/*
    This file is part of the KDE project
    SPDX-FileCopyrightText: 2025 Mirco Miranda <mircomir@outlook.com>

    SPDX-License-Identifier: LGPL-2.0-or-later
*/

#include "chunks_p.h"
#include "packbits_p.h"

#include <QDebug>

IFFChunk::~IFFChunk()
{

}

IFFChunk::IFFChunk()
    : _chunkId{0}
    , _size{0}
    , _align{2}
    , _dataPos{0}
{
}

bool IFFChunk::operator ==(const IFFChunk &other) const
{
    if (chunkId() != other.chunkId()) {
        return false;
    }
    return _size == other._size && _dataPos == other._dataPos;
}

bool IFFChunk::isValid() const
{
    auto cid = chunkId();
    for (auto &&c : cid) {
        if (!((c >= '0' && c <= '9') || (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || (c == ' ')))
            return false;
    }
    return true;
}

qint32 IFFChunk::alignBytes() const
{
    return _align;
}

bool IFFChunk::readStructure(QIODevice *d)
{
    auto ok = readInfo(d);
    ok = ok && innerReadStructure(d);
    if (ok) {
        auto pos = _dataPos + _size;
        if (auto align = pos % alignBytes())
            pos += alignBytes() - align;
        ok = d->seek(pos);
    }
    return ok;
}

QByteArray IFFChunk::chunkId() const
{
    return QByteArray(_chunkId, 4);
}

quint32 IFFChunk::bytes() const
{
    return _size;
}

const QByteArray &IFFChunk::data() const
{
    return _data;
}

const IFFChunk::ChunkList &IFFChunk::chunks() const
{
    return _chunks;
}

quint8 IFFChunk::chunkVersion(const QByteArray &cid)
{
    if (cid.size() != 4) {
        return 0;
    }
    if (cid.at(3) >= char('2') && cid.at(3) <= char('9')) {
        return quint8(cid.at(3) - char('0'));
    }
    return 1;
}

bool IFFChunk::isChunkType(const QByteArray &cid) const
{
    if (chunkId() == cid) {
        return true;
    }
    if (chunkId().startsWith(cid.left(3)) && IFFChunk::chunkVersion(cid) > 1) {
        return true;
    }
    return false;
}

bool IFFChunk::readInfo(QIODevice *d)
{
    if (d == nullptr || d->read(_chunkId, 4) != 4) {
        return false;
    }
    if (!IFFChunk::isValid()) {
        return false;
    }
    auto sz = d->read(4);
    if (sz.size() != 4) {
        return false;
    }
    _size = ui32(sz.at(3), sz.at(2), sz.at(1), sz.at(0));
    _dataPos = d->pos();
    return true;
}

QByteArray IFFChunk::readRawData(QIODevice *d, qint64 relPos, qint64 size) const
{
    if (!seek(d, relPos))
        return{};
    if (size == -1)
        size = _size;
    auto read = std::min(size, _size - relPos);
    return d->read(read);
}

bool IFFChunk::seek(QIODevice *d, qint64 relPos) const
{
    if (d == nullptr)
        return false;
    return d->seek(_dataPos + relPos);
}

bool IFFChunk::innerReadStructure(QIODevice *)
{
    return true;
}

IFFChunk::ChunkList IFFChunk::search(const QByteArray &cid, const QSharedPointer<IFFChunk> &chunk)
{
    return search(cid, ChunkList() << chunk);
}

IFFChunk::ChunkList IFFChunk::search(const QByteArray &cid, const ChunkList &chunks)
{
    IFFChunk::ChunkList list;
    for (auto &&chunk : chunks) {
        if (chunk->chunkId() == cid)
            list << chunk;
        list << IFFChunk::search(cid, chunk->_chunks);
    }
    return list;
}

bool IFFChunk::cacheData(QIODevice *d)
{
    if (bytes() > 8 * 1024 * 1024)
        return false;
    _data = readRawData(d);
    return _data.size() == _size;
}

void IFFChunk::setChunks(const ChunkList &chunks)
{
    _chunks = chunks;
}

IFFChunk::ChunkList IFFChunk::innerFromDevice(QIODevice *d, bool *ok, qint32 alignBytes)
{
    auto tmp = false;
    if (ok == nullptr) {
        ok = &tmp;
    }
    *ok = false;

