// 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.

#ifndef UI_APP_LIST_FOLDER_IMAGE_H_
#define UI_APP_LIST_FOLDER_IMAGE_H_

#include <vector>

#include "base/observer_list.h"
#include "ui/app_list/app_list_export.h"
#include "ui/app_list/app_list_item_list_observer.h"
#include "ui/app_list/app_list_item_observer.h"
#include "ui/gfx/image/image_skia.h"

namespace gfx {
class Rect;
}

namespace app_list {

class AppListItem;
class AppListItemList;

class APP_LIST_EXPORT FolderImageObserver {
 public:
  // Called when the folder icon has changed.
  virtual void OnFolderImageUpdated() {}

 protected:
  virtual ~FolderImageObserver() {}
};

// The icon for an app list folder, dynamically generated by drawing the
// folder's items inside a circle. Automatically keeps itself up to date, and
// notifies observers when it changes.
class APP_LIST_EXPORT FolderImage : public AppListItemListObserver,
                                    public AppListItemObserver {
 public:
  explicit FolderImage(AppListItemList* item_list);
  ~FolderImage() override;

  // Generates the folder's icon from the icons of the items in the item list,
  // and notifies observers that the icon has changed.
  void UpdateIcon();

  const gfx::ImageSkia& icon() const { return icon_; }

  // Returns the icon of one of the top items with |item_index|.
  const gfx::ImageSkia& GetTopIcon(size_t item_index);

  // Calculates the top item icons' bounds inside |folder_icon_bounds|.
  // Returns the bounds of top item icons in sequence of top left, top right,
  // bottom left, bottom right.
  static std::vector<gfx::Rect> GetTopIconsBounds(
      const gfx::Rect& folder_icon_bounds);

  // Returns the target icon bounds for |item| to fly back to its parent folder
  // icon in animation UI. If |item| is one of the top item icon, this will
  // match its corresponding top item icon in the folder icon. Otherwise,
  // the target icon bounds is centered at the |folder_icon_bounds| with
  // the same size of the top item icon.
  // The Rect returned is in the same coordinates of |folder_icon_bounds|.
  gfx::Rect GetTargetIconRectInFolderForItem(
      AppListItem* item,
      const gfx::Rect& folder_icon_bounds);

  void AddObserver(FolderImageObserver* observer);
  void RemoveObserver(FolderImageObserver* observer);

  // AppListItemObserver overrides:
  void ItemIconChanged() override;

  // AppListItemListObserver overrides:
  void OnListItemAdded(size_t index, AppListItem* item) override;
  void OnListItemRemoved(size_t index, AppListItem* item) override;
  void OnListItemMoved(size_t from_index,
                       size_t to_index,
                       AppListItem* item) override;

 private:
  // Updates the folder's icon from the icons of |top_items_| and calls
  // OnFolderImageUpdated. Does not refresh the |top_items_| list, so should
  // only be called if the |item_list_| has not been changed (see UpdateIcon).
  void RedrawIconAndNotify();

  // The icon image.
  gfx::ImageSkia icon_;

  // List of top-level app list items (to display small in the icon).
  AppListItemList* item_list_;

  // Top items for generating folder icon.
  std::vector<AppListItem*> top_items_;

  ObserverList<FolderImageObserver> observers_;
};

}  // namespace app_list

#endif  // UI_APP_LIST_FOLDER_IMAGE_H_