/*
 * (C) 1999 Lars Knoll (knoll@kde.org)
 * (C) 2000 Gunnstein Lye (gunnstein@netcom.no)
 * (C) 2000 Frederik Holljen (frederik.holljen@hig.no)
 * (C) 2001 Peter Kelly (pmk@post.com)
 * Copyright (C) 2004-2020 Apple Inc. All rights reserved.
 * Copyright (C) 2011 Motorola Mobility. All rights reserved.
 *
 * 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.
 */

#include "config.h"
#include "Range.h"

#include "Comment.h"
#include "DOMRect.h"
#include "DOMRectList.h"
#include "DocumentFragment.h"
#include "ElementInlines.h"
#include "Event.h"
#include "Frame.h"
#include "FrameSelection.h"
#include "FrameView.h"
#include "GeometryUtilities.h"
#include "HTMLBodyElement.h"
#include "HTMLHtmlElement.h"
#include "HTMLNames.h"
#include "JSNode.h"
#include "NodeTraversal.h"
#include "NodeWithIndex.h"
#include "ProcessingInstruction.h"
#include "ScopedEventQueue.h"
#include "TextIterator.h"
#include "VisibleUnits.h"
#include "markup.h"
#include <stdio.h>
#include <wtf/IsoMallocInlines.h>
#include <wtf/RefCountedLeakCounter.h>
#include <wtf/text/CString.h>
#include <wtf/text/StringBuilder.h>

namespace WebCore {

using namespace HTMLNames;

DEFINE_DEBUG_ONLY_GLOBAL(WTF::RefCountedLeakCounter, rangeCounter, ("Range"));

enum ContentsProcessDirection { ProcessContentsForward, ProcessContentsBackward };

static ExceptionOr<void> processNodes(Range::ActionType, Vector<Ref<Node>>&, Node* oldContainer, RefPtr<Node> newContainer);
static ExceptionOr<RefPtr<Node>> processContentsBetweenOffsets(Range::ActionType, RefPtr<DocumentFragment>, RefPtr<Node> container, unsigned startOffset, unsigned endOffset);
static ExceptionOr<RefPtr<Node>> processAncestorsAndTheirSiblings(Range::ActionType, Node* container, ContentsProcessDirection, ExceptionOr<RefPtr<Node>>&& passedClonedContainer, Node* commonRoot);

WTF_MAKE_ISO_ALLOCATED_IMPL(Range);

inline Range::Range(Document& ownerDocument)
    : m_ownerDocument(ownerDocument)
    , m_start(ownerDocument)
    , m_end(ownerDocument)
{
#ifndef NDEBUG
    rangeCounter.increment();
#endif

    m_ownerDocument->attachRange(*this);
}

Ref<Range> Range::create(Document& ownerDocument)
{
    return adoptRef(*new Range(ownerDocument));
}

Range::~Range()
{
    ASSERT(!m_isAssociatedWithSelection);

    m_ownerDocument->detachRange(*this);

#ifndef NDEBUG
    rangeCounter.decrement();
#endif
}

Node* Range::commonAncestorContainer() const
{
    return commonInclusiveAncestor(startContainer(), endContainer());
}

void Range::updateAssociatedSelection()
{
    if (m_isAssociatedWithSelection)
        m_ownerDocument->selection().updateFromAssociatedLiveRange();
}

void Range::updateDocument()
{
    auto& document = startContainer().document();
    if (m_ownerDocument.ptr() == &document)
        return;
    ASSERT(!m_isAssociatedWithSelection);
    m_ownerDocument->detachRange(*this);
    m_ownerDocument = document;
    m_ownerDocument->attachRange(*this);
}

ExceptionOr<void> Range::setStart(Ref<Node>&& container, unsigned offset)
{
    auto childNode = checkNodeOffsetPair(container, offset);
    if (childNode.hasException())
        return childNode.releaseException();

    m_start.set(WTFMove(container), offset, childNode.releaseReturnValue());
    if (!is_lteq(treeOrder(makeBoundaryPoint(m_start), makeBoundaryPoint(m_end))))
        m_end = m_start;
    updateAssociatedSelection();
    updateDocument();
    return { };
}

ExceptionOr<void> Range::setEnd(Ref<Node>&& container, unsigned offset)
{
    auto childNode = checkNodeOffsetPair(container, offset);
    if (childNode.hasException())
        return childNode.releaseException();

    m_end.set(WTFMove(container), offset, childNode.releaseReturnValue());
    if (!is_lteq(treeOrder(makeBoundaryPoint(m_start), makeBoundaryPoint(m_end))))
        m_start = m_end;
    updateAssociatedSelection();
    updateDocument();
    return { };
}

void Range::collapse(bool toStart)
{
    if (toStart)
        m_end = m_start;
    else
        m_start = m_end;
    updateAssociatedSelection();
}

ExceptionOr<bool> Range::isPointInRange(Node& container, unsigned offset)
{
    if (auto checkResult = checkNodeOffsetPair(container, offset); checkResult.hasException()) {
        // DOM specification requires this check be done first but since there are no side effects,
        // we can do it in reverse order to avoid an extra root node check in the common case.
        if (&container.rootNode() != &startContainer().rootNode())
            return false;
        return checkResult.releaseException();
    }
    return contains(makeSimpleRange(*this), { container, offset });
}

