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

    This program is free software; you can redistribute it and/or modify it
    under the terms of the GNU Library General Public License as published by
    the Free Software Foundation; either version 2 of the License, or (at your
    option) any later version.

    This program is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
    License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "syntaxhighlighter.h"
#include "abstracthighlighter_p.h"
#include "definition.h"
#include "foldingregion.h"
#include "format.h"
#include "state.h"
#include "theme.h"

#include <QDebug>

Q_DECLARE_METATYPE(QTextBlock)

using namespace KSyntaxHighlighting;

namespace KSyntaxHighlighting {
class TextBlockUserData : public QTextBlockUserData
{
public:
    State state;
    QVector<FoldingRegion> foldingRegions;
};

class SyntaxHighlighterPrivate : public AbstractHighlighterPrivate
{
public:
    static FoldingRegion foldingRegion(const QTextBlock &startBlock);
    QVector<FoldingRegion> foldingRegions;
};

}

FoldingRegion SyntaxHighlighterPrivate::foldingRegion(const QTextBlock& startBlock)
{
    const auto data = dynamic_cast<TextBlockUserData*>(startBlock.userData());
    if (!data)
        return FoldingRegion();
    for (int i = data->foldingRegions.size() - 1; i >= 0; --i) {
        if (data->foldingRegions.at(i).type() == FoldingRegion::Begin)
            return data->foldingRegions.at(i);
    }
    return FoldingRegion();
}

SyntaxHighlighter::SyntaxHighlighter(QObject* parent) :
    QSyntaxHighlighter(parent),
    AbstractHighlighter(new SyntaxHighlighterPrivate)
{
    qRegisterMetaType<QTextBlock>();
}

SyntaxHighlighter::SyntaxHighlighter(QTextDocument *document) :
    QSyntaxHighlighter(document),
    AbstractHighlighter(new SyntaxHighlighterPrivate)
{
    qRegisterMetaType<QTextBlock>();
}

SyntaxHighlighter::~SyntaxHighlighter()
{
}

void SyntaxHighlighter::setDefinition(const Definition& def)
{
    const auto needsRehighlight = definition() != def;
    AbstractHighlighter::setDefinition(def);
    if (needsRehighlight)
        rehighlight();
}

bool SyntaxHighlighter::startsFoldingRegion(const QTextBlock &startBlock) const
{
    return SyntaxHighlighterPrivate::foldingRegion(startBlock).type() == FoldingRegion::Begin;
}

QTextBlock SyntaxHighlighter::findFoldingRegionEnd(const QTextBlock &startBlock) const
{
    const auto region = SyntaxHighlighterPrivate::foldingRegion(startBlock);

    auto block = startBlock;
    int depth = 1;
    while (block.isValid()) {
        block = block.next();
        const auto data = dynamic_cast<TextBlockUserData*>(block.userData());
        if (!data)
            continue;
        for (auto it = data->foldingRegions.constBegin(); it != data->foldingRegions.constEnd(); ++it) {
            if ((*it).id() != region.id())
                continue;
            if ((*it).type() == FoldingRegion::End)
                --depth;
            else if ((*it).type() == FoldingRegion::Begin)
                ++depth;
            if (depth == 0)
                return block;
        }
    }

    return QTextBlock();
}

void SyntaxHighlighter::highlightBlock(const QString& text)
{
    Q_D(SyntaxHighlighter);

    State state;
    if (currentBlock().position() > 0) {
        const auto prevBlock = currentBlock().previous();
        const auto prevData = dynamic_cast<TextBlockUserData*>(prevBlock.userData());
        if (prevData)
            state = prevData->state;
    }
    d->foldingRegions.clear();
    state = highlightLine(text, state);

    auto data = dynamic_cast<TextBlockUserData*>(currentBlockUserData());
    if (!data) { // first time we highlight this
        data = new TextBlockUserData;
        data->state = state;
        data->foldingRegions = d->foldingRegions;
        setCurrentBlockUserData(data);
        return;
    }

    if (data->state == state && data->foldingRegions == d->foldingRegions) // we ended up in the same state, so we are done here
        return;
    data->state = state;
    data->foldingRegions = d->foldingRegions;

    const auto nextBlock = currentBlock().next();
    if (nextBlock.isValid())
        QMetaObject::invokeMethod(this, "rehighlightBlock", Qt::QueuedConnection, Q_ARG(QTextBlock, nextBlock));
}

void SyntaxHighlighter::applyFormat(int offset, int length, const KSyntaxHighlighting::Format& format)
{
    if (format.isDefaultTextStyle(theme()) || length == 0)
        return;

    QTextCharFormat tf;
    if (format.hasTextColor(theme()))
        tf.setForeground(format.textColor(theme()));
    if (format.hasBackgroundColor(theme()))
        tf.setBackground(format.backgroundColor(theme()));

    if (format.isBold(theme()))
        tf.setFontWeight(QFont::Bold);
    if (format.isItalic(theme()))
        tf.setFontItalic(true);
    if (format.isUnderline(theme()))
        tf.setFontUnderline(true);
    if (format.isStrikeThrough(theme()))
        tf.setFontStrikeOut(true);

    QSyntaxHighlighter::setFormat(offset, length, tf);
}

void SyntaxHighlighter::applyFolding(int offset, int length, FoldingRegion region)
{
    Q_UNUSED(offset);
    Q_UNUSED(length);
    Q_D(SyntaxHighlighter);

    if (region.type() == FoldingRegion::Begin)
        d->foldingRegions.push_back(region);

    if (region.type() == FoldingRegion::End) {
        for (int i = d->foldingRegions.size() - 1; i >= 0; --i) {
            if (d->foldingRegions.at(i).id() != region.id() || d->foldingRegions.at(i).type() != FoldingRegion::Begin)
                continue;
            d->foldingRegions.remove(i);
            return;
        }
        d->foldingRegions.push_back(region);
    }
}
