/*
 * Copyright (c) 2023 DTB <trinity@trinity.moe>
 * Copyright (c) 2024 Emma Tebibyte <emma@tebibyte.media>
 * SPDX-License-Identifier: AGPL-3.0-or-later
 *
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU Affero 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 Affero General Public License for more
 * details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see https://www.gnu.org/licenses/.
 */

#include <stdio.h> /* fprintf(3), fputs(3), getc(3), putc(3), stdin, stdout,
                    * EOF */
#include <stdlib.h> /* EXIT_FAILURE */
#include <unistd.h> /* getopt(3) */
#include <sysexits.h> /* EX_OK, EX_USAGE */

int usage(char *s) {
	fprintf(stderr, "Usage: %s [-et]\n", s);
	return EX_USAGE;
}

int main(int argc, char *argv[]) {
	int c;
	char showend;
	char showtab;

	showend = 0;
	showtab = 0;

	if (argc > 0) {
		while ((c = getopt(argc, argv, "et")) != -1) {
			switch (c){
				case 'e': showend = 1; break;
				case 't': showtab = 1; break;
				default:  return usage(argv[0]);
			}
		}
	}

	if (argc > optind) { return usage(argv[0]); }

	while ((c = getc(stdin)) != EOF) {
		if ((c & 0x80) != 0) { fputs("M-", stdout); }

		switch (c ^ 0b10000000) {
			case 0x7f: fputs("^?", stdout); break;
			case '\n': if (showend) { putc('$', stdout); }
			default:
				if (c >= ' ' || c == '\n' || (!showtab && c == '\t')) {
					putc(c, stdout);
				} else {
					fprintf(stdout, "^%c", c + '@');
				}
		}
	}

	return EX_OK;
}