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

#define TABLE_SIZE 65536

static char *map_names[] = {
	"plain", "shift", "ctrl", "altgr", "shift_ctrl",
	"altgr_ctrl", "alt", "shift_alt", "ctrl_alt", NULL
};

static char *def_map = "us";
static char *def_ext = ".map";
static char *prog;
static int table[TABLE_SIZE];

struct hexbuf {
	int ct;
	unsigned int buf[1024];
};

struct map {
	struct hexbuf maps[9];
};

static struct map kbd;
static struct map def;

static void usage(void)
{
	fprintf(stderr, "usage: %s [ -p old_code=new_code ] ...\n"
	    "%*s[path]default_layout[.map] ] "
	    "[path]kbd_layout[.map]\n", prog, (int)strlen(prog) + 8, "");
	exit(1);
}

static void hexify(struct hexbuf *hb, char *p)
{
	while (*p) {
		char *n;
		while (*p && isspace(*p))
			p++;
		if (!*p)
			return;
		if (strncmp(p, "0x", 2)) {
			fprintf(stderr, "%s: bad format.\n", prog);
			exit(1);
		}
		n = p + 2;
		p = strchr(p, ',');
		if (p != NULL)
			*p++ = 0;
		if (sscanf(n, "%x", &hb->buf[hb->ct++]) != 1) {
			fprintf(stderr, "%s: bad format.\n", prog);
			exit(1);
		}
	}
}

static int which_map(char *p)
{
	int i;
	for (i = 0; i < 9; i++) {
		if (strcmp(p, map_names[i]) == 0)
			return i;
	}
	fprintf(stderr, "%s: bad map name '%s'.\n", prog, p);
	exit(1);
}

static void load_map(struct map *m, char *map)
{
	int empty;
	char *map_ext;
	char buf[1024];
	FILE *file;
	struct hexbuf *current;

	if (map == NULL)
		map = def_map;
	if (strchr(map, '.'))
		map_ext = "";
	else
		map_ext = def_ext;

	snprintf(buf, 1024, "loadkeys -m \"%s%s\"", map, map_ext);

	file = popen(buf, "r");
	if (file == NULL) {
		perror("loadkeys");
		exit(1);
	}

	current = NULL;
	empty = 1;

	while (fgets(buf, 1024, file) != NULL) {
		char *dp = buf;
		if (strncmp(dp, "static ", 7) == 0)
			dp += 7;
		if (strncmp(dp, "u_short ", 8) == 0) {
			if (current) {
				fprintf(stderr,
				    "%s: active at beginning of map.\n",
				    prog);
				exit(1);
			} else {
				char *ep = strchr(dp + 8, '_');
				*ep = 0;
				current = &m->maps[which_map(dp + 8)];
				continue;
			}
		}
		if (strncmp(buf, "};", 2) == 0) {
			current = NULL;
		}
		if (current == NULL)
			continue;
		hexify(current, buf);
		empty = 0;
	}
	pclose(file);
	if (empty) {
		fprintf(stderr, "%s: Keymap is empty\n", prog);
		exit(1);
	}
}

static void build_table(char *maps[])
{
	int set = 0;
	int i = 0, j;
	static unsigned int tmp[9 * 256];

	for (i = 0; maps[i] != NULL; i++) {
		struct hexbuf *hb = &def.maps[i];
		int code = set;
		for (j = 0; j < 256; j++) {
			if (tmp[code] == 0)
				tmp[code] = hb->buf[j];
			code++;
		}
		set += 256;
	}
	set = 0;

	i = 0;
	for (i = 0; maps[i] != NULL; i++) {
		struct hexbuf *hb = &kbd.maps[i];
		int code = set;
		for (j = 0; j < 256; j++) {
			if (table[tmp[code]] == 0)
				table[tmp[code]] = hb->buf[j];
			code++;
		}
		set += 256;
	}
	table[0] = 0;
}

int main(int argc, char *argv[])
{
	int i;
	prog = argv[0];
	argv++;
	/*
	 *      Load user set keyvals
	 */
	while (argv[0] && strcmp(argv[0], "-p") == 0) {
		int o, n;
		argv++;
		if (argv[0] == NULL
		    || sscanf(argv[0], "%d=%d", &o, &n) != 2) usage();
		if (o < TABLE_SIZE)
			table[o] = n;
		argv++;
	}

	if (argv[0] == NULL)
		usage();
	load_map(&def, argv[1] ? argv[0] : NULL);
	load_map(&kbd, argv[1] ? argv[1] : argv[0]);

	build_table(map_names);
	for (i = 0; i < 256; i++) {
		printf("%c", table[i] ? table[i] : i);
	}
	return 0;
}