#ifndef LAZY_IMAGE_C
#define LAZY_IMAGE_C

#include <QtGlobal>
#include <QMainWindow>
#include <QColor>

#include <iostream>

#include <math.h>

class LazyImage {
  
  private:
    QImage* img; //Not managed by us, just used.
    QImage* histogramm_image;
    double histogramm_relative_intensity[256];
    int histogramm_absolute_intensity[256];
    int intensity_average;
    int intensity_variance;
    
    void gatherHistogrammData(void) {
      // Zero existing histogramm data first
      for(int i=0; i<256; i++) {
	histogramm_relative_intensity[i] = 0;
	histogramm_absolute_intensity[i] = 0;
      }      
      // Count all the brightness values
      for(int x=0; x<this->img->width(); x++) {
	for(int y=0; y<this->img->height(); y++) {
	  int r,g,b;
	  QColor color = QColor::fromRgb(this->img->pixel(x, y));
	  color.getRgb(&r,&g,&b);
	  int intensity = this->calcIntensity(r, g, b);
	  histogramm_absolute_intensity[intensity] += 1;
	}
      }      
      // Calculate relative histogramm
      int pixels = this->img->width()*this->img->height();
      for(int i=0; i<256; i++) {
	histogramm_relative_intensity[i] = (((double) histogramm_absolute_intensity[i])/((double) pixels));
      }
    };
    
    void calcIntensityAverage(void) {
      double sum = 0;
      for(int i=0; i<256;i++) {
	sum += (i*histogramm_relative_intensity[i]);
      }
      this->intensity_average = (int) qRound(sum);
    };

    void calcIntensityVariance(void) {
      int intensity_average = this->intensity_average;
      int sum_difference = 0;
      for(int x=0; x<this->img->width(); x++) {
	for(int y=0; y<this->img->height(); y++) {
	  QColor color = QColor::fromRgb(this->img->pixel(x, y));
	  int r,g,b;
	  color.getRgb(&r,&g,&b);
	  sum_difference += std::abs(this->calcIntensity(r, g, b) - intensity_average);;
	}
      }
      this->intensity_variance = (int) qRound(sum_difference/(this->img->width()*this->img->height()));
    };
    
    void generateHistogrammImage(void) {
      if(this->histogramm_image != NULL) {
	delete this->histogramm_image;
	this->histogramm_image = NULL;
      }
      //Find biggest value in histogramm data
      double max = 0;
      for(int i=0; i<256; i++) {
	if(histogramm_relative_intensity[i] > max) max = histogramm_relative_intensity[i];
      }
      
      this->histogramm_image = new QImage(256, 100, QImage::Format_RGB32);
      this->histogramm_image->fill(QColor::fromRgb(200,200,200));
      int black = QColor::fromRgb(0,0,0).rgb();
      for(int x=0; x<256; x++) {
	int k_max = (int) qRound((100*histogramm_relative_intensity[x])/max);
	for(int y=0; y<k_max; y++) {
	  this->histogramm_image->setPixel(x, (100-y)-1, black);
	}
      }
    };
    

  public:
    LazyImage(QImage* img) {
      this->histogramm_image = NULL;
      this->setImage(img);
    };
    
    ~LazyImage() {
      if(img != NULL) {
	img = NULL;
      }
    };
    
    void setImage(QImage* img) {
      if(img != NULL) {
	this->img = img;
	this->updateStatistics();
      }
    };
    
    QImage* getImage(void) {
      return this->img;
    };
    
    void updateStatistics(void) {
      this->gatherHistogrammData();
      this->calcIntensityAverage();
      this->calcIntensityVariance();
      this->generateHistogrammImage();
    };
    
    QImage* getHistogrammImage(void) {
      return this->histogramm_image;
    };
    
    /**
     * Uses simple weights to calculate intensity of a pixel.
     * Using qRound() to reduce the error of the int cast.
     * 
     * @brief LazyImage::calcIntensity
     */
    int calcIntensity(int r, int g, int b) {
      return (int) qRound(0.299*r + 0.587*g + 0.114*b);
    };
    
    int getIntensityAverage(void) {
      return this->intensity_average;
    }
    
    int getIntensityVariance(void) {
      return this->intensity_variance;
    };
    
    int* getAbsoluteIntensityHistogramm(void) {
      return this->histogramm_absolute_intensity;
    };

    double* getRelativeIntensityHistogramm(void) {
      return this->histogramm_relative_intensity;
    };
    
    void convertToMonochrome(void) {
      for(int x=0; x<this->img->width(); x++) {
        for(int y=0; y<this->img->height(); y++) {
	  int r,g,b;
	  QColor color = QColor::fromRgb(this->img->pixel(x, y));
	  color.getRgb(&r,&g,&b);
	  int intensity = this->calcIntensity(r, g, b);
	  color = QColor::fromRgb(intensity, intensity, intensity);
	  this->img->setPixel(x, y, color.rgb());
        }
      }
    };

};


#endif