/*
    Copyright (C) 2016 Volker Krause <vkrause@kde.org>
    Copyright (C) 2018 Christoph Cullmann <cullmann@kde.org>

    Permission is hereby granted, free of charge, to any person obtaining
    a copy of this software and associated documentation files (the
    "Software"), to deal in the Software without restriction, including
    without limitation the rights to use, copy, modify, merge, publish,
    distribute, sublicense, and/or sell copies of the Software, and to
    permit persons to whom the Software is furnished to do so, subject to
    the following conditions:

    The above copyright notice and this permission notice shall be included
    in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
    IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
    CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
    TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

#include "context_p.h"
#include "definition_p.h"
#include "ksyntaxhighlighting_logging.h"
#include "rule_p.h"
#include "xml_p.h"

#include <QString>
#include <QXmlStreamReader>

using namespace KSyntaxHighlighting;

static bool isOctalChar(QChar c)
{
    return c.isNumber() && c != QLatin1Char('9') && c != QLatin1Char('8');
}

static bool isHexChar(QChar c)
{
    return c.isNumber() || c == QLatin1Char('a') || c == QLatin1Char('A') || c == QLatin1Char('b') || c == QLatin1Char('B') || c == QLatin1Char('c') || c == QLatin1Char('C') || c == QLatin1Char('d') || c == QLatin1Char('D') ||
        c == QLatin1Char('e') || c == QLatin1Char('E') || c == QLatin1Char('f') || c == QLatin1Char('F');
}

static int matchEscapedChar(const QString &text, int offset)
{
    if (text.at(offset) != QLatin1Char('\\') || text.size() < offset + 2)
        return offset;

    const auto c = text.at(offset + 1);
    static const auto controlChars = QStringLiteral("abefnrtv\"'?\\");
    if (controlChars.contains(c))
        return offset + 2;

    // hex encoded character
    if (c == QLatin1Char('x')) {
        auto newOffset = offset + 2;
        for (int i = 0; i < 2 && newOffset + i < text.size(); ++i, ++newOffset) {
            if (!isHexChar(text.at(newOffset)))
                break;
        }
        if (newOffset == offset + 2)
            return offset;
        return newOffset;
    }

    // octal encoding, simple \0 is OK, too, unlike simple \x above
    if (isOctalChar(c)) {
        auto newOffset = offset + 2;
        for (int i = 0; i < 2 && newOffset + i < text.size(); ++i, ++newOffset) {
            if (!isOctalChar(text.at(newOffset)))
                break;
        }
        return newOffset;
    }

    return offset;
}

static QString replaceCaptures(const QString &pattern, const QStringList &captures, bool quote)
{
    auto result = pattern;
    for (int i = captures.size() - 1; i >= 1; --i) {
        result.replace(QLatin1Char('%') + QString::number(i), quote ? QRegularExpression::escape(captures.at(i)) : captures.at(i));
    }
    return result;
}

Definition Rule::definition() const
{
    return m_def.definition();
}

void Rule::setDefinition(const Definition &def)
{
    m_def = def;
}

bool Rule::load(QXmlStreamReader &reader)
{
    Q_ASSERT(reader.tokenType() == QXmlStreamReader::StartElement);

    m_attribute = reader.attributes().value(QStringLiteral("attribute")).toString();
    if (reader.name() != QLatin1String("IncludeRules")) // IncludeRules uses this with a different semantic
        m_context.parse(reader.attributes().value(QStringLiteral("context")));
    m_firstNonSpace = Xml::attrToBool(reader.attributes().value(QStringLiteral("firstNonSpace")));
    m_lookAhead = Xml::attrToBool(reader.attributes().value(QStringLiteral("lookAhead")));
    bool colOk = false;
    m_column = reader.attributes().value(QStringLiteral("column")).toInt(&colOk);
    if (!colOk)
        m_column = -1;

    auto regionName = reader.attributes().value(QLatin1String("beginRegion"));
    if (!regionName.isEmpty())
        m_beginRegion = FoldingRegion(FoldingRegion::Begin, DefinitionData::get(m_def.definition())->foldingRegionId(regionName.toString()));
    regionName = reader.attributes().value(QLatin1String("endRegion"));
    if (!regionName.isEmpty())
        m_endRegion = FoldingRegion(FoldingRegion::End, DefinitionData::get(m_def.definition())->foldingRegionId(regionName.toString()));

    auto result = doLoad(reader);

    if (m_lookAhead && m_context.isStay())
        result = false;

