/* ============================================================
 *
 * This file is a part of digiKam project
 * https://www.digikam.org
 *
 * Date        : 2023-05-15
 * Description : geolocation engine based on Marble.
 *               (c) 2007-2022 Marble Team
 *               https://invent.kde.org/education/marble/-/raw/master/data/credits_authors.html
 *
 * SPDX-FileCopyrightText: 2023-2026 by Gilles Caulier <caulier dot gilles at gmail dot com>
 *
 * SPDX-License-Identifier: LGPL-2.1-or-later
 *
 * ============================================================ */

#include "TextureColorizer.h"

// Qt includes

#include <qmath.h>
#include <QFile>
#include <QSharedPointer>
#include <QVector>
#include <QElapsedTimer>
#include <QPainter>

// Local includes

#include "GeoPainter.h"
#include "ViewParams.h"
#include "ViewportParams.h"
#include "MathHelper.h"
#include "GeoDataLinearRing.h"
#include "GeoDataPolygon.h"
#include "GeoDataFeature.h"
#include "GeoDataPlacemark.h"
#include "AbstractProjection.h"
#include "digikam_debug.h"

namespace Marble
{

/**
 * 4 uchar long queue
 */
class Q_DECL_HIDDEN EmbossFifo
{
public:

    EmbossFifo()
        : data(0)
    {
    }

    inline uchar head() const
    {
        // return least significant byte as head of queue

        return data & 0x000000FF;
    }

    inline void enqueue(uchar value)
    {
        // drop current head by shifting by one byte
        // and append new value as most significant byte to queue

        data = ((data >> 8) & 0x00FFFFFF) | (value << 24);
    }

private:

    // 4 byte long queue

    quint32 data;
};

TextureColorizer::TextureColorizer(const QString& seafile,
                                   const QString& landfile)
    : m_showRelief(false),
      m_landColor(qRgb(255, 0, 0)),
      m_seaColor(qRgb(0, 255, 0))
{
    QElapsedTimer t;
    t.start();

    QImage   gradientImage(256, 1, QImage::Format_RGB32);
    QPainter  gradientPainter;
    gradientPainter.begin(&gradientImage);
    gradientPainter.setPen(Qt::NoPen);

    int shadingStart = 120;
    QImage    shadingImage(16, 1, QImage::Format_RGB32);
    QPainter  shadingPainter;
    shadingPainter.begin(&shadingImage);
    shadingPainter.setPen(Qt::NoPen);

    int offset       = 0;

    QStringList  filelist;
    filelist << seafile << landfile;

    for (const QString& filename : filelist)
    {
        QLinearGradient  gradient(0, 0, 256, 0);

        QFile  file(filename);

        if (!file.open(QIODevice::ReadOnly))
        {
            qCWarning(DIGIKAM_GEOENGINE_LOG) << Q_FUNC_INFO << "Cannot load" << filename;
            continue;
        }

        QTextStream  stream(&file);    // read the data from the file

        QString      evalstrg;

        while (!stream.atEnd())
        {
            stream >> evalstrg;

            if (!evalstrg.isEmpty() && evalstrg.contains(QLatin1Char('=')))
            {
                QString  colorValue    = evalstrg.left(evalstrg.indexOf(QLatin1Char('=')));
                QString  colorPosition = evalstrg.mid(evalstrg.indexOf(QLatin1Char('=')) + 1);
                gradient.setColorAt(colorPosition.toDouble(),
                                    QColor(colorValue));
            }
        }

        gradientPainter.setBrush(gradient);
        gradientPainter.drawRect(0, 0, 256, 1);

        QLinearGradient  shadeGradient(- shadingStart, 0, 256 - shadingStart, 0);

        shadeGradient.setColorAt(0.00, QColor(Qt::white));
        shadeGradient.setColorAt(0.15, QColor(Qt::white));
        shadeGradient.setColorAt(0.75, QColor(Qt::black));
        shadeGradient.setColorAt(1.00, QColor(Qt::black));

        const QRgb* gradientScanLine  = reinterpret_cast<QRgb*>(gradientImage.scanLine(0));
        const QRgb* shadingScanLine   = reinterpret_cast<QRgb*>(shadingImage.scanLine(0));

        for (int i = 0 ; i < 256 ; ++i)
        {

            QRgb shadeColor = *(gradientScanLine + i);
            shadeGradient.setColorAt(0.496, shadeColor);
            shadeGradient.setColorAt(0.504, shadeColor);
            shadingPainter.setBrush(shadeGradient);
            shadingPainter.drawRect(0, 0, 16, 1);

