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#include "ansiescapecodehandler.h"
#include <utils/qtcassert.h>

namespace Utils {

/*!
    \class Utils::AnsiEscapeCodeHandler

    \brief The AnsiEscapeCodeHandler class parses text and extracts ANSI escape codes from it.

    In order to preserve color information across text segments, an instance of this class
    must be stored for the lifetime of a stream.
    Also, one instance of this class should not handle multiple streams (at least not
    at the same time).

    Its main function is parseText(), which accepts text and default QTextCharFormat.
    This function is designed to parse text and split colored text to smaller strings,
    with their appropriate formatting information set inside QTextCharFormat.

    Usage:
    \list
    \li Create new instance of AnsiEscapeCodeHandler for a stream.
    \li To add new text, call parseText() with the text and a default QTextCharFormat.
        The result of this function is a list of strings with formats set in appropriate
        QTextCharFormat.
    \endlist
*/

AnsiEscapeCodeHandler::AnsiEscapeCodeHandler() :
    m_previousFormatClosed(true)
{
}

static QColor ansiColor(uint code)
{
    QTC_ASSERT(code < 8, return QColor());

    const int red   = code & 1 ? 170 : 0;
    const int green = code & 2 ? 170 : 0;
    const int blue  = code & 4 ? 170 : 0;
    return QColor(red, green, blue);
}

QList<FormattedText> AnsiEscapeCodeHandler::parseText(const FormattedText &input)
{
    enum AnsiEscapeCodes {
        ResetFormat            =  0,
        BoldText               =  1,
        TextColorStart         = 30,
        TextColorEnd           = 37,
        RgbTextColor           = 38,
        DefaultTextColor       = 39,
        BackgroundColorStart   = 40,
        BackgroundColorEnd     = 47,
        RgbBackgroundColor     = 48,
        DefaultBackgroundColor = 49
    };

    QList<FormattedText> outputData;

    QTextCharFormat charFormat = m_previousFormatClosed ? input.format : m_previousFormat;

    const QString escape = QLatin1String("\x1b[");
    const int escapePos = input.text.indexOf(escape);
    if (escapePos < 0) {
        outputData << FormattedText(input.text, charFormat);
        return outputData;
    } else if (escapePos != 0) {
        outputData << FormattedText(input.text.left(escapePos), charFormat);
    }

    const QChar semicolon       = QLatin1Char(';');
    const QChar colorTerminator = QLatin1Char('m');
    // strippedText always starts with "\e["
    QString strippedText = input.text.mid(escapePos);
    while (!strippedText.isEmpty()) {
        while (strippedText.startsWith(escape)) {
            strippedText.remove(0, 2);

            // get the number
            QString strNumber;
            QStringList numbers;
            while (strippedText.at(0).isDigit() || strippedText.at(0) == semicolon) {
                if (strippedText.at(0).isDigit()) {
                    strNumber += strippedText.at(0);
                } else {
                    numbers << strNumber;
                    strNumber.clear();
                }
                strippedText.remove(0, 1);
            }
            if (!strNumber.isEmpty())
                numbers << strNumber;

            // remove terminating char
            if (!strippedText.startsWith(colorTerminator)) {
                strippedText.remove(0, 1);
                continue;
            }
            strippedText.remove(0, 1);

            if (numbers.isEmpty()) {
                charFormat = input.format;
                endFormatScope();
            }

            for (int i = 0; i < numbers.size(); ++i) {
                const int code = numbers.at(i).toInt();

                if (code >= TextColorStart && code <= TextColorEnd) {
                    charFormat.setForeground(ansiColor(code - TextColorStart));
                    setFormatScope(charFormat);
                } else if (code >= BackgroundColorStart && code <= BackgroundColorEnd) {
                    charFormat.setBackground(ansiColor(code - BackgroundColorStart));
                    setFormatScope(charFormat);
                } else {
                    switch (code) {
                    case ResetFormat:
                        charFormat = input.format;
                        endFormatScope();
                        break;
                    case BoldText:
                        charFormat.setFontWeight(QFont::Bold);
                        setFormatScope(charFormat);
                        break;
                    case DefaultTextColor:
                        charFormat.setForeground(input.format.foreground());
                        setFormatScope(charFormat);
                        break;
                    case DefaultBackgroundColor:
                        charFormat.setBackground(input.format.background());
                        setFormatScope(charFormat);
                        break;
                    case RgbTextColor:
                    case RgbBackgroundColor:
                        if (++i >= numbers.size())
                            break;
                        if (numbers.at(i).toInt() == 2) {
                            // RGB set with format: 38;2;<r>;<g>;<b>
                            if ((i + 3) < numbers.size()) {
                                (code == RgbTextColor) ?
                                      charFormat.setForeground(QColor(numbers.at(i + 1).toInt(),
                                                                      numbers.at(i + 2).toInt(),
                                                                      numbers.at(i + 3).toInt())) :
                                      charFormat.setBackground(QColor(numbers.at(i + 1).toInt(),
                                                                      numbers.at(i + 2).toInt(),
                                                                      numbers.at(i + 3).toInt()));
                                setFormatScope(charFormat);
                            }
                            i += 3;
                        } else if (numbers.at(i).toInt() == 5) {
                            // rgb set with format: 38;5;<i>
                            // unsupported because of unclear documentation, so we just skip <i>
                            ++i;
                        }
                        break;
                    default:
                        break;
                    }
                }
            }
        }

        if (strippedText.isEmpty())
            break;
        int index = strippedText.indexOf(escape);
        if (index > 0) {
            outputData << FormattedText(strippedText.left(index), charFormat);
            strippedText.remove(0, index);
        } else if (index == -1) {
            outputData << FormattedText(strippedText, charFormat);
            break;
        }
    }
    return outputData;
}

void AnsiEscapeCodeHandler::endFormatScope()
{
    m_previousFormatClosed = true;
}

void AnsiEscapeCodeHandler::setFormatScope(const QTextCharFormat &charFormat)
{
    m_previousFormat = charFormat;
    m_previousFormatClosed = false;
}

} // namespace Utils