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/*
* Copyright (C) 2021 P. J. McDermott
*
* This file is part of @
*
* @ 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.
*
* @ 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 @. If not, see <http://www.gnu.org/licenses/>.
*/
#define _XOPEN_SOURCE
#include <ctype.h>
#include <errno.h>
#include <limits.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include "datetime.h"
static const char *DATETIME_FMTS_[] = {
#include "datetime-formats.c"
NULL
};
static char *
datetime_concat_args(int argc, const char *argv[])
{
int buf_l;
int i;
char *buf;
int buf_i;
int j;
buf_l = 0;
for (i = 0; i < argc; ++i) {
buf_l += strlen(argv[i]) + 1;
}
buf = calloc(buf_l, sizeof(*buf));
if (buf == NULL) {
fprintf(stderr, "Failed to allocate buffer: %s\n",
strerror(errno));
return NULL;
}
buf_i = 0;
for (i = 0; i < argc; ++i) {
for (j = 0; argv[i][j] != '\0'; ++j) {
buf[buf_i++] = argv[i][j];
}
buf[buf_i++] = ' ';
}
buf[--buf_i] = '\0';
return buf;
}
int
datetime_parse(int argc, const char *argv[], struct tm *arg_tm)
{
char *buf;
int i;
char *end;
time_t arg_sec;
time_t now_sec;
struct tm *now_tm;
buf = datetime_concat_args(argc, argv);
if (buf == NULL) {
return -1;
}
arg_tm->tm_mday = INT_MIN; /* Sentinel */
arg_tm->tm_sec = 0; /* Default */
for (i = 0; DATETIME_FMTS_[i] != NULL; ++i) {
/* printf("%s =~ %s\n", buf, DATETIME_FMTS_[i]); */
end = strptime(buf, DATETIME_FMTS_[i], arg_tm);
if (end != NULL && *end == '\0') {
goto found;
}
}
free(buf);
fprintf(stderr, "Unknown date format\n");
return -1;
found:
/* TODO: Support %a-only dates and optional years */
if (arg_tm->tm_mday == INT_MIN) {
/* No date specified; try today. */
now_sec = time(NULL);
now_tm = localtime(&now_sec);
arg_tm->tm_year = now_tm->tm_year;
arg_tm->tm_mon = now_tm->tm_mon;
arg_tm->tm_mday = now_tm->tm_mday;
arg_sec = mktime(arg_tm);
if (arg_sec <= mktime(now_tm)) {
/* Specified time already happened today; use tomorrow.
* Adding the number of seconds in a day is a shortcut
* that ignores leap seconds. One better method would
* be to increment tm_mday % days in tm_mon, etc. */
arg_sec += 60 * 60 * 24;
now_tm = localtime(&arg_sec);
arg_tm->tm_year = now_tm->tm_year;
arg_tm->tm_mon = now_tm->tm_mon;
arg_tm->tm_mday = now_tm->tm_mday;
}
}
free(buf);
return 0;
}
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