// 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.

#include "chrome/browser/extensions/extension_event_router.h"

#include "base/bind.h"
#include "base/command_line.h"
#include "base/message_loop.h"
#include "base/values.h"
#include "chrome/browser/extensions/api/runtime/runtime_api.h"
#include "chrome/browser/extensions/api/web_request/web_request_api.h"
#include "chrome/browser/extensions/extension_devtools_manager.h"
#include "chrome/browser/extensions/extension_host.h"
#include "chrome/browser/extensions/extension_process_manager.h"
#include "chrome/browser/extensions/extension_processes_api.h"
#include "chrome/browser/extensions/extension_processes_api_constants.h"
#include "chrome/browser/extensions/extension_service.h"
#include "chrome/browser/extensions/extension_system.h"
#include "chrome/browser/extensions/lazy_background_task_queue.h"
#include "chrome/browser/extensions/process_map.h"
#include "chrome/browser/profiles/profile.h"
#include "chrome/common/chrome_notification_types.h"
#include "chrome/common/chrome_switches.h"
#include "chrome/common/extensions/extension.h"
#include "chrome/common/extensions/extension_messages.h"
#include "chrome/common/extensions/api/extension_api.h"
#include "chrome/common/view_type.h"
#include "content/public/browser/notification_service.h"
#include "content/public/browser/render_process_host.h"

using base::Value;
using content::BrowserThread;
using extensions::Extension;
using extensions::ExtensionAPI;

namespace {

const char kDispatchEvent[] = "Event.dispatchJSON";

void NotifyEventListenerRemovedOnIOThread(
    void* profile,
    const std::string& extension_id,
    const std::string& sub_event_name) {
  ExtensionWebRequestEventRouter::GetInstance()->RemoveEventListener(
      profile, extension_id, sub_event_name);
}

}  // namespace

struct ExtensionEventRouter::ListenerProcess {
  content::RenderProcessHost* process;
  std::string extension_id;

  ListenerProcess(content::RenderProcessHost* process,
                const std::string& extension_id)
      : process(process), extension_id(extension_id) {}

  bool operator<(const ListenerProcess& that) const {
    if (process < that.process)
      return true;
    if (process == that.process && extension_id < that.extension_id)
      return true;
    return false;
  }
};

// static
void ExtensionEventRouter::DispatchEvent(
    IPC::Sender* ipc_sender,
    const std::string& extension_id,
    const std::string& event_name,
    const Value& event_args,
    const GURL& event_url,
    UserGestureState user_gesture,
    const extensions::EventFilteringInfo& info) {
  // TODO(gdk): Reduce number of DeepCopy() calls throughout the event dispatch
  // chain, starting by replacing the event_args with a Value*.
  ListValue args;
  args.Set(0, Value::CreateStringValue(event_name));
  args.Set(1, event_args.DeepCopy());
  args.Set(2, info.AsValue().release());

  ipc_sender->Send(new ExtensionMsg_MessageInvoke(MSG_ROUTING_CONTROL,
      extension_id, kDispatchEvent, args, event_url,
      user_gesture == USER_GESTURE_ENABLED));
}

// static
void ExtensionEventRouter::DispatchEvent(
    IPC::Sender* ipc_sender,
    const std::string& extension_id,
    const std::string& event_name,
    const std::string& event_args,
    const GURL& event_url,
    UserGestureState user_gesture,
    const extensions::EventFilteringInfo& info) {
  scoped_ptr<Value> event_args_value(Value::CreateStringValue(event_args));
  DispatchEvent(ipc_sender, extension_id, event_name, *event_args_value.get(),
                event_url, user_gesture, info);
}

