/*
 * Copyright (C) 2010 Google, Inc. All Rights Reserved.
 * Copyright (C) 2011 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY GOOGLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL GOOGLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef HTMLConstructionSite_h
#define HTMLConstructionSite_h

#include "core/dom/Document.h"
#include "core/dom/ParserContentPolicy.h"
#include "core/html/parser/HTMLElementStack.h"
#include "core/html/parser/HTMLFormattingElementList.h"
#include "platform/heap/Handle.h"
#include "wtf/Noncopyable.h"
#include "wtf/Vector.h"
#include "wtf/text/StringBuilder.h"

namespace blink {

struct HTMLConstructionSiteTask {
    DISALLOW_NEW_EXCEPT_PLACEMENT_NEW();
public:
    enum Operation {
        Insert,
        InsertText, // Handles possible merging of text nodes.
        InsertAlreadyParsedChild, // Insert w/o calling begin/end parsing.
        Reparent,
        TakeAllChildren,
    };

    explicit HTMLConstructionSiteTask(Operation op)
        : operation(op)
        , selfClosing(false)
    {
    }

    DEFINE_INLINE_TRACE()
    {
        visitor->trace(parent);
        visitor->trace(nextChild);
        visitor->trace(child);
    }

    ContainerNode* oldParent()
    {
        // It's sort of ugly, but we store the |oldParent| in the |child| field
        // of the task so that we don't bloat the HTMLConstructionSiteTask
        // object in the common case of the Insert operation.
        return toContainerNode(child.get());
    }

    Operation operation;
    Member<ContainerNode> parent;
    Member<Node> nextChild;
    Member<Node> child;
    bool selfClosing;
};

} // namespace blink

WTF_ALLOW_MOVE_INIT_AND_COMPARE_WITH_MEM_FUNCTIONS(blink::HTMLConstructionSiteTask);

namespace blink {

// Note: These are intentionally ordered so that when we concatonate
// strings and whitespaces the resulting whitespace is ws = min(ws1, ws2).
enum WhitespaceMode {
    WhitespaceUnknown,
    NotAllWhitespace,
    AllWhitespace,
};

enum FlushMode {
    // Flush pending text. Flush queued tasks.
    FlushAlways,

    // Flush pending text if node has length limit. Flush queued tasks.
    FlushIfAtTextLimit,
};

class AtomicHTMLToken;
class CustomElementDefinition;
class Document;
class Element;
class HTMLFormElement;
class HTMLParserReentryPermit;

class HTMLConstructionSite final {
    WTF_MAKE_NONCOPYABLE(HTMLConstructionSite);
    DISALLOW_NEW();
public:
    HTMLConstructionSite(HTMLParserReentryPermit*, Document&, ParserContentPolicy);
    ~HTMLConstructionSite();
    DECLARE_TRACE();

    void initFragmentParsing(DocumentFragment*, Element* contextElement);

    void detach();

    // executeQueuedTasks empties the queue but does not flush pending text.
    // NOTE: Possible reentrancy via JavaScript execution.
    void executeQueuedTasks();

    // flushPendingText turns pending text into queued Text insertions, but does not execute them.
    void flushPendingText(FlushMode);

    // Called before every token in HTMLTreeBuilder::processToken, thus inlined:
    void flush(FlushMode mode)
    {
        if (!hasPendingTasks())
            return;
        flushPendingText(mode);
        executeQueuedTasks(); // NOTE: Possible reentrancy via JavaScript execution.
        ASSERT(mode == FlushIfAtTextLimit || !hasPendingTasks());
    }

    bool hasPendingTasks()
    {
        return !m_pendingText.isEmpty() || !m_taskQueue.isEmpty();
    }

    void setDefaultCompatibilityMode();
    void processEndOfFile();
    void finishedParsing();

