#include <stdio.h>
#include <stdlib.h>
#include <grass/gis.h>
#include "includes.h"
#include <grass/colors.h>
#include "XDRIVER.h"

static int Red[256], Grn[256], Blu[256];
static int Gray[256];

static int r_pos, g_pos, b_pos;
static int r_size, g_size, b_size;
static int r_scale, g_scale, b_scale;

static void get_shifts(unsigned mask, int *pos, int *size, int *scale)
{
	int i, j;

	for (i = 0; (mask & 1) == 0; i++)
		mask >>= 1;
	if (pos)
		*pos = i;

	for (j = i; (mask & 1) != 0; j++)
		mask >>= 1;
	if (size)
		*size = j - i;
	if (scale)
		*scale = 8 - (j - i);
}

static int get_rgb_shifts(void)
{
	get_shifts(use_visual->red_mask,   &r_pos, &r_size, &r_scale);
	get_shifts(use_visual->green_mask, &g_pos, &g_size, &g_scale);
	get_shifts(use_visual->blue_mask,  &b_pos, &b_size, &b_scale);

	return (1 << r_size) * (1 << g_size) * (1 << b_size);
}

static unsigned long find_color_gray(unsigned int r, unsigned int g, unsigned int b)
{
	unsigned int y = (r + g + b) / 3;

	return xpixels[Gray[y]];
}

static unsigned long find_color_indexed(unsigned int r, unsigned int g, unsigned int b)
{
	return xpixels[Red[r] + Grn[g] + Blu[b]];
}

static unsigned long find_color_rgb(unsigned int r, unsigned int g, unsigned int b)
{
	unsigned int rr = r >> r_scale;
	unsigned int gg = g >> g_scale;
	unsigned int bb = b >> b_scale;

	return (rr << r_pos) + (gg << g_pos) + (bb << b_pos);
}

unsigned long find_color(unsigned int r, unsigned int g, unsigned int b)
{

	switch (use_visual->class)
	{
	case StaticGray:
	case GrayScale:
		return find_color_gray(r, g, b);
	case StaticColor:
	case PseudoColor:
		return find_color_indexed(r, g, b);
	case TrueColor:
	case DirectColor:
		return find_color_rgb(r, g, b);
	default:
		G_fatal_error("Unknown visual class %d\n", use_visual->class);
		return 0;
	}
}

static void get_max_levels(int n_colors, int *rr, int *gg, int *bb)
{
	int r, g, b, i;

	for (i = 0; i * i * i < n_colors; i++)
		;

	for (r = g = b = i; ; )
	{
		if (r * g * b <= n_colors) break;
		b--;
		if (r * g * b <= n_colors) break;
		r--;
		if (r * g * b <= n_colors) break;
		g--;
	}

	*rr = r;
	*gg = g;
	*bb = b;
}

static int get_fewer_levels(int *rr, int *gg, int *bb)
{
	int r = *rr;
	int g = *gg;
	int b = *bb;

	/* 888 -> 887 -> 787 -> 777 -> ... */

	if (r > b)		/* 887 -> 787 */
		r--;
	else
		if (g > b)	/* 787 -> 777 */
			g--;
		else		/* 888 -> 888 */
			b--;

	*rr = r;
	*gg = g;
	*bb = b;

	return r >= 2 && g >= 2 && b >= 2;
}

static int try_get_colors(Colormap cmap, int nr, int ng, int nb)
{
	XColor xcolor;
	int n_pixels;
	int r, g, b;

	xpixels = (unsigned long *) G_realloc(xpixels,
					      nr * ng * nb * sizeof(unsigned long));
	n_pixels = 0;

	xcolor.flags = DoRed | DoGreen | DoBlue;

	for (r = 0; r < nr; r++)
	{
		for (g = 0; g < ng; g++)
		{
			for (b = 0; b < nb; b++)
			{
				xcolor.red   = (unsigned short) (r * 0xFFFF / (nr - 1));
				xcolor.green = (unsigned short) (g * 0xFFFF / (ng - 1));
				xcolor.blue  = (unsigned short) (b * 0xFFFF / (nb - 1));
				if (!XAllocColor(dpy, cmap, &xcolor))
				{
					XFreeColors(dpy, cmap, xpixels, n_pixels, 0);
					return 0;
				}

