// 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 "ui/views/controls/menu/menu_runner.h"

#include <set>

#include "base/metrics/histogram.h"
#include "ui/base/models/menu_model.h"
#include "ui/views/controls/button/menu_button.h"
#include "ui/views/controls/menu/menu_controller.h"
#include "ui/views/controls/menu/menu_controller_delegate.h"
#include "ui/views/controls/menu/menu_delegate.h"
#include "ui/views/controls/menu/menu_model_adapter.h"
#include "ui/views/controls/menu/submenu_view.h"
#include "ui/views/widget/widget.h"

#if defined(OS_WIN)
#include "base/win/win_util.h"
#endif

namespace views {

namespace internal {

void RecordSelectedIndexes(const MenuItemView* menu_item) {
  if (!menu_item)
    return;
  const MenuItemView* parent = menu_item->GetParentMenuItem();
  if (!parent)
    return;

  SubmenuView* submenu = parent->GetSubmenu();
  for (int i = 0; i < submenu->GetMenuItemCount(); ++i) {
    if (submenu->GetMenuItemAt(i) == menu_item) {
      UMA_HISTOGRAM_COUNTS_100("MenuSelection.Index", i);
      break;
    }
  }

  RecordSelectedIndexes(parent);
}

void RecordMenuStats(MenuItemView* result, base::TimeDelta time_elapsed) {
  // Report if user made a selection.
  UMA_HISTOGRAM_BOOLEAN("MenuSelection.Result", result != NULL);

  if (result) {
    // Report how much time it took to make a selection.
    UMA_HISTOGRAM_TIMES("MenuSelection.Time", time_elapsed);
    RecordSelectedIndexes(result);
  }
}

// Manages the menu. To destroy a MenuRunnerImpl invoke Release(). Release()
// deletes immediately if the menu isn't showing. If the menu is showing
// Release() cancels the menu and when the nested RunMenuAt() call returns
// deletes itself and the menu.
class MenuRunnerImpl : public internal::MenuControllerDelegate {
 public:
  explicit MenuRunnerImpl(MenuItemView* menu);

  MenuItemView* menu() { return menu_; }

  bool running() const { return running_; }

  // See description above class for details.
  void Release();

  // Runs the menu.
  MenuRunner::RunResult RunMenuAt(Widget* parent,
                                  MenuButton* button,
                                  const gfx::Rect& bounds,
                                  MenuItemView::AnchorPosition anchor,
                                  int32 types) WARN_UNUSED_RESULT;

  void Cancel();

  // Returns the time from the event which closed the menu - or 0.
  base::TimeDelta closing_event_time() const;

  // MenuControllerDelegate:
  virtual void DropMenuClosed(NotifyType type, MenuItemView* menu) OVERRIDE;
  virtual void SiblingMenuCreated(MenuItemView* menu) OVERRIDE;

 private:
  virtual ~MenuRunnerImpl();

  // Cleans up after the menu is no longer showing. |result| is the menu that
  // the user selected, or NULL if nothing was selected.
  MenuRunner::RunResult MenuDone(MenuItemView* result, int mouse_event_flags);

  // Returns true if mnemonics should be shown in the menu.
  bool ShouldShowMnemonics(MenuButton* button);

  // The menu. We own this. We don't use scoped_ptr as the destructor is
  // protected and we're a friend.
  MenuItemView* menu_;

  // Any sibling menus. Does not include |menu_|. We own these too.
  std::set<MenuItemView*> sibling_menus_;

  // Created and set as the delegate of the MenuItemView if Release() is
  // invoked.  This is done to make sure the delegate isn't notified after
  // Release() is invoked. We do this as we assume the delegate is no longer
  // valid if MenuRunner has been deleted.
  scoped_ptr<MenuDelegate> empty_delegate_;

  // Are we in run waiting for it to return?
  bool running_;

  // Set if |running_| and Release() has been invoked.
  bool delete_after_run_;

  // Are we running for a drop?
  bool for_drop_;

  // The controller.
  MenuController* controller_;

  // Do we own the controller?
  bool owns_controller_;

  // The timestamp of the event which closed the menu - or 0.
  base::TimeDelta closing_event_time_;

  DISALLOW_COPY_AND_ASSIGN(MenuRunnerImpl);
};

MenuRunnerImpl::MenuRunnerImpl(MenuItemView* menu)
    : menu_(menu),
      running_(false),
      delete_after_run_(false),
      for_drop_(false),
      controller_(NULL),
      owns_controller_(false),
      closing_event_time_(base::TimeDelta()) {
}

void MenuRunnerImpl::Release() {
  if (running_) {
    if (delete_after_run_)
      return;  // We already canceled.

