// SPDX-FileCopyrightText: 2008 by Jakub Stachowski <qbast@go2.pl>

// SPDX-License-Identifier: GPL-2.0-or-later

#include "pdb_p.h"

#include <QIODevice>

#include <QtEndian>

namespace Mobipocket

{

struct PDBPrivate {

    PDBPrivate(QIODevice *dev);

    QIODevice *device;

    QByteArray fileType;

    QList<quint32> recordOffsets;

    bool valid = false;

};

PDBPrivate::PDBPrivate(QIODevice *dev)

    : device(dev)

{

    const auto pdbHead = device->read(0x4e);

    if (pdbHead.size() < 0x4e)

        return;

    fileType = pdbHead.mid(0x3c, 8);

    const auto nrecords = qFromBigEndian<quint16>(pdbHead.constData() + 0x4c);

    const auto recordData = device->read(8 * nrecords);

    if (recordData.size() < 8 * nrecords)

        return;

    quint32 lastOffset = 0x4d + 8 * nrecords;

    for (int i = 0; i < nrecords; i++) {

        const quint32 offset = qFromBigEndian<quint32>(recordData.constData() + 8 * i);

        if (offset < lastOffset) {

            return;

        }

        if (offset > dev->size()) {

            break;

        }

        recordOffsets.append(offset);

        lastOffset = offset;

    }

    valid = true;

}

PDB::~PDB() = default;

PDB::PDB(QIODevice *device)

    : d(new PDBPrivate(device))

{

}

QByteArray PDB::getRecord(quint16 i) const

{

    if (i >= d->recordOffsets.size()) {

        return QByteArray();

    }

    quint32 offset = d->recordOffsets[i];

    quint32 end = (i + 1 < d->recordOffsets.size()) ? d->recordOffsets[i + 1] : d->device->size();

    if (!d->device->seek(offset))

        return QByteArray();

    return d->device->read(end - offset);

}

QByteArray PDB::fileType() const

{

    return d->fileType;

}

bool PDB::isValid() const

{

    return d->valid;

}

quint16 PDB::recordCount() const

{

    // Range guaranteed by constructor/PDB field size

    return d->recordOffsets.size();

}

}