    if (d == nullptr) {
        return {};
    }

    IFFChunk::ChunkList list;
    for (; !d->atEnd();) {
        auto cid = d->peek(4);
        QSharedPointer<IFFChunk> chunk;
        if (cid == FORM_CHUNK) {
            chunk = QSharedPointer<IFFChunk>(new FORMChunk());
        } else if (cid == CAMG_CHUNK) {
            chunk = QSharedPointer<IFFChunk>(new CAMGChunk());
        } else if (cid == CMAP_CHUNK) {
            chunk = QSharedPointer<IFFChunk>(new CMAPChunk());
        } else if (cid == BMHD_CHUNK) {
            chunk = QSharedPointer<IFFChunk>(new BMHDChunk());
        } else if (cid == BODY_CHUNK) {
            chunk = QSharedPointer<IFFChunk>(new BODYChunk());
        } else if (cid == DPI__CHUNK) {
            chunk = QSharedPointer<IFFChunk>(new DPIChunk());
        } else if (cid == FOR4_CHUNK) {
            chunk = QSharedPointer<IFFChunk>(new FOR4Chunk());
        } else if (cid == TBHD_CHUNK) {
            chunk = QSharedPointer<IFFChunk>(new TBHDChunk());
        } else if (cid == RGBA_CHUNK) {
            chunk = QSharedPointer<IFFChunk>(new RGBAChunk());
        } else if (cid == AUTH_CHUNK) {
            chunk = QSharedPointer<IFFChunk>(new AUTHChunk());
        } else if (cid == DATE_CHUNK) {
            chunk = QSharedPointer<IFFChunk>(new DATEChunk());
        } else if (cid == FVER_CHUNK) {
            chunk = QSharedPointer<IFFChunk>(new FVERChunk());
        } else if (cid == HIST_CHUNK) {
            chunk = QSharedPointer<IFFChunk>(new HISTChunk());
        } else if (cid == VERS_CHUNK) {
            chunk = QSharedPointer<IFFChunk>(new VERSChunk());
        } else { // unknown chunk
            chunk = QSharedPointer<IFFChunk>(new IFFChunk());
            qInfo() << "IFFChunk::innerFromDevice: unkwnown chunk" << cid;
        }

        // change the alignment to the one of main chunk (required for unknown Maya IFF chunks)
        if (chunk->isChunkType(CAT__CHUNK)
            || chunk->isChunkType(FILL_CHUNK)
            || chunk->isChunkType(FORM_CHUNK)
            || chunk->isChunkType(LIST_CHUNK)
            || chunk->isChunkType(PROP_CHUNK)) {
            alignBytes = chunk->alignBytes();
        } else {
            chunk->setAlignBytes(alignBytes);
        }

        if (!chunk->readStructure(d)) {
            *ok = false;
            return {};
        }

        list << chunk;
    }

    *ok = true;
    return list;
}

IFFChunk::ChunkList IFFChunk::fromDevice(QIODevice *d, bool *ok)
{
    return innerFromDevice(d, ok, 2);
}


/* ******************
 * *** BMHD Chunk ***
 * ****************** */

BMHDChunk::~BMHDChunk()
{

}

BMHDChunk::BMHDChunk() : IFFChunk()
{
}

bool BMHDChunk::isValid() const
{
    if (bytes() < 20) {
        return false;
    }
    return chunkId() == BMHDChunk::defaultChunkId();
}

bool BMHDChunk::innerReadStructure(QIODevice *d)
{
    return cacheData(d);
}

qint32 BMHDChunk::width() const
{
    if (!isValid()) {
        return 0;
    }
    return qint32(ui16(data().at(1), data().at(0)));
}

qint32 BMHDChunk::height() const
{
    if (!isValid()) {
        return 0;
    }
    return qint32(ui16(data().at(3), data().at(2)));
}

QSize BMHDChunk::size() const
{
    return QSize(width(), height());
}

qint32 BMHDChunk::left() const
{
    if (!isValid()) {
        return 0;
    }
    return qint32(ui16(data().at(5), data().at(4)));
}

qint32 BMHDChunk::top() const
{
    if (!isValid()) {
        return 0;
    }
    return qint32(ui16(data().at(7), data().at(6)));
}

quint8 BMHDChunk::bitplanes() const
{
    if (!isValid()) {
        return 0;
    }
    return quint8(data().at(8));
}

quint8 BMHDChunk::masking() const
{
    if (!isValid()) {
        return 0;
    }
    return quint8(data().at(9));
}

BMHDChunk::Compression BMHDChunk::compression() const
{
    if (!isValid()) {
        return BMHDChunk::Compression::Uncompressed;
    }
    return BMHDChunk::Compression(data().at(10));

}

quint8 BMHDChunk::padding() const
{
    if (!isValid()) {
        return 0;
    }
    return quint8(data().at(11));
}

qint16 BMHDChunk::transparency() const
{
    if (!isValid()) {
        return 0;
    }
    return i16(data().at(13), data().at(12));
}

quint8 BMHDChunk::xAspectRatio() const
{
    if (!isValid()) {
        return 0;
    }
    return quint8(data().at(14));
}

quint8 BMHDChunk::yAspectRatio() const
{
    if (!isValid()) {
        return 0;
    }
    return quint8(data().at(15));
}

quint16 BMHDChunk::pageWidth() const
{
    if (!isValid()) {
        return 0;
    }
    return ui16(data().at(17), data().at(16));
}

quint16 BMHDChunk::pageHeight() const
{
    if (!isValid()) {
        return 0;
    }
    return ui16(data().at(19), data().at(18));
}

quint32 BMHDChunk::rowLen() const
{
    return ((quint32(width()) + 15) / 16) * 2;
}

