// Copyright (c) 2009 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_EXTENSIONS_EXTENSIONS_SERVICE_H_
#define CHROME_BROWSER_EXTENSIONS_EXTENSIONS_SERVICE_H_

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

#include "base/command_line.h"
#include "base/file_path.h"
#include "base/linked_ptr.h"
#include "base/ref_counted.h"
#include "base/task.h"
#include "base/tuple.h"
#include "base/values.h"
#include "chrome/browser/extensions/extension_prefs.h"
#include "chrome/browser/extensions/extension_process_manager.h"
#include "chrome/browser/extensions/external_extension_provider.h"
#include "chrome/browser/extensions/sandboxed_extension_unpacker.h"
#include "chrome/common/extensions/extension.h"

class Browser;
class DictionaryValue;
class Extension;
class ExtensionsServiceBackend;
class ExtensionUpdater;
class GURL;
class MessageLoop;
class PrefService;
class Profile;
class ResourceDispatcherHost;
class SiteInstance;

typedef std::vector<Extension*> ExtensionList;

// This is an interface class to encapsulate the dependencies that
// ExtensionUpdater has on ExtensionsService. This allows easy mocking.
class ExtensionUpdateService {
 public:
  virtual ~ExtensionUpdateService() {}
  virtual const ExtensionList* extensions() const = 0;
  virtual void UpdateExtension(const std::string& id, const FilePath& path) = 0;
  virtual Extension* GetExtensionById(const std::string& id) = 0;
};

// Manages installed and running Chromium extensions.
class ExtensionsService
    : public ExtensionUpdateService,
      public base::RefCountedThreadSafe<ExtensionsService> {
 public:

  // The name of the directory inside the profile where extensions are
  // installed to.
  static const char* kInstallDirectoryName;

  // If auto-updates are turned on, default to running every 5 hours.
  static const int kDefaultUpdateFrequencySeconds = 60 * 60 * 5;

  // The name of the file that the current active version number is stored in.
  static const char* kCurrentVersionFileName;

  // Hack:
  // Extensions downloaded from kGalleryDownloadURLPrefix initiated from pages
  // with kGalleryURLPrefix will not require --enable-extensions and will be
  // prompt-free.
  static const char* kGalleryDownloadURLPrefix;
  static const char* kGalleryURLPrefix;

  // Determine if a given extension download should be treated as if it came
  // from the gallery.
  static bool IsDownloadFromGallery(const GURL& download_url,
                                    const GURL& referrer_url);

  ExtensionsService(Profile* profile,
                    const CommandLine* command_line,
                    PrefService* prefs,
                    const FilePath& install_directory,
                    MessageLoop* frontend_loop,
                    MessageLoop* backend_loop,
                    bool autoupdate_enabled);
  virtual ~ExtensionsService();

  // Gets the list of currently installed extensions.
  virtual const ExtensionList* extensions() const {
    return &extensions_;
  }

  const FilePath& install_directory() const { return install_directory_; }

  // Initialize and start all installed extensions.
  void Init();

  // Install the extension file at |extension_path|.  Will install as an
  // update if an older version is already installed.
  // For fresh installs, this method also causes the extension to be
  // immediately loaded.
  // TODO(aa): This method can be removed. It is only used by the unit tests,
  // and they could use CrxInstaller directly instead.
  void InstallExtension(const FilePath& extension_path);

  // Updates a currently-installed extension with the contents from
  // |extension_path|.
  // TODO(aa): This method can be removed. ExtensionUpdater could use
  // CrxInstaller directly instead.
  virtual void UpdateExtension(const std::string& id,
                               const FilePath& extension_path);

  // Reloads the specified extension.
  void ReloadExtension(const std::string& extension_id);

  // Uninstalls the specified extension. Callers should only call this method
  // with extensions that exist. |external_uninstall| is a magical parameter
  // that is only used to send information to ExtensionPrefs, which external
  // callers should never set to true.
  // TODO(aa): Remove |external_uninstall| -- this information should be passed
  // to ExtensionPrefs some other way.
  void UninstallExtension(const std::string& extension_id,
                          bool external_uninstall);