    // be done with this rule, skip all subelements, e.g. no longer supported sub-rules
    reader.skipCurrentElement();
    return result;
}

void Rule::resolveContext()
{
    m_context.resolve(m_def.definition());

    // cache for DefinitionData::wordDelimiters, is accessed VERY often
    m_wordDelimiter = &DefinitionData::get(m_def.definition())->wordDelimiters;
}

void Rule::resolveAttributeFormat(Context *lookupContext)
{
    /**
     * try to get our format from the definition we stem from
     */
    if (!m_attribute.isEmpty()) {
        m_attributeFormat = DefinitionData::get(definition())->formatByName(m_attribute);
        if (!m_attributeFormat.isValid()) {
            qCWarning(Log) << "Rule: Unknown format" << m_attribute << "in context" << lookupContext->name() << "of definition" << definition().name();
        }
    }
}

bool Rule::doLoad(QXmlStreamReader &reader)
{
    Q_UNUSED(reader);
    return true;
}

Rule::Ptr Rule::create(const QStringRef &name)
{
    Rule *rule = nullptr;
    if (name == QLatin1String("AnyChar"))
        rule = new AnyChar;
    else if (name == QLatin1String("DetectChar"))
        rule = new DetectChar;
    else if (name == QLatin1String("Detect2Chars"))
        rule = new Detect2Char;
    else if (name == QLatin1String("DetectIdentifier"))
        rule = new DetectIdentifier;
    else if (name == QLatin1String("DetectSpaces"))
        rule = new DetectSpaces;
    else if (name == QLatin1String("Float"))
        rule = new Float;
    else if (name == QLatin1String("Int"))
        rule = new Int;
    else if (name == QLatin1String("HlCChar"))
        rule = new HlCChar;
    else if (name == QLatin1String("HlCHex"))
        rule = new HlCHex;
    else if (name == QLatin1String("HlCOct"))
        rule = new HlCOct;
    else if (name == QLatin1String("HlCStringChar"))
        rule = new HlCStringChar;
    else if (name == QLatin1String("IncludeRules"))
        rule = new IncludeRules;
    else if (name == QLatin1String("keyword"))
        rule = new KeywordListRule;
    else if (name == QLatin1String("LineContinue"))
        rule = new LineContinue;
    else if (name == QLatin1String("RangeDetect"))
        rule = new RangeDetect;
    else if (name == QLatin1String("RegExpr"))
        rule = new RegExpr;
    else if (name == QLatin1String("StringDetect"))
        rule = new StringDetect;
    else if (name == QLatin1String("WordDetect"))
        rule = new WordDetect;
    else
        qCWarning(Log) << "Unknown rule type:" << name;

    return Ptr(rule);
}

bool Rule::isWordDelimiter(QChar c) const
{
    // perf tells contains is MUCH faster than binary search here, very short array
    return m_wordDelimiter.contains(c);
}

bool AnyChar::doLoad(QXmlStreamReader &reader)
{
    m_chars = reader.attributes().value(QStringLiteral("String")).toString();
    if (m_chars.size() == 1)
        qCDebug(Log) << "AnyChar rule with just one char: use DetectChar instead.";
    return !m_chars.isEmpty();
}

MatchResult AnyChar::doMatch(const QString &text, int offset, const QStringList &) const
{
    if (m_chars.contains(text.at(offset)))
        return offset + 1;
    return offset;
}

bool DetectChar::doLoad(QXmlStreamReader &reader)
{
    const auto s = reader.attributes().value(QStringLiteral("char"));
    if (s.isEmpty())
        return false;
    m_char = s.at(0);
    m_dynamic = Xml::attrToBool(reader.attributes().value(QStringLiteral("dynamic")));
    if (m_dynamic) {
        m_captureIndex = m_char.digitValue();
    }
    return true;
}

MatchResult DetectChar::doMatch(const QString &text, int offset, const QStringList &captures) const
{
    if (m_dynamic) {
        if (m_captureIndex == 0 || captures.size() <= m_captureIndex || captures.at(m_captureIndex).isEmpty())
            return offset;
        if (text.at(offset) == captures.at(m_captureIndex).at(0))
            return offset + 1;
        return offset;
    }

    if (text.at(offset) == m_char)
        return offset + 1;
    return offset;
}

bool Detect2Char::doLoad(QXmlStreamReader &reader)
{
    const auto s1 = reader.attributes().value(QStringLiteral("char"));
    const auto s2 = reader.attributes().value(QStringLiteral("char1"));
    if (s1.isEmpty() || s2.isEmpty())
        return false;
    m_char1 = s1.at(0);
    m_char2 = s2.at(0);
    return true;
}

