/****************************************************************************
**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtDeclarative module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** GNU Lesser General Public License Usage
** This file may be used under the terms of the GNU Lesser General Public
** License version 2.1 as published by the Free Software Foundation and
** appearing in the file LICENSE.LGPL included in the packaging of this
** file. Please review the following information to ensure the GNU Lesser
** General Public License version 2.1 requirements will be met:
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU General
** Public License version 3.0 as published by the Free Software Foundation
** and appearing in the file LICENSE.GPL included in the packaging of this
** file. Please review the following information to ensure the GNU General
** Public License version 3.0 requirements will be met:
** http://www.gnu.org/copyleft/gpl.html.
**
** Other Usage
** Alternatively, this file may be used in accordance with the terms and
** conditions contained in a signed written agreement between you and Nokia.
**
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**
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include <QStack>
#include <QVector>
#include <QPainter>
#include <QTextLayout>
#include <QDebug>
#include <qmath.h>
#include "qdeclarativestyledtext_p.h"

/*
    QDeclarativeStyledText supports few tags:

    <b></b> - bold
    <i></i> - italic
    <br> - new line
    <p> - paragraph
    <u> - underlined text
    <font color="color_name" size="1-7"></font>
    <h1> to <h6> - headers
    <a href=""> - anchor
    <ol type="">, <ul type=""> and <li> - ordered and unordered lists

    The opening and closing tags must be correctly nested.
*/

QT_BEGIN_NAMESPACE

class QDeclarativeStyledTextPrivate
{
public:
    enum ListType { Ordered, Unordered };
    enum ListFormat { Bullet, Disc, Square, Decimal, LowerAlpha, UpperAlpha, LowerRoman, UpperRoman };

    struct List {
        int level;
        ListType type;
        ListFormat format;
    };

    QDeclarativeStyledTextPrivate(const QString &t, QTextLayout &l)
        : text(t), layout(l), baseFont(layout.font()), hasNewLine(false)
    {
    }

    void parse();
    bool parseTag(const QChar *&ch, const QString &textIn, QString &textOut, QTextCharFormat &format);
    bool parseCloseTag(const QChar *&ch, const QString &textIn, QString &textOut);
    void parseEntity(const QChar *&ch, const QString &textIn, QString &textOut);
    bool parseFontAttributes(const QChar *&ch, const QString &textIn, QTextCharFormat &format);
    bool parseOrderedListAttributes(const QChar *&ch, const QString &textIn);
    bool parseUnorderedListAttributes(const QChar *&ch, const QString &textIn);
    bool parseAnchorAttributes(const QChar *&ch, const QString &textIn, QTextCharFormat &format);
    QPair<QStringRef,QStringRef> parseAttribute(const QChar *&ch, const QString &textIn);
    QStringRef parseValue(const QChar *&ch, const QString &textIn);

    inline void skipSpace(const QChar *&ch) {
        while (ch->isSpace() && !ch->isNull())
            ++ch;
    }

    static QString toAlpha(int value, bool upper);
    static QString toRoman(int value, bool upper);

    QString text;
    QTextLayout &layout;
    QFont baseFont;
    QStack<List> listStack;
    bool hasNewLine;

    static const QChar lessThan;
    static const QChar greaterThan;
    static const QChar equals;
    static const QChar singleQuote;
    static const QChar doubleQuote;
    static const QChar slash;
    static const QChar ampersand;
    static const QChar bullet;
    static const QChar disc;
    static const QChar square;
    static const int tabsize = 6;
};

const QChar QDeclarativeStyledTextPrivate::lessThan(QLatin1Char('<'));
const QChar QDeclarativeStyledTextPrivate::greaterThan(QLatin1Char('>'));
const QChar QDeclarativeStyledTextPrivate::equals(QLatin1Char('='));
const QChar QDeclarativeStyledTextPrivate::singleQuote(QLatin1Char('\''));
const QChar QDeclarativeStyledTextPrivate::doubleQuote(QLatin1Char('\"'));
const QChar QDeclarativeStyledTextPrivate::slash(QLatin1Char('/'));
const QChar QDeclarativeStyledTextPrivate::ampersand(QLatin1Char('&'));
const QChar QDeclarativeStyledTextPrivate::bullet(0x2022);
const QChar QDeclarativeStyledTextPrivate::disc(0x25e6);
const QChar QDeclarativeStyledTextPrivate::square(0x25a1);

