// Copyright 2014 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 "athena/content/app_activity_registry.h"

#include "athena/activity/public/activity_manager.h"
#include "athena/content/app_activity.h"
#include "athena/content/app_activity_proxy.h"
#include "athena/content/public/app_registry.h"
#include "athena/extensions/public/extensions_delegate.h"
#include "athena/resource_manager/public/resource_manager.h"
#include "athena/wm/public/window_list_provider.h"
#include "athena/wm/public/window_manager.h"
#include "base/bind.h"
#include "base/location.h"
#include "base/single_thread_task_runner.h"
#include "base/thread_task_runner_handle.h"
#include "ui/aura/window.h"
#include "ui/views/view.h"
#include "ui/views/widget/widget.h"

namespace athena {

AppActivityRegistry::AppActivityRegistry(
    const std::string& app_id,
    content::BrowserContext* browser_context) :
      app_id_(app_id),
      browser_context_(browser_context),
      unloaded_activity_proxy_(NULL) {}

AppActivityRegistry::~AppActivityRegistry() {
  CHECK(activity_list_.empty());
  if (unloaded_activity_proxy_)
    ActivityManager::Get()->RemoveActivity(unloaded_activity_proxy_);
  DCHECK(!unloaded_activity_proxy_);
}

void AppActivityRegistry::RegisterAppActivity(AppActivity* app_activity) {
  // The same window should never be added twice.
  CHECK(std::find(activity_list_.begin(),
                  activity_list_.end(),
                  app_activity) == activity_list_.end());
  activity_list_.push_back(app_activity);
}

void AppActivityRegistry::UnregisterAppActivity(AppActivity* app_activity) {
  // It is possible that a detach gets called without ever being attached.
  std::vector<AppActivity*>::iterator it =
      std::find(activity_list_.begin(), activity_list_.end(), app_activity);
  if (it == activity_list_.end())
    return;

  activity_list_.erase(it);
  // When the last window gets destroyed and there is no proxy to restart, we
  // delete ourselves.
  if (activity_list_.empty() && !unloaded_activity_proxy_) {
    AppRegistry::Get()->RemoveAppActivityRegistry(this);
    // after this call this object should be gone.
  }
}

AppActivity* AppActivityRegistry::GetAppActivityAt(size_t index) {
  if (index >= activity_list_.size())
    return NULL;
  return activity_list_[index];
}

void AppActivityRegistry::Unload() {
  CHECK(!unloaded_activity_proxy_);
  DCHECK(!activity_list_.empty());
  // In order to allow an entire application to unload we require that all of
  // its activities are marked as unloaded.
  for (std::vector<AppActivity*>::iterator it = activity_list_.begin();
       it != activity_list_.end(); ++it) {
    if ((*it)->GetCurrentState() != Activity::ACTIVITY_UNLOADED)
      return;
  }

  // Create an activity proxy which can be used to re-activate the app. Insert
  // the proxy then into the activity stream at the location of the (newest)
  // current activity.
  unloaded_activity_proxy_ = new AppActivityProxy(GetMruActivity(), this);
  ActivityManager::Get()->AddActivity(unloaded_activity_proxy_);

  // This function can be called through an observer call. When that happens,
  // several activities will be closed / started. That can then cause a crash.
  // We postpone therefore the activity destruction till after the observer is
  // done.
  base::ThreadTaskRunnerHandle::Get()->PostTask(
      FROM_HERE,
      base::Bind(&AppActivityRegistry::DelayedUnload, base::Unretained(this)));
}

void AppActivityRegistry::ProxyDestroyed(AppActivityProxy* proxy) {
  DCHECK_EQ(unloaded_activity_proxy_, proxy);
  unloaded_activity_proxy_ = NULL;
  if (activity_list_.empty()) {
    AppRegistry::Get()->RemoveAppActivityRegistry(this);
    // |This| is gone now.
  }
}

void AppActivityRegistry::RestartApplication(AppActivityProxy* proxy) {
  DCHECK_EQ(unloaded_activity_proxy_, proxy);
  // Restart the application. Note that the first created app window will make
  // sure that the proxy gets deleted - after - the new activity got moved
  // to the proxies activity location.
  ExtensionsDelegate::Get(browser_context_)->LaunchApp(app_id_);
}

void AppActivityRegistry::DelayedUnload() {
  if (!ExtensionsDelegate::Get(browser_context_)->UnloadApp(app_id_)) {
    while(!activity_list_.empty())
      Activity::Delete(activity_list_.back());
  }
}

AppActivity* AppActivityRegistry::GetMruActivity() {
  DCHECK(activity_list_.size());
  WindowListProvider* window_list_provider =
      WindowManager::Get()->GetWindowListProvider();
  const aura::Window::Windows& children =
      window_list_provider->GetWindowList();
  // Find the first window in the container which is part of the application.
  for (aura::Window::Windows::const_iterator child_iterator = children.begin();
      child_iterator != children.end(); ++child_iterator) {
    for (std::vector<AppActivity*>::iterator app_iterator =
             activity_list_.begin();
         app_iterator != activity_list_.end(); ++app_iterator) {
      if (*child_iterator == (*app_iterator)->GetWindow())
        return *app_iterator;
    }
  }
  NOTREACHED() << "The application does not get tracked by the mru list";
  return NULL;
}

}  // namespace athena