/*
 * Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies)
 * Copyright (C) 2009 Antonio Gomes <tonikitoo@webkit.org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_PAGE_SPATIAL_NAVIGATION_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_PAGE_SPATIAL_NAVIGATION_H_

#include "third_party/blink/public/platform/web_focus_type.h"
#include "third_party/blink/renderer/core/core_export.h"
#include "third_party/blink/renderer/core/dom/node.h"
#include "third_party/blink/renderer/platform/geometry/layout_rect.h"

#include <limits>

namespace blink {

class LocalFrame;
class HTMLAreaElement;
class HTMLFrameOwnerElement;

inline double MaxDistance() {
  return std::numeric_limits<double>::max();
}

inline int FudgeFactor() {
  return 2;
}

CORE_EXPORT bool IsSpatialNavigationEnabled(const LocalFrame*);
bool SpatialNavigationIgnoresEventHandlers(const LocalFrame*);

// Spatially speaking, two given elements in a web page can be:
// 1) Fully aligned: There is a full intersection between the rects, either
//    vertically or horizontally.
//
// * Horizontally       * Vertically
//    _
//   |_|                   _ _ _ _ _ _
//   |_|...... _          |_|_|_|_|_|_|
//   |_|      |_|         .       .
//   |_|......|_|   OR    .       .
//   |_|      |_|         .       .
//   |_|......|_|          _ _ _ _
//   |_|                  |_|_|_|_|
//
//
// 2) Partially aligned: There is a partial intersection between the rects,
//    either vertically or horizontally.
//
// * Horizontally       * Vertically
//    _                   _ _ _ _ _
//   |_|                 |_|_|_|_|_|
//   |_|.... _      OR           . .
//   |_|    |_|                  . .
//   |_|....|_|                  ._._ _
//          |_|                  |_|_|_|
//          |_|
//
// 3) Or, otherwise, not aligned at all.
//
// * Horizontally       * Vertically
//         _              _ _ _ _
//        |_|            |_|_|_|_|
//        |_|                    .
//        |_|                     .
//       .          OR             .
//    _ .                           ._ _ _ _ _
//   |_|                            |_|_|_|_|_|
//   |_|
//   |_|
//
// "Totally Aligned" elements are preferable candidates to move
// focus to over "Partially Aligned" ones, that on its turns are
// more preferable than "Not Aligned".
enum RectsAlignment { kNone = 0, kPartial, kFull };

struct FocusCandidate {
  STACK_ALLOCATED();

 public:
  FocusCandidate()
      : visible_node(nullptr),
        focusable_node(nullptr),
        enclosing_scrollable_box(nullptr),
        distance(MaxDistance()),
        is_offscreen(true),
        is_offscreen_after_scrolling(true) {}

  FocusCandidate(Node*, WebFocusType);
  explicit FocusCandidate(HTMLAreaElement*, WebFocusType);
  bool IsNull() const { return !visible_node; }
  bool InScrollableContainer() const {
    return visible_node && enclosing_scrollable_box;
  }
  bool IsFrameOwnerElement() const {
    return visible_node && visible_node->IsFrameOwnerElement();
  }
  Document* GetDocument() const {
    return visible_node ? &visible_node->GetDocument() : nullptr;
  }

  // We handle differently visibleNode and FocusableNode to properly handle the
  // areas of imagemaps, where visibleNode would represent the image element and
  // focusableNode would represent the area element.  In all other cases,
  // visibleNode and focusableNode are one and the same.
  Member<Node> visible_node;
  Member<Node> focusable_node;
  Member<Node> enclosing_scrollable_box;
  double distance;
  LayoutRect rect_in_root_frame;
  bool is_offscreen;
  bool is_offscreen_after_scrolling;
};

bool HasOffscreenRect(const Node*, WebFocusType = kWebFocusTypeNone);
bool ScrollInDirection(LocalFrame*, WebFocusType);
bool ScrollInDirection(Node* container, WebFocusType);
bool IsNavigableContainer(const Node*, WebFocusType);
CORE_EXPORT bool IsScrollableAreaOrDocument(const Node*);
CORE_EXPORT Node* ScrollableAreaOrDocumentOf(Node*);
bool CanScrollInDirection(const Node* container, WebFocusType);
bool CanScrollInDirection(const LocalFrame*, WebFocusType);
bool CanBeScrolledIntoView(WebFocusType, const FocusCandidate&);
bool AreElementsOnSameLine(const FocusCandidate& first_candidate,
                           const FocusCandidate& second_candidate);
void DistanceDataForNode(WebFocusType,
                         const FocusCandidate& current,
                         FocusCandidate&);
LayoutRect NodeRectInRootFrame(const Node*, bool ignore_border = false);
LayoutRect VirtualRectForDirection(WebFocusType,
                                   const LayoutRect& starting_rect,
                                   LayoutUnit width = LayoutUnit());
LayoutRect VirtualRectForAreaElementAndDirection(const HTMLAreaElement&,
                                                 WebFocusType);
HTMLFrameOwnerElement* FrameOwnerElement(FocusCandidate&);
LayoutRect FindSearchStartPoint(const LocalFrame*, WebFocusType);

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_PAGE_SPATIAL_NAVIGATION_H_