QDeclarativeStyledText::QDeclarativeStyledText(const QString &string, QTextLayout &layout)
: d(new QDeclarativeStyledTextPrivate(string, layout))
{
}

QDeclarativeStyledText::~QDeclarativeStyledText()
{
    delete d;
}

void QDeclarativeStyledText::parse(const QString &string, QTextLayout &layout)
{
    if (string.isEmpty())
        return;
    QDeclarativeStyledText styledText(string, layout);
    styledText.d->parse();
}

void QDeclarativeStyledTextPrivate::parse()
{
    QList<QTextLayout::FormatRange> ranges;
    QStack<QTextCharFormat> formatStack;

    QString drawText;
    drawText.reserve(text.count());

    int textStart = 0;
    int textLength = 0;
    int rangeStart = 0;
    const QChar *ch = text.constData();
    while (!ch->isNull()) {
        if (*ch == lessThan) {
            if (textLength) {
                QStringRef ref = QStringRef(&text, textStart, textLength);
                const QChar *c = ref.constData();
                bool isWhiteSpace = true;
                for (int i = 0; isWhiteSpace && (i < textLength); ++c, ++i) {
                    if (!c->isSpace())
                        isWhiteSpace = false;
                }
                if (!isWhiteSpace) {
                    drawText.append(ref);
                    hasNewLine = false;
                }
            }
            if (rangeStart != drawText.length() && formatStack.count()) {
                QTextLayout::FormatRange formatRange;
                formatRange.format = formatStack.top();
                formatRange.start = rangeStart;
                formatRange.length = drawText.length() - rangeStart;
                ranges.append(formatRange);
            }
            rangeStart = drawText.length();
            ++ch;
            if (*ch == slash) {
                ++ch;
                if (parseCloseTag(ch, text, drawText)) {
                    if (formatStack.count())
                        formatStack.pop();
                }
            } else {
                QTextCharFormat format;
                if (formatStack.count())
                    format = formatStack.top();
                if (parseTag(ch, text, drawText, format))
                    formatStack.push(format);
            }
            textStart = ch - text.constData() + 1;
            textLength = 0;
        } else if (*ch == ampersand) {
            ++ch;
            drawText.append(QStringRef(&text, textStart, textLength));
            parseEntity(ch, text, drawText);
            textStart = ch - text.constData() + 1;
            textLength = 0;
        } else {
            ++textLength;
        }
        if (!ch->isNull())
            ++ch;
    }
    if (textLength)
        drawText.append(QStringRef(&text, textStart, textLength));
    if (rangeStart != drawText.length() && formatStack.count()) {
        QTextLayout::FormatRange formatRange;
        formatRange.format = formatStack.top();
        formatRange.start = rangeStart;
        formatRange.length = drawText.length() - rangeStart;
        ranges.append(formatRange);
    }

    layout.setText(drawText);
    layout.setAdditionalFormats(ranges);
}

bool QDeclarativeStyledTextPrivate::parseTag(const QChar *&ch, const QString &textIn, QString &textOut, QTextCharFormat &format)
{
    skipSpace(ch);

