/*
 * Copyright (c) 2023 YAC
 * SPDX-License-Identifier: AGPL-3.0-or-later
 *
 * This file is part of YAC coreutils.
 *
 * YAC coreutils 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.
 * 
 * YAC coreutils 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 <errno.h>
#include <fcntl.h>
#include <sysexits.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

int main(int argc, char *argv[]) {
	int i = 1;
	bool u = false;

	char *usage_text = "(-u) [file...]";
	int buf_size = strlen(argv[0]) + strlen("Usage: ") + strlen(usage_text) + 3;
	char *usage = calloc(buf_size, buf_size);

	if ((
		snprintf(usage, buf_size, "Usage: %s (-u) [file...]\n", argv[0])
	) < 0 ) {}

	int opt;

	while ((opt = getopt(argc, argv, "u")) != -1) {
		switch(opt) {
			/*
			 * From cat(1p):
			 *
			 * -u        Write bytes from the input file to the standard output
			 *           without delay as each is read.
			 */
			case 'u':
				i = 2;
				u = true;
				break;
			default:
				break;
		}
	}

	FILE *file;

	for (; i <= (argc - 1); i++) {
	  /*
		 * From cat(1p):
		 *
		 * file      A pathname of an input file. If no file operands are
		 *           specified, the standard input shall be used. If a file is
		 *           '-', the cat utility shall read from the standard input at
		 *           that point in the sequence. The cat utility shall not close
		 *           and reopen standard input when it is referenced in this way,
		 *           but shall accept multiple occurrences of '-' as a file
		 *           operand.
		 */
		printf("argv[%d]: %s\n", i, argv[i]);
		if (argv[i] == "-" || u && (argc - 1) == 1 || !u && argc == 1) {
			file = fdopen(0, "r");
		} else if ((file = fopen(argv[i], "r")) == NULL) {
			// TODO: Add error handling
			fputs(usage, stderr);
			return EX_NOINPUT;
		}

		int byte = 0;

		if (u) {
			while (byte != EOF) {
				byte = fgetc(file);
				putchar(byte);
			}
		} else {
			char *buf = calloc(1, 4096);
			while (byte != EOF) {
				byte = fgetc(file);
				fputc(byte, fdopen(1, "r"));
			}
		}
		if (fclose(file) == -1) {
			fprintf(stderr, "%s: %s: Error closing file.\n", argv[0], argv[i]);
			return EX_OSERR;
		}
	}

	return EX_OK;
}