				xpixels[n_pixels++] = xcolor.pixel;
			}
		}
	}

	return 1;
}

static int try_get_grays(Colormap cmap, int ny)
{
	XColor xcolor;
	int n_pixels;
	int y;

	xpixels = (unsigned long *) G_realloc(xpixels, ny * sizeof(unsigned long));
	n_pixels = 0;

	xcolor.flags = DoRed | DoGreen | DoBlue;

	for (y = 0; y < ny; y++)
	{
		unsigned short v = (unsigned short) (y * 0xFFFF / (ny - 1));
		xcolor.red   = v;
		xcolor.green = v;
		xcolor.blue  = v;
		if (!XAllocColor(dpy, cmap, &xcolor))
		{
			XFreeColors(dpy, cmap, xpixels, n_pixels, 0);
			return y;
		}

		xpixels[n_pixels++] = xcolor.pixel;
	}

	return ny;
}

static Colormap ramp_colormap(void)
{
	int n_colors = use_visual->map_entries;
	Colormap cmap = XCreateColormap(dpy, RootWindow(dpy, scrn),
					use_visual, AllocAll);
	int i;

	for (i = 0; i < n_colors; i++)
	{
		int k = i * 65535 / (n_colors - 1);
		int l = i * 255 / (n_colors - 1);
		XColor xcolor;

		xcolor.flags = DoRed | DoGreen | DoBlue;
		xcolor.blue  = k;
		xcolor.green = k;
		xcolor.red   = k;
		xcolor.pixel = find_color_rgb(l, l, l);

		XStoreColor(dpy, cmap, &xcolor);
	}

	return cmap;
}

Colormap init_color_table(Colormap cmap)
{
	int n_colors = use_visual->map_entries;
	int r, g, b, y, i;

	switch (use_visual->class)
	{
	case GrayScale:
	case PseudoColor:
		truecolor = 0;
		break;
	case StaticGray:
	case StaticColor:
	case TrueColor:
	case DirectColor:
		truecolor = 1;
		break;
	}

	switch (use_visual->class)
	{
	case StaticGray:
	case GrayScale:
		/* determine how many levels of gray we can actually get */
		y = try_get_grays(cmap, n_colors);
		if (y > 2 && y < n_colors)
			y = try_get_grays(cmap, y);
		if (y < 2)
			G_fatal_error("Unable to get sufficient gray shades\n");

		NCOLORS = y;

		for (i = 0; i < 256; i++)
			Gray[i] = i * y / 256;

		break;

	case StaticColor:
	case PseudoColor:
		/* determine how many levels of r, g, and b are possible */
		get_max_levels(n_colors, &r, &g, &b);

		/* now see how many we can actually get */
		while (!try_get_colors(cmap, r, g, b))
			if (!get_fewer_levels(&r, &g, &b))
				G_fatal_error("Unable to get sufficient colors\n");

		NCOLORS = r * g * b;

		for (i = 0; i < 256; i++)
		{
			Red[i] = (i * r / 256) * g * b;
			Grn[i] = (i * g / 256) * b;
			Blu[i] = (i * b / 256);
		}

		break;

	case DirectColor:
		G_warning("Using private colormap for DirectColor visual\n");

		/* free any previously-allocated Colormap */
		if (cmap != DefaultColormap(dpy, scrn))
			XFreeColormap(dpy, cmap);

		/* get shift factors for R,G,B masks */
		NCOLORS = get_rgb_shifts();

		/* create colormap (emulates TrueColor visual) */
		cmap = ramp_colormap();
		break;

	case TrueColor:
		/* get shift factors for R,G,B masks */
		NCOLORS = get_rgb_shifts();
		break;

	default:
		G_fatal_error("Unknown visual class %d\n", use_visual->class);
		break;
	}

	return cmap;
}


int XD_lookup_color(int r, int g, int b)
{
	switch (use_visual->class)
	{
	case StaticGray:
	case GrayScale:
		return Gray[(r + g + b) / 3];
		break;

	case StaticColor:
	case PseudoColor:
		return Red[r] + Grn[g] + Blu[b];
		break;

	case DirectColor:
	case TrueColor:
		return find_color_rgb(r, g, b);
		break;

	default:
		G_fatal_error("Unknown visual class %d\n", use_visual->class);
		return 0;
		break;
	}
}

