// Copyright (c) 2010 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 CHROME_BROWSER_TABS_TAB_STRIP_MODEL_ORDER_CONTROLLER_H_
#define CHROME_BROWSER_TABS_TAB_STRIP_MODEL_ORDER_CONTROLLER_H_
#pragma once

#include "chrome/browser/tabs/tab_strip_model.h"
#include "chrome/common/page_transition_types.h"

class TabContents;

///////////////////////////////////////////////////////////////////////////////
// TabStripModelOrderController
//
//  An object that allows different types of ordering and reselection to be
//  heuristics plugged into a TabStripModel.
//
class TabStripModelOrderController : public TabStripModelObserver {
 public:
  explicit TabStripModelOrderController(TabStripModel* tabstrip);
  virtual ~TabStripModelOrderController();

  // Sets the insertion policy. Default is INSERT_AFTER.
  void set_insertion_policy(TabStripModel::InsertionPolicy policy) {
    insertion_policy_ = policy;
  }
  TabStripModel::InsertionPolicy insertion_policy() const {
    return insertion_policy_;
  }

  // Determine where to place a newly opened tab by using the supplied
  // transition and foreground flag to figure out how it was opened.
  int DetermineInsertionIndex(TabContents* new_contents,
                              PageTransition::Type transition,
                              bool foreground);

  // Returns the index to append tabs at.
  int DetermineInsertionIndexForAppending();

  // Determine where to shift selection after a tab is closed is made phantom.
  // If |is_remove| is false, the tab is not being removed but rather made
  // phantom (see description of phantom tabs in TabStripModel).
  int DetermineNewSelectedIndex(int removed_index,
                                bool is_remove) const;

  // Overridden from TabStripModelObserver:
  virtual void TabSelectedAt(TabContents* old_contents,
                             TabContents* new_contents,
                             int index,
                             bool user_gesture);

 private:
  // Returns a valid index to be selected after the tab at |removing_index| is
  // closed. If |index| is after |removing_index| and |is_remove| is true,
  // |index| is adjusted to reflect the fact that |removing_index| is going
  // away. This also skips any phantom tabs.
  int GetValidIndex(int index, int removing_index, bool is_remove) const;

  TabStripModel* tabstrip_;

  TabStripModel::InsertionPolicy insertion_policy_;

  DISALLOW_COPY_AND_ASSIGN(TabStripModelOrderController);
};

#endif  // CHROME_BROWSER_TABS_TAB_STRIP_MODEL_ORDER_CONTROLLER_H_