#include <math.h>
#include "image.h"

typedef double (* function_t) (double x);

#define SCALE    32.0

typedef struct
{
    double r, g, b;
} color_t;

static void
plot (complex_image_t *image, color_t color, function_t f)
{
    int i;
    double max, min;
    int first = 1;
    double a, b;
    
    for (i = 0; i < image->width; ++i)
    {
	double v = f(i / SCALE);
	
	if (first || v < min)
	    min = v;
	if (first || v > max)
	    max = v;
	
	first = 0;
    }
    
    if (max - min < DBL_EPSILON)
	return;
    
    max = 2;
    min = -2;
    
    printf ("min %f max %f\n", min, max);
    
    a = (image->height - 1) / (max - min);
    b = - (min * (image->height - 1)) / (max - min);
    
    for (i = 0; i < image->width; ++i)
    {
	double v = f (i / SCALE);
	int idx;
	complex_t p;
	
	v = a * v + b;
	
	printf ("scaled: %f\n", v);
	
	idx = v + 0.5;
	
	if (idx > image->height - 1)
	    idx = image->height - 1;
	if (idx < 0)
	    idx = 0;
	
	idx = idx * image->width + i;
	
	p.re = 0;
	p.im = 0;
	
	image->red[idx] = image->green[idx] = image->blue[idx] = p;
	
	image->red[idx].re = color.r;
	image->green[idx].re = color.g;
	image->blue[idx].re = color.b;
    }
}

static const color_t red =
{
    1.0, 0.0, 0.0
};

static const color_t blue =
{
    0.4, 0.4, 1.0
};

static const color_t green =
{
    0.0, 1.0, 0.0
};

static const color_t yellow =
{
    1.0, 1.0, 0.0
};

#define HIGH  (2)
#define ALIAS (1)

static double
orig (double x)
{
    double v = (0.4 * sin (HIGH * x) + sin (0.3 * x));
    
    return v;
}

static double
antialiased (double x)
{
    double v = sin (0.3 * x);
    
    return v;
}

static double
imperfect  (double x)
{
    return sin (0.3 * x) + 0.1 * sin (ALIAS * x);
}

static double
aliased (double x)
{
    return sin (0.3 * x) + 0.4 * sin (ALIAS * x);
}

int
main ()
{
    complex_image_t *image = complex_image_new (1024, 256);
    
    plot (image, red, orig);
    plot (image, blue, antialiased);
    plot (image, green, aliased);
    plot (image, yellow, imperfect);
    
    complex_image_show ("func", image, CONVERT_RE);
}