/* ******************
 * *** CMAP Chunk ***
 * ****************** */

CMAPChunk::~CMAPChunk()
{

}

CMAPChunk::CMAPChunk() : IFFChunk()
{
}

bool CMAPChunk::isValid() const
{
    return chunkId() == CMAPChunk::defaultChunkId();
}

bool CMAPChunk::innerReadStructure(QIODevice *d)
{
    return cacheData(d);
}

QList<QRgb> CMAPChunk::palette() const
{
    QList<QRgb> l;
    auto &&d = data();
    for (quint32 i = 0, n = bytes() / 3; i < n; ++i) {
        l << qRgb(d.at(i * 3), d.at(i * 3 + 1), d.at(i * 3 + 2));
    }
    return l;
}

/* ******************
 * *** CAMG Chunk ***
 * ****************** */

CAMGChunk::~CAMGChunk()
{

}

CAMGChunk::CAMGChunk() : IFFChunk()
{
}

bool CAMGChunk::isValid() const
{
    if (bytes() != 4) {
        return false;
    }
    return chunkId() == CAMGChunk::defaultChunkId();
}

CAMGChunk::ModeIds CAMGChunk::modeId() const
{
    if (!isValid()) {
        return CAMGChunk::ModeIds();
    }
    return CAMGChunk::ModeIds(ui32(data().at(3), data().at(2), data().at(1), data().at(0)));
}

bool CAMGChunk::innerReadStructure(QIODevice *d)
{
    return cacheData(d);
}

/* ******************
 * *** DPI  Chunk ***
 * ****************** */

DPIChunk::~DPIChunk()
{

}

DPIChunk::DPIChunk() : IFFChunk()
{
}

bool DPIChunk::isValid() const
{
    if (dpiX() == 0 || dpiY() == 0) {
        return false;
    }
    return chunkId() == DPIChunk::defaultChunkId();
}

quint16 DPIChunk::dpiX() const
{
    if (bytes() < 4) {
        return 0;
    }
    return i16(data().at(1), data().at(0));
}

quint16 DPIChunk::dpiY() const
{
    if (bytes() < 4) {
        return 0;
    }
    return i16(data().at(3), data().at(2));
}

qint32 DPIChunk::dotsPerMeterX() const
{
    return qRound(dpiX() / 25.4 * 1000);
}

qint32 DPIChunk::dotsPerMeterY() const
{
    return qRound(dpiY() / 25.4 * 1000);
}

bool DPIChunk::innerReadStructure(QIODevice *d)
{
    return cacheData(d);
}

/* ******************
 * *** BODY Chunk ***
 * ****************** */

BODYChunk::~BODYChunk()
{

}

BODYChunk::BODYChunk() : IFFChunk()
{
}

bool BODYChunk::isValid() const
{
    return chunkId() == BODYChunk::defaultChunkId();
}

QByteArray BODYChunk::strideRead(QIODevice *d, const BMHDChunk *header, const CAMGChunk *camg, const CMAPChunk *cmap) const
{
    if (!isValid() || header == nullptr) {
        return {};
    }

    auto readSize = header->rowLen() * header->bitplanes();
    for(;!d->atEnd() && _readBuffer.size() < readSize;) {
        QByteArray buf(readSize, char());
        qint64 rr = -1;
        if (header->compression() == BMHDChunk::Compression::Rle) {
            // WARNING: The online spec says it's the same as TIFF but that's
            // not accurate: the RLE -128 code is not a noop.
            rr = packbitsDecompress(d, buf.data(), buf.size(), true);
        } else if (header->compression() == BMHDChunk::Compression::Uncompressed) {
            rr = d->read(buf.data(), buf.size());
        }
        if (rr != readSize)
            return {};
        _readBuffer.append(buf.data(), rr);
    }

    auto planes = _readBuffer.left(readSize);
    _readBuffer.remove(0, readSize);
    return BODYChunk::deinterleave(planes, header, camg, cmap);
}

bool BODYChunk::resetStrideRead(QIODevice *d) const
{
    _readBuffer.clear();
    return seek(d);
}

QByteArray BODYChunk::deinterleave(const QByteArray &planes, const BMHDChunk *header, const CAMGChunk *camg, const CMAPChunk *cmap)
{
    auto rowLen = qint32(header->rowLen());
    auto bitplanes = header->bitplanes();
    if (planes.size() != rowLen * bitplanes) {
        return {};
    }

    auto modeId = CAMGChunk::ModeIds();
    if (camg) {
        modeId = camg->modeId();
    }