            // populate texturepalette[][]

            for (int j = 0 ; j < 16 ; ++j)
            {
                texturepalette[j][offset + i] = *(shadingScanLine + j);
            }
        }

        offset += 256;
    }

    shadingPainter.end();  // Need to explicitly tell painter lifetime to avoid crash
    gradientPainter.end(); // on some systems.

    qCDebug(DIGIKAM_GEOENGINE_LOG) << Q_FUNC_INFO << "Time elapsed:" << t.elapsed() << "ms";
}

void TextureColorizer::addSeaDocument(const GeoDataDocument* seaDocument)
{
    m_seaDocuments.append(seaDocument);
}

void TextureColorizer::addLandDocument(const GeoDataDocument* landDocument)
{
    m_landDocuments.append(landDocument);
}

void TextureColorizer::setShowRelief(bool show)
{
    m_showRelief = show;
}

// This function takes two images, both in viewParams:
//  - The coast image, which has a number of colors where each color
//    represents a sort of terrain (ex: land/sea)
//  - The canvas image, which has a gray scale image, often
//    representing a height field.
//
// It then uses the values of the pixels in the coast image to select
// a color map.  The value of the pixel in the canvas image is used as
// an index into the selected color map and the resulting color is
// written back to the canvas image.  This way we can have different
// color schemes for land and water.
//
// In addition to this, a simple form of bump mapping is performed to
// increase the illusion of height differences (see the variable
// showRelief).
//

void TextureColorizer::drawIndividualDocument(GeoPainter* painter, const GeoDataDocument* document)
{
    QVector<GeoDataFeature*>::ConstIterator i   = document->constBegin();
    QVector<GeoDataFeature*>::ConstIterator end = document->constEnd();

    for ( ; i != end ; ++i)
    {
        if (const GeoDataPlacemark* placemark = geodata_cast<GeoDataPlacemark>(*i))
        {
            if (const GeoDataLineString* child = geodata_cast<GeoDataLineString>(placemark->geometry()))
            {
                const GeoDataLinearRing ring(*child);
                painter->drawPolygon(ring);
            }

            if (const GeoDataPolygon* child = geodata_cast<GeoDataPolygon>(placemark->geometry()))
            {
                painter->drawPolygon(*child);
            }

            if (const GeoDataLinearRing* child = geodata_cast<GeoDataLinearRing>(placemark->geometry()))
            {
                painter->drawPolygon(*child);
            }
        }
    }
}

void TextureColorizer::drawTextureMap(GeoPainter* painter)
{
    for (const GeoDataDocument* doc : m_landDocuments)
    {
        painter->setPen(QPen(Qt::NoPen));
        painter->setBrush(QBrush(m_landColor));
        drawIndividualDocument(painter, doc);
    }

    for (const GeoDataDocument* doc : m_seaDocuments)
    {
        if (doc->isVisible())
        {
            painter->setPen(Qt::NoPen);
            painter->setBrush(QBrush(m_seaColor));
            drawIndividualDocument(painter, doc);
        }
    }
}

void TextureColorizer::colorize(QImage* origimg, const ViewportParams* viewport, MapQuality mapQuality)
{
    if (m_coastImage.size() != viewport->size())
    {
        m_coastImage = QImage(viewport->size(), QImage::Format_RGB32);
    }

    // update coast image.

    m_coastImage.fill(QColor(0, 0, 255, 0).rgb());

    const bool antialiased = (mapQuality == HighQuality) || (mapQuality == PrintQuality);

    GeoPainter painter(&m_coastImage, viewport, mapQuality);
    painter.setRenderHint(QPainter::Antialiasing, antialiased);

    drawTextureMap(&painter);

    const qint64 radius  = viewport->radius() * viewport->currentProjection()->clippingRadius();

    const int  imgheight = origimg->height();
    const int  imgwidth  = origimg->width();
    const int  imgrx     = imgwidth / 2;
    const int  imgry     = imgheight / 2;

    // This variable is not used anywhere.

