#include <glib.h>
#include <gdk-pixbuf/gdk-pixbuf.h>

#include "util.h"

/*
 * derived from http://www.gnu.org/software/guile-gnome/docs/gdk/html/The-GdkPixbuf-Structure.html
 */
guchar *pixbuf_point(GdkPixbuf *pixbuf, point_t point)
{
#if 0
	g_assert(point.x >= 0 && point.x < gdk_pixbuf_get_width (pixbuf));
	g_assert(point.y >= 0 && point.y < gdk_pixbuf_get_height(pixbuf));
	g_assert(gdk_pixbuf_get_bits_per_sample(pixbuf) == 8);
#endif

	return gdk_pixbuf_get_pixels(pixbuf) 
		+ point.y * gdk_pixbuf_get_rowstride (pixbuf)
		+ point.x * gdk_pixbuf_get_n_channels(pixbuf);
}

void put_pixel(GdkPixbuf *pixbuf, point_t point, color_t color)
{
	//const gint n_channels = gdk_pixbuf_get_n_channels(pixbuf);
#if 0
	g_assert(n_channels == 4 || n_channels == 3);
	g_assert(gdk_pixbuf_get_colorspace(pixbuf) == GDK_COLORSPACE_RGB);
	g_assert(gdk_pixbuf_get_bits_per_sample(pixbuf) == 8);
#endif

	guchar *p = pixbuf_point(pixbuf, point);

	p[0] = color.r;
	p[1] = color.g;
	p[2] = color.b;
#if 0
	if (n_channels == 4)
		p[3] = color.a;
#endif
}

color_t get_pixel(GdkPixbuf *pixbuf, point_t point)
{
	//const gint n_channels = gdk_pixbuf_get_n_channels(pixbuf);
#if 0
	g_assert(gdk_pixbuf_get_colorspace(pixbuf) == GDK_COLORSPACE_RGB);
	g_assert(gdk_pixbuf_get_bits_per_sample(pixbuf) == 8);
	g_assert(n_channels == 4 || n_channels == 3);
#endif

	guchar *p = pixbuf_point(pixbuf, point);

	return COLOR(p[0], p[1], p[2], 0 /*n_channels == 4 ? p[3] : COL_MAX*/);
}

void color_to_yiq(color_t color, guint8 *y, guint8 *i, guint8 *q)
{
	if (y)
		*y = 0.299    * color.r + 0.587    * color.g + 0.115    * color.b;
	if (i)
		*i = 0.595716 * color.r - 0.274453 * color.g - 0.321263 * color.b;
	if (q)
		*q = 0.211456 * color.r - 0.522591 * color.g + 0.311135 * color.b;
}

/*
 * http://en.wikipedia.org/wiki/Digital_compositing
 */
color_t tint(color_t src, color_t tint_color)
{
	return COLOR(
		(tint_color.a * tint_color.r + (255 - tint_color.a) * src.r) / 255,
		(tint_color.a * tint_color.g + (255 - tint_color.a) * src.g) / 255,
		(tint_color.a * tint_color.b + (255 - tint_color.a) * src.b) / 255,
		src.a);
}


color32_t color32_add(color32_t a, color32_t b)
{
	return COLOR32(
			a.r + b.r,
			a.g + b.g,
			a.b + b.b
	);
}

color32_t color32_mult(color32_t a, gint multiplier)
{
	return COLOR32(
			multiplier * a.r,
			multiplier * a.g,
			multiplier * a.b
	);
}
color32_t to_color32(color_t a)
{
	return COLOR32(a.r, a.g, a.b);
}

colord_t colord_add(colord_t a, colord_t b)
{
	return COLORD(
			a.r + b.r,
			a.g + b.g,
			a.b + b.b,
			a.a + b.a
	);
}
colord_t colord_mult(colord_t a, gdouble multiplier)
{
	return COLORD(
			multiplier * a.r,
			multiplier * a.g,
			multiplier * a.b,
			multiplier * a.a
	);
}
colord_t to_colord(color_t a)
{
	return COLORD(a.r, a.g, a.b, a.a);
}


void ring_shift(void *_pntr, gint num, size_t size)
{
	g_assert(num >= 2);

	guint8 *pntr = (guint8*) _pntr;

	char *tmp = g_malloc(size);
	g_memmove(tmp, pntr, size);

	for (gint i = 0; i < (num-1)*size; i+=size)
		g_memmove(pntr+i, pntr+i+size, size);

	g_memmove(pntr + (num-1)*size, tmp, size);
	g_free(tmp);
}