ExceptionOr<short> Range::comparePoint(Node& container, unsigned offset) const
{
    if (auto checkResult = checkNodeOffsetPair(container, offset); checkResult.hasException()) {
        // DOM specification requires this check be done first but since there are no side effects,
        // we can do it in reverse order to avoid an extra root node check in the common case.
        if (&container.rootNode() != &startContainer().rootNode())
            return Exception { WrongDocumentError };
        return checkResult.releaseException();
    }
    auto ordering = treeOrder({ container, offset }, makeSimpleRange(*this));
    if (is_lt(ordering))
        return -1;
    if (is_eq(ordering))
        return 0;
    if (is_gt(ordering))
        return 1;
    return Exception { WrongDocumentError };
}

ExceptionOr<Range::CompareResults> Range::compareNode(Node& node) const
{
    // FIXME: This deprecated function should be removed.
    // We originally added it for interoperability with Firefox.
    // Recent versions of Firefox have removed it.

    // http://developer.mozilla.org/en/docs/DOM:range.compareNode
    // This method returns 0, 1, 2, or 3 based on if the node is before, after,
    // before and after(surrounds), or inside the range, respectively.

    if (!node.isConnected() || &node.document() != m_ownerDocument.ptr()) {
        // Match historical Firefox behavior.
        return NODE_BEFORE;
    }

    auto nodeRange = makeRangeSelectingNode(node);
    if (!nodeRange) {
        // Match historical Firefox behavior.
        return Exception { NotFoundError };
    }

    auto startOrdering = treeOrder(nodeRange->start, makeBoundaryPoint(m_start));
    auto endOrdering = treeOrder(nodeRange->end, makeBoundaryPoint(m_end));
    if (is_gteq(startOrdering) && is_lteq(endOrdering))
        return NODE_INSIDE;
    if (is_lteq(startOrdering) && is_gteq(endOrdering))
        return NODE_BEFORE_AND_AFTER;
    if (is_lteq(startOrdering))
        return NODE_BEFORE;
    if (is_gteq(endOrdering))
        return NODE_AFTER;
    return Exception { WrongDocumentError };
}

ExceptionOr<short> Range::compareBoundaryPoints(unsigned short how, const Range& sourceRange) const
{
    const RangeBoundaryPoint* thisPoint;
    const RangeBoundaryPoint* otherPoint;
    switch (how) {
    case START_TO_START:
        thisPoint = &m_start;
        otherPoint = &sourceRange.m_start;
        break;
    case START_TO_END:
        thisPoint = &m_end;
        otherPoint = &sourceRange.m_start;
        break;
    case END_TO_END:
        thisPoint = &m_end;
        otherPoint = &sourceRange.m_end;
        break;
    case END_TO_START:
        thisPoint = &m_start;
        otherPoint = &sourceRange.m_end;
        break;
    default:
        return Exception { NotSupportedError };
    }
    auto ordering = treeOrder(makeBoundaryPoint(*thisPoint), makeBoundaryPoint(*otherPoint));
    if (is_lt(ordering))
        return -1;
    if (is_eq(ordering))
        return 0;
    if (is_gt(ordering))
        return 1;
    return Exception { WrongDocumentError };
}

ExceptionOr<void> Range::deleteContents()
{
    auto result = processContents(Delete);
    if (result.hasException())
        return result.releaseException();
    return { };
}

bool Range::intersectsNode(Node& node) const
{
    return intersects(makeSimpleRange(*this), node);
}

static inline Node* highestAncestorUnderCommonRoot(Node* node, Node* commonRoot)
{
    if (node == commonRoot)
        return 0;

    ASSERT(commonRoot->contains(node));

    while (node->parentNode() != commonRoot)
        node = node->parentNode();

    return node;
}

static inline Node* childOfCommonRootBeforeOffset(Node* container, unsigned offset, Node* commonRoot)
{
    ASSERT(container);
    ASSERT(commonRoot);
    
    if (!commonRoot->contains(container))
        return 0;

    if (container == commonRoot) {
        container = container->firstChild();
        for (unsigned i = 0; container && i < offset; i++)
            container = container->nextSibling();
    } else {
        while (container->parentNode() != commonRoot)
            container = container->parentNode();
    }

    return container;
}

ExceptionOr<RefPtr<DocumentFragment>> Range::processContents(ActionType action)
{
    RefPtr<DocumentFragment> fragment;
    if (action == Extract || action == Clone)
        fragment = DocumentFragment::create(m_ownerDocument);

    if (collapsed())
        return fragment;

    RefPtr<Node> commonRoot = commonAncestorContainer();
    ASSERT(commonRoot);

    if (&startContainer() == &endContainer()) {
        auto result = processContentsBetweenOffsets(action, fragment, &startContainer(), m_start.offset(), m_end.offset());
        if (result.hasException())
            return result.releaseException();
        return fragment;
    }

