// 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.

#include "third_party/blink/renderer/core/editing/editing_strategy.h"

#include "third_party/blink/renderer/core/core_export.h"
#include "third_party/blink/renderer/core/dom/text.h"
#include "third_party/blink/renderer/core/editing/editing_utilities.h"
#include "third_party/blink/renderer/core/html/html_element.h"
#include "third_party/blink/renderer/core/layout/layout_text.h"
#include "third_party/blink/renderer/core/layout/layout_text_fragment.h"

namespace blink {

namespace {

EUserSelect UsedValueOfUserSelect(const Node& node) {
  auto* html_element = DynamicTo<HTMLElement>(node);
  if (html_element && html_element->IsTextControl())
    return EUserSelect::kText;
  if (!node.GetLayoutObject())
    return EUserSelect::kNone;

  const ComputedStyle& style = node.GetLayoutObject()->StyleRef();
  if (style.UsedUserModify() != EUserModify::kReadOnly) {
    return EUserSelect::kText;
  }

  return style.UsedUserSelect();
}

}  // namespace

// If a node can contain candidates for VisiblePositions, return the offset of
// the last candidate, otherwise return the number of children for container
// nodes and the length for unrendered text nodes.
template <typename Traversal>
wtf_size_t EditingAlgorithm<Traversal>::CaretMaxOffset(const Node& node) {
  // For rendered text nodes, return the last position that a caret could
  // occupy.
  if (auto* text = DynamicTo<Text>(node); text && text->GetLayoutObject()) {
    LayoutText* layout_object = text->GetLayoutObject();

    // ::first-letter
    if (auto* first_letter_remaining_part =
            DynamicTo<LayoutTextFragment>(layout_object)) {
      return first_letter_remaining_part->Start() +
             first_letter_remaining_part->CaretMaxOffset();
    }

    return layout_object->CaretMaxOffset();
  }

  // For containers return the number of children. For others do the same as
  // above.
  return LastOffsetForEditing(&node);
}

template <typename Traversal>
wtf_size_t EditingAlgorithm<Traversal>::LastOffsetForEditing(const Node* node) {
  DCHECK(node);
  if (!node)
    return 0;
  if (auto* character_data = DynamicTo<CharacterData>(node))
    return character_data->length();

  if (Traversal::HasChildren(*node))
    return Traversal::CountChildren(*node);

  // FIXME: Try return 0 here.

  if (!EditingIgnoresContent(*node))
    return 0;

  // editingIgnoresContent uses the same logic in
  // IsEmptyNonEditableNodeInEditable (editing_utilities.cc). We don't
  // understand why this function returns 1 even when the node doesn't have
  // children.
  return 1;
}

template <typename Strategy>
Node* EditingAlgorithm<Strategy>::RootUserSelectAllForNode(Node* node) {
  if (!node || UsedValueOfUserSelect(*node) != EUserSelect::kAll)
    return nullptr;
  Node* parent = Strategy::Parent(*node);
  if (!parent)
    return node;

  Node* candidate_root = node;
  while (parent) {
    if (!parent->GetLayoutObject()) {
      parent = Strategy::Parent(*parent);
      continue;
    }
    if (UsedValueOfUserSelect(*parent) != EUserSelect::kAll)
      break;
    candidate_root = parent;
    parent = Strategy::Parent(*candidate_root);
  }
  return candidate_root;
}

template class CORE_TEMPLATE_EXPORT EditingAlgorithm<NodeTraversal>;
template class CORE_TEMPLATE_EXPORT EditingAlgorithm<FlatTreeTraversal>;

}  // namespace blink