ExtensionEventRouter::ExtensionEventRouter(Profile* profile)
    : profile_(profile),
      extension_devtools_manager_(
          ExtensionSystem::Get(profile)->devtools_manager()),
      listeners_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
  registrar_.Add(this, content::NOTIFICATION_RENDERER_PROCESS_TERMINATED,
                 content::NotificationService::AllSources());
  registrar_.Add(this, content::NOTIFICATION_RENDERER_PROCESS_CLOSED,
                 content::NotificationService::AllSources());
  registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_LOADED,
                 content::Source<Profile>(profile_));
  registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_UNLOADED,
                 content::Source<Profile>(profile_));
  registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_INSTALLED,
                 content::Source<Profile>(profile_));
}

ExtensionEventRouter::~ExtensionEventRouter() {}

void ExtensionEventRouter::AddEventListener(
    const std::string& event_name,
    content::RenderProcessHost* process,
    const std::string& extension_id) {
  listeners_.AddListener(scoped_ptr<EventListener>(new EventListener(
      event_name, extension_id, process, scoped_ptr<DictionaryValue>())));
}

void ExtensionEventRouter::RemoveEventListener(
    const std::string& event_name,
    content::RenderProcessHost* process,
    const std::string& extension_id) {
  EventListener listener(event_name, extension_id, process,
                         scoped_ptr<DictionaryValue>());
  listeners_.RemoveListener(&listener);
}

void ExtensionEventRouter::OnListenerAdded(const EventListener* listener) {
  // We don't care about lazy events being added.
  if (!listener->process)
    return;

  if (extension_devtools_manager_.get())
    extension_devtools_manager_->AddEventListener(listener->event_name,
                                                  listener->process->GetID());

  // We lazily tell the TaskManager to start updating when listeners to the
  // processes.onUpdated or processes.onUpdatedWithMemory events arrive.
  const std::string& event_name = listener->event_name;
  if (event_name.compare(extension_processes_api_constants::kOnUpdated) == 0 ||
      event_name.compare(
          extension_processes_api_constants::kOnUpdatedWithMemory) == 0)
    ExtensionProcessesEventRouter::GetInstance()->ListenerAdded();
}

void ExtensionEventRouter::OnListenerRemoved(const EventListener* listener) {
  // We don't care about lazy events being removed.
  if (!listener->process)
    return;

  const std::string& event_name = listener->event_name;
  if (extension_devtools_manager_.get())
    extension_devtools_manager_->RemoveEventListener(
        event_name, listener->process->GetID());

  // If a processes.onUpdated or processes.onUpdatedWithMemory event listener
  // is removed (or a process with one exits), then we let the extension API
  // know that it has one fewer listener.
  if (event_name.compare(extension_processes_api_constants::kOnUpdated) == 0 ||
      event_name.compare(
          extension_processes_api_constants::kOnUpdatedWithMemory) == 0)
    ExtensionProcessesEventRouter::GetInstance()->ListenerRemoved();

  BrowserThread::PostTask(
      BrowserThread::IO, FROM_HERE,
      base::Bind(
          &NotifyEventListenerRemovedOnIOThread,
          profile_, listener->extension_id, listener->event_name));
}

void ExtensionEventRouter::AddLazyEventListener(
    const std::string& event_name,
    const std::string& extension_id) {
  scoped_ptr<EventListener> listener(new EventListener(
      event_name, extension_id, NULL, scoped_ptr<DictionaryValue>()));
  bool is_new = listeners_.AddListener(listener.Pass());

  if (is_new) {
    ExtensionPrefs* prefs = profile_->GetExtensionService()->extension_prefs();
    std::set<std::string> events = prefs->GetRegisteredEvents(extension_id);
    bool prefs_is_new = events.insert(event_name).second;
    if (prefs_is_new)
      prefs->SetRegisteredEvents(extension_id, events);
  }
}

void ExtensionEventRouter::RemoveLazyEventListener(
    const std::string& event_name,
    const std::string& extension_id) {
  EventListener listener(event_name, extension_id, NULL,
                         scoped_ptr<DictionaryValue>());
  bool did_exist = listeners_.RemoveListener(&listener);

