// Copyright 2014 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_MEDIA_GALLERIES_MEDIA_SCAN_MANAGER_H_
#define CHROME_BROWSER_MEDIA_GALLERIES_MEDIA_SCAN_MANAGER_H_

#include <map>
#include <set>
#include <string>

#include "base/basictypes.h"
#include "base/compiler_specific.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/scoped_observer.h"
#include "base/time/time.h"
#include "chrome/browser/media_galleries/media_folder_finder.h"
#include "chrome/browser/media_galleries/media_scan_types.h"
#include "extensions/browser/extension_registry_observer.h"

class MediaScanManagerObserver;
class Profile;

namespace extensions {
class Extension;
class ExtensionRegistry;
}

// The MediaScanManager is owned by MediaFileSystemRegistry, which is global.
// This class manages multiple 'virtual' media scans, up to one per extension
// per profile, and also manages the one physical scan backing them.
// This class lives and is called on the UI thread.
class MediaScanManager : public extensions::ExtensionRegistryObserver {
 public:
  MediaScanManager();
  virtual ~MediaScanManager();

  // There can only be ever one observer registered per profile. Does not take
  // ownership of |observer|. An observer must be registered before scanning.
  void AddObserver(Profile* profile, MediaScanManagerObserver* observer);
  void RemoveObserver(Profile* profile);

  // Must be called when |profile| is shut down.
  void CancelScansForProfile(Profile* profile);

  // The results of the scan are reported to the registered
  // MediaScanManagerObserver via OnScanFinished. There must be an observer
  // registered for |profile| before the scan starts.
  void StartScan(Profile* profile, const extensions::Extension* extension,
                 bool user_gesture);
  void CancelScan(Profile* profile, const extensions::Extension* extension);

 protected:
  friend class MediaGalleriesPlatformAppBrowserTest;
  friend class MediaScanManagerTest;

  typedef base::Callback<MediaFolderFinder*(
      const MediaFolderFinder::MediaFolderFinderResultsCallback&)>
          MediaFolderFinderFactory;

  void SetMediaFolderFinderFactory(const MediaFolderFinderFactory& factory);

  // Here so that friend MediaScanManagerTest can access it.
  static MediaFolderFinder::MediaFolderFinderResults FindContainerScanResults(
      const MediaFolderFinder::MediaFolderFinderResults& found_folders,
      const std::vector<base::FilePath>& sensitive_locations);

 private:
  struct ScanObservers {
    ScanObservers();
    ~ScanObservers();
    MediaScanManagerObserver* observer;
    std::set<std::string /*extension id*/> scanning_extensions;
  };
  typedef std::map<Profile*, ScanObservers> ScanObserverMap;

  // extensions::ExtensionRegistryObserver implementation.
  virtual void OnExtensionUnloaded(
      content::BrowserContext* browser_context,
      const extensions::Extension* extension,
      extensions::UnloadedExtensionInfo::Reason reason) OVERRIDE;

  bool ScanInProgress() const;

  void OnScanCompleted(
      bool success,
      const MediaFolderFinder::MediaFolderFinderResults& found_folders);

  void OnFoundContainerDirectories(
      const MediaFolderFinder::MediaFolderFinderResults& found_folders,
      const MediaFolderFinder::MediaFolderFinderResults& container_folders);

  scoped_ptr<MediaFolderFinder> folder_finder_;

  base::Time scan_start_time_;

  // If not NULL, used to create |folder_finder_|. Used for testing.
  MediaFolderFinderFactory testing_folder_finder_factory_;

  // Set of extensions (on all profiles) that have an in-progress scan.
  ScanObserverMap observers_;

  ScopedObserver<extensions::ExtensionRegistry,
                 extensions::ExtensionRegistryObserver>
      scoped_extension_registry_observer_;

  base::WeakPtrFactory<MediaScanManager> weak_factory_;

  DISALLOW_COPY_AND_ASSIGN(MediaScanManager);
};

#endif  // CHROME_BROWSER_MEDIA_GALLERIES_MEDIA_SCAN_MANAGER_H_