  // Load the extension from the directory |extension_path|.
  void LoadExtension(const FilePath& extension_path);

  // Load all known extensions (used by startup and testing code).
  void LoadAllExtensions();

  // Check for updates (or potentially new extensions from external providers)
  void CheckForExternalUpdates();

  // Unload the specified extension.
  void UnloadExtension(const std::string& extension_id);

  // Unload all extensions.
  void UnloadAllExtensions();

  // Called only by testing.
  void ReloadExtensions();

  // Scan the extension directory and clean up the cruft.
  void GarbageCollectExtensions();

  // Lookup an extension by |id|.
  virtual Extension* GetExtensionById(const std::string& id);

  // Lookup an extension by |url|.  This uses the host of the URL as the id.
  Extension* GetExtensionByURL(const GURL& url);

  // Clear all ExternalExtensionProviders.
  void ClearProvidersForTesting();

  // Sets an ExternalExtensionProvider for the service to use during testing.
  // |location| specifies what type of provider should be added.
  void SetProviderForTesting(Extension::Location location,
                             ExternalExtensionProvider* test_provider);

  // Called by the backend when the initial extension load has completed.
  void OnLoadedInstalledExtensions();

  // Called by the backend when extensions have been loaded.
  void OnExtensionsLoaded(ExtensionList* extensions);

  // Called by the backend when an extension has been installed.
  void OnExtensionInstalled(Extension* extension);

  // Called by the backend when an attempt was made to reinstall the same
  // version of an existing extension.
  void OnExtensionOverinstallAttempted(const std::string& id);

  // Called by the backend when an external extension is found.
  void OnExternalExtensionFound(const std::string& id,
                                const std::string& version,
                                const FilePath& path,
                                Extension::Location location);

  void set_extensions_enabled(bool enabled) { extensions_enabled_ = enabled; }
  bool extensions_enabled() { return extensions_enabled_; }

  void set_show_extensions_prompts(bool enabled) {
    show_extensions_prompts_ = enabled;
  }

  bool show_extensions_prompts() {
    return show_extensions_prompts_;
  }

  // Profile calls this when it is destroyed so that we know not to call it.
  void ProfileDestroyed() { profile_ = NULL; }

  ExtensionPrefs* extension_prefs() { return extension_prefs_.get(); }

  // Whether the extension service is ready.
  bool is_ready() { return ready_; }

 private:
  // The profile this ExtensionsService is part of.
  Profile* profile_;

  // Preferences for the owning profile.
  scoped_ptr<ExtensionPrefs> extension_prefs_;

  // The message loop to use with the backend.
  MessageLoop* backend_loop_;

  // The current list of installed extensions.
  ExtensionList extensions_;

  // The full path to the directory where extensions are installed.
  FilePath install_directory_;

  // Whether or not extensions are enabled.
  bool extensions_enabled_;

  // Whether to notify users when they attempt to install an extension.
  bool show_extensions_prompts_;

  // The backend that will do IO on behalf of this instance.
  scoped_refptr<ExtensionsServiceBackend> backend_;

  // Is the service ready to go?
  bool ready_;

  // Our extension updater, if updates are turned on.
  scoped_refptr<ExtensionUpdater> updater_;

  DISALLOW_COPY_AND_ASSIGN(ExtensionsService);
};

// Implements IO for the ExtensionsService.
// TODO(aa): This can probably move into the .cc file.
class ExtensionsServiceBackend
    : public base::RefCountedThreadSafe<ExtensionsServiceBackend>,
      public ExternalExtensionProvider::Visitor {
 public:
  // |rdh| can be NULL in the case of test environment.
  // |extension_prefs| contains a dictionary value that points to the extension
  // preferences.
  ExtensionsServiceBackend(const FilePath& install_directory,
                           MessageLoop* frontend_loop);

  virtual ~ExtensionsServiceBackend();