    QByteArray ba;
    switch (bitplanes) {
    case 1: // bitmap
        ba = QByteArray((7 + header->width() * bitplanes) / 8, char());
        for (qint32 i = 0, n = std::min(planes.size(), ba.size()); i < n; ++i) {
            ba[i] = ~planes.at(i);
        }
        break;

    case 2: // gray, indexed and rgb Ham mode
    case 3:
    case 4:
    case 5:
    case 6:
    case 7:
    case 8:
        if (modeId == CAMGChunk::ModeId::Ham && cmap && bitplanes == 6) {
            // From A Quick Introduction to IFF.txt:
            //
            // Amiga HAM (Hold and Modify) mode lets the Amiga display all 4096 RGB values.
            // In HAM mode, the bits in the two last planes describe an R G or B
            // modification to the color of the previous pixel on the line to create the
            // color of the current pixel.  So a 6-plane HAM picture has 4 planes for
            // specifying absolute color pixels giving up to 16 absolute colors which would
            // be specified in the ILBM CMAP chunk.  The bits in the last two planes are
            // color modification bits which cause the Amiga, in HAM mode, to take the RGB
            // value of the previous pixel (Hold and), substitute the 4 bits in planes 0-3
            // for the previous color's R G or B component (Modify) and display the result
            // for the current pixel.  If the first pixel of a scan line is a modification
            // pixel, it modifies the RGB value of the border color (register 0).  The color
            // modification bits in the last two planes (planes 4 and 5) are interpreted as
            // follows:
            //    00 - no modification.  Use planes 0-3 as normal color register index
            //    10 - hold previous, replacing Blue component with bits from planes 0-3
            //    01 - hold previous, replacing Red component with bits from planes 0-3
            //    11 - hold previous. replacing Green component with bits from planes 0-3
            ba = QByteArray(rowLen * 8 * 3, char());
            auto pal = cmap->palette();
            quint8 prev[3] = {};
            for (qint32 i = 0, cnt = 0; i < rowLen; ++i) {
                for (qint32 j = 0; j < 8; ++j, ++cnt) {
                    quint8 idx = 0, ctl = 0;
                    for (qint32 k = 0, msk = (1 << (7 - j)); k < bitplanes; ++k) {
                        if ((planes.at(k * rowLen + i) & msk) == 0)
                            continue;
                        if (k < 4) {
                            idx |= 1 << k;
                        } else {
                            ctl |= 1 << (bitplanes - k - 1);
                        }
                    }
                    switch (ctl) {
                    case 1: // red
                        prev[0] = idx | (idx << 4);
                        break;
                    case 2: // blue
                        prev[2] = idx | (idx << 4);
                        break;
                    case 3: // green
                        prev[1] = idx | (idx << 4);
                        break;
                    default:
                        if (idx < pal.size()) {
                            prev[0] = qRed(pal.at(idx));
                            prev[1] = qGreen(pal.at(idx));
                            prev[2] = qBlue(pal.at(idx));
                        } else {
                            qWarning() << "BODYChunk::deinterleave: palette index" << idx << "is out of range";
                        }
                        break;
                    }
                    auto cnt3 = cnt * 3;
                    ba[cnt3] = char(prev[0]);
                    ba[cnt3 + 1] = char(prev[1]);
                    ba[cnt3 + 2] = char(prev[2]);
                }
            }
        } else if (modeId == CAMGChunk::ModeIds()) {
            // From A Quick Introduction to IFF.txt:
            //
            // If the ILBM is not HAM or HALFBRITE, then after parsing and uncompacting if
            // necessary, you will have N planes of pixel data.  Color register used for
            // each pixel is specified by looking at each pixel thru the planes.  I.e.,
            // if you have 5 planes, and the bit for a particular pixel is set in planes
            // 0 and 3:
            //
            //        PLANE     4 3 2 1 0
            //        PIXEL     0 1 0 0 1
            //
            // then that pixel uses color register binary 01001 = 9
            ba = QByteArray(rowLen * 8, char());
            for (qint32 i = 0; i < rowLen; ++i) {
                for (qint32 k = 0, i8 = i * 8; k < bitplanes; ++k) {
                    auto v = planes.at(k * rowLen + i);
                    if (v & (1 << 7))
                        ba[i8] |= 1 << k;
                    if (v & (1 << 6))
                        ba[i8 + 1] |= 1 << k;
                    if (v & (1 << 5))
                        ba[i8 + 2] |= 1 << k;
                    if (v & (1 << 4))
                        ba[i8 + 3] |= 1 << k;
                    if (v & (1 << 3))
                        ba[i8 + 4] |= 1 << k;
                    if (v & (1 << 2))
                        ba[i8 + 5] |= 1 << k;
                    if (v & (1 << 1))
                        ba[i8 + 6] |= 1 << k;
                    if (v & 1)
                        ba[i8 + 7] |= 1 << k;
                }
            }
        }
        break;

