// Copyright 2011 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ui/views/focus/external_focus_tracker.h"

#include <memory>

#include "base/check.h"
#include "ui/views/view.h"
#include "ui/views/view_tracker.h"

namespace views {

ExternalFocusTracker::ExternalFocusTracker(View* parent_view,
                                           FocusManager* focus_manager)
    : focus_manager_(focus_manager),
      parent_view_(parent_view),
      last_focused_view_tracker_(std::make_unique<ViewTracker>()) {
  DCHECK(parent_view);
  // Store the view which is focused when we're created.
  if (focus_manager_) {
    StartTracking();
  }
}

ExternalFocusTracker::~ExternalFocusTracker() {
  if (focus_manager_) {
    focus_manager_->RemoveFocusChangeListener(this);
  }
}

void ExternalFocusTracker::OnWillChangeFocus(View* focused_before,
                                             View* focused_now) {
  if (focused_now && !parent_view_->Contains(focused_now) &&
      parent_view_ != focused_now) {
    // Store the newly focused view.
    StoreLastFocusedView(focused_now);
  }
}

void ExternalFocusTracker::OnDidChangeFocus(View* focused_before,
                                            View* focused_now) {}

void ExternalFocusTracker::FocusLastFocusedExternalView() {
  View* last_focused_view = last_focused_view_tracker_->view();
  if (last_focused_view) {
    last_focused_view->RequestFocus();
  }
}

void ExternalFocusTracker::SetFocusManager(FocusManager* focus_manager) {
  if (focus_manager_) {
    focus_manager_->RemoveFocusChangeListener(this);
  }
  focus_manager_ = focus_manager;
  if (focus_manager_) {
    StartTracking();
  }
}

void ExternalFocusTracker::StoreLastFocusedView(View* view) {
  last_focused_view_tracker_->SetView(view);
}

void ExternalFocusTracker::StartTracking() {
  View* current_focused_view = focus_manager_->GetFocusedView();
  // During focus restore events, it's possible for focus to already be within
  // the parent_view_.
  if (!parent_view_->Contains(current_focused_view)) {
    StoreLastFocusedView(current_focused_view);
  }

  focus_manager_->AddFocusChangeListener(this);
}

}  // namespace views