    // The menu is running a nested message loop, we can't delete it now
    // otherwise the stack would be in a really bad state (many frames would
    // have deleted objects on them). Instead cancel the menu, when it returns
    // Holder will delete itself.
    delete_after_run_ = true;

    // Swap in a different delegate. That way we know the original MenuDelegate
    // won't be notified later on (when it's likely already been deleted).
    if (!empty_delegate_.get())
      empty_delegate_.reset(new MenuDelegate());
    menu_->set_delegate(empty_delegate_.get());

    DCHECK(controller_);
    // Release is invoked when MenuRunner is destroyed. Assume this is happening
    // because the object referencing the menu has been destroyed and the menu
    // button is no longer valid.
    controller_->Cancel(MenuController::EXIT_DESTROYED);
  } else {
    delete this;
  }
}

MenuRunner::RunResult MenuRunnerImpl::RunMenuAt(
    Widget* parent,
    MenuButton* button,
    const gfx::Rect& bounds,
    MenuItemView::AnchorPosition anchor,
    int32 types) {
  closing_event_time_ = base::TimeDelta();
  if (running_) {
    // Ignore requests to show the menu while it's already showing. MenuItemView
    // doesn't handle this very well (meaning it crashes).
    return MenuRunner::NORMAL_EXIT;
  }

  MenuController* controller = MenuController::GetActiveInstance();
  if (controller) {
    if ((types & MenuRunner::IS_NESTED) != 0) {
      if (!controller->IsBlockingRun()) {
        controller->CancelAll();
        controller = NULL;
      }
    } else {
      // There's some other menu open and we're not nested. Cancel the menu.
      controller->CancelAll();
      if ((types & MenuRunner::FOR_DROP) == 0) {
        // We can't open another menu, otherwise the message loop would become
        // twice nested. This isn't necessarily a problem, but generally isn't
        // expected.
        return MenuRunner::NORMAL_EXIT;
      }
      // Drop menus don't block the message loop, so it's ok to create a new
      // MenuController.
      controller = NULL;
    }
  }

  running_ = true;
  for_drop_ = (types & MenuRunner::FOR_DROP) != 0;
  bool has_mnemonics = (types & MenuRunner::HAS_MNEMONICS) != 0 && !for_drop_;
  owns_controller_ = false;
  if (!controller) {
    // No menus are showing, show one.
    ui::NativeTheme* theme = parent ? parent->GetNativeTheme() :
        ui::NativeTheme::instance();
    controller = new MenuController(theme, !for_drop_, this);
    owns_controller_ = true;
  }
  controller_ = controller;
  menu_->set_controller(controller_);
  menu_->PrepareForRun(owns_controller_,
                       has_mnemonics,
                       !for_drop_ && ShouldShowMnemonics(button));

  // Run the loop.
  base::TimeTicks start_time = base::TimeTicks::Now();
  int mouse_event_flags = 0;
  MenuItemView* result = controller->Run(parent, button, menu_, bounds, anchor,
                                        (types & MenuRunner::CONTEXT_MENU) != 0,
                                         &mouse_event_flags);
  // Get the time of the event which closed this menu.
  closing_event_time_ = controller->closing_event_time();
  if (for_drop_) {
    // Drop menus return immediately. We finish processing in DropMenuClosed.
    return MenuRunner::NORMAL_EXIT;
  }
  RecordMenuStats(result, base::TimeTicks::Now() - start_time);
  return MenuDone(result, mouse_event_flags);
}

void MenuRunnerImpl::Cancel() {
  if (running_)
    controller_->Cancel(MenuController::EXIT_ALL);
}

base::TimeDelta MenuRunnerImpl::closing_event_time() const {
  return closing_event_time_;
}

void MenuRunnerImpl::DropMenuClosed(NotifyType type, MenuItemView* menu) {
  MenuDone(NULL, 0);

  if (type == NOTIFY_DELEGATE && menu->GetDelegate()) {
    // Delegate is null when invoked from the destructor.
    menu->GetDelegate()->DropMenuClosed(menu);
  }
}

void MenuRunnerImpl::SiblingMenuCreated(MenuItemView* menu) {
  if (menu != menu_ && sibling_menus_.count(menu) == 0)
    sibling_menus_.insert(menu);
}