    case 24: // rgb
        // From A Quick Introduction to IFF.txt:
        //
        // If a deep ILBM (like 12 or 24 planes), there should be no CMAP
        // and instead the BODY planes are interpreted as the bits of RGB
        // in the order R0...Rn G0...Gn B0...Bn
        //
        // NOTE: This code does not support 12-planes images
        ba = QByteArray(rowLen * bitplanes, char());
        for (qint32 i = 0, cnt = 0, p = bitplanes / 8; i < rowLen; ++i) {
            for (qint32 j = 0; j < 8; ++j)
                for (qint32 k = 0; k < p; ++k, ++cnt) {
                    auto k8 = k * 8;
                    auto msk = (1 << (7 - j));
                    if (planes.at(k8 * rowLen + i) & msk)
                        ba[cnt] |= 0x01;
                    if (planes.at((1 + k8) * rowLen + i) & msk)
                        ba[cnt] |= 0x02;
                    if (planes.at((2 + k8) * rowLen + i) & msk)
                        ba[cnt] |= 0x04;
                    if (planes.at((3 + k8) * rowLen + i) & msk)
                        ba[cnt] |= 0x08;
                    if (planes.at((4 + k8) * rowLen + i) & msk)
                        ba[cnt] |= 0x10;
                    if (planes.at((5 + k8) * rowLen + i) & msk)
                        ba[cnt] |= 0x20;
                    if (planes.at((6 + k8) * rowLen + i) & msk)
                        ba[cnt] |= 0x40;
                    if (planes.at((7 + k8) * rowLen + i) & msk)
                        ba[cnt] |= 0x80;
                }
        }
        break;
    }
    return ba;
}

/* ******************
 * *** FORM Chunk ***
 * ****************** */

FORMChunk::~FORMChunk()
{

}

FORMChunk::FORMChunk() : IFFChunk()
{
}

bool FORMChunk::isValid() const
{
    return chunkId() == FORMChunk::defaultChunkId();
}

bool FORMChunk::isSupported() const
{
    return format() != QImage::Format_Invalid;
}

bool FORMChunk::innerReadStructure(QIODevice *d)
{
    if (bytes() < 4) {
        return false;
    }
    _type = d->read(4);
    auto ok = true;
    if (_type == QByteArray("ILBM")) {
        setChunks(IFFChunk::innerFromDevice(d, &ok, alignBytes()));
    }
    return ok;
}

QByteArray FORMChunk::formType() const
{
    return _type;
}

QImage::Format FORMChunk::format() const
{
    auto headers = IFFChunk::searchT<BMHDChunk>(chunks());
    if (headers.isEmpty()) {
        return QImage::Format_Invalid;
    }

    if (auto &&h = headers.first()) {
        auto cmaps = IFFChunk::searchT<CMAPChunk>(chunks());
        auto camgs = IFFChunk::searchT<CAMGChunk>(chunks());

        auto modeId = CAMGChunk::ModeIds();
        if (!camgs.isEmpty()) {
            modeId = camgs.first()->modeId();
        } else if (h->bitplanes() == 6) {
            // If no CAMG chunk is present, and image is 6 planes deep,
            // assume HAM and you'll probably be right.
            modeId = CAMGChunk::ModeIds(CAMGChunk::ModeId::Ham);
        }

        if (h->bitplanes() == 24) {
            return QImage::Format_RGB888;
        }
        if (h->bitplanes() >= 2 && h->bitplanes() <= 8) {
            // Currently supported modes: HAM6 and No HAM/HALFBRITE.
            if (modeId != CAMGChunk::ModeIds() && (modeId != CAMGChunk::ModeId::Ham || h->bitplanes() != 6))
                return QImage::Format_Invalid;

            if (modeId & CAMGChunk::ModeId::Ham) {
                if (IFFChunk::search(SHAM_CHUNK, chunks()).isEmpty())
                    return QImage::Format_RGB888;
                else // Images with the SHAM chunk do not load correctly.
                    return QImage::Format_Invalid;
            } else if (!cmaps.isEmpty()) {
                return QImage::Format_Indexed8;
            } else {
                return QImage::Format_Grayscale8;
            }
        }
        if (h->bitplanes() == 1) {
            return QImage::Format_Mono;
        }
    }

    return QImage::Format_Invalid;
}

QSize FORMChunk::size() const
{
    auto headers = IFFChunk::searchT<BMHDChunk>(chunks());
    if (headers.isEmpty()) {
        return {};
    }
    return headers.first()->size();
}