  if (did_exist) {
    ExtensionPrefs* prefs = profile_->GetExtensionService()->extension_prefs();
    std::set<std::string> events = prefs->GetRegisteredEvents(extension_id);
    bool prefs_did_exist = events.erase(event_name) > 0;
    DCHECK(prefs_did_exist);
    prefs->SetRegisteredEvents(extension_id, events);
  }
}

void ExtensionEventRouter::AddFilteredEventListener(
    const std::string& event_name,
    content::RenderProcessHost* process,
    const std::string& extension_id,
    const base::DictionaryValue& filter,
    bool add_lazy_listener) {
  listeners_.AddListener(scoped_ptr<EventListener>(new EventListener(
      event_name, extension_id, process,
      scoped_ptr<DictionaryValue>(filter.DeepCopy()))));

  if (add_lazy_listener) {
    bool added = listeners_.AddListener(scoped_ptr<EventListener>(
        new EventListener(event_name, extension_id, NULL,
        scoped_ptr<DictionaryValue>(filter.DeepCopy()))));

    if (added) {
      ExtensionPrefs* prefs =
          profile_->GetExtensionService()->extension_prefs();
      prefs->AddFilterToEvent(event_name, extension_id, &filter);
    }
  }
}

void ExtensionEventRouter::RemoveFilteredEventListener(
    const std::string& event_name,
    content::RenderProcessHost* process,
    const std::string& extension_id,
    const base::DictionaryValue& filter,
    bool remove_lazy_listener) {
  EventListener listener(event_name, extension_id, process,
                         scoped_ptr<DictionaryValue>(filter.DeepCopy()));

  listeners_.RemoveListener(&listener);

  if (remove_lazy_listener) {
    listener.process = NULL;
    bool removed = listeners_.RemoveListener(&listener);

    if (removed) {
      ExtensionPrefs* prefs =
          profile_->GetExtensionService()->extension_prefs();
      prefs->RemoveFilterFromEvent(event_name, extension_id, &filter);
    }
  }
}

bool ExtensionEventRouter::HasEventListener(const std::string& event_name) {
  return listeners_.HasListenerForEvent(event_name);
}

bool ExtensionEventRouter::ExtensionHasEventListener(
    const std::string& extension_id, const std::string& event_name) {
  return listeners_.HasListenerForExtension(extension_id, event_name);
}

bool ExtensionEventRouter::HasEventListenerImpl(
    const ListenerMap& listener_map,
    const std::string& extension_id,
    const std::string& event_name) {
  ListenerMap::const_iterator it = listener_map.find(event_name);
  if (it == listener_map.end())
    return false;

  const std::set<ListenerProcess>& listeners = it->second;
  if (extension_id.empty())
    return !listeners.empty();

  for (std::set<ListenerProcess>::const_iterator listener = listeners.begin();
       listener != listeners.end(); ++listener) {
    if (listener->extension_id == extension_id)
      return true;
  }
  return false;
}

void ExtensionEventRouter::DispatchEventToRenderers(
    const std::string& event_name,
    const std::string& event_args,
    Profile* restrict_to_profile,
    const GURL& event_url,
    extensions::EventFilteringInfo info) {
  DCHECK(!event_args.empty());
  StringValue event_args_value(event_args);
  linked_ptr<ExtensionEvent> event(
      new ExtensionEvent(event_name, event_args_value, event_url,
                         restrict_to_profile, USER_GESTURE_UNKNOWN, info));
  DispatchEventImpl("", event);
}

void ExtensionEventRouter::DispatchEventToRenderers(
    const std::string& event_name,
    const std::string& event_args,
    Profile* restrict_to_profile,
    const GURL& event_url) {
  DispatchEventToRenderers(event_name, event_args, restrict_to_profile,
                           event_url, extensions::EventFilteringInfo());
}

