// Copyright 2015 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_BROWSER_TAB_STRIP_TRACKER_H_
#define CHROME_BROWSER_UI_BROWSER_TAB_STRIP_TRACKER_H_

#include "base/memory/raw_ptr.h"
#include "base/scoped_observation.h"
#include "chrome/browser/ui/browser_window/public/browser_collection_observer.h"

class BrowserTabStripTrackerDelegate;
class BrowserWindowInterface;
class GlobalBrowserCollection;
class TabStripModelObserver;

// BrowserTabStripTracker attaches a TabStripModelObserver to a subset of
// pre-existing and future Browsers. The subset of Browsers that are tracked is
// determined by an optional BrowserTabStripTrackerDelegate.
//
// This class is typically not the right helper to use. Its primary purpose is
// to hook up a TabStripModelObserver across multiple TabStripModels. As per the
// documentation for TabStripModelObserver, only features that need to interact
// with the tab strip like tab groups and tab search should use
// TabStripModelObserver. Other features should use TabInterface and
// TabFeatures. Furthermore, this class mixes state across multiple
// TabStripModels. This is typically not desirable and instead features should
// hold state on a per-browser-window basis, using BrowserWindowFeatures.
class BrowserTabStripTracker : public BrowserCollectionObserver {
 public:
  // |tab_strip_model_observer| is a non-nullptr TabStripModelObserver
  // registered on tracked Browsers. |delegate| determines which Browsers are
  // tracked. If nullptr, all Browsers are tracked.
  BrowserTabStripTracker(TabStripModelObserver* tab_strip_model_observer,
                         BrowserTabStripTrackerDelegate* delegate);

  BrowserTabStripTracker(const BrowserTabStripTracker&) = delete;
  BrowserTabStripTracker& operator=(const BrowserTabStripTracker&) = delete;

  ~BrowserTabStripTracker() override;

  // Registers the TabStripModelObserver on existing tracked Browsers and starts
  // observing Browser creation to register the TabStripModelObserver on future
  // tracked Browsers. When the TabStripModelObserver is registered on an
  // existing of future Browser, OnTabStripModelChanged() is invoked to indicate
  // the initial state of the Browser. If a delegate needs to differentiate
  // between Browsers observed by way of Init() vs. a Browser added after the
  // fact use is_processing_initial_browsers().
  void Init();

  // Returns true if processing an existing Browser in Init().
  bool is_processing_initial_browsers() const {
    return is_processing_initial_browsers_;
  }

 private:
  // Returns true if a TabStripModelObserver should be added to |browser|.
  bool ShouldTrackBrowser(BrowserWindowInterface* browser);

  // If ShouldTrackBrowser() returns true for |browser| then a
  // TabStripModelObserver is attached.
  void MaybeTrackBrowser(BrowserWindowInterface* browser);

  // BrowserListObserver:
  void OnBrowserCreated(BrowserWindowInterface* browser) override;
  void OnBrowserClosed(BrowserWindowInterface* browser) override;

  raw_ptr<TabStripModelObserver> const tab_strip_model_observer_;
  raw_ptr<BrowserTabStripTrackerDelegate> const delegate_;
  bool is_processing_initial_browsers_;
  // TODO(crbug.com/495697669): remove when the BrowserTabStripTracker is no
  // longer outliving the GlobalBrowserCollection it observes.
  base::ScopedObservation<GlobalBrowserCollection,
                          BrowserCollectionObserver>::LeakedDanglingUntriaged
      browser_collection_observation_{this};
};

#endif  // CHROME_BROWSER_UI_BROWSER_TAB_STRIP_TRACKER_H_