// Copyright 2008, Google Inc.
//
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// modification, are permitted provided that the following conditions are met:
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//     this list of conditions and the following disclaimer.
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//     used to endorse or promote products derived from this software without
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#ifndef GEARS_CONSOLE_JS_CALLBACK_LOGGING_BACKEND_H__
#define GEARS_CONSOLE_JS_CALLBACK_LOGGING_BACKEND_H__

#include "gears/base/common/common.h"
#include "gears/base/common/js_runner.h"
#include "gears/base/common/string16.h"
#include "gears/console/log_event.h"
#include "third_party/scoped_ptr/scoped_ptr.h"

class GearsConsole;

// JsCallbackLoggingBackend provides a means of accessing the log stream
// via a JavaScript callback function.
// Console instances provide access to a JavaScript callback backend via the
// onlog property.
// JsCallbackLoggingBackend is an example implementation of a logging backend.
class JsCallbackLoggingBackend : public MessageObserverInterface {
 public:
  JsCallbackLoggingBackend(const std::string16 &topic,
                           JsRunnerInterface *js_runner,
                           GearsConsole *console);
  ~JsCallbackLoggingBackend();

  virtual void OnNotify(MessageService *service,
                        const char16 *topic,
                        const NotificationData *data);

  JsRootedCallback *GetCallback();
  void SetCallback(JsRootedCallback *callback);
  void ClearCallback();

 private:
  std::string16 observer_topic_;

  // A callback for receiving log messages
  scoped_ptr<JsRootedCallback> callback_;

  // The JavaScript context for accessing and running callbacks
  JsRunnerInterface *js_runner_;

  // A weak pointer to the GearsConsole object that owns us.  We Addref this
  // during callback dispatch so that it doesn't get released and delete us.
  GearsConsole *console_;

  DISALLOW_EVIL_CONSTRUCTORS(JsCallbackLoggingBackend);
};

#endif // GEARS_CONSOLE_JS_CALLBACK_LOGGING_BACKEND_H__