postscriptdscextractor.cpp

/*
    Copyright (C) 2018  Stefan Brüns <stefan.bruens@rwth-aachen.de>

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/


#include "postscriptdscextractor.h"
#include "kfilemetadata_debug.h"

#include <QDebug>
#include <QFile>

namespace KFileMetaData
{

DscExtractor::DscExtractor(QObject* parent)
    : ExtractorPlugin(parent)
{

}

QStringList DscExtractor::mimetypes() const
{
    QStringList list;
    list << QStringLiteral("application/postscript")
         << QStringLiteral("image/x-eps");

    return list;
}

void DscExtractor::extract(ExtractionResult* result)
{
    auto flags = result->inputFlags();
    if (!(flags & ExtractionResult::ExtractMetaData)) {
        return;
    }

    QFile file(result->inputUrl());
    if (!file.open(QIODevice::ReadOnly)) {
        qCWarning(KFILEMETADATA_LOG) << "Document is not a valid file";
        return;
    }

    // A little bit heuristic - assume EPS files are images, PS complete documents
    if (result->inputMimetype() == QLatin1String("application/postscript")) {
        result->addType(Type::Document);
    } else {
        result->addType(Type::Image);
    }

    // Try to find some DSC (PostScript Language Document Structuring Conventions) conforming data
    QTextStream stream(&file);
    QString line;

    while (stream.readLineInto(&line)) {
        if (!line.startsWith(QLatin1String("%%"))) {
            continue;
        }

        if (line.startsWith(QLatin1String("%%Pages:"))) {
            bool ok = false;
            int pages = line.midRef(8).toInt(&ok, 10);
            if (ok) {
                result->add(Property::PageCount, pages);
            }

        } else if (line.startsWith(QLatin1String("%%Title:"))) {
            QStringRef title = line.midRef(8);
            title = title.trimmed();
            if (title.startsWith(QLatin1Char('(')) && title.endsWith(QLatin1Char(')'))) {
                title = title.mid(1, title.size() - 2);
            }
            if (!title.isEmpty()) {
                result->add(Property::Title, title.toString());
            }

        } else if (line.startsWith(QLatin1String("%%CreationDate:"))) {
            // "Neither the date nor time need be in any standard format."
            QStringRef date = line.midRef(15);
            date = date.trimmed();
            if (date.startsWith(QLatin1Char('(')) && date.endsWith(QLatin1Char(')'))) {
                date = date.mid(1, date.size() - 2);
                date = date.trimmed();
            }
            if (date.startsWith(QLatin1String("D:")) && date.size() >= 23) {
                // Standard PDF date format, ASN.1 like - (D:YYYYMMDDHHmmSSOHH'mm')
                auto dt = QDateTime::fromString(date.mid(2, 14).toString(), QLatin1String("yyyyMMddhhmmss"));
                auto offset = QTime::fromString(date.mid(17, 5).toString(), QLatin1String("hh'\\''mm"));
                if (date.mid(16,1) == QLatin1String("+")) {
                    dt.setOffsetFromUtc(QTime(0, 0).secsTo(offset));
                } else {
                    dt.setOffsetFromUtc(-1 * QTime(0, 0).secsTo(offset));
                }
                result->add(Property::CreationDate, dt);
            } else {
                auto dt = QDateTime::fromString(date.toString());
                if (dt.isValid()) {
                    result->add(Property::CreationDate, dt);
                }
            }

        } else if (line.startsWith(QLatin1String("%%EndComments"))) {
            break;
        }
    }
}

} // namespace KFileMetaData