    void insertDoctype(AtomicHTMLToken*);
    void insertComment(AtomicHTMLToken*);
    void insertCommentOnDocument(AtomicHTMLToken*);
    void insertCommentOnHTMLHtmlElement(AtomicHTMLToken*);
    void insertHTMLElement(AtomicHTMLToken*);
    void insertSelfClosingHTMLElementDestroyingToken(AtomicHTMLToken*);
    void insertFormattingElement(AtomicHTMLToken*);
    void insertHTMLHeadElement(AtomicHTMLToken*);
    void insertHTMLBodyElement(AtomicHTMLToken*);
    void insertHTMLFormElement(AtomicHTMLToken*, bool isDemoted = false);
    void insertScriptElement(AtomicHTMLToken*);
    void insertTextNode(const String&, WhitespaceMode = WhitespaceUnknown);
    void insertForeignElement(AtomicHTMLToken*, const AtomicString& namespaceURI);

    void insertHTMLHtmlStartTagBeforeHTML(AtomicHTMLToken*);
    void insertHTMLHtmlStartTagInBody(AtomicHTMLToken*);
    void insertHTMLBodyStartTagInBody(AtomicHTMLToken*);

    void reparent(HTMLElementStack::ElementRecord* newParent, HTMLElementStack::ElementRecord* child);
    void reparent(HTMLElementStack::ElementRecord* newParent, HTMLStackItem* child);
    // insertAlreadyParsedChild assumes that |child| has already been parsed (i.e., we're just
    // moving it around in the tree rather than parsing it for the first time). That means
    // this function doesn't call beginParsingChildren / finishParsingChildren.
    void insertAlreadyParsedChild(HTMLStackItem* newParent, HTMLElementStack::ElementRecord* child);
    void takeAllChildren(HTMLStackItem* newParent, HTMLElementStack::ElementRecord* oldParent);

    HTMLStackItem* createElementFromSavedToken(HTMLStackItem*);

    bool shouldFosterParent() const;
    void fosterParent(Node*);

    bool indexOfFirstUnopenFormattingElement(unsigned& firstUnopenElementIndex) const;
    void reconstructTheActiveFormattingElements();

    void generateImpliedEndTags();
    void generateImpliedEndTagsWithExclusion(const AtomicString& tagName);

    bool inQuirksMode();

    bool isEmpty() const { return !m_openElements.stackDepth(); }
    HTMLElementStack::ElementRecord* currentElementRecord() const { return m_openElements.topRecord(); }
    Element* currentElement() const { return m_openElements.top(); }
    ContainerNode* currentNode() const { return m_openElements.topNode(); }
    HTMLStackItem* currentStackItem() const { return m_openElements.topStackItem(); }
    HTMLStackItem* oneBelowTop() const { return m_openElements.oneBelowTop(); }
    Document& ownerDocumentForCurrentNode();
    HTMLElementStack* openElements() const { return &m_openElements; }
    HTMLFormattingElementList* activeFormattingElements() const { return &m_activeFormattingElements; }
    bool currentIsRootNode() { return m_openElements.topNode() == m_openElements.rootNode(); }

    Element* head() const { return m_head->element(); }
    HTMLStackItem* headStackItem() const { return m_head.get(); }

    bool isFormElementPointerNonNull() const { return m_form; }
    HTMLFormElement* takeForm();

    ParserContentPolicy getParserContentPolicy() { return m_parserContentPolicy; }

    class RedirectToFosterParentGuard {
        STACK_ALLOCATED();
        WTF_MAKE_NONCOPYABLE(RedirectToFosterParentGuard);
    public:
        RedirectToFosterParentGuard(HTMLConstructionSite& tree)
            : m_tree(tree)
            , m_wasRedirectingBefore(tree.m_redirectAttachToFosterParent)
        {
            m_tree.m_redirectAttachToFosterParent = true;
        }