    int tagStart = ch - textIn.constData();
    int tagLength = 0;
    while (!ch->isNull()) {
        if (*ch == greaterThan) {
            if (tagLength == 0)
                return false;
            QStringRef tag(&textIn, tagStart, tagLength);
            const QChar char0 = tag.at(0);
            if (char0 == QLatin1Char('b')) {
                if (tagLength == 1)
                    format.setFontWeight(QFont::Bold);
                else if (tagLength == 2 && tag.at(1) == QLatin1Char('r')) {
                    textOut.append(QChar(QChar::LineSeparator));
                    return false;
                }
            } else if (char0 == QLatin1Char('i')) {
                if (tagLength == 1)
                    format.setFontItalic(true);
            } else if (char0 == QLatin1Char('p')) {
                if (tagLength == 1) {
                    if (!hasNewLine)
                        textOut.append(QChar::LineSeparator);
                }
            } else if (char0 == QLatin1Char('u')) {
                if (tagLength == 1)
                    format.setFontUnderline(true);
                else if (tag == QLatin1String("ul")) {
                    List listItem;
                    listItem.level = 0;
                    listItem.type = Unordered;
                    listItem.format = Bullet;
                    listStack.push(listItem);
                }
            } else if (char0 == QLatin1Char('h') && tagLength == 2) {
                int level = tag.at(1).digitValue();
                if (level >= 1 && level <= 6) {
                    static const qreal scaling[] = { 2.0, 1.5, 1.2, 1.0, 0.8, 0.7 };
                    if (!hasNewLine)
                        textOut.append(QChar::LineSeparator);
                    format.setFontPointSize(baseFont.pointSize() * scaling[level - 1]);
                    format.setFontWeight(QFont::Bold);
                }
            } else if (tag == QLatin1String("ol")) {
                List listItem;
                listItem.level = 0;
                listItem.type = Ordered;
                listItem.format = Decimal;
                listStack.push(listItem);
            } else if (tag == QLatin1String("li")) {
                if (!hasNewLine)
                    textOut.append(QChar(QChar::LineSeparator));
                if (!listStack.isEmpty()) {
                    int count = ++listStack.top().level;
                    for (int i = 0; i < listStack.size(); ++i)
                        textOut += QString(tabsize, QChar::Nbsp);
                    switch (listStack.top().format) {
                    case Decimal:
                        textOut += QString::number(count) % QLatin1Char('.');
                        break;
                    case LowerAlpha:
                        textOut += toAlpha(count, false) % QLatin1Char('.');
                        break;
                    case UpperAlpha:
                        textOut += toAlpha(count, true) % QLatin1Char('.');
                        break;
                    case LowerRoman:
                        textOut += toRoman(count, false) % QLatin1Char('.');
                        break;
                    case UpperRoman:
                        textOut += toRoman(count, true) % QLatin1Char('.');
                        break;
                    case Bullet:
                        textOut += bullet;
                        break;
                    case Disc:
                        textOut += disc;
                        break;
                    case Square:
                        textOut += square;
                        break;
                    }
                    textOut += QString(2, QChar::Nbsp);
                }
            }
            return true;
        } else if (ch->isSpace()) {
            // may have params.
            QStringRef tag(&textIn, tagStart, tagLength);
            if (tag == QLatin1String("font"))
                return parseFontAttributes(ch, textIn, format);
            if (tag == QLatin1String("ol"))
                return parseOrderedListAttributes(ch, textIn);
            if (tag == QLatin1String("ul"))
                return parseUnorderedListAttributes(ch, textIn);
            if (tag == QLatin1String("a")) {
                return parseAnchorAttributes(ch, textIn, format);
            }
            if (*ch == greaterThan || ch->isNull())
                continue;
        } else if (*ch != slash) {
            tagLength++;
        }
        ++ch;
    }
    return false;
}

bool QDeclarativeStyledTextPrivate::parseCloseTag(const QChar *&ch, const QString &textIn, QString &textOut)
{
    skipSpace(ch);