void ExtensionEventRouter::DispatchEventToExtension(
    const std::string& extension_id,
    const std::string& event_name,
    const Value& event_args,
    Profile* restrict_to_profile,
    const GURL& event_url) {
  DCHECK(!extension_id.empty());
  linked_ptr<ExtensionEvent> event(
      new ExtensionEvent(event_name, event_args, event_url,
                         restrict_to_profile, USER_GESTURE_UNKNOWN,
                         EventFilteringInfo()));
  DispatchEventImpl(extension_id, event);
}

void ExtensionEventRouter::DispatchEventToExtension(
    const std::string& extension_id,
    const std::string& event_name,
    const std::string& event_args,
    Profile* restrict_to_profile,
    const GURL& event_url) {
  StringValue event_args_value(event_args);
  DispatchEventToExtension(extension_id, event_name, event_args_value,
                           restrict_to_profile, event_url);
}

void ExtensionEventRouter::DispatchEventToExtension(
    const std::string& extension_id,
    const std::string& event_name,
    const std::string& event_args,
    Profile* restrict_to_profile,
    const GURL& event_url,
    UserGestureState user_gesture) {
  DCHECK(!extension_id.empty());
  StringValue event_args_value(event_args);
  linked_ptr<ExtensionEvent> event(
      new ExtensionEvent(event_name, event_args_value, event_url,
                         restrict_to_profile, user_gesture,
                         EventFilteringInfo()));
  DispatchEventImpl(extension_id, event);
}

void ExtensionEventRouter::DispatchEventsToRenderersAcrossIncognito(
    const std::string& event_name,
    const std::string& event_args,
    Profile* restrict_to_profile,
    const std::string& cross_incognito_args,
    const GURL& event_url) {
  linked_ptr<ExtensionEvent> event(
      new ExtensionEvent(event_name, event_args, event_url,
                         restrict_to_profile, cross_incognito_args,
                         USER_GESTURE_UNKNOWN, EventFilteringInfo()));
  DispatchEventImpl("", event);
}

void ExtensionEventRouter::DispatchEventImpl(
    const std::string& restrict_to_extension_id,
    const linked_ptr<ExtensionEvent>& event) {
  // We don't expect to get events from a completely different profile.
  DCHECK(!event->restrict_to_profile ||
         profile_->IsSameProfile(event->restrict_to_profile));

  std::set<const EventListener*> listeners(
      listeners_.GetEventListeners(*event));
  for (std::set<const EventListener*>::iterator it = listeners.begin();
       it != listeners.end(); it++) {
    const EventListener* listener = *it;
    if (listener->process) {
      if (restrict_to_extension_id.empty() ||
          restrict_to_extension_id == listener->extension_id)
        DispatchEventToProcess(listener->extension_id, listener->process,
                               event);
    } else {
      DispatchLazyEvent(listener->extension_id, event);
    }
  }
}

void ExtensionEventRouter::DispatchLazyEvent(
    const std::string& extension_id,
    const linked_ptr<ExtensionEvent>& event) {
  ExtensionService* service = profile_->GetExtensionService();
  // Check both the original and the incognito profile to see if we
  // should load a lazy bg page to handle the event. The latter case
  // occurs in the case of split-mode extensions.
  const Extension* extension = service->extensions()->GetByID(extension_id);
  if (extension) {
    MaybeLoadLazyBackgroundPageToDispatchEvent(profile_, extension, event);
    if (profile_->HasOffTheRecordProfile() &&
        extension->incognito_split_mode()) {
      MaybeLoadLazyBackgroundPageToDispatchEvent(
          profile_->GetOffTheRecordProfile(), extension, event);
    }
  }
}

void ExtensionEventRouter::DispatchEventToProcess(
    const std::string& extension_id,
    content::RenderProcessHost* process,
    const linked_ptr<ExtensionEvent>& event) {
  ExtensionService* service = profile_->GetExtensionService();
  const Extension* extension = service->extensions()->GetByID(extension_id);