    // Since mutation events can modify the range during the process, the boundary points need to be saved.
    RangeBoundaryPoint originalStart(m_start);
    RangeBoundaryPoint originalEnd(m_end);

    // what is the highest node that partially selects the start / end of the range?
    RefPtr<Node> partialStart = highestAncestorUnderCommonRoot(&originalStart.container(), commonRoot.get());
    RefPtr<Node> partialEnd = highestAncestorUnderCommonRoot(&originalEnd.container(), commonRoot.get());

    // Start and end containers are different.
    // There are three possibilities here:
    // 1. Start container == commonRoot (End container must be a descendant)
    // 2. End container == commonRoot (Start container must be a descendant)
    // 3. Neither is commonRoot, they are both descendants
    //
    // In case 3, we grab everything after the start (up until a direct child
    // of commonRoot) into leftContents, and everything before the end (up until
    // a direct child of commonRoot) into rightContents. Then we process all
    // commonRoot children between leftContents and rightContents
    //
    // In case 1 or 2, we skip either processing of leftContents or rightContents,
    // in which case the last lot of nodes either goes from the first or last
    // child of commonRoot.
    //
    // These are deleted, cloned, or extracted (i.e. both) depending on action.

    // Note that we are verifying that our common root hierarchy is still intact
    // after any DOM mutation event, at various stages below. See webkit bug 60350.

    RefPtr<Node> leftContents;
    if (&originalStart.container() != commonRoot && commonRoot->contains(&originalStart.container())) {
        auto firstResult = processContentsBetweenOffsets(action, nullptr, &originalStart.container(), originalStart.offset(), originalStart.container().length());
        auto secondResult = processAncestorsAndTheirSiblings(action, &originalStart.container(), ProcessContentsForward, WTFMove(firstResult), commonRoot.get());
        // FIXME: A bit peculiar that we silently ignore the exception here, but we do have at least some regression tests that rely on this behavior.
        if (!secondResult.hasException())
            leftContents = secondResult.releaseReturnValue();
    }

    RefPtr<Node> rightContents;
    if (&endContainer() != commonRoot && commonRoot->contains(&originalEnd.container())) {
        auto firstResult = processContentsBetweenOffsets(action, nullptr, &originalEnd.container(), 0, originalEnd.offset());
        auto secondResult = processAncestorsAndTheirSiblings(action, &originalEnd.container(), ProcessContentsBackward, WTFMove(firstResult), commonRoot.get());
        // FIXME: A bit peculiar that we silently ignore the exception here, but we do have at least some regression tests that rely on this behavior.
        if (!secondResult.hasException())
            rightContents = secondResult.releaseReturnValue();
    }

    // delete all children of commonRoot between the start and end container
    RefPtr<Node> processStart = childOfCommonRootBeforeOffset(&originalStart.container(), originalStart.offset(), commonRoot.get());
    if (processStart && &originalStart.container() != commonRoot) // processStart contains nodes before m_start.
        processStart = processStart->nextSibling();
    RefPtr<Node> processEnd = childOfCommonRootBeforeOffset(&originalEnd.container(), originalEnd.offset(), commonRoot.get());

    // Collapse the range, making sure that the result is not within a node that was partially selected.
    if (action == Extract || action == Delete) {
        if (partialStart && commonRoot->contains(partialStart.get())) {
            auto result = setStart(*partialStart->parentNode(), partialStart->computeNodeIndex() + 1);
            if (result.hasException())
                return result.releaseException();
        } else if (partialEnd && commonRoot->contains(partialEnd.get())) {
            auto result = setStart(*partialEnd->parentNode(), partialEnd->computeNodeIndex());
            if (result.hasException())
                return result.releaseException();
        }
        collapse(true);
    }

    // Now add leftContents, stuff in between, and rightContents to the fragment
    // (or just delete the stuff in between)

    if ((action == Extract || action == Clone) && leftContents) {
        auto result = fragment->appendChild(*leftContents);
        if (result.hasException())
            return result.releaseException();
    }

    if (processStart) {
        Vector<Ref<Node>> nodes;
        for (Node* node = processStart.get(); node && node != processEnd; node = node->nextSibling())
            nodes.append(*node);
        auto result = processNodes(action, nodes, commonRoot.get(), fragment.get());
        if (result.hasException())
            return result.releaseException();
    }

    if ((action == Extract || action == Clone) && rightContents) {
        auto result = fragment->appendChild(*rightContents);
        if (result.hasException())
            return result.releaseException();
    }

    return fragment;
}

static inline ExceptionOr<void> deleteCharacterData(CharacterData& data, unsigned startOffset, unsigned endOffset)
{
    if (data.length() - endOffset) {
        auto result = data.deleteData(endOffset, data.length() - endOffset);
        if (result.hasException())
            return result.releaseException();
    }
    if (startOffset) {
        auto result = data.deleteData(0, startOffset);
        if (result.hasException())
            return result.releaseException();
    }
    return { };
}

static ExceptionOr<RefPtr<Node>> processContentsBetweenOffsets(Range::ActionType action, RefPtr<DocumentFragment> fragment, RefPtr<Node> container, unsigned startOffset, unsigned endOffset)
{
    ASSERT(container);
    ASSERT(startOffset <= endOffset);