MatchResult Detect2Char::doMatch(const QString &text, int offset, const QStringList &) const
{
    if (text.size() - offset < 2)
        return offset;
    if (text.at(offset) == m_char1 && text.at(offset + 1) == m_char2)
        return offset + 2;
    return offset;
}

MatchResult DetectIdentifier::doMatch(const QString &text, int offset, const QStringList &) const
{
    if (!text.at(offset).isLetter() && text.at(offset) != QLatin1Char('_'))
        return offset;

    for (int i = offset + 1; i < text.size(); ++i) {
        const auto c = text.at(i);
        if (!c.isLetterOrNumber() && c != QLatin1Char('_'))
            return i;
    }

    return text.size();
}

MatchResult DetectSpaces::doMatch(const QString &text, int offset, const QStringList &) const
{
    while (offset < text.size() && text.at(offset).isSpace())
        ++offset;
    return offset;
}

MatchResult Float::doMatch(const QString &text, int offset, const QStringList &) const
{
    if (offset > 0 && !isWordDelimiter(text.at(offset - 1)))
        return offset;

    auto newOffset = offset;
    while (newOffset < text.size() && text.at(newOffset).isDigit())
        ++newOffset;

    if (newOffset >= text.size() || text.at(newOffset) != QLatin1Char('.'))
        return offset;
    ++newOffset;

    while (newOffset < text.size() && text.at(newOffset).isDigit())
        ++newOffset;

    if (newOffset == offset + 1) // we only found a decimal point
        return offset;

    auto expOffset = newOffset;
    if (expOffset >= text.size() || (text.at(expOffset) != QLatin1Char('e') && text.at(expOffset) != QLatin1Char('E')))
        return newOffset;
    ++expOffset;

    if (expOffset < text.size() && (text.at(expOffset) == QLatin1Char('+') || text.at(expOffset) == QLatin1Char('-')))
        ++expOffset;
    bool foundExpDigit = false;
    while (expOffset < text.size() && text.at(expOffset).isDigit()) {
        ++expOffset;
        foundExpDigit = true;
    }

    if (!foundExpDigit)
        return newOffset;
    return expOffset;
}

MatchResult HlCChar::doMatch(const QString &text, int offset, const QStringList &) const
{
    if (text.size() < offset + 3)
        return offset;

    if (text.at(offset) != QLatin1Char('\'') || text.at(offset + 1) == QLatin1Char('\''))
        return offset;

    auto newOffset = matchEscapedChar(text, offset + 1);
    if (newOffset == offset + 1) {
        if (text.at(newOffset) == QLatin1Char('\\'))
            return offset;
        else
            ++newOffset;
    }
    if (newOffset >= text.size())
        return offset;

    if (text.at(newOffset) == QLatin1Char('\''))
        return newOffset + 1;

    return offset;
}

MatchResult HlCHex::doMatch(const QString &text, int offset, const QStringList &) const
{
    if (offset > 0 && !isWordDelimiter(text.at(offset - 1)))
        return offset;

    if (text.size() < offset + 3)
        return offset;

    if (text.at(offset) != QLatin1Char('0') || (text.at(offset + 1) != QLatin1Char('x') && text.at(offset + 1) != QLatin1Char('X')))
        return offset;

    if (!isHexChar(text.at(offset + 2)))
        return offset;

    offset += 3;
    while (offset < text.size() && isHexChar(text.at(offset)))
        ++offset;

    // TODO Kate matches U/L suffix, QtC does not?

    return offset;
}

MatchResult HlCOct::doMatch(const QString &text, int offset, const QStringList &) const
{
    if (offset > 0 && !isWordDelimiter(text.at(offset - 1)))
        return offset;

    if (text.size() < offset + 2)
        return offset;

    if (text.at(offset) != QLatin1Char('0'))
        return offset;

    if (!isOctalChar(text.at(offset + 1)))
        return offset;

    offset += 2;
    while (offset < text.size() && isOctalChar(text.at(offset)))
        ++offset;

    return offset;
}

MatchResult HlCStringChar::doMatch(const QString &text, int offset, const QStringList &) const
{
    return matchEscapedChar(text, offset);
}