        ~RedirectToFosterParentGuard()
        {
            m_tree.m_redirectAttachToFosterParent = m_wasRedirectingBefore;
        }

    private:
        HTMLConstructionSite& m_tree;
        bool m_wasRedirectingBefore;
    };

private:
    // In the common case, this queue will have only one task because most
    // tokens produce only one DOM mutation.
    typedef HeapVector<HTMLConstructionSiteTask, 1> TaskQueue;

    void setCompatibilityMode(Document::CompatibilityMode);
    void setCompatibilityModeFromDoctype(const String& name, const String& publicId, const String& systemId);

    void attachLater(ContainerNode* parent, Node* child, bool selfClosing = false);

    void findFosterSite(HTMLConstructionSiteTask&);

    CreateElementFlags getCreateElementFlags() const;
    HTMLElement* createHTMLElement(AtomicHTMLToken*);
    Element* createElement(AtomicHTMLToken*, const AtomicString& namespaceURI);

    void mergeAttributesFromTokenIntoElement(AtomicHTMLToken*, Element*);

    void executeTask(HTMLConstructionSiteTask&);
    void queueTask(const HTMLConstructionSiteTask&);

    CustomElementDefinition* lookUpCustomElementDefinition(Document&, AtomicHTMLToken*);

    HTMLParserReentryPermit* m_reentryPermit;
    Member<Document> m_document;

    // This is the root ContainerNode to which the parser attaches all newly
    // constructed nodes. It points to a DocumentFragment when parsing fragments
    // and a Document in all other cases.
    Member<ContainerNode> m_attachmentRoot;

    // https://html.spec.whatwg.org/multipage/syntax.html#head-element-pointer
    Member<HTMLStackItem> m_head;
    // https://html.spec.whatwg.org/multipage/syntax.html#form-element-pointer
    Member<HTMLFormElement> m_form;
    mutable HTMLElementStack m_openElements;
    mutable HTMLFormattingElementList m_activeFormattingElements;

    TaskQueue m_taskQueue;

    class PendingText final {
        DISALLOW_NEW();
    public:
        PendingText()
            : whitespaceMode(WhitespaceUnknown)
        {
        }

        void append(ContainerNode* newParent, Node* newNextChild, const String& newString, WhitespaceMode newWhitespaceMode)
        {
            ASSERT(!parent || parent == newParent);
            parent = newParent;
            ASSERT(!nextChild || nextChild == newNextChild);
            nextChild = newNextChild;
            stringBuilder.append(newString);
            whitespaceMode = std::min(whitespaceMode, newWhitespaceMode);
        }

        void swap(PendingText& other)
        {
            std::swap(whitespaceMode, other.whitespaceMode);
            parent.swap(other.parent);
            nextChild.swap(other.nextChild);
            stringBuilder.swap(other.stringBuilder);
        }

        void discard()
        {
            PendingText discardedText;
            swap(discardedText);
        }

        bool isEmpty()
        {
            // When the stringbuilder is empty, the parent and whitespace should also be "empty".
            ASSERT(stringBuilder.isEmpty() == !parent);
            ASSERT(!stringBuilder.isEmpty() || !nextChild);
            ASSERT(!stringBuilder.isEmpty() || (whitespaceMode == WhitespaceUnknown));
            return stringBuilder.isEmpty();
        }

        DECLARE_TRACE();

        Member<ContainerNode> parent;
        Member<Node> nextChild;
        StringBuilder stringBuilder;
        WhitespaceMode whitespaceMode;
    };

    PendingText m_pendingText;

    ParserContentPolicy m_parserContentPolicy;
    bool m_isParsingFragment;

    // http://www.whatwg.org/specs/web-apps/current-work/multipage/tokenization.html#parsing-main-intable
    // In the "in table" insertion mode, we sometimes get into a state where
    // "whenever a node would be inserted into the current node, it must instead
    // be foster parented."  This flag tracks whether we're in that state.
    bool m_redirectAttachToFosterParent;

    bool m_inQuirksMode;
};

} // namespace blink

#endif