    RefPtr<Node> result;

    switch (container->nodeType()) {
    case Node::TEXT_NODE:
    case Node::CDATA_SECTION_NODE:
    case Node::COMMENT_NODE:
        endOffset = std::min(endOffset, downcast<CharacterData>(*container).length());
        startOffset = std::min(startOffset, endOffset);
        if (action == Range::Extract || action == Range::Clone) {
            Ref<CharacterData> characters = downcast<CharacterData>(container->cloneNode(true).get());
            auto deleteResult = deleteCharacterData(characters, startOffset, endOffset);
            if (deleteResult.hasException())
                return deleteResult.releaseException();
            if (fragment) {
                result = fragment;
                auto appendResult = result->appendChild(characters);
                if (appendResult.hasException())
                    return appendResult.releaseException();
            } else
                result = WTFMove(characters);
        }
        if (action == Range::Extract || action == Range::Delete) {
            auto deleteResult = downcast<CharacterData>(*container).deleteData(startOffset, endOffset - startOffset);
            if (deleteResult.hasException())
                return deleteResult.releaseException();
        }
        break;
    case Node::PROCESSING_INSTRUCTION_NODE: {
        auto& instruction = downcast<ProcessingInstruction>(*container);
        endOffset = std::min(endOffset, downcast<ProcessingInstruction>(*container).data().length());
        startOffset = std::min(startOffset, endOffset);
        if (action == Range::Extract || action == Range::Clone) {
            Ref<ProcessingInstruction> processingInstruction = downcast<ProcessingInstruction>(container->cloneNode(true).get());
            processingInstruction->setData(processingInstruction->data().substring(startOffset, endOffset - startOffset));
            if (fragment) {
                result = fragment;
                auto appendResult = result->appendChild(processingInstruction);
                if (appendResult.hasException())
                    return appendResult.releaseException();
            } else
                result = WTFMove(processingInstruction);
        }
        if (action == Range::Extract || action == Range::Delete) {
            auto data = makeStringByRemoving(instruction.data(), startOffset, endOffset - startOffset);
            instruction.setData(WTFMove(data));
        }
        break;
    }
    case Node::ELEMENT_NODE:
    case Node::ATTRIBUTE_NODE:
    case Node::DOCUMENT_NODE:
    case Node::DOCUMENT_TYPE_NODE:
    case Node::DOCUMENT_FRAGMENT_NODE:
        // FIXME: Should we assert that some nodes never appear here?
        if (action == Range::Extract || action == Range::Clone) {
            if (fragment)
                result = fragment;
            else
                result = container->cloneNode(false);
        }
        Vector<Ref<Node>> nodes;
        Node* n = container->firstChild();
        for (unsigned i = startOffset; n && i; i--)
            n = n->nextSibling();
        for (unsigned i = startOffset; n && i < endOffset; i++, n = n->nextSibling()) {
            if (action != Range::Delete && n->isDocumentTypeNode()) {
                return Exception { HierarchyRequestError };
            }
            nodes.append(*n);
        }
        auto processResult = processNodes(action, nodes, container.get(), result);
        if (processResult.hasException())
            return processResult.releaseException();
        break;
    }

    return result;
}

static ExceptionOr<void> processNodes(Range::ActionType action, Vector<Ref<Node>>& nodes, Node* oldContainer, RefPtr<Node> newContainer)
{
    for (auto& node : nodes) {
        switch (action) {
        case Range::Delete: {
            auto result = oldContainer->removeChild(node);
            if (result.hasException())
                return result.releaseException();
            break;
        }
        case Range::Extract: {
            auto result = newContainer->appendChild(node); // will remove node from its parent
            if (result.hasException())
                return result.releaseException();
            break;
        }
        case Range::Clone: {
            auto result = newContainer->appendChild(node->cloneNode(true));
            if (result.hasException())
                return result.releaseException();
            break;
        }
        }
    }
    return { };
}

ExceptionOr<RefPtr<Node>> processAncestorsAndTheirSiblings(Range::ActionType action, Node* container, ContentsProcessDirection direction, ExceptionOr<RefPtr<Node>>&& passedClonedContainer, Node* commonRoot)
{
    if (passedClonedContainer.hasException())
        return WTFMove(passedClonedContainer);

    RefPtr<Node> clonedContainer = passedClonedContainer.releaseReturnValue();

    Vector<Ref<ContainerNode>> ancestors;
    for (ContainerNode* ancestor = container->parentNode(); ancestor && ancestor != commonRoot; ancestor = ancestor->parentNode())
        ancestors.append(*ancestor);

    RefPtr<Node> firstChildInAncestorToProcess = direction == ProcessContentsForward ? container->nextSibling() : container->previousSibling();
    for (auto& ancestor : ancestors) {
        if (action == Range::Extract || action == Range::Clone) {
            auto clonedAncestor = ancestor->cloneNode(false); // Might have been removed already during mutation event.
            if (clonedContainer) {
                auto result = clonedAncestor->appendChild(*clonedContainer);
                if (result.hasException())
                    return result.releaseException();
            }
            clonedContainer = WTFMove(clonedAncestor);
        }

