// Copyright (c) 2012 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_SCRIPT_EXECUTOR_H_
#define CHROME_BROWSER_EXTENSIONS_SCRIPT_EXECUTOR_H_

#include <string>

#include "base/callback_forward.h"
#include "base/observer_list.h"
#include "chrome/common/extensions/user_script.h"

class GURL;

namespace base {
class ListValue;
}  // namespace base

namespace content {
class WebContents;
}

namespace extensions {

// Interface for executing extension content scripts (e.g. executeScript) as
// described by the ExtensionMsg_ExecuteCode_Params IPC, and notifying the
// caller when responded with ExtensionHostMsg_ExecuteCodeFinished.
class ScriptExecutor {
 public:
  explicit ScriptExecutor(content::WebContents* web_contents);

  ~ScriptExecutor();

  // The type of script being injected.
  enum ScriptType {
    JAVASCRIPT,
    CSS,
  };

  // The scope of the script injection across the frames.
  enum FrameScope {
    TOP_FRAME,
    ALL_FRAMES,
  };

  // The type of world to inject into (main world, or its own isolated world).
  enum WorldType {
    MAIN_WORLD,
    ISOLATED_WORLD,
  };

  // Callback from ExecuteScript. The arguments are (error, on_page_id, on_url,
  // result). Success is implied by an empty error.
  typedef base::Callback<void(const std::string&, int32, const GURL&,
                              const base::ListValue&)>
      ExecuteScriptCallback;

  class Observer {
   public:
    // Automatically observes and unobserves *script_executor on construction
    // and destruction. *script_executor must outlive *this.
    explicit Observer(ScriptExecutor* script_executor);
    virtual ~Observer();

    virtual void OnExecuteScriptFinished(const std::string& extension_id,
                                         const std::string& error,
                                         int32 on_page_id,
                                         const GURL& on_url,
                                         const base::ListValue&) = 0;
   private:
    ScriptExecutor& script_executor_;
  };

  // Executes a script. The arguments match ExtensionMsg_ExecuteCode_Params in
  // extension_messages.h (request_id is populated automatically).
  //
  // |callback| will always be called even if the IPC'd renderer is destroyed
  // before a response is received (in this case the callback will be with a
  // failure and appropriate error message).
  void ExecuteScript(const std::string& extension_id,
                     ScriptType script_type,
                     const std::string& code,
                     FrameScope frame_scope,
                     UserScript::RunLocation run_at,
                     WorldType world_type,
                     const ExecuteScriptCallback& callback);

  void AddObserver(Observer* obs) {
    observer_list_.AddObserver(obs);
  }

  void RemoveObserver(Observer* obs) {
    observer_list_.RemoveObserver(obs);
  }

 private:
  // The next value to use for request_id in ExtensionMsg_ExecuteCode_Params.
  int next_request_id_;

  // The WebContents this is bound to.
  content::WebContents* web_contents_;

  ObserverList<Observer> observer_list_;
};

}  // namespace extensions

#endif  // CHROME_BROWSER_EXTENSIONS_SCRIPT_EXECUTOR_H_