/*
 * Copyright (C) 2018 Matthias Schnöll (matthias.schnoell AT gmail.com)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include "frei0r.hpp"

// Limits (min/max values) of various data types
#include <limits>
// For the CHAR_BIT constant
#include <climits>
// pow() and other mathematical functions
#include <cmath>

#define PI 3.141592654

/**
This is a frei0r filter which allows to scale video footage non-linearly.
In combination with a linear scale filter, it allows to scale 4:3 footage
to 16:9 and maintain the original aspect ratio in the center part of the image.
*/

typedef struct {
    unsigned int higherXPos;
    unsigned int lowerXPos;
    double lowerWeight;
    double higherWeight;
} TransformationElem;


class ElasticScale : public frei0r::filter
{

public:

    ElasticScale(unsigned int width, unsigned int height)

    {
        this->width = width;
        this->height = height;

        register_param(m_scaleCenter,"Center","Horizontal center position of the linear area");
        register_param(m_linearScaleArea,"Linear Width","Width of the linear area");
        register_param(m_linearScaleFactor,"Linear Scale Factor","Amount how much the linear area is scaled");
        register_param(m_nonLinearScaleFactor,"Non-Linear Scale Factor","Amount how much the outer left and outer right areas are scaled non linearly");

        // default values for sinus based scaling
        m_scaleCenter = 0.5;
        m_linearScaleArea = 0.0;
        m_linearScaleFactor = 0.7;
        m_nonLinearScaleFactor = 0.7125;

        updateScalingFactors();
        calcTransformationFactors();
    }

    ~ElasticScale()
    {
        // Delete member variables if necessary.
        delete[] m_transformationCalculations;
    }

    virtual void update(double time,
	                    uint32_t* out,
                        const uint32_t* in)
    {

        if (m_prev_scaleCenter != m_scaleCenter || m_prev_linearScaleArea != m_linearScaleArea || m_prev_linearScaleFactor != m_linearScaleFactor || m_prev_nonLinearScaleFactor != m_nonLinearScaleFactor)
        {
            updateScalingFactors();
            calcTransformationFactors();
        }

        // pad the rowWidth to be a multiple of 8
        unsigned int paddedRowWidth = width;
        if (paddedRowWidth % 8 != 0)
        {
            paddedRowWidth = (unsigned int)(ceil((double)width/8)*8);
        }

        for (unsigned int colIdx = 0; colIdx < width; colIdx++)
        {
            double lowerWeight = m_transformationCalculations[colIdx].lowerWeight;
            double higherWeight = m_transformationCalculations[colIdx].higherWeight;

            for (unsigned int rowIdx = 0; rowIdx < height; rowIdx++)
            {
                uint32_t newValue = 0;
                unsigned int lowerXPos = paddedRowWidth * rowIdx + m_transformationCalculations[colIdx].lowerXPos;
                unsigned int higherXPos = paddedRowWidth * rowIdx + m_transformationCalculations[colIdx].higherXPos;
                unsigned int curPosDst = paddedRowWidth * rowIdx + colIdx;

                if (higherXPos == lowerXPos) {
                    newValue = in[higherXPos];
                } else {
                    for (int i=0; i<4; i++)
                    {
                        uint16_t cFold = uint8_t(in[lowerXPos] >> 8*i);
                        uint16_t cCold = uint8_t(in[higherXPos] >> 8*i);
                        cFold = (uint16_t)((double)cFold*(1-lowerWeight));
                        cCold = (uint16_t)((double)cCold*(1-higherWeight));
                        newValue |= ((uint8_t)((cFold + cCold)) << 8*i);
                    }
                }

                out[curPosDst] = newValue;
            }

        }

    }

private:

    // input params    
    double m_linearScaleArea;
    double m_scaleCenter;
    double m_linearScaleFactor;
    double m_nonLinearScaleFactor;

    // remember the input params to detect any changes during runtime
    double m_prev_scaleCenter;
    double m_prev_linearScaleArea;
    double m_prev_linearScaleFactor;
    double m_prev_nonLinearScaleFactor;

    // intern params for mapping the input parameters
    double m_intern_scaleCenter;
    double m_intern_linearScaleArea;
    double m_intern_linearScaleFactor;
    double m_intern_nonLinearScaleFactor;

    unsigned int m_borderXAbsLeftSrc;
    unsigned int m_borderXAbsRightSrc;

    unsigned int m_borderXAbsLeftDst;
    unsigned int m_borderXAbsRightDst;

    TransformationElem* m_transformationCalculations = NULL;

    void updateScalingFactors()
    {
        // update changed parameters
        m_prev_scaleCenter = m_scaleCenter;
        m_prev_linearScaleArea = m_linearScaleArea;
        m_prev_linearScaleFactor = m_linearScaleFactor;
        m_prev_nonLinearScaleFactor = m_nonLinearScaleFactor;

        // write to internal parameters
        m_intern_scaleCenter = m_scaleCenter;
        m_intern_linearScaleArea = m_linearScaleArea;
        m_intern_linearScaleFactor = m_linearScaleFactor;
        m_intern_nonLinearScaleFactor = m_nonLinearScaleFactor;

        // limit internal parameters to ranges [0,1]
        if (m_intern_scaleCenter <= 0)
        { m_intern_scaleCenter = 0; }
        else if (m_intern_scaleCenter >= 1)
        { m_intern_scaleCenter = 1; }

        if (m_intern_linearScaleArea <= 0)
        { m_intern_linearScaleArea = 0; }
        else if (m_intern_linearScaleArea >= 1)
        { m_intern_linearScaleArea = 1; }

        if (m_intern_linearScaleFactor <= 0)
        { m_intern_linearScaleFactor = 0; }
        else if (m_intern_linearScaleFactor >= 1)
        { m_intern_linearScaleFactor = 1; }

        if (m_intern_nonLinearScaleFactor <= 0)
        { m_intern_nonLinearScaleFactor = 0; }
        else if (m_intern_nonLinearScaleFactor >= 1)
        { m_intern_nonLinearScaleFactor = 1; }