QString IncludeRules::contextName() const
{
    return m_contextName;
}

QString IncludeRules::definitionName() const
{
    return m_defName;
}

bool IncludeRules::includeAttribute() const
{
    return m_includeAttribute;
}

bool IncludeRules::doLoad(QXmlStreamReader &reader)
{
    const auto s = reader.attributes().value(QLatin1String("context"));
#if QT_VERSION < QT_VERSION_CHECK(5, 15, 0)
    const auto split = s.split(QLatin1String("##"), QString::KeepEmptyParts);
#else
    const auto split = s.split(QLatin1String("##"), Qt::KeepEmptyParts);
#endif
    if (split.isEmpty())
        return false;
    m_contextName = split.at(0).toString();
    if (split.size() > 1)
        m_defName = split.at(1).toString();
    m_includeAttribute = Xml::attrToBool(reader.attributes().value(QLatin1String("includeAttrib")));

    return !m_contextName.isEmpty() || !m_defName.isEmpty();
}

MatchResult IncludeRules::doMatch(const QString &text, int offset, const QStringList &) const
{
    Q_UNUSED(text);
    qCWarning(Log) << "Unresolved include rule for" << m_contextName << "##" << m_defName;
    return offset;
}

MatchResult Int::doMatch(const QString &text, int offset, const QStringList &) const
{
    if (offset > 0 && !isWordDelimiter(text.at(offset - 1)))
        return offset;

    while (offset < text.size() && text.at(offset).isDigit())
        ++offset;
    return offset;
}

bool KeywordListRule::doLoad(QXmlStreamReader &reader)
{
    /**
     * get our keyword list, if not found => bail out
     */
    auto defData = DefinitionData::get(definition());
    m_keywordList = defData->keywordList(reader.attributes().value(QLatin1String("String")).toString());
    if (!m_keywordList) {
        return false;
    }

    /**
     * we might overwrite the case sensitivity
     * then we need to init the list for lookup of that sensitivity setting
     */
    if (reader.attributes().hasAttribute(QLatin1String("insensitive"))) {
        m_hasCaseSensitivityOverride = true;
        m_caseSensitivityOverride = Xml::attrToBool(reader.attributes().value(QLatin1String("insensitive"))) ? Qt::CaseInsensitive : Qt::CaseSensitive;
        m_keywordList->initLookupForCaseSensitivity(m_caseSensitivityOverride);
    } else {
        m_hasCaseSensitivityOverride = false;
    }

    return !m_keywordList->isEmpty();
}

MatchResult KeywordListRule::doMatch(const QString &text, int offset, const QStringList &) const
{
    auto newOffset = offset;
    while (text.size() > newOffset && !isWordDelimiter(text.at(newOffset)))
        ++newOffset;
    if (newOffset == offset)
        return offset;

    if (m_hasCaseSensitivityOverride) {
        if (m_keywordList->contains(text.midRef(offset, newOffset - offset), m_caseSensitivityOverride))
            return newOffset;
    } else {
        if (m_keywordList->contains(text.midRef(offset, newOffset - offset)))
            return newOffset;
    }

    // we don't match, but we can skip until newOffset as we can't start a keyword in-between
    return MatchResult(offset, newOffset);
}

bool LineContinue::doLoad(QXmlStreamReader &reader)
{
    const auto s = reader.attributes().value(QStringLiteral("char"));
    if (s.isEmpty())
        m_char = QLatin1Char('\\');
    else
        m_char = s.at(0);
    return true;
}

MatchResult LineContinue::doMatch(const QString &text, int offset, const QStringList &) const
{
    if (offset == text.size() - 1 && text.at(offset) == m_char)
        return offset + 1;
    return offset;
}

bool RangeDetect::doLoad(QXmlStreamReader &reader)
{
    const auto s1 = reader.attributes().value(QStringLiteral("char"));
    const auto s2 = reader.attributes().value(QStringLiteral("char1"));
    if (s1.isEmpty() || s2.isEmpty())
        return false;
    m_begin = s1.at(0);
    m_end = s2.at(0);
    return true;
}

