// 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_EXTENSION_FUNCTION_DISPATCHER_H_
#define CHROME_BROWSER_EXTENSIONS_EXTENSION_FUNCTION_DISPATCHER_H_

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

#include "app/gfx/native_widget_types.h"
#include "base/ref_counted.h"
#include "googleurl/src/gurl.h"

class Browser;
class Extension;
class ExtensionDOMUI;
class ExtensionFunction;
class ExtensionHost;
class ExtensionPopupHost;
class Profile;
class RenderViewHost;
class RenderViewHostDelegate;
class Value;

// A factory function for creating new ExtensionFunction instances.
typedef ExtensionFunction* (*ExtensionFunctionFactory)();

// ExtensionFunctionDispatcher receives requests to execute functions from
// Chromium extensions running in a RenderViewHost and dispatches them to the
// appropriate handler. It lives entirely on the UI thread.
class ExtensionFunctionDispatcher {
 public:
  class Delegate {
   public:
    virtual Browser* GetBrowser() const = 0;

    // Returns the gfx::NativeWindow that contains the view hosting the
    // environment in which the function dispatcher resides.
    virtual gfx::NativeWindow GetFrameNativeWindow();

    virtual ExtensionHost* GetExtensionHost() { return NULL; }
    virtual ExtensionDOMUI* GetExtensionDOMUI() { return NULL; }

   protected:
    virtual ~Delegate() {}
  };

  // The peer object allows us to notify ExtensionFunctions when we are
  // destroyed.
  // TODO: this should use WeakPtr
  struct Peer : public base::RefCounted<Peer> {
    explicit Peer(ExtensionFunctionDispatcher* dispatcher)
        : dispatcher_(dispatcher) {}
    ExtensionFunctionDispatcher* dispatcher_;

   private:
    friend class base::RefCounted<Peer>;

    ~Peer() {}
  };

  // Gets a list of all known extension function names.
  static void GetAllFunctionNames(std::vector<std::string>* names);

  // Override a previously registered function. Returns true if successful,
  // false if no such function was registered.
  static bool OverrideFunction(const std::string& name,
                               ExtensionFunctionFactory factory);

  // Resets all functions to their initial implementation.
  static void ResetFunctions();

  // Retrieves a vector of all EFD instances.
  static std::set<ExtensionFunctionDispatcher*>* all_instances();

  ExtensionFunctionDispatcher(RenderViewHost* render_view_host,
                              Delegate* delegate,
                              const GURL& url);
  ~ExtensionFunctionDispatcher();

  // Handle a request to execute an extension function.
  void HandleRequest(const std::string& name, const Value* args,
                     int request_id, bool has_callback);

  // Send a response to a function.
  void SendResponse(ExtensionFunction* api, bool success);

  // Gets the browser extension functions should operate relative to. For
  // example, for positioning windows, or alert boxes, or creating tabs.
  Browser* GetBrowser();

  // Get the extension popup hosting environment for the ExtensionHost
  // or ExtensionDOMUI associted with this dispatcher.
  ExtensionPopupHost* GetPopupHost();

  // Gets the ExtensionHost associated with this object.  In the case of
  // tab hosted extension pages, this will return NULL.
  ExtensionHost* GetExtensionHost();

  // Gets the ExtensionDOMUI associated with this object.  In the case of
  // non-tab-hosted extension pages, this will return NULL.
  ExtensionDOMUI* GetExtensionDOMUI();

  // Returns the gfx::NativeWindow that frames the view of the extension
  // containing the function dispatcher.  This may return NULL.  Refer to the
  // ExtensionFunctionDispatcher::Delegate::GetFrameNativeWindow()
  // implementation for an explanation.
  gfx::NativeWindow GetFrameNativeWindow();

  // Gets the extension the function is being invoked by. This should not ever
  // return NULL.
  Extension* GetExtension();

  // Handle a malformed message.  Possibly the result of an attack, so kill
  // the renderer.
  void HandleBadMessage(ExtensionFunction* api);

  // Gets the URL for the view we're displaying.
  const GURL& url() { return url_; }

  // Gets the ID for this extension.
  const std::string extension_id() { return url_.host(); }

  // The profile that this dispatcher is associated with.
  Profile* profile();

  // The RenderViewHost this dispatcher is associated with.
  RenderViewHost* render_view_host() { return render_view_host_; }

 private:
  RenderViewHost* render_view_host_;

  Delegate* delegate_;

  GURL url_;

  scoped_refptr<Peer> peer_;

  // AutomationExtensionFunction requires access to the RenderViewHost
  // associated with us.  We make it a friend rather than exposing the
  // RenderViewHost as a public method as we wouldn't want everyone to
  // start assuming a 1:1 relationship between us and RenderViewHost,
  // whereas AutomationExtensionFunction is by necessity "tight" with us.
  friend class AutomationExtensionFunction;
};

#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_FUNCTION_DISPATCHER_H_