#include "vnc_pixel_codecs.h"

namespace VncPixelCodecs {

QRgb rgbFromPixelBytes(const uchar* bytes)
{
    // Byte order B,G,R,pad -- matches VncSessionBackend's negotiated
    // SetPixelFormat (32bpp little-endian, R at shift 16 / G at 8 / B at 0).
    return qRgb(bytes[2], bytes[1], bytes[0]);
}

int hextileFixedMetaByteCount(quint8 subencoding)
{
    int count = 0;
    if ((subencoding & HextileFlags::kBackgroundSpecified) != 0) {
        count += 4;
    }
    if ((subencoding & HextileFlags::kForegroundSpecified) != 0) {
        count += 4;
    }
    if ((subencoding & HextileFlags::kAnySubrects) != 0) {
        count += 1;
    }
    return count;
}

int decodeHextileFixedMeta(quint8 subencoding, const QByteArray& data, QRgb* background,
                           QRgb* foreground)
{
    int offset = 0;
    const auto* bytes = reinterpret_cast<const uchar*>(data.constData());

    if ((subencoding & HextileFlags::kBackgroundSpecified) != 0) {
        *background = rgbFromPixelBytes(bytes + offset);
        offset += 4;
    }
    if ((subencoding & HextileFlags::kForegroundSpecified) != 0) {
        *foreground = rgbFromPixelBytes(bytes + offset);
        offset += 4;
    }
    if ((subencoding & HextileFlags::kAnySubrects) != 0) {
        return static_cast<int>(static_cast<quint8>(data.at(offset)));
    }
    return 0;
}

int hextileSubrectByteCount(bool coloured, int subrectCount)
{
    return subrectCount * (coloured ? 6 : 2);
}

QVector<HextileSubrect> decodeHextileSubrects(bool coloured, int subrectCount,
                                              const QByteArray& data, QRgb foreground)
{
    QVector<HextileSubrect> subrects;
    subrects.reserve(subrectCount);

    const auto* bytes = reinterpret_cast<const uchar*>(data.constData());
    const int stride = coloured ? 6 : 2;
    for (int i = 0; i < subrectCount; ++i) {
        const uchar* entry = bytes + (i * stride);
        QRgb color = foreground;
        int fieldOffset = 0;
        if (coloured) {
            color = rgbFromPixelBytes(entry);
            fieldOffset = 4;
        }
        const uchar xy = entry[fieldOffset];
        const uchar wh = entry[fieldOffset + 1];
        // High nibble = x (or width-1), low nibble = y (or height-1).
        const int x = (xy >> 4) & 0x0F;
        const int y = xy & 0x0F;
        const int width = ((wh >> 4) & 0x0F) + 1;
        const int height = (wh & 0x0F) + 1;
        subrects.append(HextileSubrect{QRect(x, y, width, height), color});
    }
    return subrects;
}

}