/* ******************
 * *** FOR4 Chunk ***
 * ****************** */

FOR4Chunk::~FOR4Chunk()
{

}

FOR4Chunk::FOR4Chunk() : IFFChunk()
{

}

bool FOR4Chunk::isValid() const
{
    return chunkId() == FOR4Chunk::defaultChunkId();
}

qint32 FOR4Chunk::alignBytes() const
{
    return 4;
}

bool FOR4Chunk::isSupported() const
{
    return format() != QImage::Format_Invalid;
}

bool FOR4Chunk::innerReadStructure(QIODevice *d)
{
    if (bytes() < 4) {
        return false;
    }
    _type = d->read(4);
    auto ok = true;
    if (_type == QByteArray("CIMG")) {
        setChunks(IFFChunk::innerFromDevice(d, &ok, alignBytes()));
    } else if (_type == QByteArray("TBMP")) {
        setChunks(IFFChunk::innerFromDevice(d, &ok, alignBytes()));
    }
    return ok;
}

QByteArray FOR4Chunk::formType() const
{
    return _type;
}

QImage::Format FOR4Chunk::format() const
{
    auto headers = IFFChunk::searchT<TBHDChunk>(chunks());
    if (headers.isEmpty()) {
        return QImage::Format_Invalid;
    }
    return headers.first()->format();
}

QSize FOR4Chunk::size() const
{
    auto headers = IFFChunk::searchT<TBHDChunk>(chunks());
    if (headers.isEmpty()) {
        return {};
    }
    return headers.first()->size();
}


/* ******************
 * *** TBHD Chunk ***
 * ****************** */

TBHDChunk::~TBHDChunk()
{

}

TBHDChunk::TBHDChunk()
{

}

bool TBHDChunk::isValid() const
{
    if (bytes() != 24 && bytes() != 32) {
        return false;
    }
    return chunkId() == TBHDChunk::defaultChunkId();
}

qint32 TBHDChunk::alignBytes() const
{
    return 4;
}

qint32 TBHDChunk::width() const
{
    if (!isValid()) {
        return 0;
    }
    return i32(data().at(3), data().at(2), data().at(1), data().at(0));
}

qint32 TBHDChunk::height() const
{
    if (!isValid()) {
        return 0;
    }
    return i32(data().at(7), data().at(6), data().at(5), data().at(4));
}

QSize TBHDChunk::size() const
{
    return QSize(width(), height());
}

qint32 TBHDChunk::left() const
{
    if (bytes() != 32) {
        return 0;
    }
    return i32(data().at(27), data().at(26), data().at(25), data().at(24));
}

qint32 TBHDChunk::top() const
{
    if (bytes() != 32) {
        return 0;
    }
    return i32(data().at(31), data().at(30), data().at(29), data().at(28));
}

TBHDChunk::Flags TBHDChunk::flags() const
{
    if (!isValid()) {
        return TBHDChunk::Flags();
    }
    return TBHDChunk::Flags(ui32(data().at(15), data().at(14), data().at(13), data().at(12)));
}

qint32 TBHDChunk::bpc() const
{
    if (!isValid()) {
        return 0;
    }
    return ui16(data().at(17), data().at(16)) ? 2 : 1;
}

qint32 TBHDChunk::channels() const
{
    if (flags() == TBHDChunk::Flag::RgbA) {
        return 4;
    }
    if (flags() == TBHDChunk::Flag::Rgb) {
        return 3;
    }
    return 0;
}

quint16 TBHDChunk::tiles() const
{
    if (!isValid()) {
        return 0;
    }
    return ui16(data().at(19), data().at(18));
}

QImage::Format TBHDChunk::format() const
{
    // Support for RGBA and RGB only for now.
    if (flags() == TBHDChunk::Flag::RgbA) {
        if (bpc() == 2)
            return QImage::Format_RGBA64;
        else if (bpc() == 1)
            return QImage::Format_RGBA8888;
    } else if (flags() == TBHDChunk::Flag::Rgb) {
        if (bpc() == 2)
            return QImage::Format_RGBX64;
        else if (bpc() == 1)
            return QImage::Format_RGB888;
    }

    return QImage::Format_Invalid;
}

TBHDChunk::Compression TBHDChunk::compression() const
{
    if (!isValid()) {
        return TBHDChunk::Compression::Uncompressed;
    }
    return TBHDChunk::Compression(ui32(data().at(23), data().at(22), data().at(21), data().at(20)));
}

bool TBHDChunk::innerReadStructure(QIODevice *d)
{
    return cacheData(d);
}

/* ******************
 * *** RGBA Chunk ***
 * ****************** */

RGBAChunk::~RGBAChunk()
{
}

RGBAChunk::RGBAChunk()
{

}

bool RGBAChunk::isValid() const
{
    if (bytes() < 8) {
        return false;
    }
    return chunkId() == RGBAChunk::defaultChunkId();
}

qint32 RGBAChunk::alignBytes() const
{
    return 4;
}

bool RGBAChunk::isTileCompressed(const TBHDChunk *header) const
{
    if (!isValid() || header == nullptr) {
        return false;
    }
    return qint64(header->channels()) * size().width() * size().height() * header->bpc() > qint64(bytes() - 8);
}