        // adjust internal parameters where necessary
        m_intern_nonLinearScaleFactor = m_intern_nonLinearScaleFactor*0.4-0.2;

        // calculate borders based on parameters
        // use 'int' instead of 'unsigned int' as possible results can be negative
        m_borderXAbsLeftSrc = (int)(m_intern_scaleCenter * width - m_intern_linearScaleArea / 2 * width);
        m_borderXAbsLeftDst = (int)(m_intern_scaleCenter * width - m_intern_linearScaleArea / 2 * width * m_intern_linearScaleFactor);

        m_borderXAbsRightSrc = (int)(m_intern_scaleCenter * width + m_intern_linearScaleArea / 2 * width);
        m_borderXAbsRightDst = (int)(m_intern_scaleCenter * width + m_intern_linearScaleArea / 2 * width * m_intern_linearScaleFactor);

        // validate if resulting borders are still within the valid range for later calculations [1,width-1]
        // negative results are limited
        if ((int)m_borderXAbsLeftSrc <= 1)
        { m_borderXAbsLeftSrc = 1; }
        else if ((int)m_borderXAbsLeftSrc >= (int)width-1)
        { m_borderXAbsLeftSrc = width-1; }

        if ((int)m_borderXAbsRightSrc <= 1)
        { m_borderXAbsRightSrc = 1; }
        else if ((int)m_borderXAbsRightSrc >= (int)width-1)
        { m_borderXAbsRightSrc = width-1; }

        if ((int)m_borderXAbsLeftDst <= 1)
        { m_borderXAbsLeftDst = 1; }
        else if ((int)m_borderXAbsLeftDst >= (int)width-1)
        { m_borderXAbsLeftDst = width-1; }

        if ((int)m_borderXAbsRightDst <= 1)
        { m_borderXAbsRightDst = 1; }
        else if ((int)m_borderXAbsRightDst >= (int)width-1)
        { m_borderXAbsRightDst = width-1; }
        
    }

    void calcTransformationFactors()
    {

        if (m_transformationCalculations == NULL)
        {
            m_transformationCalculations = new TransformationElem[width];
        }

        for (unsigned int colIdx = 0; colIdx < width; colIdx++)
        {
            double relativeSrcXPos = 0;
            unsigned int higherXPos = 0, lowerXPos = 0;
            double lowerWeight = 0;
            double higherWeight = 0;

            unsigned int offsetSrcX = 0;
            unsigned int offsetDstX = 0;
            unsigned int lengthSrcSection = m_borderXAbsLeftSrc - offsetSrcX - 1;
            unsigned int lengthDstSection = m_borderXAbsLeftDst - offsetDstX - 1;

            // y=SIN(x*pi-pi)*a+x
            double linearRatio = (double)(colIdx - offsetDstX) / lengthDstSection;
            double ratio = sin(linearRatio * PI - PI) * m_intern_nonLinearScaleFactor + linearRatio;

            if (colIdx > m_borderXAbsLeftDst)
            {
                offsetSrcX = m_borderXAbsLeftSrc;
                offsetDstX = m_borderXAbsLeftDst;
                lengthSrcSection = m_borderXAbsRightSrc - offsetSrcX - 1;
                lengthDstSection = m_borderXAbsRightDst - offsetDstX - 1;
                // linear section
                double linearRatio = (double)(colIdx - offsetDstX) / lengthDstSection;
                ratio = ((double)(colIdx - offsetDstX) / lengthDstSection);
            }
                
            if (colIdx > m_borderXAbsRightDst)
            {
                offsetSrcX = m_borderXAbsRightSrc;
                offsetDstX = m_borderXAbsRightDst;
                lengthSrcSection = width - offsetSrcX - 1;
                lengthDstSection = width - offsetDstX - 1;

                // y=SIN(x*pi)*a+x
                double linearRatio = (double)(colIdx-offsetDstX) / lengthDstSection;
                ratio = sin(linearRatio * PI) * m_intern_nonLinearScaleFactor + linearRatio;
            }

            // limit ratio to 0
            ratio = ratio <= 0 ? 0 : ratio;

            relativeSrcXPos = ratio * lengthSrcSection;
            
            lowerXPos = (unsigned int)floor(relativeSrcXPos);
            higherXPos = (unsigned int)ceil(relativeSrcXPos);
            if (higherXPos >= lengthSrcSection)
            {
                higherXPos = lengthSrcSection;
            }
            if (lowerXPos >= lengthSrcSection)
            {
                lowerXPos = lengthSrcSection;
            }
            
            if (higherXPos == lowerXPos)
            {
                lowerWeight = higherWeight = 0.5;
            } else {
                lowerWeight = relativeSrcXPos - (double)lowerXPos;
                higherWeight = (double)higherXPos - relativeSrcXPos;
            }

            m_transformationCalculations[colIdx].higherXPos = higherXPos + offsetSrcX;
            m_transformationCalculations[colIdx].lowerXPos = lowerXPos + offsetSrcX;
            m_transformationCalculations[colIdx].higherWeight = higherWeight;
            m_transformationCalculations[colIdx].lowerWeight = lowerWeight;

        }
    }

};

frei0r::construct<ElasticScale> plugin("Elastic scale filter",
                "This is a frei0r filter which allows to scale video footage non-linearly.",
                "Matthias Schnoell",
                0,2,
                F0R_COLOR_MODEL_RGBA8888);
