/*
 * step.cc - Copyright 2005 Frerich Raabe   <raabe@kde.org>
 *           Copyright 2010 Maksim Orlovich <maksim@kde.org>
 *
 * 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 THE AUTHOR ``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 THE AUTHOR 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.
 */
#include "step.h"

#include "dom/dom3_xpath.h"
#include "xml/dom_docimpl.h"
#include "xml/dom_nodeimpl.h"
#include "xml/dom_textimpl.h"
#include "xml/dom3_xpathimpl.h"

#include "step.h"

#include <QtDebug>

using namespace DOM;
using namespace DOM::XPath;
using namespace khtml;
using namespace khtml::XPath;

static bool areAdjacentTextNodes(NodeImpl *n, NodeImpl *m)
{
    if (!n || !m) {
        return false;
    }

    if (n->nodeType() != Node::TEXT_NODE && n->nodeType() != Node::CDATA_SECTION_NODE) {
        return false;
    }
    if (m->nodeType() != Node::TEXT_NODE && m->nodeType() != Node::CDATA_SECTION_NODE) {
        return false;
    }

    // ###
#ifdef __GNUC__
#warning "Might need more generic adjacency -- check"
#endif

    return (n->nextSibling() && (n->nextSibling() == m)) ||
           (m->nextSibling() && (m->nextSibling() == n));
}

static DomNodeList compressTextNodes(const DomNodeList &nodes)
{
    DomNodeList outNodes = new StaticNodeListImpl;

    for (unsigned long n = 0; n < nodes->length(); ++n) {
        NodeImpl *node = nodes->item(n);
        NodeImpl *next = n + 1 < nodes->length() ? nodes->item(n + 1) : 0;

        if (!next || !areAdjacentTextNodes(node, next)) {
            outNodes->append(node);
        } else if (areAdjacentTextNodes(node, next)) {
            QString s = node->nodeValue().string();

            // n2 is a potential successor, and is always in-range
            unsigned long n2 = n + 1;
            while (n2 < nodes->length() && areAdjacentTextNodes(nodes->item(n2), nodes->item(n2 - 1))) {
                s += nodes->item(n2)->nodeValue().string();
                ++n2;
            }
            outNodes->append(node->document()->createTextNode(new DOMStringImpl(s.data(), s.length())));
        }
    }
    return outNodes;
}

QString Step::axisAsString(AxisType axis)
{
    switch (axis) {
    case AncestorAxis: return "ancestor";
    case AncestorOrSelfAxis: return "ancestor-or-self";
    case AttributeAxis: return "attribute";
    case ChildAxis: return "child";
    case DescendantAxis: return "descendant";
    case DescendantOrSelfAxis: return "descendant-or-self";
    case FollowingAxis: return "following";
    case FollowingSiblingAxis: return "following-sibling";
    case NamespaceAxis: return "namespace";
    case ParentAxis: return "parent";
    case PrecedingAxis: return "preceding";
    case PrecedingSiblingAxis: return "preceding-sibling";
    case SelfAxis: return "self";
    }
    return QString();
}

Step::Step(): m_compileState(NotCompiled)
{
}

Step::Step(AxisType axis, const DOMString &nodeTest,
           const QList<Predicate *> &predicates)
    : m_axis(axis),
      m_nodeTest(nodeTest),
      m_compileState(NotCompiled),
      m_predicates(predicates)
{
}

Step::~Step()
{
    qDeleteAll(m_predicates);
}

DomNodeList Step::evaluate(NodeImpl *context) const
{
    assert(context);
#ifdef XPATH_VERBOSE
    qDebug() << "Evaluating step, axis='" << axisAsString(m_axis) << "'"
             << ", nodetest='" << m_nodeTest << "'"
             << ", " << m_predicates.count() << " predicates";
    qDebug() << DOM::getPrintableName(context->id());
#endif

    DomNodeList inNodes = nodesInAxis(context), outNodes;

    // ### optimization opportunity: can say DocumentOrder for most
    StaticNodeListImpl::NormalizationKind known = StaticNodeListImpl::AxisOrder;
    inNodes->setKnownNormalization(known);

#ifdef XPATH_VERBOSE
    qDebug() << "Axis " << axisAsString(m_axis) << " matches " << inNodes->length() << " nodes.";
#endif

    inNodes = nodeTestMatches(context, inNodes);
    inNodes->setKnownNormalization(known); // nodeTest doesn't change order

