// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CHROME_BROWSER_UI_TABS_TAB_GROUP_MODEL_H_
#define CHROME_BROWSER_UI_TABS_TAB_GROUP_MODEL_H_

#include <stddef.h>
#include <stdint.h>

#include <list>
#include <map>
#include <memory>
#include <optional>
#include <vector>

#include "base/memory/raw_ptr.h"
#include "base/types/pass_key.h"

class TabGroup;
class TabStripModel;
namespace tab_groups {
enum class TabGroupColorId;
class TabGroupId;
}  // namespace tab_groups

// A model for all tab groups with at least one tab in the tabstrip. Keeps a map
// of tab_groups::TabGroupIds and TabGroups and provides an API for maintaining
// it. It is owned and used primarily by TabStripModel, which handles
// tab-to-group correspondences and any groupedness state changes on tabs.
// TabStipModel then notifies TabStrip of any groupedness state changes that
// need to be reflected in the view.
class TabGroupModel {
 public:
  TabGroupModel();
  ~TabGroupModel();

  // Returns whether a tab group with the given `id` exists.
  bool ContainsTabGroup(const tab_groups::TabGroupId& id) const;

  // Returns the tab group with the given `id`. The group must exist.
  TabGroup* GetTabGroup(const tab_groups::TabGroupId& id) const;

  // Registers a tab group. It will initially be empty,
  // but the expectation is that at least one tab will be
  // added to it immediately.
  void AddTabGroup(TabGroup* group, base::PassKey<TabStripModel>);

  // Removes the tab group from the registry. Should be
  // called whenever the group becomes empty.
  void RemoveTabGroup(const tab_groups::TabGroupId& id,
                      base::PassKey<TabStripModel>);

  // Returns the least-used color in the color set, breaking ties toward the
  // first color in the set. Used to initialize a new group's color, which
  // should be as distinct from the other groups as possible.
  tab_groups::TabGroupColorId GetNextColor(base::PassKey<TabStripModel>) const;

  static std::vector<tab_groups::TabGroupColorId> GetColorOrdering();

  std::vector<tab_groups::TabGroupId> ListTabGroups() const;

  // Returns the TabGroupId of the group that most recently contained the active
  // tab. Returns std::nullopt if there are no groups.
  std::optional<tab_groups::TabGroupId> GetMostRecentTabGroupId() const;

  void OnTabGroupActivated(const tab_groups::TabGroupId& id,
                           base::PassKey<TabStripModel>);

 private:
  std::map<tab_groups::TabGroupId, raw_ptr<TabGroup>> groups_;

  // Used to maintain insertion order of TabGroupsIds added to the
  // TabGroupModel.
  std::vector<tab_groups::TabGroupId> group_ids_;

  // Container of groups ordered according to when they had the active tab.
  std::list<tab_groups::TabGroupId> group_ids_by_activity_;
};

#endif  // CHROME_BROWSER_UI_TABS_TAB_GROUP_MODEL_H_