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/*
* UNG's Not GNU
*
* Copyright (c) 2011-2019, Jakob Kaivo <jkk@ung.org>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#define _XOPEN_SOURCE 700
#include <locale.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#define MONTHWIDTH (20) /* 7 two-digit days + spacing */
#define MONTHHEIGHT (8) /* labels + max 6 weeks */
#define COLUMNS (3) /* arbitrary, but looks decent */
#define COLUMNSEP " " /* arbitrary, but looks decent */
/* FIXME: Sep 1752 cuts off after the 27th */
static char displaymonth[COLUMNS][MONTHHEIGHT][MONTHWIDTH+2];
static int daysin(int year, int month)
{
int mdays[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
if (month == 1 && ((year % 4 == 0 && year % 400 == 0)
|| (year % 4 == 0 && year % 100 != 0))) {
return 29;
}
return mdays[month];
}
static int dow(int y, int m, int d)
{
int t[] = { 0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4 };
int shift = 0;
/* Julian dates prior to 1752-09-14 (1752-09-02 is the day before) */
if (y < 1752 || (y == 1752 && m < 9) || (y == 1752 && m == 9 && d < 14)) {
shift = 3;
}
y -= m < 3;
return ((y + (y / 4) - (y / 100) + (y / 400) + t[m - 1] + d) - shift) % 7;
}
static char *center(char *s, size_t n)
{
char centered[n+1];
size_t len = strlen(s);
size_t lpad = (n - len) / 2;
memset(centered, ' ', n);
strcpy(centered + lpad, s);
centered[lpad + len] = ' ';
centered[n] = '\0';
return strcpy(s, centered);
}
static int cal_week(char *buf, int year, int month, int week)
{
int first = dow(year, month, 1);
int start = (week * 7) - first;
int chars = 0;
if (start < 0) {
start = 0;
}
int days = daysin(year, month - 1);
if (week == 0) {
for (int day = 0; day < first; day++) {
chars += sprintf(buf + chars, " ");
}
}
for (int day = start + 1; day < start + 8; day++) {
int shift = 0;
/* Julian dates prior to 1752-09-14 (1752-09-02 is the day before) */
if (year == 1752 && month == 9 && day > 2) {
shift = 11;
}
if (day + shift > days) {
return chars;
}
chars += snprintf(buf + chars, MONTHWIDTH+1-chars, "%2d%s", day + shift, dow(year, month, day) == 6 ? "" : " ");
if (dow(year, month, day) == 6) {
return chars;
}
}
return 0;
}
void genmonth(struct tm *tm, int withyear)
{
strftime(displaymonth[tm->tm_mon % COLUMNS][0], MONTHWIDTH,
withyear ? "%B %Y" : "%B", tm);
center(displaymonth[tm->tm_mon % COLUMNS][0], MONTHWIDTH);
char *header = "Su Mo Tu We Th Fr Sa";
strcpy(displaymonth[tm->tm_mon % COLUMNS][1], header);
for (int i = 0; i < MONTHHEIGHT-2; i++) {
memset(displaymonth[tm->tm_mon % COLUMNS][i+2], ' ',
MONTHWIDTH);
cal_week(displaymonth[tm->tm_mon % COLUMNS][i+2],
tm->tm_year + 1900, tm->tm_mon + 1, i);
displaymonth[tm->tm_mon % COLUMNS][i+2][strlen(displaymonth[tm->tm_mon % COLUMNS][i+2])] = ' ';
displaymonth[tm->tm_mon % COLUMNS][i+2][MONTHWIDTH] = '\0';
}
}
int main(int argc, char *argv[])
{
setlocale(LC_ALL, "");
while (getopt(argc, argv, "") != -1) {
return 1;
}
time_t now = time(NULL);
struct tm *tm = localtime(&now);
tm->tm_mday = 1;
if (argc > optind + 2) {
fprintf(stderr, "cal: too many operands\n");
return 1;
}
if (argc > optind) {
char *year = argv[argc - 1];
tm->tm_year = atoi(year) - 1900;
if (tm->tm_year > 9999-1900 || tm->tm_year < 1-1900) {
fprintf(stderr, "cal: invalid year %s\n", year);
return 1;
}
}
if (argc > optind + 1) {
char *month = argv[optind];
tm->tm_mon = atoi(month) - 1;
if (tm->tm_mon > 11 || tm->tm_mon < 0) {
fprintf(stderr, "cal: invalid month %s\n", month);
return 1;
}
}
if (argc != optind + 1) {
genmonth(tm, 1);
for (int i = 0; i < MONTHHEIGHT; i++) {
puts(displaymonth[tm->tm_mon % COLUMNS][i]);
}
return 0;
}
char year[MONTHWIDTH * COLUMNS + (sizeof(COLUMNSEP) - 1) * (COLUMNS - 1)] = {0};
strftime(year, sizeof(year), "%Y", tm);
printf("%s\n\n", center(year, sizeof(year)));
tm->tm_mon = 0;
while (tm->tm_mon < 12) {
for (int row = 0; row < MONTHHEIGHT; row++) {
for (int col = 0; col < COLUMNS; col++) {
if (row == 0) {
genmonth(tm, 0);
tm->tm_mon++;
}
printf("%s%s", displaymonth[col][row],
col == 2 ? "\n" : COLUMNSEP);
}
}
}
return 0;
}
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