    int tagStart = ch - textIn.constData();
    int tagLength = 0;
    while (!ch->isNull()) {
        if (*ch == greaterThan) {
            if (tagLength == 0)
                return false;
            QStringRef tag(&textIn, tagStart, tagLength);
            const QChar char0 = tag.at(0);
            hasNewLine = false;
            if (char0 == QLatin1Char('b')) {
                if (tagLength == 1)
                    return true;
                else if (tag.at(1) == QLatin1Char('r') && tagLength == 2)
                    return true;
            } else if (char0 == QLatin1Char('i')) {
                if (tagLength == 1)
                    return true;
            } else if (char0 == QLatin1Char('a')) {
                if (tagLength == 1)
                    return true;
            } else if (char0 == QLatin1Char('p')) {
                if (tagLength == 1) {
                    textOut.append(QChar::LineSeparator);
                    hasNewLine = true;
                    return true;
                }
            } else if (char0 == QLatin1Char('u')) {
                if (tagLength == 1)
                    return true;
                else if (tag == QLatin1String("ul")) {
                    if (!listStack.isEmpty()) {
                        listStack.pop();
                        if (!listStack.count())
                            textOut.append(QChar::LineSeparator);
                    }
                    return true;
                }
            } else if (char0 == QLatin1Char('h') && tagLength == 2) {
                textOut.append(QChar::LineSeparator);
                hasNewLine = true;
                return true;
            } else if (tag == QLatin1String("font")) {
                return true;
            } else if (tag == QLatin1String("ol")) {
                if (!listStack.isEmpty()) {
                    listStack.pop();
                    if (!listStack.count())
                        textOut.append(QChar::LineSeparator);
                }
                return true;
            } else if (tag == QLatin1String("li")) {
                return true;
            }
            return false;
        } else if (!ch->isSpace()){
            tagLength++;
        }
        ++ch;
    }

    return false;
}

void QDeclarativeStyledTextPrivate::parseEntity(const QChar *&ch, const QString &textIn, QString &textOut)
{
    int entityStart = ch - textIn.constData();
    int entityLength = 0;
    while (!ch->isNull()) {
        if (*ch == QLatin1Char(';')) {
            QStringRef entity(&textIn, entityStart, entityLength);
            if (entity == QLatin1String("gt"))
                textOut += QChar(62);
            else if (entity == QLatin1String("lt"))
                textOut += QChar(60);
            else if (entity == QLatin1String("amp"))
                textOut += QChar(38);
            return;
        }
        ++entityLength;
        ++ch;
    }
}

bool QDeclarativeStyledTextPrivate::parseFontAttributes(const QChar *&ch, const QString &textIn, QTextCharFormat &format)
{
    bool valid = false;
    QPair<QStringRef,QStringRef> attr;
    do {
        attr = parseAttribute(ch, textIn);
        if (attr.first == QLatin1String("color")) {
            valid = true;
            format.setForeground(QColor(attr.second.toString()));
        } else if (attr.first == QLatin1String("size")) {
            valid = true;
            int size = attr.second.toString().toInt();
            if (attr.second.at(0) == QLatin1Char('-') || attr.second.at(0) == QLatin1Char('+'))
                size += 3;
            if (size >= 1 && size <= 7) {
                static const qreal scaling[] = { 0.7, 0.8, 1.0, 1.2, 1.5, 2.0, 2.4 };
                format.setFontPointSize(baseFont.pointSize() * scaling[size-1]);
            }
        }
    } while (!ch->isNull() && !attr.first.isEmpty());

    return valid;
}

bool QDeclarativeStyledTextPrivate::parseOrderedListAttributes(const QChar *&ch, const QString &textIn)
{
    bool valid = false;

    List listItem;
    listItem.level = 0;
    listItem.type = Ordered;
    listItem.format = Decimal;

    QPair<QStringRef,QStringRef> attr;
    do {
        attr = parseAttribute(ch, textIn);
        if (attr.first == QLatin1String("type")) {
            valid = true;
            if (attr.second == QLatin1String("a"))
                listItem.format = LowerAlpha;
            else if (attr.second == QLatin1String("A"))
                listItem.format = UpperAlpha;
            else if (attr.second == QLatin1String("i"))
                listItem.format = LowerRoman;
            else if (attr.second == QLatin1String("I"))
                listItem.format = UpperRoman;
        }
    } while (!ch->isNull() && !attr.first.isEmpty());

    listStack.push(listItem);
    return valid;
}

bool QDeclarativeStyledTextPrivate::parseUnorderedListAttributes(const QChar *&ch, const QString &textIn)
{
    bool valid = false;

    List listItem;
    listItem.level = 0;
    listItem.type = Unordered;
    listItem.format = Bullet;