#ifdef XPATH_VERBOSE
    qDebug() << "\tNodetest " << m_nodeTest << " trims this number to " << inNodes->length();
#endif

    if (m_predicates.isEmpty()) {
        return inNodes;
    }

    foreach (Predicate *predicate, m_predicates) {
        outNodes = new StaticNodeListImpl;
        Expression::evaluationContext().size = int(inNodes->length());
        Expression::evaluationContext().position = 1;

        for (unsigned long n = 0; n < inNodes->length(); ++n) {
            NodeImpl *node = inNodes->item(n);
            Expression::evaluationContext().node = node;
            EvaluationContext backupCtx = Expression::evaluationContext();
#ifdef XPATH_VERBOSE
            qDebug() << Expression::evaluationContext().position << "/" << node;
#endif
            if (predicate->evaluate()) {
                outNodes->append(node);
            }
            Expression::evaluationContext() = backupCtx;
            ++Expression::evaluationContext().position;
        }
#ifdef XPATH_VERBOSE
        qDebug() << "\tPredicate trims this number to " << outNodes->length();
#endif
        inNodes = outNodes;
        inNodes->setKnownNormalization(known); // predicates don't change order
    }

    return outNodes;
}

DomNodeList Step::nodesInAxis(NodeImpl *context) const
{
    //assert(context);
    DomNodeList nodes = new StaticNodeListImpl;
    switch (m_axis) {
    case ChildAxis: {
        NodeImpl *n = xpathFirstChild(context);
        while (n) {
            nodes->append(n);
            n = n->nextSibling();
        }
        return nodes;
    }
    case DescendantAxis: {
        collectChildrenRecursively(nodes, context);
        return nodes;
    }
    case ParentAxis: {
        NodeImpl *p = xpathParentNode(context);

        if (p) {
            nodes->append(p);
        }
        return nodes;
    }
    case AncestorAxis: {
        NodeImpl *n = xpathParentNode(context);
        while (n) {
            nodes->append(n);
            n = xpathParentNode(n);
        }
        return nodes;
    }
    case FollowingSiblingAxis: {
        if (context->nodeType() == Node::ATTRIBUTE_NODE ||
                context->nodeType() == Node::XPATH_NAMESPACE_NODE) {
            return nodes; // empty
        }

        NodeImpl *n = context->nextSibling();
        while (n) {
            nodes->append(n);
            n = n->nextSibling();
        }
        return nodes;
    }
    case PrecedingSiblingAxis: {
        if (context->nodeType() == Node::ATTRIBUTE_NODE ||
                context->nodeType() == Node::XPATH_NAMESPACE_NODE) {
            return nodes; // empty
        }

        NodeImpl *n = context->previousSibling();
        while (n) {
            nodes->append(n);
            n = n->previousSibling();
        }
        return nodes;
    }
    case FollowingAxis: {
        NodeImpl *p = context;
        while (!isRootDomNode(p)) {
            NodeImpl *n = nextSiblingForFollowing(p);
            while (n) {
                nodes->append(n);
                collectChildrenRecursively(nodes, n);
                n = n->nextSibling();
            }
            p = xpathParentNode(p);
        }
        return nodes;
    }
    case PrecedingAxis: {
        NodeImpl *p = context;
        while (!isRootDomNode(p)) {
            NodeImpl *n = p->previousSibling();
            while (n) {
                collectChildrenReverse(nodes, n);
                nodes->append(n);
                n = n->previousSibling();
            }
            p = xpathParentNode(p);
        }
        return nodes;
    }
    case AttributeAxis: {
        if (context->nodeType() != Node::ELEMENT_NODE) {
            return nodes; // empty
        }

        NamedAttrMapImpl *attrs = static_cast<ElementImpl *>(context)->attributes(true /*read-only*/);
        if (!attrs) {
            return nodes;
        }

        for (unsigned long i = 0; i < attrs->length(); ++i) {
            nodes->append(attrs->item(i));
        }
        return nodes;
    }
    case NamespaceAxis: {
        // ### TODO: Need to implement this, but not a priority, since
        // other impls don't.
#if 0
        if (context->nodeType() != Node::ELEMENT_NODE) {
            return nodes;
        }

        bool foundXmlNsNode = false;
        NodeImpl *node = context;
        while (node) {
            NamedAttrMapImpl *attrs =
                node->isElementNode() ? static_cast<ElementImpl *>(node)->attributes() : 0;
            if (!attrs) {
                node = xpathParentNode(node);
                continue;
            }

            for (unsigned long i = 0; i < attrs->length(); ++i) {
                NodeImpl *n = attrs->item(i);
                if (n->nodeName().string().startsWith("xmlns:")) {
                    nodes->append(n);
                } else if (n->nodeName() == "xmlns" &&
                           !foundXmlNsNode
                          ) {
                    foundXmlNsNode = true;
                    if (!n->nodeValue().string().isEmpty()) {
                        nodes->append(n);
                    }
                }
            }
            node = xpathParentNode(node);
        }
#endif
        return nodes;
    }
    case SelfAxis:
        nodes->append(context);
        return nodes;
    case DescendantOrSelfAxis:
        nodes->append(context);
        collectChildrenRecursively(nodes, context);
        return nodes;
    case AncestorOrSelfAxis: {
        nodes->append(context);
        NodeImpl *n = xpathParentNode(context);
        while (n) {
            nodes->append(n);
            n = xpathParentNode(n);
        }
        return nodes;
    }
    default:
        qWarning() << "Unknown axis " << axisAsString(m_axis) << " passed to Step::nodesInAxis";
    }

    return nodes; // empty
}

void Step::compileNodeTest(bool htmlCompat) const
{
    m_compileState = htmlCompat ? CompiledForHTML : CompiledForXML;

    if (m_nodeTest == "*") {
        m_nodeTestType = NT_Star;
    } else if (m_nodeTest == "text()") {
        m_nodeTestType = NT_Text;
    } else if (m_nodeTest == "comment()") {
        m_nodeTestType = NT_Comment;
    } else if (m_nodeTest.startsWith("processing-instruction")) {
        DOMString param;