  // The extension could have been removed, but we do not unregister it until
  // the extension process is unloaded.
  if (!extension)
    return;

  Profile* listener_profile = Profile::FromBrowserContext(
      process->GetBrowserContext());
  extensions::ProcessMap* process_map =
      listener_profile->GetExtensionService()->process_map();
  // If the event is privileged, only send to extension processes. Otherwise,
  // it's OK to send to normal renderers (e.g., for content scripts).
  if (ExtensionAPI::GetSharedInstance()->IsPrivileged(event->event_name) &&
      !process_map->Contains(extension->id(), process->GetID())) {
    return;
  }

  const Value* event_args = NULL;
  if (!CanDispatchEventToProfile(listener_profile, extension,
                                 event, &event_args)) {
    return;
  }

  DispatchEvent(process, extension_id,
                event->event_name, *event_args,
                event->event_url, event->user_gesture,
                event->info);
  IncrementInFlightEvents(listener_profile, extension);
}

bool ExtensionEventRouter::CanDispatchEventToProfile(
    Profile* profile,
    const Extension* extension,
    const linked_ptr<ExtensionEvent>& event,
    const Value** event_args) {
  *event_args = event->event_args.get();

  // Is this event from a different profile than the renderer (ie, an
  // incognito tab event sent to a normal process, or vice versa).
  bool cross_incognito = event->restrict_to_profile &&
      profile != event->restrict_to_profile;
  if (cross_incognito &&
      !profile->GetExtensionService()->CanCrossIncognito(extension)) {
    if (!event->cross_incognito_args.get())
      return false;
    // Send the event with different arguments to extensions that can't
    // cross incognito.
    *event_args = event->cross_incognito_args.get();
  }

  return true;
}

void ExtensionEventRouter::MaybeLoadLazyBackgroundPageToDispatchEvent(
    Profile* profile,
    const Extension* extension,
    const linked_ptr<ExtensionEvent>& event) {
  const Value* event_args = NULL;
  if (!CanDispatchEventToProfile(profile, extension, event, &event_args))
    return;

  extensions::LazyBackgroundTaskQueue* queue =
      ExtensionSystem::Get(profile)->lazy_background_task_queue();
  if (queue->ShouldEnqueueTask(profile, extension)) {
    queue->AddPendingTask(
        profile, extension->id(),
        base::Bind(&ExtensionEventRouter::DispatchPendingEvent,
                   base::Unretained(this), event));
  }
}

void ExtensionEventRouter::IncrementInFlightEvents(
    Profile* profile, const Extension* extension) {
  // Only increment in-flight events if the lazy background page is active,
  // because that's the only time we'll get an ACK.
  if (extension->has_lazy_background_page()) {
    ExtensionProcessManager* pm =
        ExtensionSystem::Get(profile)->process_manager();
    ExtensionHost* host = pm->GetBackgroundHostForExtension(extension->id());
    if (host)
      pm->IncrementLazyKeepaliveCount(extension);
  }
}

void ExtensionEventRouter::OnEventAck(
    Profile* profile, const std::string& extension_id) {
  ExtensionProcessManager* pm =
      ExtensionSystem::Get(profile)->process_manager();
  ExtensionHost* host = pm->GetBackgroundHostForExtension(extension_id);
  // The event ACK is routed to the background host, so this should never be
  // NULL.
  CHECK(host);
  // TODO(mpcomplete): We should never get this message unless
  // has_lazy_background_page is true. Find out why we're getting it anyway.
  if (host->extension() && host->extension()->has_lazy_background_page())
    pm->DecrementLazyKeepaliveCount(host->extension());
}

void ExtensionEventRouter::DispatchPendingEvent(
    const linked_ptr<ExtensionEvent>& event,
    ExtensionHost* host) {
  if (!host)
    return;

  if (listeners_.HasProcessListener(host->render_process_host(),
                                    host->extension()->id()))
    DispatchEventToProcess(host->extension()->id(),
                           host->render_process_host(), event);
}