        // Copy siblings of an ancestor of start/end containers
        // FIXME: This assertion may fail if DOM is modified during mutation event
        // FIXME: Share code with Range::processNodes
        ASSERT(!firstChildInAncestorToProcess || firstChildInAncestorToProcess->parentNode() == ancestor.ptr());
        
        Vector<Ref<Node>> nodes;
        for (Node* child = firstChildInAncestorToProcess.get(); child;
            child = (direction == ProcessContentsForward) ? child->nextSibling() : child->previousSibling())
            nodes.append(*child);

        for (auto& child : nodes) {
            switch (action) {
            case Range::Delete: {
                auto result = ancestor->removeChild(child);
                if (result.hasException())
                    return result.releaseException();
                break;
            }
            case Range::Extract: // will remove child from ancestor
                if (direction == ProcessContentsForward) {
                    auto result = clonedContainer->appendChild(child);
                    if (result.hasException())
                        return result.releaseException();
                } else {
                    auto result = clonedContainer->insertBefore(child, clonedContainer->firstChild());
                    if (result.hasException())
                        return result.releaseException();
                }
                break;
            case Range::Clone:
                if (direction == ProcessContentsForward) {
                    auto result = clonedContainer->appendChild(child->cloneNode(true));
                    if (result.hasException())
                        return result.releaseException();
                } else {
                    auto result = clonedContainer->insertBefore(child->cloneNode(true), clonedContainer->firstChild());
                    if (result.hasException())
                        return result.releaseException();
                }
                break;
            }
        }
        firstChildInAncestorToProcess = direction == ProcessContentsForward ? ancestor->nextSibling() : ancestor->previousSibling();
    }

    return clonedContainer;
}

ExceptionOr<Ref<DocumentFragment>> Range::extractContents()
{
    auto result = processContents(Extract);
    if (result.hasException())
        return result.releaseException();
    return result.releaseReturnValue().releaseNonNull();
}

ExceptionOr<Ref<DocumentFragment>> Range::cloneContents()
{
    auto result = processContents(Clone);
    if (result.hasException())
        return result.releaseException();
    return result.releaseReturnValue().releaseNonNull();
}

ExceptionOr<void> Range::insertNode(Ref<Node>&& node)
{
    auto startContainerNodeType = startContainer().nodeType();

    if (startContainerNodeType == Node::COMMENT_NODE || startContainerNodeType == Node::PROCESSING_INSTRUCTION_NODE)
        return Exception { HierarchyRequestError };
    bool startIsText = startContainerNodeType == Node::TEXT_NODE;
    if (startIsText && !startContainer().parentNode())
        return Exception { HierarchyRequestError };
    if (node.ptr() == &startContainer())
        return Exception { HierarchyRequestError };

    RefPtr<Node> referenceNode = startIsText ? &startContainer() : startContainer().traverseToChildAt(startOffset());
    Node* parentNode = referenceNode ? referenceNode->parentNode() : &startContainer();
    if (!is<ContainerNode>(parentNode))
        return Exception { HierarchyRequestError };

    Ref<ContainerNode> parent = downcast<ContainerNode>(*parentNode);

    auto result = parent->ensurePreInsertionValidity(node, referenceNode.get());
    if (result.hasException())
        return result.releaseException();

    EventQueueScope scope;
    if (startIsText) {
        auto result = downcast<Text>(startContainer()).splitText(startOffset());
        if (result.hasException())
            return result.releaseException();
        referenceNode = result.releaseReturnValue();
    }

    if (referenceNode == node.ptr())
        referenceNode = referenceNode->nextSibling();

    auto removeResult = node->remove();
    if (removeResult.hasException())
        return removeResult.releaseException();

    unsigned newOffset = referenceNode ? referenceNode->computeNodeIndex() : parent->countChildNodes();
    if (is<DocumentFragment>(node))
        newOffset += downcast<DocumentFragment>(node.get()).countChildNodes();
    else
        ++newOffset;

    auto insertResult = parent->insertBefore(node, referenceNode.get());
    if (insertResult.hasException())
        return insertResult.releaseException();

    if (collapsed())
        return setEnd(WTFMove(parent), newOffset);

    return { };
}

String Range::toString() const
{
    auto range = makeSimpleRange(*this);
    StringBuilder builder;
    for (auto& node : intersectingNodes(range)) {
        if (is<Text>(node)) {
            auto offsetRange = characterDataOffsetRange(range, node);
            builder.appendSubstring(downcast<Text>(node).data(), offsetRange.start, offsetRange.end - offsetRange.start);
        }
    }
    return builder.toString();
}

// https://w3c.github.io/DOM-Parsing/#widl-Range-createContextualFragment-DocumentFragment-DOMString-fragment
ExceptionOr<Ref<DocumentFragment>> Range::createContextualFragment(const String& markup)
{
    Node& node = startContainer();
    RefPtr<Element> element;
    if (is<Document>(node) || is<DocumentFragment>(node))
        element = nullptr;
    else if (is<Element>(node))
        element = &downcast<Element>(node);
    else
        element = node.parentElement();
    if (!element || (element->document().isHTMLDocument() && is<HTMLHtmlElement>(*element)))
        element = HTMLBodyElement::create(node.document());
    return WebCore::createContextualFragment(*element, markup, AllowScriptingContentAndDoNotMarkAlreadyStarted);
}

