// 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.

#ifndef UI_APP_LIST_APP_LIST_MODEL_H_
#define UI_APP_LIST_APP_LIST_MODEL_H_

#include <string>
#include <vector>

#include "base/basictypes.h"
#include "base/memory/scoped_ptr.h"
#include "base/observer_list.h"
#include "ui/app_list/app_list_export.h"
#include "ui/app_list/app_list_item_list.h"
#include "ui/app_list/app_list_item_list_observer.h"
#include "ui/app_list/search_result.h"
#include "ui/base/models/list_model.h"

namespace app_list {

class AppListFolderItem;
class AppListItem;
class AppListItemList;
class AppListModelObserver;
class SearchBoxModel;

// Master model of app list that consists of three sub models: AppListItemList,
// SearchBoxModel and SearchResults. The AppListItemList sub model owns a list
// of AppListItems and is displayed in the grid view. SearchBoxModel is
// the model for SearchBoxView. SearchResults owns a list of SearchResult.
// NOTE: Currently this class observes |top_level_item_list_|. The View code may
// move entries in the item list directly (but can not add or remove them) and
// the model needs to notify its observers when this occurs.
class APP_LIST_EXPORT AppListModel : public AppListItemListObserver {
 public:
  enum Status {
    STATUS_NORMAL,
    STATUS_SYNCING,  // Syncing apps or installing synced apps.
  };

  enum State {
    STATE_APPS,
    STATE_SEARCH_RESULTS,
    STATE_START,
    STATE_CUSTOM_LAUNCHER_PAGE,

    INVALID_STATE,
  };

  typedef ui::ListModel<SearchResult> SearchResults;

  AppListModel();
  ~AppListModel() override;

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

  void SetStatus(Status status);

  void SetState(State state);
  State state() { return state_; }

  // Finds the item matching |id|.
  AppListItem* FindItem(const std::string& id);

  // Find a folder item matching |id|.
  AppListFolderItem* FindFolderItem(const std::string& id);

  // Adds |item| to the model. The model takes ownership of |item|. Returns a
  // pointer to the item that is safe to use (e.g. after passing ownership).
  AppListItem* AddItem(scoped_ptr<AppListItem> item);

  // Adds |item| to an existing folder or creates a new folder. If |folder_id|
  // is empty, adds the item to the top level model instead. The model takes
  // ownership of |item|. Returns a pointer to the item that is safe to use.
  AppListItem* AddItemToFolder(scoped_ptr<AppListItem> item,
                               const std::string& folder_id);

  // Merges two items. If the target item is a folder, the source item is added
  // to the end of the target folder. Otherwise a new folder is created in the
  // same position as the target item with the target item as the first item in
  // the new folder and the source item as the second item. Returns the id of
  // the target folder, or an empty string if the merge failed. The source item
  // may already be in a folder. See also the comment for RemoveItemFromFolder.
  // NOTE: This should only be called by the View code (not the sync code); it
  // enforces folder restrictions (e.g. the target can not be an OEM folder).
  const std::string MergeItems(const std::string& target_item_id,
                               const std::string& source_item_id);

  // Move |item| to the folder matching |folder_id| or to the top level if
  // |folder_id| is empty. |item|->position will determine where the item
  // is positioned. See also the comment for RemoveItemFromFolder.
  void MoveItemToFolder(AppListItem* item, const std::string& folder_id);

  // Move |item| to the folder matching |folder_id| or to the top level if
  // |folder_id| is empty. The item will be inserted before |position| or at
  // the end of the list if |position| is invalid. Note: |position| is copied
  // in case it refers to the containing folder which may get deleted. See also
  // the comment for RemoveItemFromFolder. Returns true if the item was moved.
  // NOTE: This should only be called by the View code (not the sync code); it
  // enforces folder restrictions (e.g. the source folder can not be type OEM).
  bool MoveItemToFolderAt(AppListItem* item,
                          const std::string& folder_id,
                          syncer::StringOrdinal position);

  // Sets the position of |item| either in |top_level_item_list_| or the folder
  // specified by |item|->folder_id(). If |new_position| is invalid, move the
  // item to the end of the list.
  void SetItemPosition(AppListItem* item,
                       const syncer::StringOrdinal& new_position);