MenuRunnerImpl::~MenuRunnerImpl() {
  delete menu_;
  for (std::set<MenuItemView*>::iterator i = sibling_menus_.begin();
       i != sibling_menus_.end(); ++i)
    delete *i;
}

MenuRunner::RunResult MenuRunnerImpl::MenuDone(MenuItemView* result,
                                               int mouse_event_flags) {
  menu_->RemoveEmptyMenus();
  menu_->set_controller(NULL);

  if (owns_controller_) {
    // We created the controller and need to delete it.
    delete controller_;
    owns_controller_ = false;
  }
  controller_ = NULL;
  // Make sure all the windows we created to show the menus have been
  // destroyed.
  menu_->DestroyAllMenuHosts();
  if (delete_after_run_) {
    delete this;
    return MenuRunner::MENU_DELETED;
  }
  running_ = false;
  if (result && menu_->GetDelegate()) {
    menu_->GetDelegate()->ExecuteCommand(result->GetCommand(),
                                         mouse_event_flags);
  }
  return MenuRunner::NORMAL_EXIT;
}

bool MenuRunnerImpl::ShouldShowMnemonics(MenuButton* button) {
  // Show mnemonics if the button has focus or alt is pressed.
  bool show_mnemonics = button ? button->HasFocus() : false;
#if defined(OS_WIN)
  // This is only needed on Windows.
  if (!show_mnemonics)
    show_mnemonics = base::win::IsAltPressed();
#endif
  return show_mnemonics;
}

// In theory we could implement this every where, but for now we're only
// implementing it on aura.
#if !defined(USE_AURA)
// static
DisplayChangeListener* DisplayChangeListener::Create(Widget* widget,
                                                     MenuRunner* runner) {
  return NULL;
}
#endif

}  // namespace internal

MenuRunner::MenuRunner(ui::MenuModel* menu_model)
    : menu_model_adapter_(new MenuModelAdapter(menu_model)),
      holder_(new internal::MenuRunnerImpl(menu_model_adapter_->CreateMenu())) {
}

MenuRunner::MenuRunner(MenuItemView* menu)
    : holder_(new internal::MenuRunnerImpl(menu)) {
}

MenuRunner::~MenuRunner() {
  holder_->Release();
}

MenuItemView* MenuRunner::GetMenu() {
  return holder_->menu();
}

MenuRunner::RunResult MenuRunner::RunMenuAt(Widget* parent,
                                            MenuButton* button,
                                            const gfx::Rect& bounds,
                                            MenuItemView::AnchorPosition anchor,
                                            ui::MenuSourceType source_type,
                                            int32 types) {
  // The parent of the nested menu will have created a DisplayChangeListener, so
  // we avoid creating a DisplayChangeListener if nested. Drop menus are
  // transient, so we don't cancel in that case.
  if ((types & (IS_NESTED | FOR_DROP)) == 0 && parent) {
    display_change_listener_.reset(
        internal::DisplayChangeListener::Create(parent, this));
  }

  if (types & CONTEXT_MENU) {
    switch (source_type) {
      case ui::MENU_SOURCE_NONE:
      case ui::MENU_SOURCE_KEYBOARD:
      case ui::MENU_SOURCE_MOUSE:
        anchor = MenuItemView::TOPLEFT;
        break;
      case ui::MENU_SOURCE_TOUCH:
      case ui::MENU_SOURCE_TOUCH_EDIT_MENU:
        anchor = MenuItemView::BOTTOMCENTER;
        break;
      default:
        break;
    }
  }

  return holder_->RunMenuAt(parent, button, bounds, anchor, types);
}

bool MenuRunner::IsRunning() const {
  return holder_->running();
}

void MenuRunner::Cancel() {
  holder_->Cancel();
}

base::TimeDelta MenuRunner::closing_event_time() const {
  return holder_->closing_event_time();
}

}  // namespace views