  // Loads the installed extensions.
  // Errors are reported through ExtensionErrorReporter. On completion,
  // OnExtensionsLoaded() is called with any successfully loaded extensions.
  void LoadInstalledExtensions(scoped_refptr<ExtensionsService> frontend,
                               InstalledExtensions* installed);

  // Loads a single extension from |path| where |path| is the top directory of
  // a specific extension where its manifest file lives.
  // Errors are reported through ExtensionErrorReporter. On completion,
  // OnExtensionsLoadedFromDirectory() is called with any successfully loaded
  // extensions.
  // TODO(erikkay): It might be useful to be able to load a packed extension
  // (presumably into memory) without installing it.
  void LoadSingleExtension(const FilePath &path,
                           scoped_refptr<ExtensionsService> frontend);

  // Check externally updated extensions for updates and install if necessary.
  // Errors are reported through ExtensionErrorReporter. Succcess is not
  // reported.
  void CheckForExternalUpdates(std::set<std::string> ids_to_ignore,
                               scoped_refptr<ExtensionsService> frontend);

  // Clear all ExternalExtensionProviders.
  void ClearProvidersForTesting();

  // Sets an ExternalExtensionProvider for the service to use during testing.
  // |location| specifies what type of provider should be added.
  void SetProviderForTesting(Extension::Location location,
                             ExternalExtensionProvider* test_provider);

  // ExternalExtensionProvider::Visitor implementation.
  virtual void OnExternalExtensionFound(const std::string& id,
                                        const Version* version,
                                        const FilePath& path,
                                        Extension::Location location);
 private:
  // Loads a single installed extension.
  void LoadInstalledExtension(const std::string& id, const FilePath& path,
                              Extension::Location location);

  // Finish installing the extension in |crx_path| after it has been unpacked to
  // |unpacked_path|.  If |expected_id| is not empty, it's verified against the
  // extension's manifest before installation. If |silent| is true, there will
  // be no install confirmation dialog. |from_gallery| indicates whether the
  // crx was installed from our gallery, which results in different UI.
  //
  // Note: We take ownership of |extension|.
  void OnExtensionUnpacked(
      const FilePath& crx_path,
      const FilePath& unpacked_path,
      Extension* extension,
      const std::string expected_id);

  // Notify the frontend that there was an error loading an extension.
  void ReportExtensionLoadError(const FilePath& extension_path,
                                const std::string& error);

  // Notify the frontend that extensions were loaded.
  void ReportExtensionsLoaded(ExtensionList* extensions);

  // Notify the frontend that there was an error installing an extension.
  void ReportExtensionInstallError(const FilePath& extension_path,
                                   const std::string& error);

  // Lookup an external extension by |id| by going through all registered
  // external extension providers until we find a provider that contains an
  // extension that matches. If |version| is not NULL, the extension version
  // will be returned (caller is responsible for deleting that pointer).
  // |location| can also be null, if not needed. Returns true if extension is
  // found, false otherwise.
  bool LookupExternalExtension(const std::string& id,
                               Version** version,
                               Extension::Location* location);

  // For the extension in |version_path| with |id|, check to see if it's an
  // externally managed extension.  If so return true if it should be
  // uninstalled.
  bool CheckExternalUninstall(const std::string& id,
                              Extension::Location location);

  // This is a naked pointer which is set by each entry point.
  // The entry point is responsible for ensuring lifetime.
  ExtensionsService* frontend_;

  // The top-level extensions directory being installed to.
  FilePath install_directory_;

  // Whether errors result in noisy alerts.
  bool alert_on_error_;

  // The message loop to use to call the frontend.
  MessageLoop* frontend_loop_;

  // A map of all external extension providers.
  typedef std::map<Extension::Location,
                   linked_ptr<ExternalExtensionProvider> > ProviderMap;
  ProviderMap external_extension_providers_;

  DISALLOW_COPY_AND_ASSIGN(ExtensionsServiceBackend);
};

#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSIONS_SERVICE_H_