chrome/browser/browsing_data/browsing_data_counter.h

// Copyright (c) 2015 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_BROWSING_DATA_BROWSING_DATA_COUNTER_H_
#define CHROME_BROWSER_BROWSING_DATA_BROWSING_DATA_COUNTER_H_

#include <stdint.h>
#include <string>

#include "base/callback.h"
#include "base/macros.h"
#include "chrome/browser/browsing_data/browsing_data_remover.h"
#include "chrome/browser/profiles/profile.h"
#include "components/prefs/pref_member.h"

class BrowsingDataCounter {
 public:
  typedef int64_t ResultInt;

  // Base class of results returned by BrowsingDataCounter. When the computation
  // has started, an instance is returned to represent a pending result.
  class Result {
   public:
    explicit Result(const BrowsingDataCounter* source);
    virtual ~Result();

    const BrowsingDataCounter* source() const { return source_; }
    virtual bool Finished() const;

   private:
    const BrowsingDataCounter* source_;

    DISALLOW_COPY_AND_ASSIGN(Result);
  };

  // A subclass of Result returned when the computation has finished. The result
  // value can be retrieved by calling |Value()|. Some BrowsingDataCounter
  // subclasses might use a subclass of FinishedResult to provide more complex
  // results.
  class FinishedResult : public Result {
   public:
    FinishedResult(const BrowsingDataCounter* source, ResultInt value);
    ~FinishedResult() override;

    // Result:
    bool Finished() const override;

    ResultInt Value() const;

   private:
    ResultInt value_;

    DISALLOW_COPY_AND_ASSIGN(FinishedResult);
  };

  typedef base::Callback<void(scoped_ptr<Result>)> Callback;

  BrowsingDataCounter();
  virtual ~BrowsingDataCounter();

  // Should be called once to initialize this class.
  void Init(Profile* profile,
            const Callback& callback);

  // Name of the preference associated with this counter.
  virtual const std::string& GetPrefName() const = 0;

  // The profile associated with this counter.
  Profile* GetProfile() const;

  // Restarts the counter. Will be called automatically if the counting needs
  // to be restarted, e.g. when the deletion preference changes state or when
  // we are notified of data changes.
  void Restart();

 protected:
  // Should be called from |Count| by any overriding class to indicate that
  // counting is finished and report |value| as the result.
  void ReportResult(ResultInt value);

  // A convenience overload of the previous method that allows subclasses to
  // provide a custom |result|.
  void ReportResult(scoped_ptr<Result> result);

  // Calculates the beginning of the counting period as |period_| before now.
  base::Time GetPeriodStart();

 private:
  // Called after the class is initialized by calling |Init|.
  virtual void OnInitialized();

  // Count the data.
  virtual void Count() = 0;

  // The profile for which we will count the data volume.
  Profile* profile_;

  // The callback that will be called when the UI should be updated with a new
  // counter value.
  Callback callback_;

  // The boolean preference indicating whether this data type is to be deleted.
  // If false, we will not count it.
  BooleanPrefMember pref_;

  // The integer preference describing the time period for which this data type
  // is to be deleted.
  IntegerPrefMember period_;

  // Whether this class was properly initialized by calling |Init|.
  bool initialized_ = false;
};

#endif  // CHROME_BROWSER_BROWSING_DATA_BROWSING_DATA_COUNTER_H_