#include "gschighlighter.h"

GSCHighlighter::GSCHighlighter(QTextDocument *aParent)
    : QSyntaxHighlighter(aParent)
{
    HighlightingRule rule;

    keywordFormat.setForeground(Qt::darkCyan);
    keywordFormat.setFontWeight(QFont::Bold);

    // TODO: Tailor these to GSC
    const QString keywordPatterns[] = {
        QStringLiteral("\\bchar\\b"), QStringLiteral("\\bclass\\b"), QStringLiteral("\\bconst\\b"),
        QStringLiteral("\\bdouble\\b"), QStringLiteral("\\benum\\b"), QStringLiteral("\\bexplicit\\b"),
        QStringLiteral("\\bfriend\\b"), QStringLiteral("\\binline\\b"), QStringLiteral("\\bint\\b"),
        QStringLiteral("\\blong\\b"), QStringLiteral("\\bnamespace\\b"), QStringLiteral("\\boperator\\b"),
        QStringLiteral("\\bprivate\\b"), QStringLiteral("\\bprotected\\b"), QStringLiteral("\\bpublic\\b"),
        QStringLiteral("\\bshort\\b"), QStringLiteral("\\bsignals\\b"), QStringLiteral("\\bsigned\\b"),
        QStringLiteral("\\bslots\\b"), QStringLiteral("\\bstatic\\b"), QStringLiteral("\\bstruct\\b"),
        QStringLiteral("\\btemplate\\b"), QStringLiteral("\\btypedef\\b"), QStringLiteral("\\btypename\\b"),
        QStringLiteral("\\bunion\\b"), QStringLiteral("\\bunsigned\\b"), QStringLiteral("\\bvirtual\\b"),
        QStringLiteral("\\bvoid\\b"), QStringLiteral("\\bvolatile\\b"), QStringLiteral("\\bbool\\b")
    };

    for (const QString &pattern : keywordPatterns) {
        rule.pattern = QRegularExpression(pattern);
        rule.format = keywordFormat;
        highlightingRules.append(rule);
    }

    classFormat.setFontWeight(QFont::Bold);
    classFormat.setForeground(Qt::darkMagenta);
    rule.pattern = QRegularExpression(QStringLiteral("\\bQ[A-Za-z]+\\b"));
    rule.format = classFormat;
    highlightingRules.append(rule);

    quotationFormat.setForeground(Qt::darkGreen);
    rule.pattern = QRegularExpression(QStringLiteral("\".*\""));
    rule.format = quotationFormat;
    highlightingRules.append(rule);

    functionFormat.setFontItalic(true);
    functionFormat.setForeground(Qt::cyan);
    rule.pattern = QRegularExpression(QStringLiteral("\\b[A-Za-z0-9_]+(?=\\()"));
    rule.format = functionFormat;
    highlightingRules.append(rule);

    singleLineCommentFormat.setForeground(Qt::red);
    rule.pattern = QRegularExpression(QStringLiteral("//[^\n]*"));
    rule.format = singleLineCommentFormat;
    highlightingRules.append(rule);

    multiLineCommentFormat.setForeground(Qt::red);

    commentStartExpressionA = QRegularExpression(QStringLiteral("/\\*"));
    commentEndExpressionA = QRegularExpression(QStringLiteral("\\*/"));
    commentStartExpressionB = QRegularExpression(QStringLiteral("/@"));
    commentEndExpressionB = QRegularExpression(QStringLiteral("@/"));
}

void GSCHighlighter::highlightCommentBlock(const QString& aText, const QRegularExpression& aStartExp, const QRegularExpression& aEndExp)
{
    setCurrentBlockState(0);

    int startIndex = 0;
    if (previousBlockState() != 1)
    {
        startIndex = aText.indexOf(aStartExp);
    }

    while (startIndex >= 0)
    {
        QRegularExpressionMatch match = aEndExp.match(aText, startIndex);
        int endIndex = match.capturedStart();
        int commentLength = 0;
        if (endIndex == -1)
        {
            setCurrentBlockState(1);
            commentLength = aText.length() - startIndex;
        }
        else
        {
            commentLength = endIndex - startIndex + match.capturedLength();
        }
        setFormat(startIndex, commentLength, multiLineCommentFormat);
        startIndex = aText.indexOf(aStartExp, startIndex + commentLength);
    }
}

void GSCHighlighter::highlightBlock(const QString& aText)
{
    // Highlight regular rules
    for (const HighlightingRule &rule : std::as_const(highlightingRules))
    {
        QRegularExpressionMatchIterator matchIterator = rule.pattern.globalMatch(aText);
        while (matchIterator.hasNext())
        {
            QRegularExpressionMatch match = matchIterator.next();
            setFormat(match.capturedStart(), match.capturedLength(), rule.format);
        }
    }

    // Highlight comment blocks
    highlightCommentBlock(aText, commentStartExpressionA, commentEndExpressionA);
    highlightCommentBlock(aText, commentStartExpressionB, commentEndExpressionB);
}