// Copyright (c) 2008 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_GREASEMONKEY_MASTER_H_
#define CHROME_BROWSER_GREASEMONKEY_MASTER_H_

#include "base/directory_watcher.h"
#include "base/process.h"
#include "base/scoped_ptr.h"
#include "base/shared_memory.h"

class MessageLoop;

// Manages a segment of shared memory that contains the Greasemonkey scripts the
// user has installed.  Lives on the UI thread.
class GreasemonkeyMaster : public base::RefCounted<GreasemonkeyMaster>,
                           public DirectoryWatcher::Delegate {
 public:
  // For testability, the constructor takes the MessageLoop to run the
  // script-reloading worker on as well as the path the scripts live in.
  // These are normally the file thread and DIR_USER_SCRIPTS.
  GreasemonkeyMaster(MessageLoop* worker, const FilePath& script_dir);
  ~GreasemonkeyMaster();

  // Gets the segment of shared memory for the scripts.
  base::SharedMemory* GetSharedMemory() const {
    return shared_memory_.get();
  }

  // Called by the script reloader when new scripts have been loaded.
  void NewScriptsAvailable(base::SharedMemory* handle);

  // Return true if we have any scripts ready.
  bool ScriptsReady() const { return shared_memory_.get() != NULL; }

 private:
  class ScriptReloader;

  // DirectoryWatcher::Delegate implementation.
  virtual void OnDirectoryChanged(const FilePath& path);

  // Kicks off a process on the file thread to reload scripts from disk
  // into a new chunk of shared memory and notify renderers.
  void StartScan();

  // The directory containing user scripts.
  scoped_ptr<FilePath> user_script_dir_;

  // The watcher watches the profile's user scripts directory for new scripts.
  scoped_ptr<DirectoryWatcher> dir_watcher_;

  // The MessageLoop that the scanner worker runs on.
  // Typically the file thread; configurable for testing.
  MessageLoop* worker_loop_;

  // ScriptReloader (in another thread) reloads script off disk.
  // We hang on to our pointer to know if we've already got one running.
  scoped_refptr<ScriptReloader> script_reloader_;

  // Contains the scripts that were found the last time scripts were updated.
  scoped_ptr<base::SharedMemory> shared_memory_;

  // If the script directory is modified while we're rescanning it, we note
  // that we're currently mid-scan and then start over again once the scan
  // finishes.  This boolean tracks whether another scan is pending.
  bool pending_scan_;

  DISALLOW_COPY_AND_ASSIGN(GreasemonkeyMaster);
};

#endif  // CHROME_BROWSER_GREASEMONKEY_MASTER_H_