QPoint RGBAChunk::pos() const
{
    return _pos;
}

QSize RGBAChunk::size() const
{
    return _size;
}

// Maya version of IFF uses a slightly different algorithm for RLE compression.
qint64 rleMayaDecompress(QIODevice *input, char *output, qint64 olen)
{
    qint64  j = 0;
    for (qint64 rr = 0, available = olen; j < olen; available = olen - j) {
        char n;

        // check the output buffer space for the next run
        if (available < 128) {
            if (input->peek(&n, 1) != 1) { // end of data (or error)
                break;
            }
            rr = qint64(n & 0x7f) + 1;
            if (rr > available)
                break;
        }

        // decompress
        if (input->read(&n, 1) != 1) { // end of data (or error)
            break;
        }

        rr = qint64(n & 0x7f) + 1;
        if ((n & 0x80) == 0) {
            auto read = input->read(output + j, rr);
            if (rr != read) {
                return -1;
            }
        } else {
            char b;
            if (input->read(&b, 1) != 1) {
                break;
            }
            std::memset(output + j, b, size_t(rr));
        }

        j += rr;
    }
    return j;
}

QByteArray RGBAChunk::readStride(QIODevice *d, const TBHDChunk *header) const
{
    auto readSize = size().width();
    if (readSize == 0) {
        return {};
    }

    // detect if the tile is compressed (8 is the size of 4 uint16 before the tile data).
    auto compressed = isTileCompressed(header);
    for(;!d->atEnd() && _readBuffer.size() < readSize;) {
        QByteArray buf(readSize * size().height(), char());
        qint64 rr = -1;
        if (compressed) {
            // It seems that tiles are compressed independently only if there is space savings.
            // The compression method specified in the header is only to indicate the type of
            // compression if used.
            if (header->compression() == TBHDChunk::Compression::Rle) {
                rr = rleMayaDecompress(d, buf.data(), buf.size());
            }
        } else {
            rr = d->read(buf.data(), buf.size());
        }
        if (rr != buf.size()) {
            return {};
        }
        _readBuffer.append(buf.data(), rr);
    }

    auto buff = _readBuffer.left(readSize);
    _readBuffer.remove(0, readSize);

    return buff;
}

QImage RGBAChunk::compressedTile(QIODevice *d, const TBHDChunk *header) const
{
    QImage img(size(), header->format());
    auto bpc = header->bpc();

    if (bpc == 1) {
        for (auto c = 0, cs = header->channels(); c < cs; ++c) {
            for (auto y = 0, h = img.height(); y < h; ++y) {
                auto ba = readStride(d, header);
                if (ba.isEmpty()) {
                    return {};
                }
                auto scl = reinterpret_cast<quint8*>(img.scanLine(y));
                for (auto x = 0, w = std::min(int(ba.size()), img.width()); x < w; ++x) {
                    scl[x * cs + cs - c - 1] = ba.at(x);
                }
            }
        }
    } else if (bpc == 2) {
        auto cs = header->channels();
        if (cs < 4) { // alpha on 64-bit images must be 0xFF
            std::memset(img.bits(), 0xFF, img.sizeInBytes());
        }
        for (auto c = 0, cc = header->channels() * header->bpc(); c < cc; ++c) {
#if Q_BYTE_ORDER == Q_BIG_ENDIAN
            auto c_bcp = c / cs;
#else
            auto c_bcp = 1 - c / cs;
#endif
            auto c_cs = (cs - 1 - c % cs) * bpc + c_bcp;
            for (auto y = 0, h = img.height(); y < h; ++y) {
                auto ba = readStride(d, header);
                if (ba.isEmpty()) {
                    return {};
                }
                auto scl = reinterpret_cast<quint8*>(img.scanLine(y));
                for (auto x = 0, w = std::min(int(ba.size()), img.width()); x < w; ++x) {
                    scl[x * 4 * bpc + c_cs] = ba.at(x); // * 4 -> Qt RGB 64-bit formats are always 4 channels
                }
            }
        }
    }

    return img;
}

QImage RGBAChunk::uncompressedTile(QIODevice *d, const TBHDChunk *header) const
{
    QImage img(size(), header->format());
    auto bpc = header->bpc();

    if (bpc == 1) {
        auto cs = header->channels();
        auto lineSize = img.width() * bpc * cs;

