/*
 * _NET_WM_ICON helpers for slide puzzle game
 * Copyright © 2022 Nick Bowler
 *
 * 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 3 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, see <https://www.gnu.org/licenses/>.
 */

#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#if !X_DISPLAY_MISSING
#  include <X11/Intrinsic.h>
#  include <X11/Xatom.h>
#endif
#include "ewmhicon.h"
#include "colour.h"

static unsigned long scale16to8(unsigned x)
{
	return x*0xfful / 0xffff;
}

static unsigned long wm_pixel(const XColor *c)
{
	return 0xff000000
	     | scale16to8(c->red) << 16
	     | scale16to8(c->green) << 8
	     | scale16to8(c->blue);
}

static void format_row(unsigned long *row, const XColor *c,
                       unsigned s, unsigned y, unsigned w, unsigned h)
{
	unsigned x;

	for (x = 0; x < w; x++) {
		row[x] = wm_pixel(&c[COLOUR_PRIMARY]);
		if (x < s || y < s)
			row[x] = wm_pixel(&c[COLOUR_LIGHT]);
		if ((x+s >= w && x+y >= w) || (y+s >= h && x+y >= h))
			row[x] = wm_pixel(&c[COLOUR_DARK]);
	}
}

/*
 * The 16x16 icon is drawn with 1px shadow, 6x6 tiles, with 1 pixel cropped off
 * all the edge tiles
 */
void ewmh_tile16(unsigned long *icon, const XColor *c, int tile_x, int tile_y)
{
	int out_x, out_y, out_w, y;
	unsigned long row[6];

	out_x = tile_x * 11 / 2;
	out_y = tile_y * 11 / 2;
	out_w = (5 + (tile_x == 1)) * sizeof row[0];

	for (y = 0+(tile_y == 0); y < 6-(tile_y == 2); y++) {
		format_row(row, c, 1, y, 6, 6);
		memcpy(&icon[16 * out_y++ + out_x], &row[tile_x == 0], out_w);
	}
}

/*
 * The 24x24 icon is drawn with 1px shadow and 8x8 tiles.
 */
void ewmh_tile24(unsigned long *icon, const XColor *c, int tile_x, int tile_y)
{
	int out_x, out_y, y;
	unsigned long row[8];

	out_x = tile_x * 8;
	out_y = tile_y * 8;

	for (y = 0; y < 8; y++) {
		format_row(row, c, 1, y, 8, 8);
		memcpy(&icon[24 * out_y++ + out_x], row, sizeof row);
	}
}

/*
 * The 32x32 icon is drawn with 1px shadow with slightly uneven tiles on
 * an 11-10-11 pixel grid.
 */
void ewmh_tile32(unsigned long *icon, const XColor *c, int tile_x, int tile_y)
{
	int out_x, out_y, out_w, out_h, y;
	unsigned long row[11];

	out_x = 10*tile_x + (tile_x > 0);
	out_y = 10*tile_y + (tile_y > 0);
	out_w = 10 + (tile_x != 1);
	out_h = 10 + (tile_y != 1);

	for (y = 0; y < out_h; y++) {
		format_row(row, c, 1, y, out_w, out_h);
		memcpy(&icon[32 * out_y++ + out_x], row, out_w * sizeof row[0]);
	}
}

/*
 * The 48x48 icon is drawn with 2px shadow and 16x16 tiles.
 */
void ewmh_tile48(unsigned long *icon, const XColor *c, int tile_x, int tile_y)
{
	int out_x, out_y, y;
	unsigned long row[16];

	out_x = tile_x * 16;
	out_y = tile_y * 16;

	for (y = 0; y < 16; y++) {
		format_row(row, c, 2, y, 16, 16);
		memcpy(&icon[48 * out_y++ + out_x], row, sizeof row);
	}
}

void *ewmh_icon_alloc(unsigned long **sizes)
{
	unsigned long *buf;

	buf = calloc(sizeof *buf, EWMH_ICON_NELEM);
	if (buf) {
		sizes[ICON_16x16] = buf;
		*sizes[ICON_16x16]++ = 16;
		*sizes[ICON_16x16]++ = 16;

		sizes[ICON_24x24] = sizes[ICON_16x16] + 16*16;
		*sizes[ICON_24x24]++ = 24;
		*sizes[ICON_24x24]++ = 24;

		sizes[ICON_32x32] = sizes[ICON_24x24] + 24*24;
		*sizes[ICON_32x32]++ = 32;
		*sizes[ICON_32x32]++ = 32;

		sizes[ICON_48x48] = sizes[ICON_32x32] + 32*32;
		*sizes[ICON_48x48]++ = 48;
		*sizes[ICON_48x48]++ = 48;
	}

	return buf;
}

#if !X_DISPLAY_MISSING

/*
 * EWMH-supporting window managers that handle _NET_WM_ICON add this atom to
 * the _NET_SUPPORTED list on the root window.  Look for that and return 1
 * if it is found, or 0 otherwise.
 */
int ewmh_probe_wm_icon(Widget shell)
{
	Display *display = XtDisplay(shell);
	Screen *screen = XtScreen(shell);
	Window root = RootWindowOfScreen(screen);
	Atom net_supported, net_wm_icon, type;

	unsigned long offset = 0, i, nitems, bytes_after, *props;
	unsigned char *prop_return;
	int format;

	net_wm_icon = XInternAtom(display, "_NET_WM_ICON", 0);
	net_supported = XInternAtom(display, "_NET_SUPPORTED", 0);
	do {
		XGetWindowProperty(display, root, net_supported, offset, 10,
		                            0, XA_ATOM, &type, &format,
		                            &nitems, &bytes_after,
		                            &prop_return);

		if (format != 32 || type != XA_ATOM)
			break;
		offset += nitems;

		props = (void *)prop_return;
		for (i = 0; i < nitems; i++) {
			if (props[i] == net_wm_icon) {
				return 1;
			}
		}
	} while (nitems > 0 && bytes_after > 0);

	return 0;
}

#endif