/*
 * Icon generation helpers for slide puzzle game
 * Copyright © 2022-2023 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 <string.h>

#include "colour.h"
#include "icon.h"

#define MIN(a, b) ((a) < (b) ? (a) : (b))

#define primary(c) (((c) >> 8*COLOUR_PRIMARY) & 0xff)
#define dark(c)    (((c) >> 8*COLOUR_DARK) & 0xff)
#define light(c)   (((c) >> 8*COLOUR_LIGHT) & 0xff)

static void format_row(unsigned char *row, unsigned long c, unsigned s,
                       unsigned y, unsigned w, unsigned h)
{
	memset(row, dark(c), w);
	memset(row, primary(c), y+s < h ? w-s : 0);
	memset(row, light(c), y >= s ? MIN(s, h-y) : w-y);
}

static void format_row2(unsigned char *row, unsigned long c, unsigned s,
                        unsigned y, unsigned w, unsigned h, unsigned stride)
{
	row += stride*y;
	if (y > s && y+s < h) {
		if (stride)
			memcpy(row, row-stride, w);
	} else {
		format_row(row, c, s, y, w, h);
	}
}

/*
 * The 16x16 icon is drawn with 1px shadow, 6x6 tiles, with 1 pixel cropped
 * off all the edge tiles.
 */
void icon_tile16(unsigned char *icon, unsigned long c, int tile_x, int tile_y)
{
	unsigned char row[6];
	unsigned y, w;

	icon += 16*(11u*tile_y / 2) + (11u*tile_x / 2);

	w = 5+(tile_x&1u);
	for (y = !tile_y; y < 6-(tile_y==2); y++) {
		format_row2(row, c, 1, y, 6, 6, 0);
		memcpy(&icon[16*(y-!tile_y)], &row[!tile_x], w);
	}
}

/*
 * The 24x24 icon is drawn with 1px shadow and 8x8 tiles.
 */
void icon_tile24(unsigned char *icon, unsigned long c, int tile_x, int tile_y)
{
	unsigned y;

	icon += 8*(24u*tile_y + tile_x);

	for (y = 0; y < 8; y++) {
		format_row2(icon, c, 1, y, 8, 8, 24);
	}
}

/*
 * The 32x32 icon is drawn with 1px shadow with slightly uneven tiles on
 * an 11-10-11 pixel grid.
 */
void icon_tile32(unsigned char *icon, unsigned long c, int tile_x, int tile_y)
{
	unsigned y, w, h;

	icon += 32*(10u*tile_y + !!tile_y) + (10u*tile_x + !!tile_x);

	w = 10u + (tile_x != 1);
	h = 10u + (tile_y != 1);
	for (y = 0; y < h; y++) {
		format_row2(icon, c, 1, y, w, h, 32);
	}
}

/*
 * The 48x48 icon is drawn with 2px shadow and 16x16 tiles.
 */
void icon_tile48(unsigned char *icon, unsigned long c, int tile_x, int tile_y)
{
	unsigned y;

	icon += 16*(48u*tile_y + tile_x);

	for (y = 0; y < 16; y++) {
		format_row2(icon, c, 2, y, 16, 16, 48);
	}
}