        for (auto y = 0, h = img.height(); y < h; ++y) {
            auto ba = d->read(lineSize);
            if (ba.isEmpty()) {
                return {};
            }
            auto scl = reinterpret_cast<quint8*>(img.scanLine(y));
            for (auto c = 0; c < cs; ++c) {
                for (auto x = 0, w = std::min(int(ba.size() / cs), img.width()); x < w; ++x) {
                    auto xcs = x * cs;
                    scl[xcs + cs - c - 1] = ba.at(xcs + c);
                }
            }
        }
    } else if (bpc == 2) {
        auto cs = header->channels();
        auto lineSize = img.width() * bpc * cs;
        if (cs < 4) { // alpha on 64-bit images must be 0xFF
            std::memset(img.bits(), 0xFF, img.sizeInBytes());
        }

        for (auto y = 0, h = img.height(); y < h; ++y) {
            auto ba = d->read(lineSize);
            if (ba.isEmpty()) {
                return {};
            }
            auto scl = reinterpret_cast<quint16*>(img.scanLine(y));
            auto src = reinterpret_cast<const quint16*>(ba.data());
            for (auto c = 0; c < cs; ++c) {
                for (auto x = 0, w = std::min(int(ba.size() / cs / bpc), img.width()); x < w; ++x) {
                    auto xcs = x * cs;
                    auto xcs4 = x * 4;
#if Q_BYTE_ORDER == Q_BIG_ENDIAN
                    scl[xcs4 + cs - c - 1] = src[xcs + c];
#else
                    scl[xcs4 + cs - c - 1] = (src[xcs + c] >> 8) | (src[xcs + c] << 8);
#endif
                }
            }
        }
    }

    return img;
}

QImage RGBAChunk::tile(QIODevice *d, const TBHDChunk *header) const
{
    if (!isValid() || header == nullptr) {
        return {};
    }
    if (!seek(d, 8)) {
        return {};
    }

    if (isTileCompressed(header)) {
        return compressedTile(d, header);
    }

    return uncompressedTile(d, header);
}

bool RGBAChunk::innerReadStructure(QIODevice *d)
{
    auto ba = d->read(8);
    if (ba.size() != 8) {
        return false;
    }

    auto x0 = ui16(ba.at(1), ba.at(0));
    auto y0 = ui16(ba.at(3), ba.at(2));
    auto x1 = ui16(ba.at(5), ba.at(4));
    auto y1 = ui16(ba.at(7), ba.at(6));
    if (x0 > x1 || y0 > y1) {
        return false;
    }

    _pos = QPoint(x0, y0);
    _size = QSize(qint32(x1) - x0 + 1, qint32(y1) - y0 + 1);

    return true;
}

/* ******************
 * *** AUTH Chunk ***
 * ****************** */

AUTHChunk::~AUTHChunk()
{

}

AUTHChunk::AUTHChunk()
{

}

bool AUTHChunk::isValid() const
{
    return chunkId() == AUTHChunk::defaultChunkId();
}

QString AUTHChunk::value() const
{
    return QString::fromLatin1(data());
}

bool AUTHChunk::innerReadStructure(QIODevice *d)
{
    return cacheData(d);
}

/* ******************
 * *** DATE Chunk ***
 * ****************** */

DATEChunk::~DATEChunk()
{

}

DATEChunk::DATEChunk()
{

}

bool DATEChunk::isValid() const
{
    return chunkId() == DATEChunk::defaultChunkId();
}

QDateTime DATEChunk::value() const
{
    return QDateTime::fromString(QString::fromLatin1(data()), Qt::TextDate);
}

bool DATEChunk::innerReadStructure(QIODevice *d)
{
    return cacheData(d);
}

/* ******************
 * *** FVER Chunk ***
 * ****************** */

FVERChunk::~FVERChunk()
{

}

FVERChunk::FVERChunk()
{

}

bool FVERChunk::isValid() const
{
    return chunkId() == FVERChunk::defaultChunkId();
}

bool FVERChunk::innerReadStructure(QIODevice *d)
{
    return cacheData(d);
}

/* ******************
 * *** HIST Chunk ***
 * ****************** */

HISTChunk::~HISTChunk()
{

}

HISTChunk::HISTChunk()
{

}

bool HISTChunk::isValid() const
{
    return chunkId() == HISTChunk::defaultChunkId();
}

QString HISTChunk::value() const
{
    return QString::fromLatin1(data());
}

bool HISTChunk::innerReadStructure(QIODevice *d)
{
    return cacheData(d);
}

/* ******************
 * *** VERS Chunk ***
 * ****************** */

VERSChunk::~VERSChunk()
{

}

VERSChunk::VERSChunk()
{

}

bool VERSChunk::isValid() const
{
    return chunkId() == VERSChunk::defaultChunkId();
}

QString VERSChunk::value() const
{
    return QString::fromLatin1(data());
}

bool VERSChunk::innerReadStructure(QIODevice *d)
{
    return cacheData(d);
}