    const int  imgradius = imgrx * imgrx + imgry * imgry;

    int     bump = 8;

    if (
        ((radius * radius) > imgradius) ||
        !viewport->currentProjection()->isClippedToSphere()
       )
    {
        int yTop    = 0;
        int yBottom = imgheight;

        if (!viewport->currentProjection()->isClippedToSphere() && !viewport->currentProjection()->traversablePoles())
        {
            qreal realYTop, realYBottom, dummyX;
            GeoDataCoordinates yNorth(0, viewport->currentProjection()->maxLat(), 0);
            GeoDataCoordinates ySouth(0, viewport->currentProjection()->minLat(), 0);
            viewport->screenCoordinates(yNorth, dummyX, realYTop);
            viewport->screenCoordinates(ySouth, dummyX, realYBottom);
            yTop    = qBound(qreal(0.0), realYTop, qreal(imgheight));
            yBottom = qBound(qreal(0.0), realYBottom, qreal(imgheight));
        }

        const int itEnd = yBottom;

        for (int y = yTop ; y < itEnd ; ++y)
        {
            QRgb*  writeData         = reinterpret_cast<QRgb*>(origimg->scanLine(y));
            const QRgb*  coastData   = reinterpret_cast<QRgb*>(m_coastImage.scanLine(y));

            uchar* readDataStart     = origimg->scanLine(y);
            const uchar* readDataEnd = readDataStart + imgwidth * 4;

            EmbossFifo  emboss;

            for (uchar* readData = readDataStart;
                 readData < readDataEnd;
                 readData += 4, ++writeData, ++coastData)
            {
                // Cheap Emboss / Bumpmapping

                uchar&  grey = *readData; // qBlue(*data);

                if (m_showRelief)
                {
                    emboss.enqueue(grey);
                    bump = (emboss.head() + 8 - grey);

                    if (bump < 0)
                    {
                        bump = 0;
                    }

                    else if (bump > 15)
                    {
                        bump = 15;
                    }
                }

                setPixel(coastData, writeData, bump, grey);
            }
        }
    }

    else
    {
        int yTop          = (imgry - radius < 0) ? 0 : imgry - radius;
        const int yBottom = (yTop == 0) ? imgheight : imgry + radius;

        EmbossFifo  emboss;

        for (int y = yTop ; y < yBottom ; ++y)
        {
            const int  dy = imgry - y;
            int  rx       = (int)sqrt((qreal)(radius * radius - dy * dy));
            int  xLeft    = 0;
            int  xRight   = imgwidth;

            if (imgrx - rx > 0)
            {
                xLeft  = imgrx - rx;
                xRight = imgrx + rx;
            }

            QRgb*  writeData         = reinterpret_cast<QRgb*>(origimg->scanLine(y))     + xLeft;
            const QRgb* coastData    = reinterpret_cast<QRgb*>(m_coastImage.scanLine(y)) + xLeft;

            uchar* readDataStart     = origimg->scanLine(y) + xLeft * 4;
            const uchar* readDataEnd = origimg->scanLine(y) + xRight * 4;


            for (uchar* readData = readDataStart;
                 readData < readDataEnd;
                 readData += 4, ++writeData, ++coastData)
            {
                // Cheap Emboss / Bumpmapping

                uchar& grey = *readData; // qBlue(*data);

                if (m_showRelief)
                {
                    emboss.enqueue(grey);
                    bump = (emboss.head() + 16 - grey) >> 1;

                    if (bump < 0)
                    {
                        bump = 0;
                    }

                    else if (bump > 15)
                    {
                        bump = 15;
                    }
                }

                setPixel(coastData, writeData, bump, grey);
            }
        }
    }
}

void TextureColorizer::setPixel(const QRgb* coastData, QRgb* writeData, int bump, uchar grey)
{
    int alpha = qRed(*coastData);

    if (alpha == 255)
    {
        *writeData = texturepalette[bump][grey + 0x100];
    }

    else if (alpha == 0)
    {
        *writeData = texturepalette[bump][grey];
    }

    else
    {
        qreal c = 1.0 / 255.0;

        QRgb landcolor  = (QRgb)(texturepalette[bump][grey + 0x100]);
        QRgb watercolor = (QRgb)(texturepalette[bump][grey]);

        *writeData = qRgb(
                         (int)(c * (alpha * qRed(landcolor)
                                    + (255 - alpha) * qRed(watercolor))),
                         (int)(c * (alpha * qGreen(landcolor)
                                    + (255 - alpha) * qGreen(watercolor))),
                         (int)(c * (alpha * qBlue(landcolor)
                                    + (255 - alpha) * qBlue(watercolor)))
                     );
    }
}

} // namespace Marble
