// Copyright (c) 2011 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_WEBREQUEST_API_H_
#define CHROME_BROWSER_EXTENSIONS_EXTENSION_WEBREQUEST_API_H_
#pragma once

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

#include "base/memory/singleton.h"
#include "chrome/browser/extensions/extension_function.h"
#include "chrome/browser/profiles/profile.h"
#include "ipc/ipc_message.h"
#include "net/base/completion_callback.h"
#include "webkit/glue/resource_type.h"

class ExtensionEventRouterForwarder;
class GURL;

namespace net {
class HostPortPair;
class HttpRequestHeaders;
class URLRequest;
}

// This class observes network events and routes them to the appropriate
// extensions listening to those events. All methods must be called on the IO
// thread unless otherwise specified.
class ExtensionWebRequestEventRouter {
 public:
  enum EventTypes {
    kInvalidEvent = 0,
    kOnBeforeRequest = 1 << 0,
    kOnBeforeSendHeaders = 1 << 1,
    kOnRequestSent = 1 << 2,
    kOnBeforeRedirect = 1 << 3,
    kOnResponseStarted = 1 << 4,
    kOnErrorOccurred = 1 << 5,
    kOnCompleted = 1 << 6,
  };

  struct RequestFilter;
  struct ExtraInfoSpec;

  static ExtensionWebRequestEventRouter* GetInstance();

  // Dispatches the OnBeforeRequest event to any extensions whose filters match
  // the given request. Returns net::ERR_IO_PENDING if an extension is
  // intercepting the request, OK otherwise.
  int OnBeforeRequest(ProfileId profile_id,
                      ExtensionEventRouterForwarder* event_router,
                      net::URLRequest* request,
                      net::CompletionCallback* callback,
                      GURL* new_url);

  // Dispatches the onBeforeSendHeaders event. This is fired for HTTP(s)
  // requests only, and allows modification of the outgoing request headers.
  // Returns net::ERR_IO_PENDING if an extension is intercepting the request, OK
  // otherwise.
  int OnBeforeSendHeaders(ProfileId profile_id,
                          ExtensionEventRouterForwarder* event_router,
                          uint64 request_id,
                          net::CompletionCallback* callback,
                          net::HttpRequestHeaders* headers);

  // Dispatches the onRequestSent event. This is fired for HTTP(s) requests
  // only.
  void OnRequestSent(ProfileId profile_id,
                     ExtensionEventRouterForwarder* event_router,
                     uint64 request_id,
                     const net::HostPortPair& socket_address);

  // Dispatches the onBeforeRedirect event. This is fired for HTTP(s) requests
  // only.
  void OnBeforeRedirect(ProfileId profile_id,
                        ExtensionEventRouterForwarder* event_router,
                        net::URLRequest* request,
                        const GURL& new_location);

  // Dispatches the onResponseStarted event indicating that the first bytes of
  // the response have arrived.
  void OnResponseStarted(ProfileId profile_id,
                         ExtensionEventRouterForwarder* event_router,
                         net::URLRequest* request);

  // Dispatches the onComplete event.
  void OnCompleted(ProfileId profile_id,
                   ExtensionEventRouterForwarder* event_router,
                   net::URLRequest* request);

  // Dispatches an onErrorOccurred event.
  void OnErrorOccurred(ProfileId profile_id,
                      ExtensionEventRouterForwarder* event_router,
                      net::URLRequest* request);

  // Notifications when objects are going away.
  void OnURLRequestDestroyed(ProfileId profile_id, net::URLRequest* request);
  void OnHttpTransactionDestroyed(ProfileId profile_id, uint64 request_id);

  // Called when an event listener handles a blocking event and responds.
  // TODO(mpcomplete): modify request
  void OnEventHandled(
      ProfileId profile_id,
      const std::string& extension_id,
      const std::string& event_name,
      const std::string& sub_event_name,
      uint64 request_id,
      bool cancel,
      const GURL& new_url,
      net::HttpRequestHeaders* request_headers);