void ExtensionEventRouter::Observe(
    int type,
    const content::NotificationSource& source,
    const content::NotificationDetails& details) {
  switch (type) {
    case content::NOTIFICATION_RENDERER_PROCESS_TERMINATED:
    case content::NOTIFICATION_RENDERER_PROCESS_CLOSED: {
      content::RenderProcessHost* renderer =
          content::Source<content::RenderProcessHost>(source).ptr();
      // Remove all event listeners associated with this renderer.
      listeners_.RemoveListenersForProcess(renderer);
      break;
    }
    case chrome::NOTIFICATION_EXTENSION_LOADED: {
      // Add all registered lazy listeners to our cache.
      const Extension* extension =
          content::Details<const Extension>(details).ptr();
      ExtensionPrefs* prefs =
          profile_->GetExtensionService()->extension_prefs();
      std::set<std::string> registered_events =
          prefs->GetRegisteredEvents(extension->id());
      listeners_.LoadUnfilteredLazyListeners(extension->id(),
                                             registered_events);
      const DictionaryValue* filtered_events =
          prefs->GetFilteredEvents(extension->id());
      if (filtered_events)
        listeners_.LoadFilteredLazyListeners(extension->id(), *filtered_events);
      break;
    }
    case chrome::NOTIFICATION_EXTENSION_UNLOADED: {
      // Remove all registered lazy listeners from our cache.
      extensions::UnloadedExtensionInfo* unloaded =
          content::Details<extensions::UnloadedExtensionInfo>(details).ptr();
      listeners_.RemoveLazyListenersForExtension(unloaded->extension->id());
      break;
    }
    case chrome::NOTIFICATION_EXTENSION_INSTALLED: {
      // Dispatch the onInstalled event.
      const Extension* extension =
          content::Details<const Extension>(details).ptr();
      MessageLoop::current()->PostTask(FROM_HERE,
          base::Bind(&extensions::RuntimeEventRouter::DispatchOnInstalledEvent,
                     profile_, extension->id()));
      break;
    }
    default:
      NOTREACHED();
      return;
  }
}

ExtensionEvent::ExtensionEvent(
    const std::string& event_name,
    const Value& event_args,
    const GURL& event_url,
    Profile* restrict_to_profile,
    const Value& cross_incognito_args,
    ExtensionEventRouter::UserGestureState user_gesture,
    const extensions::EventFilteringInfo& info)
    : event_name(event_name),
      event_args(event_args.DeepCopy()),
      event_url(event_url),
      restrict_to_profile(restrict_to_profile),
      cross_incognito_args(cross_incognito_args.DeepCopy()),
      user_gesture(user_gesture),
      info(info) {
}

ExtensionEvent::ExtensionEvent(
    const std::string& event_name,
    const std::string& event_args,
    const GURL& event_url,
    Profile* restrict_to_profile,
    const std::string& cross_incognito_args,
    ExtensionEventRouter::UserGestureState user_gesture,
    const extensions::EventFilteringInfo& info)
    : event_name(event_name),
      event_args(Value::CreateStringValue(event_args)),
      event_url(event_url),
      restrict_to_profile(restrict_to_profile),
      cross_incognito_args(Value::CreateStringValue(cross_incognito_args)),
      user_gesture(user_gesture),
      info(info) {
}

ExtensionEvent::ExtensionEvent(
    const std::string& event_name,
    const Value& event_args,
    const GURL& event_url,
    Profile* restrict_to_profile,
    ExtensionEventRouter::UserGestureState user_gesture,
    const extensions::EventFilteringInfo& info)
    : event_name(event_name),
      event_args(event_args.DeepCopy()),
      event_url(event_url),
      restrict_to_profile(restrict_to_profile),
      cross_incognito_args(NULL),
      user_gesture(user_gesture),
      info(info) {
}

ExtensionEvent::~ExtensionEvent() {
}