/*
  ==============================================================================

   This file is part of the JUCE 6 technical preview.
   Copyright (c) 2020 - Raw Material Software Limited

   You may use this code under the terms of the GPL v3
   (see www.gnu.org/licenses).

   For this technical preview, this file is not subject to commercial licensing.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

ImageConvolutionKernel::ImageConvolutionKernel (int sizeToUse)
    : values ((size_t) (sizeToUse * sizeToUse)),
      size (sizeToUse)
{
    clear();
}

ImageConvolutionKernel::~ImageConvolutionKernel()
{
}

//==============================================================================
float ImageConvolutionKernel::getKernelValue (const int x, const int y) const noexcept
{
    if (isPositiveAndBelow (x, size) && isPositiveAndBelow (y, size))
        return values [x + y * size];

    jassertfalse;
    return 0;
}

void ImageConvolutionKernel::setKernelValue (const int x, const int y, const float value) noexcept
{
    if (isPositiveAndBelow (x, size) && isPositiveAndBelow (y, size))
    {
        values [x + y * size] = value;
    }
    else
    {
        jassertfalse;
    }
}

void ImageConvolutionKernel::clear()
{
    for (int i = size * size; --i >= 0;)
        values[i] = 0;
}

void ImageConvolutionKernel::setOverallSum (const float desiredTotalSum)
{
    double currentTotal = 0.0;

    for (int i = size * size; --i >= 0;)
        currentTotal += values[i];

    rescaleAllValues ((float) (desiredTotalSum / currentTotal));
}

void ImageConvolutionKernel::rescaleAllValues (const float multiplier)
{
    for (int i = size * size; --i >= 0;)
        values[i] *= multiplier;
}

//==============================================================================
void ImageConvolutionKernel::createGaussianBlur (const float radius)
{
    const double radiusFactor = -1.0 / (radius * radius * 2);
    const int centre = size >> 1;

    for (int y = size; --y >= 0;)
    {
        for (int x = size; --x >= 0;)
        {
            auto cx = x - centre;
            auto cy = y - centre;

            values [x + y * size] = (float) std::exp (radiusFactor * (cx * cx + cy * cy));
        }
    }

    setOverallSum (1.0f);
}

//==============================================================================
void ImageConvolutionKernel::applyToImage (Image& destImage,
                                           const Image& sourceImage,
                                           const Rectangle<int>& destinationArea) const
{
    if (sourceImage == destImage)
    {
        destImage.duplicateIfShared();
    }
    else
    {
        if (sourceImage.getWidth() != destImage.getWidth()
             || sourceImage.getHeight() != destImage.getHeight()
             || sourceImage.getFormat() != destImage.getFormat())
        {
            jassertfalse;
            return;
        }
    }

    auto area = destinationArea.getIntersection (destImage.getBounds());

    if (area.isEmpty())
        return;

    auto right = area.getRight();
    auto bottom = area.getBottom();

    const Image::BitmapData destData (destImage, area.getX(), area.getY(), area.getWidth(), area.getHeight(),
                                      Image::BitmapData::writeOnly);
    uint8* line = destData.data;

    const Image::BitmapData srcData (sourceImage, Image::BitmapData::readOnly);

    if (destData.pixelStride == 4)
    {
        for (int y = area.getY(); y < bottom; ++y)
        {
            uint8* dest = line;
            line += destData.lineStride;

            for (int x = area.getX(); x < right; ++x)
            {
                float c1 = 0;
                float c2 = 0;
                float c3 = 0;
                float c4 = 0;

                for (int yy = 0; yy < size; ++yy)
                {
                    const int sy = y + yy - (size >> 1);

                    if (sy >= srcData.height)
                        break;

                    if (sy >= 0)
                    {
                        int sx = x - (size >> 1);
                        const uint8* src = srcData.getPixelPointer (sx, sy);

                        for (int xx = 0; xx < size; ++xx)
                        {
                            if (sx >= srcData.width)
                                break;

                            if (sx >= 0)
                            {
                                const float kernelMult = values [xx + yy * size];
                                c1 += kernelMult * *src++;
                                c2 += kernelMult * *src++;
                                c3 += kernelMult * *src++;
                                c4 += kernelMult * *src++;
                            }
                            else
                            {
                                src += 4;
                            }

                            ++sx;
                        }
                    }
                }

                *dest++ = (uint8) jmin (0xff, roundToInt (c1));
                *dest++ = (uint8) jmin (0xff, roundToInt (c2));
                *dest++ = (uint8) jmin (0xff, roundToInt (c3));
                *dest++ = (uint8) jmin (0xff, roundToInt (c4));
            }
        }
    }
    else if (destData.pixelStride == 3)
    {
        for (int y = area.getY(); y < bottom; ++y)
        {
            uint8* dest = line;
            line += destData.lineStride;

            for (int x = area.getX(); x < right; ++x)
            {
                float c1 = 0;
                float c2 = 0;
                float c3 = 0;

                for (int yy = 0; yy < size; ++yy)
                {
                    const int sy = y + yy - (size >> 1);

                    if (sy >= srcData.height)
                        break;

                    if (sy >= 0)
                    {
                        int sx = x - (size >> 1);
                        const uint8* src = srcData.getPixelPointer (sx, sy);

                        for (int xx = 0; xx < size; ++xx)
                        {
                            if (sx >= srcData.width)
                                break;

                            if (sx >= 0)
                            {
                                const float kernelMult = values [xx + yy * size];
                                c1 += kernelMult * *src++;
                                c2 += kernelMult * *src++;
                                c3 += kernelMult * *src++;
                            }
                            else
                            {
                                src += 3;
                            }

                            ++sx;
                        }
                    }
                }

                *dest++ = (uint8) roundToInt (c1);
                *dest++ = (uint8) roundToInt (c2);
                *dest++ = (uint8) roundToInt (c3);
            }
        }
    }
    else if (destData.pixelStride == 1)
    {
        for (int y = area.getY(); y < bottom; ++y)
        {
            uint8* dest = line;
            line += destData.lineStride;

            for (int x = area.getX(); x < right; ++x)
            {
                float c1 = 0;

                for (int yy = 0; yy < size; ++yy)
                {
                    const int sy = y + yy - (size >> 1);

                    if (sy >= srcData.height)
                        break;

                    if (sy >= 0)
                    {
                        int sx = x - (size >> 1);
                        const uint8* src = srcData.getPixelPointer (sx, sy);

                        for (int xx = 0; xx < size; ++xx)
                        {
                            if (sx >= srcData.width)
                                break;

                            if (sx >= 0)
                            {
                                const float kernelMult = values [xx + yy * size];
                                c1 += kernelMult * *src++;
                            }
                            else
                            {
                                src += 3;
                            }

                            ++sx;
                        }
                    }
                }

                *dest++ = (uint8) roundToInt (c1);
            }
        }
    }
}

} // namespace juce