#include "depth/DepthService.h"

#include <algorithm>

namespace core {

QImage DepthService::computeFakeDepth(const QSize& size) {
    if (size.isEmpty() || size.width() <= 0 || size.height() <= 0) {
        return {};
    }
    QImage depth(size, QImage::Format_Grayscale8);
    if (depth.isNull()) {
        return {};
    }
    depth.fill(0);
    return depth;
}

QImage DepthService::computeFakeDepthFromBackground(const QImage& background) {
    if (background.isNull()) {
        return {};
    }
    return computeFakeDepth(background.size());
}

QImage DepthService::depthToColormapOverlay(const QImage& depth8, int alpha) {
    if (depth8.isNull()) {
        return {};
    }
    const QImage src = (depth8.format() == QImage::Format_Grayscale8) ? depth8 : depth8.convertToFormat(QImage::Format_Grayscale8);
    if (src.isNull()) {
        return {};
    }

    const int a = std::clamp(alpha, 0, 255);
    QImage out(src.size(), QImage::Format_ARGB32_Premultiplied);
    if (out.isNull()) {
        return {};
    }

    for (int y = 0; y < src.height(); ++y) {
        const uchar* row = src.constScanLine(y);
        QRgb* dst = reinterpret_cast<QRgb*>(out.scanLine(y));
        for (int x = 0; x < src.width(); ++x) {
            const int d = static_cast<int>(row[x]); // 0..255
            // depth=0（远）-> 蓝；depth=255（近）-> 红
            const int r = d;
            const int g = 0;
            const int b = 255 - d;
            dst[x] = qRgba(r, g, b, a);
        }
    }

    return out;
}

}  // namespace core