#include <stdlib.h>
#include <string.h>
#include <err.h>

#include <xkbcommon/xkbcommon.h>

#define ARRAY_SIZE(a) (sizeof (a) / sizeof ((a)[0]))

/* Offset between evdev keycodes (where KEY_ESCAPE is 1), and the evdev XKB
 * keycode set (where ESC is 9). */
#define EVDEV_OFFSET 8

int main(int argc, char **argv)
{
	struct xkb_context *ctx;

	ctx = xkb_context_new(XKB_CONTEXT_NO_FLAGS);
	if (!ctx)
		errx(EXIT_FAILURE, "xkb_context_new failed");

	struct xkb_rule_names names = {
		.rules = "evdev",
		.model = "pc105",
		.layout = "us,ru",
		.variant = NULL,
		.options = "grp:lctrl_toggle"
	};

	struct xkb_keymap *keymap;

	keymap = xkb_keymap_new_from_names(ctx, &names, XKB_KEYMAP_COMPILE_NO_FLAGS);
	if (!keymap)
		errx(EXIT_FAILURE, "xkb_keymap_new_from_names failed");

	xkb_mod_index_t num_mods = xkb_keymap_num_mods(keymap);

	for (xkb_keycode_t keycode = 1; keycode < 255; keycode++) {
		xkb_keycode_t evdev_keycode = keycode + EVDEV_OFFSET;
		xkb_layout_index_t num_layouts = xkb_keymap_num_layouts_for_key(keymap, evdev_keycode);

		printf("keycode %3d =", keycode);

		for (xkb_layout_index_t layout = 0; layout < num_layouts; layout++) {
			xkb_level_index_t num_levels = xkb_keymap_num_levels_for_key(keymap, evdev_keycode, layout);

			printf(" | {%s}", xkb_keymap_layout_get_name(keymap, layout));

			for (xkb_level_index_t level = 0; level < num_levels; level++) {
				xkb_mod_mask_t masks[100];
				size_t num_masks;
				const xkb_keysym_t *syms;
				int num_syms;

				memset(masks, 0, sizeof(masks));

				num_masks = xkb_keymap_key_get_mods_for_level(keymap, evdev_keycode, layout, level, masks, ARRAY_SIZE(masks));
				num_syms  = xkb_keymap_key_get_syms_by_level(keymap, evdev_keycode, layout, level, &syms);

				for (int i = 0; i < num_syms; i++) {
					xkb_keysym_t sym = syms[i];

					for (size_t m = 0; m < num_masks; m++) {
						xkb_mod_mask_t mask = masks[m];

						char s[255];
						int ret;

						ret = xkb_keysym_get_name(sym, s, sizeof(s));

						if (ret < 0 || (size_t) ret >= sizeof(s))
							errx(EXIT_FAILURE, "Failed to get name of keysym");

						xkb_mod_index_t num_mods = xkb_keymap_num_mods(keymap);

						printf(" (");

						if (!mask)
							printf("Plain");

						int delim = 0;
						for (xkb_mod_index_t mod = 0; mod < num_mods; mod++) {
							if ((mask & (1 << mod)) == 0)
								continue;

							printf("%s%s",
									(delim ? " " : ""),
									xkb_keymap_mod_get_name(keymap, mod));

							delim = 1;
						}

						printf(") %s,", s);
					}
				}
			}
		}
		printf("\n");
	}

	return EXIT_SUCCESS;
}