ExceptionOr<Node*> Range::checkNodeOffsetPair(Node& node, unsigned offset)
{
    switch (node.nodeType()) {
    case Node::DOCUMENT_TYPE_NODE:
        return Exception { InvalidNodeTypeError };
    case Node::CDATA_SECTION_NODE:
    case Node::COMMENT_NODE:
    case Node::TEXT_NODE:
    case Node::PROCESSING_INSTRUCTION_NODE:
        if (offset > downcast<CharacterData>(node).length())
            return Exception { IndexSizeError };
        return nullptr;
    case Node::ATTRIBUTE_NODE:
    case Node::DOCUMENT_FRAGMENT_NODE:
    case Node::DOCUMENT_NODE:
    case Node::ELEMENT_NODE:
        if (!offset)
            return nullptr;
        auto childBefore = node.traverseToChildAt(offset - 1);
        if (!childBefore)
            return Exception { IndexSizeError };
        return childBefore;
    }
    ASSERT_NOT_REACHED();
    return Exception { InvalidNodeTypeError };
}

Ref<Range> Range::cloneRange() const
{
    auto result = create(m_ownerDocument);
    result->setStart(startContainer(), m_start.offset());
    result->setEnd(endContainer(), m_end.offset());
    return result;
}

ExceptionOr<void> Range::setStartAfter(Node& node)
{
    auto parent = node.parentNode();
    if (!parent)
        return Exception { InvalidNodeTypeError };
    return setStart(*parent, node.computeNodeIndex() + 1);
}

ExceptionOr<void> Range::setEndBefore(Node& node)
{
    auto parent = node.parentNode();
    if (!parent)
        return Exception { InvalidNodeTypeError };
    return setEnd(*parent, node.computeNodeIndex());
}

ExceptionOr<void> Range::setEndAfter(Node& node)
{
    auto parent = node.parentNode();
    if (!parent)
        return Exception { InvalidNodeTypeError };
    return setEnd(*parent, node.computeNodeIndex() + 1);
}

ExceptionOr<void> Range::selectNode(Node& node)
{
    auto parent = node.parentNode();
    if (!parent)
        return Exception { InvalidNodeTypeError };
    unsigned index = node.computeNodeIndex();
    auto result = setStart(*parent, index);
    if (result.hasException())
        return result.releaseException();
    return setEnd(*parent, index + 1);
}

ExceptionOr<void> Range::selectNodeContents(Node& node)
{
    if (node.isDocumentTypeNode())
        return Exception { InvalidNodeTypeError };
    m_start.setToBeforeContents(node);
    m_end.setToAfterContents(node);
    updateAssociatedSelection();
    updateDocument();
    return { };
}

// https://dom.spec.whatwg.org/#dom-range-surroundcontents
ExceptionOr<void> Range::surroundContents(Node& newParent)
{
    Ref<Node> protectedNewParent(newParent);

    // Step 1: If a non-Text node is partially contained in the context object, then throw an InvalidStateError.
    Node* startNonTextContainer = &startContainer();
    if (startNonTextContainer->nodeType() == Node::TEXT_NODE)
        startNonTextContainer = startNonTextContainer->parentNode();
    Node* endNonTextContainer = &endContainer();
    if (endNonTextContainer->nodeType() == Node::TEXT_NODE)
        endNonTextContainer = endNonTextContainer->parentNode();
    if (startNonTextContainer != endNonTextContainer)
        return Exception { InvalidStateError };

    // Step 2: If newParent is a Document, DocumentType, or DocumentFragment node, then throw an InvalidNodeTypeError.
    switch (newParent.nodeType()) {
        case Node::ATTRIBUTE_NODE:
        case Node::DOCUMENT_FRAGMENT_NODE:
        case Node::DOCUMENT_NODE:
        case Node::DOCUMENT_TYPE_NODE:
            return Exception { InvalidNodeTypeError };
        case Node::CDATA_SECTION_NODE:
        case Node::COMMENT_NODE:
        case Node::ELEMENT_NODE:
        case Node::PROCESSING_INSTRUCTION_NODE:
        case Node::TEXT_NODE:
            break;
    }

    // Step 3: Let fragment be the result of extracting context object.
    auto fragment = extractContents();
    if (fragment.hasException())
        return fragment.releaseException();

    // Step 4: If newParent has children, replace all with null within newParent.
    if (newParent.hasChildNodes())
        downcast<ContainerNode>(newParent).replaceAll(nullptr);

    // Step 5: Insert newParent into context object.
    auto insertResult = insertNode(newParent);
    if (insertResult.hasException())
        return insertResult.releaseException();

    // Step 6: Append fragment to newParent.
    auto appendResult = newParent.appendChild(fragment.releaseReturnValue());
    if (appendResult.hasException())
        return appendResult.releaseException();