    QPair<QStringRef,QStringRef> attr;
    do {
        attr = parseAttribute(ch, textIn);
        if (attr.first == QLatin1String("type")) {
            valid = true;
            if (attr.second == QLatin1String("disc"))
                listItem.format = Disc;
            else if (attr.second == QLatin1String("square"))
                listItem.format = Square;
        }
    } while (!ch->isNull() && !attr.first.isEmpty());

    listStack.push(listItem);
    return valid;
}

bool QDeclarativeStyledTextPrivate::parseAnchorAttributes(const QChar *&ch, const QString &textIn, QTextCharFormat &format)
{
    bool valid = false;

    QPair<QStringRef,QStringRef> attr;
    do {
        attr = parseAttribute(ch, textIn);
        if (attr.first == QLatin1String("href")) {
            format.setAnchorHref(attr.second.toString());
            format.setAnchor(true);
            format.setFontUnderline(true);
            format.setForeground(QColor("blue"));
            valid = true;
        }
    } while (!ch->isNull() && !attr.first.isEmpty());

    return valid;
}

QPair<QStringRef,QStringRef> QDeclarativeStyledTextPrivate::parseAttribute(const QChar *&ch, const QString &textIn)
{
    skipSpace(ch);

    int attrStart = ch - textIn.constData();
    int attrLength = 0;
    while (!ch->isNull()) {
        if (*ch == greaterThan) {
            break;
        } else if (*ch == equals) {
            ++ch;
            if (*ch != singleQuote && *ch != doubleQuote) {
                while (*ch != greaterThan && !ch->isNull())
                    ++ch;
                break;
            }
            ++ch;
            if (!attrLength)
                break;
            QStringRef attr(&textIn, attrStart, attrLength);
            QStringRef val = parseValue(ch, textIn);
            if (!val.isEmpty())
                return QPair<QStringRef,QStringRef>(attr,val);
            break;
        } else {
            ++attrLength;
        }
        ++ch;
    }

    return QPair<QStringRef,QStringRef>();
}

QStringRef QDeclarativeStyledTextPrivate::parseValue(const QChar *&ch, const QString &textIn)
{
    int valStart = ch - textIn.constData();
    int valLength = 0;
    while (*ch != singleQuote && *ch != doubleQuote && !ch->isNull()) {
        ++valLength;
        ++ch;
    }
    if (ch->isNull())
        return QStringRef();
    ++ch; // skip quote

    return QStringRef(&textIn, valStart, valLength);
}

QString QDeclarativeStyledTextPrivate::toAlpha(int value, bool upper)
{
    const char baseChar = upper ? 'A' : 'a';

    QString result;
    int c = value;
    while (c > 0) {
        c--;
        result.prepend(QChar(baseChar + (c % 26)));
        c /= 26;
    }
    return result;
}

QString QDeclarativeStyledTextPrivate::toRoman(int value, bool upper)
{
    QString result = QLatin1String("?");
    // works for up to 4999 items
    if (value < 5000) {
        QByteArray romanNumeral;

        static const char romanSymbolsLower[] = "iiivixxxlxcccdcmmmm";
        static const char romanSymbolsUpper[] = "IIIVIXXXLXCCCDCMMMM";
        QByteArray romanSymbols;
        if (!upper)
            romanSymbols = QByteArray::fromRawData(romanSymbolsLower, sizeof(romanSymbolsLower));
        else
            romanSymbols = QByteArray::fromRawData(romanSymbolsUpper, sizeof(romanSymbolsUpper));

        int c[] = { 1, 4, 5, 9, 10, 40, 50, 90, 100, 400, 500, 900, 1000 };
        int n = value;
        for (int i = 12; i >= 0; n %= c[i], i--) {
            int q = n / c[i];
            if (q > 0) {
                int startDigit = i + (i + 3) / 4;
                int numDigits;
                if (i % 4) {
                    if ((i - 2) % 4)
                        numDigits = 2;
                    else
                        numDigits = 1;
                }
                else
                    numDigits = q;
                romanNumeral.append(romanSymbols.mid(startDigit, numDigits));
            }
        }
        result = QString::fromLatin1(romanNumeral);
    }
    return result;
}

QT_END_NAMESPACE