
  // }
  //
  // Public for unit testing.
  void UnpackLogoSignal(const DictionaryValue& parsed_json);

  int cache_update_delay() const { return cache_update_delay_; }

  Profile* profile() const { return profile_; }

  static const char* kCurrentTipPrefName;
  static const char* kTipCachePrefName;

  // Default server of dynamically loaded NTP HTML elements (promotions, tips):
  static const char* kDefaultWebResourceServer;

 private:
  class WebResourceFetcher;
  friend class WebResourceFetcher;

  class UnpackerClient;

  ~WebResourceService();

  void Init();

  // Set in_fetch_ to false, clean up temp directories (in the future).
  void EndFetch();

  // Puts parsed json data in the right places, and writes to prefs file.
  void OnWebResourceUnpacked(const DictionaryValue& parsed_json);

  // Notify listeners that the state of a web resource has changed.
  void WebResourceStateChange();

  // Schedule a notification that a web resource is either going to become
  // available or be no longer valid.
  void ScheduleNotification(double ms_start_time, double ms_end_time);

  // We need to be able to load parsed resource data into preferences file,
  // and get proper install directory.
  PrefService* prefs_;

  // Display and fetch of promo lines depends on data associated with a user's
  // profile.
  Profile* profile_;

  scoped_ptr<WebResourceFetcher> web_resource_fetcher_;

  ResourceDispatcherHost* resource_dispatcher_host_;

  // Allows the creation of tasks to send a WEB_RESOURCE_STATE_CHANGED
  // notification. This allows the WebResourceService to notify the New Tab
  // Page immediately when a new web resource should be shown or removed.
  ScopedRunnableMethodFactory<WebResourceService> service_factory_;

  // Gets mutable dictionary attached to user's preferences, so that we
  // can write resource data back to user's pref file.
  DictionaryValue* web_resource_cache_;

  // True if we are currently mid-fetch.  If we are asked to start a fetch
  // when we are still fetching resource data, schedule another one in
  // kCacheUpdateDelay time, and silently exit.
  bool in_fetch_;

  // Delay between calls to update the web resource cache. This delay may be
  // different for different builds of Chrome.
  int cache_update_delay_;

  // True if a task has been set to update the cache when a new web resource
  // becomes available.
  bool web_resource_update_scheduled_;

  DISALLOW_COPY_AND_ASSIGN(WebResourceService);
};

#endif  // CHROME_BROWSER_WEB_RESOURCE_WEB_RESOURCE_SERVICE_H_