    // Step 7: Select newParent within context object.
    return selectNode(newParent);
}

ExceptionOr<void> Range::setStartBefore(Node& node)
{
    auto parent = node.parentNode();
    if (!parent)
        return Exception { InvalidNodeTypeError };
    return setStart(*parent, node.computeNodeIndex());
}

#if ENABLE(TREE_DEBUGGING)
String Range::debugDescription() const
{
    return makeString("from offset ", m_start.offset(), " of ", startContainer().debugDescription(), " to offset ", m_end.offset(), " of ", endContainer().debugDescription());
}
#endif

static inline void boundaryNodeChildrenChanged(RangeBoundaryPoint& boundary, ContainerNode& container)
{
    if (boundary.childBefore() && &boundary.container() == &container)
        boundary.invalidateOffset();
}

void Range::nodeChildrenChanged(ContainerNode& container)
{
    ASSERT(&container.document() == m_ownerDocument.ptr());
    boundaryNodeChildrenChanged(m_start, container);
    boundaryNodeChildrenChanged(m_end, container);
}

static inline void boundaryNodeChildrenWillBeRemoved(RangeBoundaryPoint& boundary, ContainerNode& containerOfNodesToBeRemoved)
{
    if (containerOfNodesToBeRemoved.contains(&boundary.container()))
        boundary.setToBeforeContents(containerOfNodesToBeRemoved);
}

void Range::nodeChildrenWillBeRemoved(ContainerNode& container)
{
    ASSERT(&container.document() == m_ownerDocument.ptr());
    boundaryNodeChildrenWillBeRemoved(m_start, container);
    boundaryNodeChildrenWillBeRemoved(m_end, container);
}

static inline void boundaryNodeWillBeRemoved(RangeBoundaryPoint& boundary, Node& nodeToBeRemoved)
{
    if (boundary.childBefore() == &nodeToBeRemoved)
        boundary.childBeforeWillBeRemoved();
    else if (nodeToBeRemoved.contains(&boundary.container()))
        boundary.setToBeforeNode(nodeToBeRemoved);
}

void Range::nodeWillBeRemoved(Node& node)
{
    ASSERT(&node.document() == m_ownerDocument.ptr());
    ASSERT(&node != m_ownerDocument.ptr());
    ASSERT(node.parentNode());
    boundaryNodeWillBeRemoved(m_start, node);
    boundaryNodeWillBeRemoved(m_end, node);
}

bool Range::parentlessNodeMovedToNewDocumentAffectsRange(Node& node)
{
    return node.containsIncludingShadowDOM(&m_start.container());
}

void Range::updateRangeForParentlessNodeMovedToNewDocument(Node& node)
{
    m_ownerDocument->detachRange(*this);
    m_ownerDocument = node.document();
    m_ownerDocument->attachRange(*this);
}

static inline void boundaryTextInserted(RangeBoundaryPoint& boundary, Node& text, unsigned offset, unsigned length)
{
    if (&boundary.container() != &text)
        return;
    unsigned boundaryOffset = boundary.offset();
    if (offset >= boundaryOffset)
        return;
    boundary.setOffset(boundaryOffset + length);
}

void Range::textInserted(Node& text, unsigned offset, unsigned length)
{
    ASSERT(&text.document() == m_ownerDocument.ptr());
    boundaryTextInserted(m_start, text, offset, length);
    boundaryTextInserted(m_end, text, offset, length);
}

static inline void boundaryTextRemoved(RangeBoundaryPoint& boundary, Node& text, unsigned offset, unsigned length)
{
    if (&boundary.container() != &text)
        return;
    unsigned boundaryOffset = boundary.offset();
    if (offset >= boundaryOffset)
        return;
    if (offset + length >= boundaryOffset)
        boundary.setOffset(offset);
    else
        boundary.setOffset(boundaryOffset - length);
}

void Range::textRemoved(Node& text, unsigned offset, unsigned length)
{
    ASSERT(&text.document() == m_ownerDocument.ptr());
    boundaryTextRemoved(m_start, text, offset, length);
    boundaryTextRemoved(m_end, text, offset, length);
}

static inline void boundaryTextNodesMerged(RangeBoundaryPoint& boundary, NodeWithIndex& oldNode, unsigned offset)
{
    if (&boundary.container() == oldNode.node())
        boundary.set(*oldNode.node()->previousSibling(), boundary.offset() + offset, 0);
    else if (&boundary.container() == oldNode.node()->parentNode() && boundary.offset() == static_cast<unsigned>(oldNode.index()))
        boundary.set(*oldNode.node()->previousSibling(), offset, 0);
}

void Range::textNodesMerged(NodeWithIndex& oldNode, unsigned offset)
{
    ASSERT(oldNode.node());
    ASSERT(&oldNode.node()->document() == m_ownerDocument.ptr());
    ASSERT(oldNode.node()->parentNode());
    ASSERT(oldNode.node()->isTextNode());
    ASSERT(oldNode.node()->previousSibling());
    ASSERT(oldNode.node()->previousSibling()->isTextNode());
    boundaryTextNodesMerged(m_start, oldNode, offset);
    boundaryTextNodesMerged(m_end, oldNode, offset);
}