MatchResult RangeDetect::doMatch(const QString &text, int offset, const QStringList &) const
{
    if (text.size() - offset < 2)
        return offset;
    if (text.at(offset) != m_begin)
        return offset;

    auto newOffset = offset + 1;
    while (newOffset < text.size()) {
        if (text.at(newOffset) == m_end)
            return newOffset + 1;
        ++newOffset;
    }
    return offset;
}

bool RegExpr::doLoad(QXmlStreamReader &reader)
{
    m_regexp.setPattern(reader.attributes().value(QStringLiteral("String")).toString());

    const auto isMinimal = Xml::attrToBool(reader.attributes().value(QStringLiteral("minimal")));
    const auto isCaseInsensitive = Xml::attrToBool(reader.attributes().value(QStringLiteral("insensitive")));
    m_regexp.setPatternOptions((isMinimal ? QRegularExpression::InvertedGreedinessOption : QRegularExpression::NoPatternOption) | (isCaseInsensitive ? QRegularExpression::CaseInsensitiveOption : QRegularExpression::NoPatternOption));

    // optimize the pattern for the non-dynamic case, we use them OFTEN
    m_dynamic = Xml::attrToBool(reader.attributes().value(QStringLiteral("dynamic")));
    if (!m_dynamic) {
        m_regexp.optimize();
    }

    // always using m_regexp.isValid() would be better, but parses the regexp and thus is way too expensive for release builds

    if (Log().isDebugEnabled()) {
        if (!m_regexp.isValid())
            qCDebug(Log) << "Invalid regexp:" << m_regexp.pattern();
    }
    return !m_regexp.pattern().isEmpty();
}

MatchResult RegExpr::doMatch(const QString &text, int offset, const QStringList &captures) const
{
    /**
     * for dynamic case: create new pattern with right instantiation
     */
    const auto &regexp = m_dynamic ? QRegularExpression(replaceCaptures(m_regexp.pattern(), captures, true), m_regexp.patternOptions()) : m_regexp;

    /**
     * match the pattern
     */
    const auto result = regexp.match(text, offset, QRegularExpression::NormalMatch, QRegularExpression::DontCheckSubjectStringMatchOption);
    if (result.capturedStart() == offset) {
        /**
         * we only need to compute the captured texts if we have real capture groups
         * highlightings should only address %1..%.., see e.g. replaceCaptures
         * DetectChar ignores %0, too
         */
        if (result.lastCapturedIndex() > 0) {
            return MatchResult(offset + result.capturedLength(), result.capturedTexts());
        }

        /**
         * else: ignore the implicit 0 group we always capture, no need to allocate stuff for that
         */
        return MatchResult(offset + result.capturedLength());
    }

    /**
     * no match
     * the pattern of a dynamic regex depends on the previous contexts
     * so that skipOffset cannot be computed
     */
    return MatchResult(offset, m_dynamic ? 0 : result.capturedStart());
}

bool StringDetect::doLoad(QXmlStreamReader &reader)
{
    m_string = reader.attributes().value(QStringLiteral("String")).toString();
    m_caseSensitivity = Xml::attrToBool(reader.attributes().value(QStringLiteral("insensitive"))) ? Qt::CaseInsensitive : Qt::CaseSensitive;
    m_dynamic = Xml::attrToBool(reader.attributes().value(QStringLiteral("dynamic")));
    return !m_string.isEmpty();
}

MatchResult StringDetect::doMatch(const QString &text, int offset, const QStringList &captures) const
{
    /**
     * for dynamic case: create new pattern with right instantiation
     */
    const auto &pattern = m_dynamic ? replaceCaptures(m_string, captures, false) : m_string;

    if (text.midRef(offset, pattern.size()).compare(pattern, m_caseSensitivity) == 0)
        return offset + pattern.size();
    return offset;
}

bool WordDetect::doLoad(QXmlStreamReader &reader)
{
    m_word = reader.attributes().value(QStringLiteral("String")).toString();
    m_caseSensitivity = Xml::attrToBool(reader.attributes().value(QStringLiteral("insensitive"))) ? Qt::CaseInsensitive : Qt::CaseSensitive;
    return !m_word.isEmpty();
}

MatchResult WordDetect::doMatch(const QString &text, int offset, const QStringList &) const
{
    if (text.size() - offset < m_word.size())
        return offset;

    /**
     * detect delimiter characters on the inner and outer boundaries of the string
     * NOTE: m_word isn't empty
     */
    if (offset > 0 && !isWordDelimiter(text.at(offset - 1)) && !isWordDelimiter(text.at(offset)))
        return offset;

    if (text.midRef(offset, m_word.size()).compare(m_word, m_caseSensitivity) != 0)
        return offset;

    if (text.size() == offset + m_word.size() || isWordDelimiter(text.at(offset + m_word.size())) || isWordDelimiter(text.at(offset + m_word.size() - 1)))
        return offset + m_word.size();

    return offset;
}