  // Adds a listener to the given event. |event_name| specifies the event being
  // listened to. |sub_event_name| is an internal event uniquely generated in
  // the extension process to correspond to the given filter and
  // extra_info_spec.
  void AddEventListener(
      ProfileId profile_id,
      const std::string& extension_id,
      const std::string& event_name,
      const std::string& sub_event_name,
      const RequestFilter& filter,
      int extra_info_spec);

  // Removes the listener for the given sub-event.
  void RemoveEventListener(
      ProfileId profile_id,
      const std::string& extension_id,
      const std::string& sub_event_name);

 private:
  friend struct DefaultSingletonTraits<ExtensionWebRequestEventRouter>;
  struct EventListener;
  struct BlockedRequest;
  typedef std::map<std::string, std::set<EventListener> > ListenerMapForProfile;
  typedef std::map<ProfileId, ListenerMapForProfile> ListenerMap;
  typedef std::map<uint64, BlockedRequest> BlockedRequestMap;
  typedef std::map<uint64, net::URLRequest*> HttpRequestMap;
  // Map of request_id -> bit vector of EventTypes already signaled
  typedef std::map<uint64, int> SignaledRequestMap;

  ExtensionWebRequestEventRouter();
  ~ExtensionWebRequestEventRouter();

  bool DispatchEvent(
      ProfileId profile_id,
      ExtensionEventRouterForwarder* event_router,
      net::URLRequest* request,
      const std::vector<const EventListener*>& listeners,
      const ListValue& args);

  // Returns a list of event listeners that care about the given event, based
  // on their filter parameters.
  std::vector<const EventListener*> GetMatchingListeners(
      ProfileId profile_id,
      const std::string& event_name,
      const GURL& url,
      int tab_id,
      int window_id,
      ResourceType::Type resource_type);

  // Same as above, but retrieves the filter parameters from the request.
  std::vector<const EventListener*> GetMatchingListeners(
      ProfileId profile_id,
      const std::string& event_name,
      net::URLRequest* request);

  // Decrements the count of event handlers blocking the given request. When the
  // count reaches 0 (or immediately if the request is being cancelled or
  // modified headers are provided), we stop blocking the request and either
  // resume or cancel it. If |request_headers| is non-NULL, this method assumes
  // ownership.
  void DecrementBlockCount(
      uint64 request_id,
      bool cancel,
      const GURL& new_url,
      net::HttpRequestHeaders* request_headers);

  void OnRequestDeleted(net::URLRequest* request);

  // Sets the flag that |event_type| has been signaled for |request_id|.
  // Returns the value of the flag before setting it.
  bool GetAndSetSignaled(uint64 request_id, EventTypes event_type);

  // Clears the flag that |event_type| has been signaled for |request_id|.
  void ClearSignaled(uint64 request_id, EventTypes event_type);

  // A map for each profile that maps an event name to a set of extensions that
  // are listening to that event.
  ListenerMap listeners_;

  // A map of network requests that are waiting for at least one event handler
  // to respond.
  BlockedRequestMap blocked_requests_;

  // A map of HTTP(s) network requests. We use this to look up the URLRequest
  // from the request ID given to us for HTTP-specific events.
  HttpRequestMap http_requests_;

  // A map of request ids to a bitvector indicating which events have been
  // signaled and should not be sent again.
  SignaledRequestMap signaled_requests_;

  DISALLOW_COPY_AND_ASSIGN(ExtensionWebRequestEventRouter);
};

class WebRequestAddEventListener : public SyncExtensionFunction {
 public:
  virtual bool RunImpl();
  DECLARE_EXTENSION_FUNCTION_NAME("experimental.webRequest.addEventListener");
};

class WebRequestEventHandled : public SyncExtensionFunction {
 public:
  virtual bool RunImpl();
  DECLARE_EXTENSION_FUNCTION_NAME("experimental.webRequest.eventHandled");
};

#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_WEBREQUEST_API_H_