static inline void boundaryTextNodesSplit(RangeBoundaryPoint& boundary, Text& oldNode)
{
    auto* parent = oldNode.parentNode();
    if (&boundary.container() == &oldNode) {
        unsigned splitOffset = oldNode.length();
        unsigned boundaryOffset = boundary.offset();
        if (boundaryOffset > splitOffset) {
            if (parent)
                boundary.set(*oldNode.nextSibling(), boundaryOffset - splitOffset, 0);
            else
                boundary.setOffset(splitOffset);
        }
        return;
    }
    if (!parent)
        return;
    if (&boundary.container() == parent && boundary.childBefore() == &oldNode) {
        auto* newChild = oldNode.nextSibling();
        ASSERT(newChild);
        boundary.setToAfterNode(*newChild);
    }
}

void Range::textNodeSplit(Text& oldNode)
{
    ASSERT(&oldNode.document() == m_ownerDocument.ptr());
    ASSERT(!oldNode.parentNode() || oldNode.nextSibling());
    ASSERT(!oldNode.parentNode() || oldNode.nextSibling()->isTextNode());
    boundaryTextNodesSplit(m_start, oldNode);
    boundaryTextNodesSplit(m_end, oldNode);
}

ExceptionOr<void> Range::expand(const String& unit)
{
    auto start = VisiblePosition { makeContainerOffsetPosition(&startContainer(), startOffset()) };
    auto end = VisiblePosition { makeContainerOffsetPosition(&endContainer(), endOffset()) };
    if (unit == "word"_s) {
        start = startOfWord(start);
        end = endOfWord(end);
    } else if (unit == "sentence"_s) {
        start = startOfSentence(start);
        end = endOfSentence(end);
    } else if (unit == "block"_s) {
        start = startOfParagraph(start);
        end = endOfParagraph(end);
    } else if (unit == "document"_s) {
        start = startOfDocument(start);
        end = endOfDocument(end);
    } else
        return { };

    auto* startContainer = start.deepEquivalent().containerNode();
    if (!startContainer)
        return Exception { TypeError };
    auto result = setStart(*startContainer, start.deepEquivalent().computeOffsetInContainerNode());
    if (result.hasException())
        return result.releaseException();
    auto* endContainer = end.deepEquivalent().containerNode();
    if (!endContainer)
        return Exception { TypeError };
    return setEnd(*endContainer, end.deepEquivalent().computeOffsetInContainerNode());
}

Ref<DOMRectList> Range::getClientRects() const
{
    startContainer().document().updateLayout();
    return DOMRectList::create(RenderObject::clientBorderAndTextRects(makeSimpleRange(*this)));
}

Ref<DOMRect> Range::getBoundingClientRect() const
{
    startContainer().document().updateLayout();
    return DOMRect::create(unionRectIgnoringZeroRects(RenderObject::clientBorderAndTextRects(makeSimpleRange(*this))));
}

static void setBothEndpoints(Range& range, const SimpleRange& value)
{
    auto startContainer = value.start.container;
    range.setStart(WTFMove(startContainer), value.start.offset);
    auto endContainer = value.end.container;
    range.setEnd(WTFMove(endContainer), value.end.offset);
}

void Range::updateFromSelection(const SimpleRange& value)
{
    ASSERT(m_isAssociatedWithSelection);
    m_isAssociatedWithSelection = false;
    setBothEndpoints(*this, value);
    m_isAssociatedWithSelection = true;
}

DOMWindow* Range::window() const
{
    return m_isAssociatedWithSelection ? m_ownerDocument->domWindow() : nullptr;
}

SimpleRange makeSimpleRange(const Range& range)
{
    return { { range.startContainer(), range.startOffset() }, { range.endContainer(), range.endOffset() } };
}

SimpleRange makeSimpleRange(const Ref<Range>& range)
{
    return makeSimpleRange(range.get());
}

std::optional<SimpleRange> makeSimpleRange(const Range* range)
{
    if (!range)
        return std::nullopt;
    return makeSimpleRange(*range);
}

std::optional<SimpleRange> makeSimpleRange(const RefPtr<Range>& range)
{
    return makeSimpleRange(range.get());
}

Ref<Range> createLiveRange(const SimpleRange& range)
{
    auto result = Range::create(range.start.document());
    setBothEndpoints(result, range);
    return result;
}

RefPtr<Range> createLiveRange(const std::optional<SimpleRange>& range)
{
    if (!range)
        return nullptr;
    return createLiveRange(*range);
}

void Range::visitNodesConcurrently(JSC::AbstractSlotVisitor& visitor) const
{
    addWebCoreOpaqueRoot(visitor, m_start.container());
    addWebCoreOpaqueRoot(visitor, m_end.container());
}

} // namespace WebCore

#if ENABLE(TREE_DEBUGGING)

void showTree(const WebCore::Range* range)
{
    if (range) {
        range->startContainer().showTreeAndMark(&range->startContainer(), "S", &range->endContainer(), "E");
        fprintf(stderr, "start offset: %d, end offset: %d\n", range->startOffset(), range->endOffset());
    }
}

#endif