  // Sets the name of |item| and notifies observers.
  void SetItemName(AppListItem* item, const std::string& name);

  // Sets the name and short name of |item| and notifies observers.
  void SetItemNameAndShortName(AppListItem* item,
                               const std::string& name,
                               const std::string& short_name);

  // Deletes the item matching |id| from |top_level_item_list_| or from the
  // appropriate folder.
  void DeleteItem(const std::string& id);

  // Call OnExtensionPreferenceChanged() for all items in the model.
  void NotifyExtensionPreferenceChanged();

  // Sets whether or not the folder UI should be enabled. If |folders_enabled|
  // is false, removes any non-OEM folders.
  void SetFoldersEnabled(bool folders_enabled);

  // Sets whether or not the custom launcher page should be enabled.
  void SetCustomLauncherPageEnabled(bool enabled);
  bool custom_launcher_page_enabled() { return custom_launcher_page_enabled_; }

  // Pushes a custom launcher page's subpage into the state stack in the model.
  void PushCustomLauncherPageSubpage();

  // If the state stack is not empty, pops a subpage from the stack and returns
  // true. Returns false if the stack was empty.
  bool PopCustomLauncherPageSubpage();

  // Clears the custom launcher page's subpage state stack from the model.
  void ClearCustomLauncherPageSubpages();

  int custom_launcher_page_subpage_depth() {
    return custom_launcher_page_subpage_depth_;
  }

  // Filters the given |results| by |display_type|. The returned list is
  // truncated to |max_results|.
  static std::vector<SearchResult*> FilterSearchResultsByDisplayType(
      SearchResults* results,
      SearchResult::DisplayType display_type,
      size_t max_results);

  AppListItemList* top_level_item_list() { return top_level_item_list_.get(); }

  SearchBoxModel* search_box() { return search_box_.get(); }
  SearchResults* results() { return results_.get(); }
  Status status() const { return status_; }
  bool folders_enabled() const { return folders_enabled_; }

 private:
  // AppListItemListObserver
  void OnListItemMoved(size_t from_index,
                       size_t to_index,
                       AppListItem* item) override;

  // Returns an existing folder matching |folder_id| or creates a new folder.
  AppListFolderItem* FindOrCreateFolderItem(const std::string& folder_id);

  // Adds |item_ptr| to |top_level_item_list_| and notifies observers.
  AppListItem* AddItemToItemListAndNotify(
      scoped_ptr<AppListItem> item_ptr);

  // Adds |item_ptr| to |top_level_item_list_| and notifies observers that an
  // Update occured (e.g. item moved from a folder).
  AppListItem* AddItemToItemListAndNotifyUpdate(
      scoped_ptr<AppListItem> item_ptr);

  // Adds |item_ptr| to |folder| and notifies observers.
  AppListItem* AddItemToFolderItemAndNotify(AppListFolderItem* folder,
                                            scoped_ptr<AppListItem> item_ptr);

  // Removes |item| from |top_level_item_list_| or calls RemoveItemFromFolder if
  // |item|->folder_id is set.
  scoped_ptr<AppListItem> RemoveItem(AppListItem* item);

  // Removes |item| from |folder|. If |folder| becomes empty, deletes |folder|
  // from |top_level_item_list_|. Does NOT trigger observers, calling function
  // must do so.
  scoped_ptr<AppListItem> RemoveItemFromFolder(AppListFolderItem* folder,
                                               AppListItem* item);

  scoped_ptr<AppListItemList> top_level_item_list_;

  scoped_ptr<SearchBoxModel> search_box_;
  scoped_ptr<SearchResults> results_;

  Status status_;
  State state_;
  ObserverList<AppListModelObserver, true> observers_;
  bool folders_enabled_;
  bool custom_launcher_page_enabled_;

  // The current number of subpages the custom launcher page has pushed.
  int custom_launcher_page_subpage_depth_;

  DISALLOW_COPY_AND_ASSIGN(AppListModel);
};

}  // namespace app_list

#endif  // UI_APP_LIST_APP_LIST_MODEL_H_