        // ### is this right? (parens?)
        const int space = m_nodeTest.find(' ');
        if (space > -1) {
            param = m_nodeTest.substring(space + 1);
        }

        if (param.isEmpty()) {
            m_nodeTestType = NT_PI;
        } else {
            m_nodeTestType = NT_PI_Lit;
            m_piInfo = param;
        }
    } else if (m_nodeTest == "node()") {
        m_nodeTestType = NT_AnyNode;
    } else {
        // Some sort of name combo.
        PrefixName prefix;
        LocalName localName;

        splitPrefixLocalName(m_nodeTest,  prefix, localName, htmlCompat);

        if (prefix.id() == DOM::emptyPrefix) {
            // localname only
            m_nodeTestType = NT_LocalName;
            m_localName    = localName;
        } else if (localName.toString() == "*") {
            // namespace only
            m_nodeTestType = NT_Namespace;
            m_namespace    = NamespaceName::fromString(namespaceFromNodetest(m_nodeTest));
        } else {
            // Both parts.
            m_nodeTestType = NT_QName;
            m_localName    = localName;
            m_namespace    = NamespaceName::fromString(namespaceFromNodetest(m_nodeTest));
        }
    }
}

DomNodeList Step::nodeTestMatches(NodeImpl *ctx, const DomNodeList &nodes) const
{
    CompileState desired = ctx->htmlCompat() ? CompiledForHTML : CompiledForXML;
    if (m_compileState != desired) {
        compileNodeTest(ctx->htmlCompat());
    }

    if (m_nodeTestType == NT_AnyNode) { // no need for a new set
        return nodes;
    }

    DomNodeList matches = new StaticNodeListImpl;

    // A lot of things can be handled by just checking the type,
    // and maybe a hair more special handling
    int matchType;
    switch (m_nodeTestType) {
    case NT_Star:
        matchType = primaryNodeType(m_axis);
        break;
    case NT_Comment:
        matchType = Node::COMMENT_NODE;
        break;
    case NT_Text:
        matchType = Node::TEXT_NODE;
        break;
    case NT_PI:
    case NT_PI_Lit:
        matchType = Node::PROCESSING_INSTRUCTION_NODE;
        break;
    default:
        matchType = -1;
    }

    if (matchType != -1) {
        for (unsigned long n = 0; n < nodes->length(); ++n) {
            NodeImpl *node = nodes->item(n);
            int nodeType   = node->nodeType();
            if (nodeType == matchType) {
                if (m_nodeTestType == NT_PI_Lit && node->nodeName() != m_piInfo) {
                    continue;
                }

                matches->append(node);
            }

            if (matchType == NT_Text && nodeType == Node::CDATA_SECTION_NODE) {
                matches->append(node);
            }
        }
        return matches;
    }

    // Now we are checking by name. We always want to filter out
    // the primary axis here
    // ### CHECK: this used to have special handling for some axes.
    matchType = primaryNodeType(m_axis);
    for (unsigned long n = 0; n < nodes->length(); ++n) {
        NodeImpl *node = nodes->item(n);
        if (node->nodeType() != matchType) {
            continue;
        }

        if (m_nodeTestType == NT_LocalName) {
            if (localNamePart(node->id()) == m_localName.id()) {
                matches->append(node);
            }
        } else if (m_nodeTestType == NT_Namespace) {
            if (namespacePart(node->id()) == m_namespace.id()) {
                matches->append(node);
            }
        } else {
            // NT_QName
            if (node->id() == makeId(m_namespace.id(), m_localName.id())) {
                matches->append(node);
            }
        }
    }
    return matches;
}

void Step::optimize()
{
    foreach (Predicate *predicate, m_predicates) {
        predicate->optimize();
    }
}

QString Step::dump() const
{
    QString s = QString("<step axis=\"%1\" nodetest=\"%2\">").arg(axisAsString(m_axis)).arg(m_nodeTest.string());
    foreach (Predicate *predicate, m_predicates) {
        s += predicate->dump();
    }
    s += "</step>";
    return s;
}

DOMString Step::namespaceFromNodetest(const DOMString &nodeTest) const
{
    int i = nodeTest.find(':');
    if (i == -1) {
        return DOMString();
    }

    DOMString prefix(nodeTest.substring(0, i));
    XPathNSResolverImpl *resolver = Expression::evaluationContext().resolver;

    DOM::DOMString ns;
    if (resolver) {
        ns = resolver->lookupNamespaceURI(prefix);
    }

    if (ns.isNull()) {
        Expression::reportNamespaceErr();
    }

    return ns;
}

unsigned int Step::primaryNodeType(AxisType axis) const
{
    switch (axis) {
    case AttributeAxis:
        return Node::ATTRIBUTE_NODE;
    case NamespaceAxis:
        return Node::XPATH_NAMESPACE_NODE;
    default:
        return Node::ELEMENT_NODE;
    }
}

